I moved the Moonlite focuser from the William Optics GT81 to the AT6RC scope and spent half an hour getting the focus distance more-or-less dialed in. I'm focusing on a tree line about 1600 feet / .5km away. That transmission pole is almost 500 feet closer to me. I'm using the color imaging train with the ZWO ASI071C and a longpass hydrogen-alpha filter, which is why the test frame has that white-tree IR look. In the images with the setup you can see the color in the trees. It's a beautiful fall day out there, although I don't think it's supposed to be that clear tonight. Just have to wait and see!
According to the William Optics SpaceCat 51 backfocus specs, I have a 59.7 mm backfocus from the flange face of M54->M48 adapter. The SpaceCat has a different configuration from the RedCat. It includes a tilt adjust ring with 54mm threaded facing (Takahashi wide mount 54 mm, 0.75 pitch thread) plus an M54 to M48 (T2) adapter. I think William Optics designed the thickness of the last adapter to avoid changing backfocus specifications across the various cats. And so any configuration I have will work with the original RedCat 51s as well as other breeds--WhiteCat, BlackCat, and K-Astec Limited Edition.
I have two main astro imaging trains, and both come in under 57mm. The color train is a ZWO ASI071MC, 2" filter drawer, Orion Thin Off-axis Guider with QHY5iii178 guide camera. For daytime testing I threw in a 2" hydrogen-alpha longpass filter. My narrowband imaging train consists of a ZWO ASI1600MM-Pro, ZWO EFW (Clear, 6nm Ha, 6nm OIII, 6nm SII, 685nm Near-IR), Orion Thin Off-axis Guider with ZWO ASI120M-mini guide camera.
I set up the iOptron CEM25P this morning, and used SharCap Pro to test the focus for both trains. I'm happy with the results. The color train is a bit worrying because the ZWO ASI071MC has a crazy 17.5mm depth to sensor. I was able to focus on some distant trees, but the SpaceCat's focus ring was only slightly out from infinity. We'll see what my results are with the stars!
The ZWO ASI1600MM-Pro on the narrowband train only has a 6.5mm depth to sensor with the ZWO filterwheel, and I had the focus ring on the cat further out. Should be no problem with DSOs in this case. I may miss having autofocus though.
Some shots from my morning focus testing with the beautifully machined William Optics SpaceCat 51 apochromatic refractor.
I'm pretty sure I got the last one at Highpoint Scientific. I also bought the Cat Saddle/Handle-bar.
Let's take a look at the Space Gray version of the William Optics Cat Saddle/Handle-bar. That is a beautiful piece of hardware.
Last month I picked up an iOptron SkyGuider Pro, because, well who doesn't have one of these best-in-class star trackers? I felt left out. It also gave me an excuse to get the Stronghold Tangent Alt-Az base from AstroShop on AliExpress (https://www.aliexpress.com/item/32822479423.html). I've been looking at images of this one for a while, and in reality it doesn't disappoint. It's a nicely machined piece of equipment, very sturdy, with a 10kg/22lb carrying capacity! I'm using this instead of the very compact light-weight version that comes with the SkyGuider Pro.
Here's my ultra-portable astro setup, with the William Optics ZS61 APO, ZWO ASI071MC cooled color, ZWO ASI120MM-S guide cam, DeepSkyDad AF1 focuser, homemade powerbox (2 x 12v out, 1 x 5v 4 amp out, 1 x dew control out), controlled by a Raspberry Pi 4 4GB running Stellarmate 1.4.2 beta. The SkyGuider Pro has it's own battery for power, and the scope, cameras, focuser only require a single 12v 7-10 amp input. All other cabling and control functions are mounted on the ZS61. I'm using an old Celestron tripod--I tightened the bolts on the legs, and it's definitely sturdy and stable enough for any payload the iOptron can handle.
I'm testing out my color widefield setup with the William Optics ZS61 APO, ZWO ASI071MC cooled color, ZWO ASI120MM-S guide cam, DeepSkyDad AF1 focuser, homemade powerbox (2 x 12v out, 1 x 5v 4 amp out, 1 x dew control out), controlled by a Raspberry Pi 4 4GB running Stellarmate 1.4.2 beta. I ran some test sequences in Ekos and everything appeared to function normally. I am getting an error for the focuser ("...temperature value (!100)"), but the AF1 doesn't support temperature controlled focus adjustment, so not sure if this affects anything. It focuses properly, so I'm choosing to ignore the error for now. And I'm not absolutely sure this is a Raspberry Pi 4 thing, instead of an INDI/Ekos thing on any hardware. And you may have noticed that I'm testing this out (remotely, using Jump Desktop) from my brand new Apple iMac 5k 27" i9/8core with... yes, I ordered it with 8 GB RAM, but I have 64GB on order, and I'll add that myself. (No sense paying $1000 to have someone at Apple do that for me).
What's funny is Dylan O'Donnell on his Star Stuff channel posted about upgrading his iMac and the giant performance improvement with PixInsight--same iMac I just bought, but I haven't used PixInsight processing software. I'm a Photoshop guy from way back in the 90s and version 4. https://youtu.be/J_EsH54XqjE
Tonight I'm testing out the ZWO ASI071 and the AstroTech RC6, with an Off-Axis Guider (QHY5iii178 guide camera binned 2x2). I've never tried this mix together, so we'll see how it goes. At 1350mm focal length this setup has a 0.73/pixel resolution. So, yeah, it's going to be oversampled. And there's also a big old gibbous moon out tonight, and the weather is not planning to cooperate. My hopes are fairly low.
Going to run some manual focus tests on my wide-field narrowband setup, if I can see the stars tonight. I just want to see if I have the backfocus correct for the Nikon f/2.8 180mm lens. I'm using a 2" Optolong 7nm Ha filter with the Atik 414EX mono CCD camera. No guiding with this tonight, but normally I would have the 130mm guide-scope and ZWOASI120MM-S on top of the aluminum camera/lens ring (ZWO 78mm Holder Ring for ASI Cooled Cameras). My hydrogen-alpha filter is in the AstroShop 2" Filter Drawer System with the tripod foot, which just adds more stability to this setup. You may also notice--if you're familiar with the iOptron CEM25P--that I'm using the short counterweight bar with a single weight. I can carry this whole rig around without taking anything apart.
Yesterday I set up for a couple broadband color targets, and went with the Astro-Tech 6" f/9 Ritchey–Chrétien with 1350mm focal length. I paired the RC with the ZWO ASI071MC cooled color camera. And this is the first time I'll be using the DeepSkyDad Autofocuser AF1, which fits perfectly on the stock Crayford focuser--although you can't see it in this shot because I have the focus knobs vertical on the right site of the scope. Not using an OAG with this setup, but going with the William Optics 200mm guide scope and ZWO ASI120MM-S mono camera.
NGC 7023, Iris Nebula is a beautiful reflection nebula in Cepheus, about 1,300 lightyears away.