My Astronomy and Astrophotography Stuff

Okay, I'm a complete astronomy and astrophotography amateur, just starting out on this adventure. I'll be posting images here and keeping notes so that I can remember what I've tried, what worked, and what didn't. I'm also the kind of person who has to try something and fail several times before it sinks in—before I really understand it. So, some of what you're about to read is probably full of details you don't care about, while the rest is the distilled version—the series of steps I undertake in order to capture interesting objects in the night sky using a digital camera. What I won't bore you with are the seven attempts to capture the Andromeda Galaxy—or even find it with my telescope, before I managed to get something that looks like a galaxy to show up in an image. I definitely credit some of my equipment with the modest success I've had so far with astrophotography. I have a nice DSLR, a full-frame Nikon D750—which is a pretty badass camera in anyone's hands, day or night. After several months of research I bought a William Optics GT81 refractor telescope (81mm aperture, f/5.9). Again, as far as small apochromatic refractors go, this is a pretty nice telescope. UPDATE: I have an additional scope, an Astro-Tech AT6RC Ritchey-Chrétien, and I upgraded mounts to an Orion Atlas EQ-G / EQ6 a year ago. I'm located in coastal New Hampshire, which is a pretty solid 4 on the Bortle Dark-Sky Scale--so some decent viewing just from my backyard, with an exceptionally clear night every now and then, especially in the middle of winter. (What's sad is that we were probably 3 - 4 about ten years ago).


October 4, 2017
Astrophotography with a full moon! I switched to narrowband imaging a few days ago, which has the advantage of limiting the light to a very narrow range, and not really being affected by the light of the sun reflected off the big smiling face of our moon. The requirements are far stricter than color or LRGB imaging in terms of exposure times (10 - 30 minute exposures are typical), which in turn require far tighter alignment for the mount and guiding system. I have three narrowband filters--Ha (hydrogen alpha) OIII (oxygen) and SII (sulfur), all with 6nm bandpass. For these images below I'm only imaging with the Ha filter and the Atik 414EX monochrome CCD camera. Image info: top-left: IC 1848 Soul Nebula (the center portion), bottom-left: IC 1369a Elephant Trunk Nebula, right: NGC 281 Pacman Nebula. 4 x 20 minute (1200 second) subs stacked in DSS.

October 2, 2017
I love this early autumn weather! Here's a 20 minute hydrogen alpha exposure/sub of IC 1805, the Heart Nebula, a diffuse nebula in Cassiopeia. FoV: 1.05 × 0.79° (William Optics GT-81, Atik 414Ex CCD, ZWO ASI120MM guide camera with WO 50mm guide scope, Astronomik Ha 6nm filter).

I will post my actual setup for this one soon--mainly because I want to lock down my portable gear for reference when setting up in the field. What amazed me tonight was the ability to get pretty clean 20-minute subframes with the new iOptron CEM25P mount, leveled, pointed toward the NCP, and a quick polar align. And all of this on the back deck, which isn't the most stable platform around. (There is some star elongation at the top right and bottom left corners, which I'm attributing to the image train and focuser sag. It's slight, but it's there. My next large-ish purchase for the GT-81 is a Moonlite focuser, which will significantly improve the rigidity of the system).

I have to say I am really impressed by the CEM25P mount (the latest iteration of the ZEQ25 from iOptron), and I was expecting quite a bit of precision given that the company pretty much guarantees a low periodic error (< ± 10 arc seconds). But to have this come through without even trying...well, that makes me happy.

September 23, 2017
What the backyard looked like last night. Sort of an astronomy campout under the stars. It was a pretty clear night. I hope you had clear skies wherever you were last night! (Nikon D3100, 18mm, 13 sec. exp. ISO 1600 - I used my son's camera for these shots because mine was hooked up with the AstroTech scope)

Here's one from last night's astro shoot: M42 - Orion Nebula (Yes, my favorite diffuse nebula). This time of year Orion doesn't start appearing over the horizon until the early morning hours. My Exposures started around 2am and ended around 5am. (Nikon D750, AstroTech AT6RC, William Optics field flattener/ 0.8x reducer; 162 light frames stacked in DSS, 140 dark frames).

Daytime shots of my two setups for Saturday night! Left: William Optics GT-81 (81mm, 478mm FL) with Atik 414EX monochrome CCD, Atik Filter Wheel (EFW2 with LRGB Ha O3 S2 Clear DarkFrame filters), William Optics 50mm guide scope with ZWO AS120 guide camera, all on an Orion Atlas EQ-G mount. Right: Astro-Tech AT6RC Ritchey-Chrétien telescope, Nikon D750 fullframe DSLR, on an iOptron CEM25P mount.

And another shot from last Saturday night--of the Orion Nebula (M42) and De Mairan's Nebula (M43). This was the view from my other scope, William Optics GT-81 with the Atik 414EX monochrome CCD camera--which is just going to pick up a lot more of that good old ionized interstellar hydrogen.

September 4, 2017
Nearly a full moon tonight, and here are some shots of our lunar neighbor from a batch I've taken tonight. AstroTech AT6RC Ritchey–Chrétien telescope, QHY5-III178 CMOS camera. Stacking in Registax. Some pretty decent detailing here, even though it was tough to focus with the haze and moisture in the air--that problematic atmospheric distortion.

August 21, 2017
My contribution to the 2017 Solar Eclipse craziness. I shot nearly 200GBs of video and still images with a QHY5III178 CCD camera, Nikon 300mm lens, Seymour Solar filters.

I did manage to pick up some decent sun spots on all the filtered images:

Solar eclipse and moon composite shot:

Here's the simple setup I used for these solar shots: QHY5III178 CCD camera, Geoptik Adaptor for Nikon lenses, Nikon 70-300mm lens, Seymour Solar filter. I used SharpCap under Windows 10 to capture frames. And before you ask I'll say, yes, I am using dew heater strips to hold on the solar filter, which is sized for 4.1" diameter scopes (like the William Optics GT-81). And yes, that isn't very safe if I was looking directly through the lens, but since I was doing all of this from the shady comfort of my garage...well, that's okay then, right? Sometimes you just have to rig something up to take some pictures.

July 24, 2017
I'm down with the LMC--let me hear you say Large Magellanic Cloud. I took some wide field images of a small portion of the LMC, centered on the Dragon's Head Nebula (NGC2035), that colorful stretch of star-forming cloudiness in the middle of the pic. Astro specs: 8 stacked 300 sec exposures, Takahashi SKY90 APO, SBIG ST2000 XMC camera, Paramount PME.

Now, before you go thinking that I've teleported to the southern hemisphere, which is where you have to be to see our nebulous galactic neighbor, the Large Magellanic Cloud, I assure you I haven't. I have merely bought a tiny slice of observatory time on some fantastic hardware that happens to be located at the Siding Spring Observatory, New South Wales, Australia.

