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A few months back, i bought my first mono camera, an Atik 383l+ from Martin @Xsubmariner off here. I hadn't had a chance to give it a whirl until last night.
I thought about getting the 80ED out, but i've been wanting to do some widefield stuff for a while, so i attached an old Tamron 135mm F2.8 vintage M42 lens i picked up last year for next to nothing. The lens needs to be stopped down to F5.6 (perhaps less, i haven't tested though) to produce acceptable stars in broadband, but i was hoping it could be used more wide open for Narrowband. I used step-down rings screwed on to the end of the lens hood to bring the aperture down to 37mm, which is about F3.65 (i did briefly try it wide open in Ha, and it wasn't that bad tbh, but i could still make out some comet-shaped stars in a few places so i opted to stop it down a bit to play it safe). I have a TS Optics filter drawer in the optical train, so i can still swap out filters without too much fuss. I still have about 3-4mm of extra backfocus space to spare, but i can already find focus as it is, so i'm not sure if it's that important that i haven't fully used it all up.
Focusing was tough. I was focusing using a Bahtinov mask on Deneb, and i had to use 10s subs (subframes) at 2x2 bin to get bright enough spikes for Bahtinov Grabber to pick up to the spikes ok. Even then, it was showing the focus error moving about quite a bit, even without me touching the focus ring. In the end i just got it as close as i could and went with it.
Conditions were not great. Some clear spells, but there was a lot of cloud passing through. I figures it would be good enough for a test session. The Phd guide graph looked horrific, and was somewhere in the 1-2" range (image scale is 8.4" so not a big deal hopefully). I bodged together a couple of old dovetails to add enough weight to counter-balance the 5Kg counterweight. It just about does. It's not perfect by any means, but hopefully sufficient for this purpose.
I would ideally like to shoot 1200s subs, but couldn't last night due to the constant clouds (Phd lost the guide star countless times). I was about to give up, but persisted and aimed for 600s subs. Glad i did, as i ended up with 6 useable subs, even if a couple were affected by some thin cloud.
Did a quick stack in APP and a 10 min process in PS, just to get a rough idea of what i can expect from this. I used Flats and a couple of Darks just to do a rough calibration. Didn't do any gradient reduction, was in too much of a hurry after packing up last night. Overall i'm fairly pleased with how it performed. I'm obviously not aiming for Samyang 135mm F2 levels of performance here, but for purely NB bi-colour mosaics i think it can do a job.
I've included a picture of the rig below as well, in case anyone's interested.
6 x 600s (1 Hr)
Atik 383l+ 2" Baader Ha 7nm
Tamron Adaptall2 135mm F2.8 (@F3.65)
This has been my project since the start of this season and now I think I´ll just leave it... for now 😉
I started last season (with a longer FL) but didn´t like how my Baader O3 filter matched the Astrodon Ha filter, so now I had to get a 3nm O3 as well.
This is a total of:
60*5 minutes of 3nm Ha
114*5 minutes of 3nm O3.
Shot with a ZWO ASI1600MM-Cool and a Canon 300/4L IS tele lens. The lens suffers from bad star shapes in the corners but I managed to get it decent anyway. Didn´t want to stop it down from f/4 either.
Combined as a semi-RGB (or what to call it) from R=Ha, G=70%O3+30%Ha, B=O3. Processed it as LRGB using a combined Lum from 60% Ha L and 40% O3 L.
I am really happy that I finally feel satisfied with a target! Usually I just get restless and move on when half of the data is collected.
Hope you like it!
I shot this over 6 nights. We had an amazing go of clear nights in a row. Now it's all rain until next week. But while it was clear, I managed two nights per filter on my newest scope. A total of ~ 760 3 min images. I think the total imaging time was 37.8 hours. Shot it through my newest scope the RedCat 51mm. It did well, but could have used a belt focuser. I managed to get one together from Moonlite, but only just after imaging this. The scope was able to hold focus a good bit of the night, but the quality curve looked like a swan dive towards the end as the scope lost focus at the end of the night each night. I got out my old trusty AVX to manage the aiming parts of the setup. Guided by an old Orion SSAG I had lying around and a recently acquired ZWO Mini guide scope since it matches the RedCat so well. But I think I'm going to need to swap out the guide cam for something with smaller pixels. Overall though, it worked. Main camera was ZWO ASI 1600 MMC. I used 5nm Astrodon filters.