I will also tell you that I can fly from here to Australia seven or eight times--first class--for what that equipment setup costs. It's so much easier pretending to be there under the stars near Coonabarabran, using some totally badass astronomical gear. And it's easy, and inexpensive. Besides, it's pouring rain here, and I miss seeing the sky. Wait, I don't have to justify my imaginary stargazing trip to Australia to you! Go check it out yourself: (The observatory in Spain is lovely as well).

A portion of the Large Magellanic Cloud.

August 26, 2016
So, Clear Outside says it's supposed to be clear enough to shoot stars, nebulas, galaxies. I missed a couple really nice nights last week, but was just too busy at work to think about setting up and sitting outside in the middle of the night.

Going with a simple setup tonight--just a scope, camera, and computer (no guider, barlow, focuser, etc). I was out in the backyard at lunch--see pics below. I'm just leveling the Orion Atlas, and I'll be shooting with the ZWO ASI120S-MM (monochrome CCD), through the WO x0.8 field flattener and my William Optics GT-81 APO. I won't be using any filters--RGBL or anything else. My goal tonight is to play around with Nebulosity from Stark Labs, shoot a bunch frames of M31, maybe a couple other targets, and see how it goes. I'll post pics if they're worth posting!

Tonight's setup:

I think it always takes a night or two of tinkering to get back into the groove with new equipment. I've been using the Astro-Tech RC6 for the last eight or nine months, and coming back to the William Optics refractor took more time than I had anticipated, having to make tiny adjustments everywhere, the finder was out of calibration, having to re-learn the back-focus requirements of this scope, it just took too much time last night.

August 27, 2016
I'm in the middle of processing a batch of shots from the narrow window of night sky the clouds allowed me--and thought I'd post a "where is Andromeda Galaxy" pic. (If you can find Cassiopeia--The big W shaped constellation, then you can find Andromeda). I had both the William Optics and my Nikon D750 on the Orion Atlas, shooting 30 and 60 second exposures with the telescope, and shooting wide angle shots--60 to 240 second exposures with the Nikon. On a clear night with dark skies, you can see the galaxy as an oblong cloudy area a couple stars up from Mirach. My DSLR managed to pick it up in this shot.

Central section of M31, Andromeda Galaxy, 42 stacked 30 second exposures with the ZWO ASI120S-MM (monochrome CCD) and my William Optics GT-81 APO. Pretty impressed with this little camera. Andromeda was low on the horizon during this session.

September 9, 2016
The Ring Nebula (M57) in color this time (Not a very good shot--had some focusing issues, but there it is). I set up the scopes and new camera (Atik 414EX) with filter wheel (Baader LRGB filters) last night. There was a good four hour gap of clear sky between two banks of clouds, and I managed to catch the Ring Nebula, a planetary nebula in the constellation Lyra--see pics for the stacked LRGB shots, equipment setup, charts. This is a new setup for me, with the William Optics GT-81 piggybacking on the Astro-Tech RC6. I'm using the WO as my finder and viewing scope. I have a new monochrome CCD camera, an ATIK 414EX with the ATIK filter wheel and a set of Baader Planetarium filters (Luminance, Red, Blue, Green) to capture images for each channel. I had some issues with drift and focusing (every time the filter shifted to the next slot it moved the focus a bit). This was also my first time out under the stars using EQMOD with the Atlas mount, and I have to say, it's the only way to go!

How do you find M57?

September 13, 2016
A nice night for looking at a beautiful nearly-full moon, and not a complete waste of time shooting the opposite side of the sky. I set up around 6pm, did my rough polar alignment as soon as I could see Polaris, and then 30 minutes later--with a darkening sky, used the QHY Polemaster cam and app to nail alignment down. With guiding and slewing, I was on M101 by 8:30 PM, and shooting the luminance shots (19 or 20 of them) soon after. At that point the moon was still mostly in the east. But even with a pretty bright glow, I managed to capture almost eighty shots of the Pinwheel Galaxy (M101), which is a little over 20 million lightyears away, in the Ursa Major constellation (Big Dipper). It's a little ways north of the tail star (Alkaid) of the Big Dipper. A nice bonus in this shot is NGC5477, a dwarf galaxy in the M101 Group--that's the little fuzzy cloud in the center at the top. Equipment: William Optics GT-81 (Guiding with WO 50mm scope and ZWO ASI120MM), Imaging train: 2" extension tube, Atik EFW2 filter wheel with Baader LRGB filters, Atik 414EX monochrome CCD camera. Mount: Orion Atlas EQ-G, Software: EQMOD, Cartes du Ciel, Atik Artemis, PHD2. Stacking in DSS, with stretching/post proc in CC.

Here's my setup for the shot above:

September 22, 2016
Last night I ran an experiment with M33, the Triangulum Galaxy, to prove that you don't have to have ridiculously high-end equipment or observatory-grade telescopes, mounts, and polar alignment in order to capture many of the most beautiful deep space objects--galaxies, nebulae, star clusters, and more. I chose M33 because it's bright, and at around 3 million lightyears away, it's nearby. The Triangulum Galaxy is in the constellation Triangulum, the smallest member of a local group of galaxies that includes our own Milky Way and Andromeda (M31). The shot below isn't that great, but that wasn't my goal. I just wanted to see what would show up with a low exposure time, high volume set of images--with no dark frames. I captured M33 with an Atik 414EX Monochrome CCD camera (not a cheap camera, but go with me here for a moment--because it's not about the camera. It can be any number of reasonably good cameras--CCD, CMOS, DSLRs, probably even my iPhone). The experiment wasn't primarily about the camera. It wasn't about having a nice refractor telescope on a fairly high-end mount. It wasn't about autoguiding and plate solving. It was about shooting 5 second exposures of the same target (M33) and stacking them. The key is to shoot a lot of them. In this one case--my first experiment with this method--I shot almost 700 frames at 5 seconds a piece. I used Atik Artemis Capture software that came with my Atik camera, but I will also be trying out SharpCap and other free and amazingly powerful astrophotography software out there (Just to warn Mac and Linux fans: most of it is written for Windows). I stacked all the frames in Deep Sky Stacker (also free), and then did some typical post processing (stretching, etc.) in Photoshop CC. I only shot light frames--no flats, darks, any other bias frames. I want to shoot two or three times the exposures next time--maybe 1000 or 2000 shots, with a variety of targets, not just bright galaxies. Just so you know I took this idea from Albéric's posts on the QHY forums. Check out the amazing DSO shots, some of them 3000 stacked 2.5 second exposures.

And now with more contrast...

Atmospheric turbulence and the moon - Nikon D750 - Sept. 19, 2016
I shot some test video of the moon to show the distortion of the atmosphere. The sun's light reflecting off the lunar surface has to travel the distance to the earth, and then go through miles of the earth's atmosphere before it reaches the telescope and camera sensor. The shifting focus in this set of frames is atmospheric turbulence--view in Full Screen to get a better look.

Atmospheric turbulence info:

September 24, 2016
The Witch's Broom (NGC 6960) is a prominent part of the Veil Nebula in the constellation Cygnus--about 1400 lightyears away. (This is what I was doing last night). Veil is a vast remnant of a supernova--and by vast I mean the entire Veil Nebula covers the same area in our sky as about 36 full moons. The problem is it's very faint, and not really observable without a telescope and camera--or X-ray astronomy, if you're into that sort of thing. Some notes on this particular stack: I'm still experimenting with low-exposure/high-volumes, 542 3-second exposures and 101 dark frames stacked in DSS, no filters, William Optics GT-81, WO .8x Field Flattener/Reducer, Atik 414EX Monochrome CCD camera (cooled), Orion Atlas mount--no guiding, just pretty accurate polar alignment. Stretching and post processing in PS (I had to darken the star field because it was overpowering the nebula in this one! Damn there are a lot of stars in this universe.)

Here's my setup for the shot above--with some details on the image train:

September 24, 2016
Let's call this the Great Lakes Region of the North America Nebula (NGC 7000, Caldwell 20), named that because it somewhat resembles the continent. This is another big nebula in the constellation Cygnus. Top right to middle is sort of where Chicago would be in this nebulous North America, and just above that dark break in the clouds at the bottom right is where we would find Houston, and where the Gulf begins. (Source for NGC 7000 image: Another short-exposure set: 2157 3-second exposures, 100 dark frames with the Atik 414ex (cooled).

September 25, 2016
I'm always taking pictures of someone else's galaxy, so last night I turned the camera toward our own--the Milky Way. 90 stacked 20 second exposures, Nikon D750 24mm ISO 800.

October 7, 2016
I took 120 LRGB shots of the Pleiades (M45, "Seven Sisters") last night, while I was waiting for the Horsehead Nebula to show up. At this point in the year the constellation Orion isn't completely above the horizon until midnight. William Optics GT-81, .8x Reducer, Atik 414ex monochrome CCD camera, 30 frames, 30 second exposures for each color (LRGB), stacked in DSS.

October 7, 2016
The dark nebula, Barnard 33, "Horsehead Nebula" in the constellation Orion, with the reflection nebula NGC 2023 below and to the left, and the Flame Nebula (NGC 2024) taking up most of the left side. The big star above the Flame is Alnitak, a blue supergiant. Alnitak is the leftmost star in Orion's Belt. 120 30-second exposures stacked in DSS, William Optics GT-81, Atik 414ex.


Here's a single luminosity frame for the horsehead nebula, and it's barely there--besides the stars, it's basically the ridge running horizontally in the hydrogen range that can be picked up in 30 seconds, with the dust that makes up the Horsehead standing out against it. The Flame Nebula is lit up a bit better. What makes the Horsehead Nebula difficult to shoot (or sometimes find) is I have to keep track of what the scope and camera are capturing without being able to see much of anything. I'm shooting in prime focus and everything is rotated 180°, so I have to remember that Alnitak is on the right in the captured image, but on the left when viewed from earth. If I've calculated correctly, I'm capturing 3.46 arcseconds/pixel, and with the Flame shoved over to the right, I should have enough pixels for the Horsehead to appear somewhere near the middle of the shot. I sometimes take test shots--after alignment, focusing, etc., and for this part of the sky there's no question, I have to take one and play with brightness and linear stretching to see if I'm in the right neighborhood. I think that moment when I see a hint of a nebula appear in the pixels is one of the reasons I'm out in the cold and condensation in the middle of the night. Another is after all the shots are taken and I stack them together to see how beautiful the night sky can be when you take enough pictures of it--in this case, 120 exposures, 30 seconds each, it's 4 hours, one hour for each filter (Luminosity, Red, Green, Blue). Stacking, in the simplest terms, is the process of algorithmically combining multiple images by calculating the values of all pixels through the depth of the stack and determining the combined light and dark values for a composite image. 120 frames combined into one can bring out the faint details, the nebulosity, and depending on the filter, the things humans can't see (infrared) or can barely see, wavelengths that are at the edge of the visible range, like Hydrogen alpha, which is way out at 656.28nm. The camera also has a lot to do with what's picked up, and the Atik 414ex monochrome CCD with TEC can capture things no DSLR can.

October 12, 2016
It's a waxing gibbous moon sort of night out there. I've taken five sets of 500 - 1000 frames of the moon tonight. Here's one with the Tycho Crater very prominent at the bottom right. Top right is part of Mare Nubium--the "sea of clouds". This is my first real test of the QHY5-III CCD camera, using SharpCap to do the captures. 826 frames stacked in Registax 6. Equip: QHY5-III178, 2x Barlow, AstroTech 6" f/9 Ritchey-Chrétien.

Another one from the night's moon shots--and hey, that's where Apollo 12 landed.

October 14, 2016
Gamma Cassiopeiae (γ Cas), top right, is the center star in the constellation Cassiopeia, the star that makes up the middle point of the W shape. The nebulous areas are IC 59 (sometimes called the Gamma Cas Nebula) and IC 63. Specs: WO GT-81, Atik414ex, Luminance filter, 2 hours 16 minutes total exposure time.

October 19, 2016
Spiders in the scope. I have been getting diffraction spikes on large stars shot with my William Optics GT-81 APO refractor. Without secondary mirrors (or any mirrors at all for that matter) and no support vanes crossing the visible path of light through the scope. Refractors typically don't have any diffraction artifacts. A little research turned up some interesting info: diffraction spikes in refractors isn't unusual, and can be caused by the slightest intrusion into the cone, but most responses on the forums amounted to clean the lens, make sure there isn't a hair or anything in the path--something as tiny as a hair will cause spikes. I took my GT-81 apart, down to the main tube and lenses...and found a few very fine threads of spider web. They were difficult to remove a camera lens brush to knock them down, and then the vacuum to try to pull everything out. I ran a couple quick tests last night and, although there is some improvement, a couple medium sized stars in the frames still have spikes.

On the good side, I did get a couple good stacked shots of M31 (Andromeda Galaxy - LRGBH) and IC5146 (Cocoon Nebula - LUMINANCE):

Andromeda Galaxy (M31), or the heart of it at any rate, with satellite galaxies M32 (bright oblong shape on the right) and M110 (partially visible at the bottom left). I finally got around to stacking the color frames. I stacked the Luminance frames--the "L" in LRGB a week ago, but I also shot Ha frames for this one. (Luminance, Red, Green, Blue, Hydrogen alpha). I also bumped up the vibrance in this one (targeting muted colors) because I really wanted to get some browns in the bands of dust--the "interstellar medium" that forms the dark lanes between groups of stars. I will post pics of my scope and camera setup in the comments. Here are the details: William Optics GT81 APO, Atik 414ex monochrome CCD camera, EFW2 filterwheel with Baader LRGB + Ha filters. Autoguiding with WO 50mm and ZWO ASI120MM camera. No reducer/flattener.

Pretty good for two and a half million lightyears away! On the good side, Andromeda's rather large: 220,000 lightyears in diameter, which is roughly 129,329,800,000,000,000,000 miles across. What is that, 129 quintillion miles across?

Astronomy and astrophotography 2015 and winter 2016:

The Andromeda Galaxy (M31, NGC 224). This has to be my tenth—and most successful—attempt at capturing our galactic neighbor, Andromeda. Setup: Nikon D750, Telescope: William Optics GT81, WO Field Flattener, no filters. 24 stacked frames at 30 sec and 2 x 2 minute exposures. That's a trillion stars right there, whirling around in space, 2.5 million lightyears away.

I'm fairly new at this, but I have a moderate amount of patience, a telescope with various eyepieces, a camera with various fittings, and a motorized equatorial mount good enough to hold the telescope in position and help me point it at the right part of the sky. That's pretty much all you need to find what you're looking for: beauty in the universe, the constellation Orion, the Sea of Tranquility on the moon (where Apollo 11 landed and Neil took one giant leap for mankind). It'll also get you pondering long distances, like "23 million lightyears away" for the Whirlpool Galaxy, and vast quantities of stars condensed into what looks like a relatively small area—the Andromeda Galaxy contains 1 trillion stars. Then you find out Andromeda is actually 220,000 lightyears across. (Everyone knows what a lightyear is, right? Essentially it's the distance light travels in a year—light moves at about 186,000 miles per second, a little under 300,000 kilometers per second. So, you can say the light emanating from the Whirlpool Galaxy and hitting the earth, and then coming through the lens or mirrors in your telescope to be captured by the sensor of your camera, started out from the Whirlpool Galaxy 23 million years ago. For comparison it only takes 1.3 seconds for the reflected sunlight to travel from the moon to the earth, and about 8 minutes for light to travel from our own star, the sun, to reach us. Douglas Adams said is best: Space is big.)

What do you need to get started?

1. Clear skies. A must have. You may find that as soon as you buy a telescope the clouds will roll in, and the atmosphere will thicken to the consistency of a hardy stew. For weeks! If this happens to you—it happened to me—then this is the time (during daylight hours) to align the polar scope on your equatorial mount. Yeah, you read that right, and no, that's not a euphemism. Your telescope mount (otherwise known as a really beefy tripod) may be fine-tuned right of the box. Mine was not (my original CG-5 mount). I built that from several pieces purchased off eBay and

2. Dark sky. Another obvious one, but it's worth pointing out. The darker the better. I'm lucky to live in a relatively unlighted area of the world—New Hampshire. I have to deal with some urban glow from Portsmouth and Hampton Beach, but it isn't a serious problem. I can clearly see the milky way stretching across the sky on a dark, clear night. On the other hand I've seen some amazing deep sky images from astrophotographers shooting from apartment balconies in the middle of Los Angeles. So, you either have to work with the sky you can see, or travel somewhere darker for your astrophotography. (Also, google light pollution filters, and check out one of the many Light Pollution Maps out there, and the Bortle Dark-Sky Scale.)

3. Patience. This could be one of the most important requirements. The first shots you take will look like crap, but think of it like the first pancake on the griddle (You know the first pancake rule?). You will not be able to focus the damn telescope, and don't even get me started on pointing the scope at what you're actually trying to find in a sky full of stars. You will need patience to handle questions like what the f$%k is a German Equatorial Mount, and why do I need one? Why is everything upside down? You will need the combined patience of a jeweler and a tectonic plate to align your telescope mount, polar scope, finder scope, and various other mechanisms and optical devices that will need aligning. (On the good side, once you've aligned things, you're pretty much good to go—that's been my experience so far).

What will you be able to see through an eyepiece or capture with a camera?

With a little time and effort you will see amazing things. You can see just how beautiful our edge of the galaxy (Milky Way) and the surrounding universe is through the eyepiece. What you capture—in individual frames—on your camera may look pretty good (or not, as I have found out), but what you'll see after stacking twenty or eighty or a hundred-and-ten frames together (See Deep Sky Stacker) will simply take your breath away.

I had to get up at 3:15 in the morning (Sept. 16, 2015) to catch this beauty—the Orion Nebula (M42) along with De Mairan's Nebula (M43), Running Man (NGC1977), and various other clusters, stars, and nebulae. Nikon D750, 110 stacked shots, ISO 800, 20 sec exposure, William Optics GT81.

Or closer to home... I shot this while setting up things a few days before the lunar eclipse on Sunday (Sept. 27, 2015)—one of a dozen shots of the moon with the UHC/LPR Filter (NIkon D750, 2x Barlow, UHC/LPR--which stands for Ultra High Contrast/Light Pollution Reduction Filter, William Optics GT81--no field flattener).

The Telescope

I have used other types of telescopes--reflector, Cassegrain (and by "used" I mean looked through, and maybe adjusted the focuser), but I really only have experience with good old refractor scopes, and I'm just getting started with a Ritchey-Chrétien (RC) reflector. If you're going to go with a refractor, definitely get an apochromatic scope--an "Apo", which are typically more expensive. See a good analysis of the refractor types here:

With the William Optics GT81 I've become an even bigger fan of refractors, but you shouldn't let that sway you. You should definitely check out the three main varieties:

  • Refractor (Uses lenses)
  • Reflector (Uses mirrors, e.g., Newtonian, Dobsonian)
  • Compound (Uses mirrors, e.g., catadioptric, Schmidt-Cassegrain, Maksutov-Cassegrain, Ritchey-Chrétien)
Some info on choosing which one is right for you:

The Telescope Mount

If you're planning to get into astrophotography then keep this in mind: the telescope mount may be as important as the telescope. Good discussion on the Alt-Azimuth mount and Equatorial mount here:
Everything you wanted to know about the different kinds of telescope mounts:

My gear for basic astronomy and astrophotography (September, 2015)

  • Telescope (2 inch focuser is what you want)
  • Eyepieces for your scope (2 inch)
  • Motorized Equatorial Mount (you will need to be able to track objects across the sky, due to the Earth's rotation)
  • Finder scope (red dot, or similar. Allows you to pinpoint an object in the sky using a much wider field than your telescope. Can't live without this, unless you plan to shoot the moon and nothing else).
  • CCD or at a minimum a DSLR camera (most decent Nikons or Canons that can shoot RAW will do. Your camera will also have to support interchangeable lenses and manual operations for focus, shutter speed, ISO)
  • "T" mount adapter for your camera (attaches to the camera like a lens)
  • Mirror star diagonal (optional, but it allows you to look through the eyepiece without looking weird. Some varieties also reverse the image for you too.)
  • 2x Barlow Lens (doubles the magnification, optional but nice to have)
  • Field Flattener (optional, expensive, but it cuts down on field curvature. Details here:
  • Flashlight with red lens (allows you to see in the dark without blinding yourself and everyone around you).
  • Remote control for your camera (you want to be able to take 20, 30, 60 second exposures without moving your camera). This can be wireless, wired with a button, or a USB cable so that you can remotely control your camera from your computer.
  • Narrowband Oxygen III Filter, UHC/LPR Filter, and various other filters that you can put in-line with your camera to enhance specific spectral ranges. (Optional) These can enable you to capture color in ranges outside the normal visual range for humans.

Software and other digital tools you'll need

Before or during your astronomical adventures:

Clear Sky Chart shows you how clear and dark the sky is going to be for the next 48 hours. Go to the site, and find your nearest weather location: Another weather forecast site:

Stellarium is a free powerful observatory for your computer. You should also install something similar on your iPhone or Android device--for in-the-field identification.

digiCamControl is a free remote control app for Nikon and Canon DSLR cameras. I use a TetherPro cable for the Nikon (, and it basically allows me to control every aspect of the camera from my computer, including running a series of shots with specified exposure times and ISO settings. Admittedly I use the manual cable remote as well, especially if the plan is to shoot many 30 second exposures.

Tools you will need after you get back to your computer with a pile of images:

Deep Sky Stacker (Free, Windows only) is one of the best image stacking apps out there. Google for "astrophotography image stacking". There are apps available specifically for Mac and Linux as well, but DSS is one of the most widely used. . Stacking makes all the difference. Good stacking software can take eighty images, register them (detect and align all the stars), and merge them in a way that filters out image noise and anomalies, while retaining and developing low-light areas that exist in every frame--think of the swirls and billowing clouds of a nebula. You may not even notice them in an individual image, but stack twenty of them together using some sophisticated algorithms, and you'll be able to bring out the faintest wisps of cloud in a distant nebula. Stacking isn't that difficult to do, but getting the results you want will take time and tinkering. Google Deep Sky Stacker, watch a handful of the really good DSS tutorials on Youtube.

Image processing software. You will need something to open and manipulate RAW images, image conversion (e.g., RAW -> TIFF), image refining (color saturation, contrast, curves, etc.). I use Photoshop for all of these, and I know many use GIMP.

Pics of my telescope and other gear

Image below—this is my setup for shooting the moon, getting as much magnification out of the scope as I can (with the equipment I have). Starting at the left, Nikon D750, Nikon F-mount T-adaper (can't really see this, but it's what attaches the camera to everything else), Celestron 2inch UHC/LPR Filter (attached to the end of the T-adapter, inside the tube), 2inch 2x Barlow Lens, 2inch extension tube, and finally the focuser for the William Optics GT81 refractor. This is all sitting on the Omni XLT CG-4 Equatorial Mount (motorized, with polar alignment scope). Note: this is the exact setup I used to shoot the moon above. (With the barlow and extension, I have a fair amount of back focus. In this case (not shown here) I have added an extender to the GT81's mounting shoe, one of the 12 inch Celestron mounting plates (Celestron Universal Mounting Plate - CG5) so that I can get everything balanced over the declination axis--and weights).

Here's my setup for getting the most magnification—I use this for the moon:

Here's my setup for deep sky photography—star clusters, nebulas, galaxies:

My William Optics GT81:

My William Optics GT81 set up for shooting the Andromeda Galaxy:

And here's the scope and camera actually pointed at Andromeda:

Shot of my equatorial mount:

What to expect on a typical night of stargazing?

The wonder of the universe, beautiful nebulas, galaxies, and star clusters. The moon when it's visible, and various planets wandering around the sky. Meteorites shooting across the sky, and satellites--more than you'd think.

Dew. Dripping off your scope, fogging your lens. Lots of it, depending on the time of year, and where you're located. Several companies sell small heating elements that attach to the telescope, preventing dew from building up. Dew is a hassle, but I've managed to make do with an occasional wipe down with a lens cloth.

A lot more than this... I just haven't finished yet.


Horsehead Nebula (Barnard 33) is just down from the star Alnitak, which is the leftmost star in Orion's Belt. In this shot that's the bright star to the left of the Horsehead Nebula and just up from the Flame Nebula (NGC 2024). The reflection nebula (NGC 2023) is just below and to the left of the horsehead. The bright star at the top left of the shot is the middle star in Orion's Belt, Alnilam.

Wide field view of M51, Whirlpool Galaxy. If you follow the "handle" of the Big Dipper to the end--the last star is Alkaid, you'll find M51 just down from it. In this shot Alkaid is a little ways out of frame at the top. The Whirlpool Galaxy is 23 million lightyears away. (

Wide field view of the Orion Nebula. I didn't use a field flattener when I shot this, and you can really see the stars stretching around the edges.

International Space Station: Got up at 5:30, cloud cover wasn't terrible, and managed to take about 200 shots of the International Space Station . This is just standing in the backyard with the Nikon and 300mm lens. Yeah, I think that's the best shot of the bunch. This thing is really moving--around 17,000 miles per hour, so yeah, I probably should have used a tripod.

Almost a full moon (Sept. 26 2015)

Single shot of the "Super Blood Moon", heading toward a total lunar eclipse. ( Sept. 27/28 2015)

Lunar Eclipse Sequence--Sept. 27/28 2015 (Click for the full-sized version)

I just bought another telescope, an Astro-Tech 6" f/9 Ritchey-Chrétien (an "RC" telescope,–Chrétien_telescope). Of course, the weather for the next five days is cloudy, rainy, with Hurricane Joaquin sweeping in after that.

First shots with the new Astro-Tech 6" f/9 Ritchey-Chrétien--prime focus with the Nikon D750. Aldebaran (α Tau) was above the trees last night around 11PM, and I used it to play around with the focuser, testing out the back-focus on this scope. I took around forty shots of Aldebaran (, which is just down from the Pleides ("Seven Sisters", M45). Aldebaran is a giant star, 44.2 times the diameter of our Sun. ("Aldebaran is classified as a type K5III star, which indicates it is an orange giant star that has moved off the main sequence line of the Hertzsprung–Russell diagram after exhausting the hydrogen at its core") These shots came with some crazy diffraction spikes--the lines radiating from stars, caused by light diffracting around the support vanes of the secondary mirror in the Ritchey-Chrétien, but these show up in most images shot through reflecting telescopes. I get "rays" or a diffusion ring around really bright stars with the William Optics APO, but nothing like this.

Jupiter, Mars, and Venus hanging out with the constellation Leo early this morning, Oct 4, 2015.

I haven't done much with the new telescope--pointed it at Aldebaran the other night, and that's about it. Haven't had time, and I'm fighting a nasty cold. But... I have been thinking about it, and one idea I'm going to test out when I finally do get out under the stars is to see how well an iPhone works as a finder (aligned with the telescope's altitude, azimuth, etc). I have a simple red-dot finder already, and these work pretty well for pin-pointing a spot in the sky, but I'm looking for a way to browse the stars and just stop and match what I can see through the scope with what looks interesting on the screen. The app I'm using is Orion StarSeek 4 in "Compass" mode, which uses the iPhone's accelerometer, GPS, and compass to track objects in the sky with the direction and angle of the phone. (A lot of star gazing apps do this too, but I also like StarSeek's ability to zoom in and out like Stellarium).

Pinwheel Galaxy. This is my first attempt at building a separate luminosity layer,
and using the RBG layer for color--which I've really kicked up here.

The moon

Another one of the moon. These last two were taken with the Astro-Tech RC and Nikon D750.

In the middle of a two-minute exposure of the Pleiades (M45, Seven Sisters) and I'm watching this commercial airplane moving across the sky. I'm thinking that guy might show up in the frame...he goes right through the Pleiades in the center--double blips and the solid white line in the shot are the wingtip lights, blinking red is the bottom beacon.

To make matters more difficult it's cold as hell with way too much humidity--dew all over the lenses--to be out for long tonight. I was hoping for a crisp clear one, but...the stars just weren't right. I did get to play around with the autoguiding set up--ZWO ASI120MM-S CCD camera and William Optics 50mm guide scope. I'm using PHD under OSX (handling the autoguiding), and DigiCamControl controlling the Nikon D750 running in Windows7 (in the VM). Autoguiding is a way to keep the telescope mount pinned to a specific piece of the sky--a camera continuously shoots the sky, software uses a selected star to make continuous tiny adjustments to the telescope mount to keep it where you want. In theory it should allow you to take much longer exposures.

January 2, 2016 - Setting up the telescope, guide scope, and mount for tonight's session. I'm using the William Optics GT-81 with a field flattener and the Nikon D750. As you can see I did a terrible job cleaning the snow off the back deck--I made a pathway down to the wood for the dogs, and left everything else--5-6 inches of snow that's now almost solid thanks to the 20-something degrees it dropped to overnight.

January 5, 2016 - I shot my favorite nebula tonight, the Orion Nebula (M42), using the Astro-Tech 6" f/9 Ritchey-Chrétien--prime focus with the Nikon D750, all of it sitting on an Orion Atlas EQ-G mount. 140 stacked frames, 30 second exposures. And I was doing all of this camera and telescope stuff in a nice brisk 15°F/-9.4°C, has to be the coldest night I've been out with a telescope. The sky sure was clear, though.

January 7, 2016 - Telescope and mount setup. If the weather cooperates I'm going to try for M78.

NOTE: I've just started working the following step-by-step guide to setting up the telescope, camera, taking pictures, and post-processing stuff.

I'm going to walk through a typical night's setup, observation, shooting, and post-processing.

Set up the mount and telescope. (If you can leave your mount setup and positioned correctly then you kick ass). Position the mount so that it's facing north, and if you have a polar scope, or a polar alignment tube, line up the polar axis with the celestial pole. If you're in the northern hemisphere the celestial pole is just a little off from the star Polaris. (Google polar alignment to get the details on this). This step is kind of a big deal the first few times. After you get it down, it becomes easy. I only spend a few minutes getting things settled. The first couple times I set everything up at dusk, and just waited for night show up. Now I just gather all my crap in the backyard in the middle of the night and set everything up.

If this is your first night out with a particular telescope then I'd start with an eyepiece before you start in with a camera. Just get the feel of the scope, find a few easily identifiable objects in the sky--Andromeda Galaxy (M31), the moon, the double star cluster in Perseus (NGC869 and NGC884). Get a feel for the telescope's focuser.

If you're ready to take some shots let's add the camera to the setup. I always shoot with what's called "prime focus projection", which means the camera is shooting directly through the telescope--using the telescope as a lens. Another popular way to shoot is called "eyepiece projection" in which the camera is shooting through the eyepiece and then through the telescope.

Put the T-adapter on your camera and, if you're using a remote shutter control with a cable, plug that in. (I usually do this before I go outside). Slide the T-adapter into the telescope's focuser and tighten it. (The T-adapter is usually a simple two-piece mechanism, the bayonet mount for your camera (attach it like you would any lens), and a tube--with or without a field flattener lens--that fits the focuser on your telescope). Most focusers have a tightener ring, or a couple screws that hold the camera in place. (Make sure these are secure. You don't want the camera dropping out of the scope. You also don't want it shifting).

Expect to spend a decent amount of time focusing the camera.

Set up steps (found this in one of the forums, and it's been in my notes for a while)
1. Set the tripod down pointing roughly to celestial north.
2. Level tripod.
3. Screw in mount.
4. Look through polar finder scope and rotate mount in RA axis until the orientation of the Big Dipper and Cassiopeia match what's in the sky.
5. Use the latitude L-bolts and azimuth knobs to bring Polaris into the little circle that sits on the larger circle. Lock the latitude and azimuth bolts/knobs tightly, making sure Polaris doesn't move out of the little circle.
6. Rotate the mount around the RA axis just to make sure that Polaris tracks exactly along the larger circle. This is a double-check to ensure that the polar finder-scope and the mount are aligned and looking in exactly the same direction.

Setup and alignment steps for the Orion Atlas, EQ6, and similar

I don't know if all of these are necessary, but here's what I do:

1. Set up tripod, level it--I use the compass on the iPhone, but a standard bubble level across the three legs works just as well

2. Place the mount and tighten down the AZ bolts on the pillar (that metal bar sticking up from the tripod). I always check the level on the Atlas just to see that the bubble is centered. -- This has changed a bit: I now leave the tripod and pier extension tube outside most of the time (with a cover when not in use). I then bolt the Atlas mount head to the pier as the first part of set up.

3. Add equipment, weights, and balance across both RA and DEC. Loosen the DEC clutch and see if the scope swings left or right--if so, then slide everything up, down, side-to-side until it doesn't. Loosen the RA clutch and adjust weights to balance everything along the right ascension axis. NOTE: I used to use a dual saddle config with the OTA on one and the guide scope (or sometimes my Nikon D750) on the other, but my current set up looks like this: Astro-Tech RC6 with top and bottom dovetail rails (main scope with Atik 414EX CCD & filter wheel for astro-imaging), William Optics GT-81 mounted on AT6RC top rail with 45° diagonal and eyepiece (used for viewing, finding), WO 50mm guide scope with ZWO CCD using the finder/guider mini dovetail bracket on the AT6RC for autoguiding.

4. When you can see Polaris (or σ Octantis in the southern hemisphere), do a rough polar alignment using the polar scope--adjusting AZ and Altitude bolts as needed. (I use the PS Align Pro app, which does a great job of showing me what I should see in polar scope on my particular mount). TIME: around sunset, dark enough to just see Polaris.

5. Refine polar alignment using the QHY PoleMaster camera and app. TIME: mostly dark. The QHY CCD has some minimums with light, with gain and exposure all the way down. It doesn't have to be star-viewing dark, but close to it.

6. With polar alignment done, the next step is to align the mount's GOTO accuracy. Power up the mount (if not already on), and go through the initialization steps: time, long and lat, DST, etc. Select 3 star alignment.

7. Select the first star, and when the Atlas tells you to slew to center the target star, DO NOT use the motorized slewing. Loosen the RA and DEC clutches and manually move the scope to center the first star.

8. Select the second star, and when the Atlas tells you to slew to center the target star, use the motorized slewing to center things. Repeat for third star (if doing 3-star alignment).

9. Escape up a few times to get to the menu and tell the mount to goto your first viewing of the night!

My semi-portable system:

William Optics GT-81 (81mm, 487mm focal length)

William Optics 50mm (200mm FL) guide scope

ZWO ASI120MM-S (mono) guide camera

iOptron CEM25P equatorial mount

Atik 414EX Monochrome CCD camera

Atik EFW2 Filter Wheel (filters: L R G B Ha OIII SII Clear DarkFrame)

- Raspberry Pi 3 64-bit computer
Ubuntu Mate distro with INDI, Ekos, KStars remote
observatory control software for all the hardware
- Shoestring Astronomy FCUSB Focuser Controller
- USB 3 hub (powered)
- GL-AR150 Wifi Router

Thousand Oaks Optical dew heater controller
Dew control heater strips

Deep Sky Stacker Sequence for LRGB files


Select all LRGB FITS files
Select dark files

Register but DO NOT Stack after registration
Pay attention to SCORE

Find Luminance frame with the highest score
Click on LUM image to preview
Right-click on frame and Use as a reference frame

Register checked pictures again (This time with the ref frame)


(Stacking parameters: standard, median, hot pixel detect, auto align, no cosmetic)

Uncheck all (Right side panel)
Select all Dark frames (select first, shift-select the last)
Select all LUM frames (right-click, check)

Save LUM stack

Repeat for each color--RED, GRN, BLU

Open L, R, G, B files in Photoshop for stretching and blending

[OLD] Atik Filter Wheel (EFW2) with Baader Planetarium LRGB filters:
5 HA

Filter Wheel (5 filter Solomark manual)
I mainly use this for moon shots, with the #58 Green and #80a Blue filters, but I also have the UHC and OIII filters in this wheel
5 Green - #58 Green (24% Transmission)
4 Blue - #80A Medium Blue (28% Transmission)

NOTES on blue and green filters:
#58 Green (24% Transmission)
Lunar surface detail
Contrast of blue and red structures on Jupiter, including The Great Red Spot
Melt lines around Martian polar ice caps
Contrast of Saturn's subtle cloud belts

#80A Medium Blue (28% Transmission)
Details of Jupiters cloud belts and Great Red Spot
High clouds and polar caps of Mars
Lunar surface details
Contrast of some comet tails

Field Flattener / Reducer Notes:

I have two reducers:

William Optics APO 0.8x Flattener for GT81 (F6-A)
Lens-to-chip suggested distance: 64.38 mm
Reduces f/6 to f/4.7; f/9 to f/7

2" 0.5x Reducer sold by several companies, GSO/Highpoint
Recommended working distance is 53mm

Camera info:
Atik 414EX Backfocus: 13.5mm

ZWO ASI 120MM Backfocus: 12.5mm

Nikon D750 Backfocus: 46.5mm (Lens flange to sensor, lens flange to film)

QHY5III178 Backfocus: 10mm - 12mm

Nikon Backfocus: 46.5mm

Filter Wheel Info:
Atik EFW2 width: 22mm

Spacing notes:
Nikon D750 + T-Adapter + spacer + WO 0.8x reducer...Scope
Nikon D750 + T-Adapter + M42/M48 Adapter + 0.5x Reducer...Scope

           13.5mm +  22mm +                       10mm +    20mm
Atik 414EX + Atik EFW2 Filter Wheel + spacer + M48-to-M42 Adapter + WO 0.8x reducer...

Edmund Optics spacers
Astrophotography Tutorials on Reducers and spacing: Astrophotography Field Flattener & Focal Reducer Spacing

ATIK 414EX Monochrome CCD Camera Notes: Atik Cameras, in their selecting a camera video, suggests that I should be aiming between 1 and 2 for the following image scale formula. (The Atik 414EX CCD sensor has a pixel size of 6.45µm). Calculating this out with the focal length of my two scopes will give me the number of arc-seconds / pixel. Under 1.0 means I'm over-sampling the image, and I will get large and bloated stars. Undersampling will give me blocky stars. The first time I tried out the 414EX I connected it and the Atik filter wheel right up to the AstroTech, and sure enough, I was looking at frames that looked exactly like the oversampled example below.

    Pixel size (µm)
--------------------------- x 206 = arc-seconds/pixel
Focal Length (mm)

Astro-Tech AT6RC Ritchey-Chrétien Reflector Specifications
Aperture 152mm (6”)
Focal Length 1370mm
Focal Ratio f/9

Atik 414Ex - Monochrome Camera
Pixel Size 6.45 µm
Pixel Array 1392 x 1040

Deep Space Astro camera scope combinations

WO GT81 + Atik414EX (2.78"x2.78" per pixel)
WO GT81 + Atik414EX + 2xBarlow (1.39"x1.39" per pixel)
WO GT81 + Atik414EX + 0.8x Reducer (3.47"x3.47" per pixel)
WO GT81 + Nikon D750 + 0.8x Reducer (2.57"x2.58" per pixel)
WO GT81 + QHY5III178 (1.03"x1.03" per pixel)
WO GT81 + QHY5III178 + 0.8x Reducer (1.29"x1.29" per pixel)

AT6RC + Atik414EX (0.98"x0.98" per pixel)
AT6RC + Atik414EX + 0.8x Reducer (1.23"x1.23" per pixel)
AT6RC + Nikon D750 + 0.8x Reducer (1.14"x1.14" per pixel)

Nikon NIKKOR 180mm f/2.8 + QHY5III178 (2.75"x2.75" per pixel)
Nikon NIKKOR 180mm f/2.8 + Atik414EX (7.38"x7.38" per pixel)
Nikon NIKKOR 180mm f/2.8 + Nikon D750 (6.83"x6.84" per pixel)

AstroTech RC6 with Atik 414EX
6.45 / 1370 x 206 = .9698  (Oversampled image)

AstroTech RC6 + WO 0.8 Field Flattener/Reducer with Atik 414EX
6.45 / 1096 x 206 = 1.2123  (Correctly sampled image)

AstroTech RC6 + WO 0.5 Field Flattener/Reducer with Atik 414EX
6.45 / 685 x 206 = 2.448  (Slightly undersampled image)

William Optics GT-81 (with the 2" extension to handle backfocus")
6.45 / 478mm x 206 = 2.7797  (Slightly undersampled image)

William Optics GT-81 + WO 0.8 Field Flattener/Reducer with Atik 414EX
6.45 / 382.4 x 206 = 3.474  (Undersampled image)

William Optics GT-81 + WO 0.5 Field Flattener/Reducer with Atik 414EX
6.45 / 239 x 206 = 5.559  (Undersampled image)

William Optics GT-81 + 2x Barlow with Atik 414EX
6.45 / 956 x 206 = 1.3898  (Correctly sampled image)

Nikon D750
AstroTech RC6 + 0.5x Field Flattener/Reducer with Nikon D750
5.9 / EFL 685 x 206 = 1.7743  (Correctly sampled image)

AstroTech RC6 + 0.8x Field Flattener/Reducer with Nikon D750
5.9 / EFL 1096 x 206 = 1.108  (Correctly sampled image)

Nikon 300mm Lens with Nikon D750
5.9 / 300 x 206 = 4.051  (Undersampled image)

ZWO ASI120-MM - Monochrome Camera
Pixel Size 3.75 µm
Pixel Array 1280 x 960
Minimum Exposure Time 64µs (0.000064s)
Maximum Exposure Time 1000s

AstroTech RC6 with ZWO ASI120-MM
3.75 / 1370 x 206 = .5238  (Oversampled image)

AstroTech RC6 + WO 0.8 Field Flattener/Reducer with ZWO ASI120-MM
3.75 / 1096 x 206 = .7048  (Oversampled image)

AstroTech RC6 + WO 0.5 Field Flattener/Reducer with ZWO ASI120-MM
3.75 / 685 x 206 = 1.127  (Correctly sampled image)

William Optics GT-81 with ZWO ASI120-MM
3.75 / 478mm x 206 = 1.616  (Correctly sampled image)

William Optics GT-81 + WO 0.8 Field Flattener/Reducer with ZWO ASI120MM
3.75 / 382.4 x 206 = 2.02  (Correctly sampled image)

QHYCCD - QHY5III CMOS USB 3.0 Color Camera
Pixel Size 2.4 µm
Pixel Array 3072 x 2048
50FPS, Planetary/Lunar Camera

AstroTech RC6 with QHY5III-178
2.4 / 1370 x 206 = .3607  (Oversampled for stars and DSOs)

AstroTech RC6 + WO 0.8 Field Flattener/Reducer with QHY5III
2.4 / 1096 x 206 = .4510  (Oversampled for stars and DSOs)

AstroTech RC6 + WO 0.5 Field Flattener/Reducer with QHY5III
2.4 / 685 x 206 = .7217  (Oversampled image)

William Optics GT-81 with QHY5III
2.4 / 478mm x 206 = 1.034  (Correctly sampled image)

William Optics GT-81 + WO 0.8 Field Flattener/Reducer with QHY5III
2.4 / 382.4 x 206 = 1.292  (Correctly sampled image)

Nikon 70-300mm f/4.5-5.6G ED IF AF-S VR Nikkor
Nikon AF-S FX NIKKOR 24-85mm f/3.5-4.5G ED

24 / 3.5 = 6.85mm aperture
85 / 4.5 = 18.8mm aperture
300 / 5.6 = 53.57mm aperture
70 / 4.5 = 15.5mm aperture

Imaging train:
With the Barlow I need the extension in almost every case--the barlow increases focal length, and so the camera sensor needs to be moved back in the train.
2x Barlow --> 2" Extension --> Filter Wheel --> Camera
2x Barlow --> 2" Extension --> WO 0.8 Field Flattener/Reducer --> Filter Wheel --> Camera

Setup Weight

William Optics GT81 - 81 mm f/5.9 FPL53 Apo Refractor, Gold Edition
tube weight 8 lbs. (3.7 kg), tube length 440 mm

Atik 414EX
Weight approx. 400 gr (0.4 kg)

Atik EFW2
Weight: approx. 500 gr (.5 kg, ~.85kg with filters)

William Optics 50mm CCD Guide Scope # M-G50
Tube weight (without eyepiece) = 15.0oz (0.425 kg)

ZWO ASI120MM Monochrome
Camera Weight (lb.)‎: ‎0.22, 100gr

Spacers, Extension tubes
Weight: approx. 1 kg

Total 6.475 kg, 14.27 lbs.

Block Method for Adding Saturation in Photoshop (and any layer-supporting image app)
Three copies of the RGB layer
Layer 1 Luminosity
Layer 2 Soft Light
Layer 3 No change
Merge these three layers. Done.

Other Specs:

Orion Atlas Telescope Mount Extension Tube dimensions: 102mm (4") OD, 3 5/8 ID, 8.4" length

I'm curently using this lens with the QHY5III CCD:
Nikon Lens 70 - 300 (f 4.5 - 5.6)
300 / 5.6 = 53.57mm aperture
70 / 4.5 = 15.5

William Optics GT-81 f/5.9
Focal Length: 478mm
Aperture: 81mm

Notes and Links

Catching the Light by Jerry Lodriguss
DSLR Cameras and Ha Nebulae

Camera settings

Modifying a Nikon D90 for astrophotography

DSLR and Post-processing

Polar Alignment of your Equatorial Mount

iPhone Apps:
PolarAlign (
Orion StarSeek 4 (

Astra Image


ImagesPlus 6.5 Image Processing



Astronomy Tools Actions Set for Adobe Photoshop

Deconvolution in Photoshop

DSLR-LLRGB Style Processing Workflow

Bill Snyder Astrophotography - Some good stuff on Ha, OIII, SII filter uses. Bill posts the images for each band.
Here's his page on his shots of the Wizard Nebula (NGC 7380)

Focal Pointe Observatory - Astrophotography by Bob Franke
Here's his page on his shots of the M42:

Sequence Generator Pro v2.5

APT - "AstroPhotography Tool"

Astrophotography with MacOS

Wilmslow Astro - Useful Formulae (including CCD arc-sec/pixel and Focal Ratio)

Field of View Calculators:
FOV Calculator v2 (beta)
Astronomy & Astro-imaging from East of the Meridian - Imaging Toolbox - FOV calculator
Astronomy Tools - FOV calculator

The Lake County Astronomical Society - Narrowband Imaging

Plate Solving software
PlateSolve 2 from PlaneWave Instruments

AstroTortilla beta
Astrophotography assistant

First evaluation of QHY5III 174 monochrome (uncooled)
A very interesting short exposure process using an uncooled QHY camera. Amazing DSO images, with thousands of 2 - second exposures. What a brilliant idea. I'm going to try this!

Glenn Newell astrophotography videos
Focus and Plate Solving: