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Atik383l+ First Light - Quick NAN in Ha with a vintage 135mm lens


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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.

CS.

6 x 600s (1 Hr)

Atik 383l+  2" Baader Ha 7nm

Tamron Adaptall2 135mm F2.8 (@F3.65)

NAN_60mins_QuickCalibration-St-denoise-Quick-Process.thumb.jpg.60be12c666b43b2b8ebba5d964f0bd20.jpg

20200815_125718.thumb.jpg.0f16d7ed978686541fe4a6ebdd90e23f.jpg

Edited by Xiga
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You're a true artist mate. Every single image of yours is full of clarity and detail. I still ca not understand how you manage 20min exposures on this mount. I know balance is of utmost importance but still. Hats off to you mate. 

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Looking good Ciarán and nice to see another KAF8300 getting used for widefield imaging. The 135mm gives a fair bit more FOV than the comparable shot I took with the 180mm lens. 

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Nice image and setup - Sh2-119 on the left gives a nice balance to the North American and Pelican.

I've also found vintage (and budget) M42 prime lenses work pretty well for wide-angle narrowband and give a lot of versatility to an existing telescopic setup.

My theory was that with only one wavelength to contend with in narrowband, there's no need to have expensive glass to counter chromatic aberration.

A few notes which might help in case anyone else tries this type of setup:

+Focussing - With patience, I found I could get good enough focus by hand (I measured FWHM in short test subs and adjusted the lens barrel).
+Guiding - Much easier than normal when imaging at 10''/px (works fine even if windy!)
+Drizzle - Since you'll almost certainly be oversampling compared to seeing, drizzle works well if you have lots of subs
+Aperture - With a Ha filter, wide open on a Carl Zeiss 135mm f/3.5 was pretty much the same as stopped down to f/4 and higher, same thing on a Asahi Pentax Takumar 200mm f/4.
+Mount attachment / Differential Flexure - Since the Atik314L+ doesn't have a screw mount on the bottom of the camera, I used a lens collar ring around the lens (see picture below). Even with a tight fit and extra felt tape around the lens barrel I sometimes got a bit of differential flexure (you can compensate for this to some extent using PHD2 comet tracking mode - not recommended but it worked!). Would be much better to use a side-by-side setup like Ciarán's.

As an example of what's possible, here's 60 x 300secs Ha (Carl Zeiss 135/Atik314L+), drizzled to 5''/px on an infrequently-imaged faint area in Vela (Small and brighter RCW40 top slightly right)

Sam

RCW38.jpg

M42_Atik.JPG

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On 15/08/2020 at 14:40, souls33k3r said:

You're a true artist mate. Every single image of yours is full of clarity and detail. I still ca not understand how you manage 20min exposures on this mount. I know balance is of utmost importance but still. Hats off to you mate. 

Thanks Ahmed, you're too kind. The mount is getting on a bit now, and is in serious need of a re-tune tbh. Even still, it can handle 20+ min exposures just fine. My max imaging scale is only about 1.5" (with the D5300) so nothing too strenuous, which plays a major part obviously. 

On 15/08/2020 at 16:38, Xsubmariner said:

Image looks great and interesting re-configuration of the lens. Nice to see the camera getting used by an expert.

Thanks Martin! Not sure how comfortable i am with being called an 'expert' though, lol. Happy to finally get using the camera i have to say. Thanks again for the sale, and the nice chat we had prior to it. 😀

On 15/08/2020 at 16:53, callisto said:

A very nice image indeed 👍

 

Mark

Cheers Mark. 

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On 15/08/2020 at 19:24, tooth_dr said:

Looking good Ciarán and nice to see another KAF8300 getting used for widefield imaging. The 135mm gives a fair bit more FOV than the comparable shot I took with the 180mm lens. 

Thanks Adam. I've been wanting to do some widefield work (just as a change really) for a while now. Cygnus is a veritable NB treasure-trove, so i'm hoping to start a long-term project of doing a mosaic of this area in either bi-colour, or possibly all 3 channels. I did think of opting for a lens with a slightly longer FL, but with my imaging time being so low these days i thought 135mm might mean i actually have a chance of finishing it before retirement!

On 16/08/2020 at 10:34, Allinthehead said:

Great start Ciarán. Given the quality of your dslr images i'm looking forward to seeing what you can do with the mono.

Thanks Richard. I'm really liking mono i must say, although it's still early days and i've only really done one full NB image. At the moment, for broadband imaging the plan is to use the D5300 for colour and the Atik383 for Lum. I can't see me having the time to capture separate R, G, and B channels, but the jury is out until i actually try it. 

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2 hours ago, SamK said:

Nice image and setup - Sh2-119 on the left gives a nice balance to the North American and Pelican.

I've also found vintage (and budget) M42 prime lenses work pretty well for wide-angle narrowband and give a lot of versatility to an existing telescopic setup.

My theory was that with only one wavelength to contend with in narrowband, there's no need to have expensive glass to counter chromatic aberration.

A few notes which might help in case anyone else tries this type of setup:

+Focussing - With patience, I found I could get good enough focus by hand (I measured FWHM in short test subs and adjusted the lens barrel).
+Guiding - Much easier than normal when imaging at 10''/px (works fine even if windy!)
+Drizzle - Since you'll almost certainly be oversampling compared to seeing, drizzle works well if you have lots of subs
+Aperture - With a Ha filter, wide open on a Carl Zeiss 135mm f/3.5 was pretty much the same as stopped down to f/4 and higher, same thing on a Asahi Pentax Takumar 200mm f/4.
+Mount attachment / Differential Flexure - Since the Atik314L+ doesn't have a screw mount on the bottom of the camera, I used a lens collar ring around the lens (see picture below). Even with a tight fit and extra felt tape around the lens barrel I sometimes got a bit of differential flexure (you can compensate for this to some extent using PHD2 comet tracking mode - not recommended but it worked!). Would be much better to use a side-by-side setup like Ciarán's.

As an example of what's possible, here's 60 x 300secs Ha (Carl Zeiss 135/Atik314L+), drizzled to 5''/px on an infrequently-imaged faint area in Vela (Small and brighter RCW40 top slightly right)

Sam

RCW38.jpg

M42_Atik.JPG

Thanks Sam. Nice to hear from another local member on here 👋

Great to see someone else trying this out too 😀  I agree, for NB work you don't need expensive glass at all, so there's plenty of opportunities for adding a cheap widefield setup, as long as you are prepared to accept it's limitations. 

It's early days yet whether or not i'll suffer from differential flexure. I'm just using an arca-swiss adaptor screwed to the bottom of the camera, but the lens isn't heavy, so fingers-crossed. The whole thing is sitting on a manfrotto 'thingy' (can't remember what it's called, lol), but it allows for about 150 degrees of rotation (in one axis only), which should be enough for most situations i hope. I also was thinking about Drizzling. However, my plan is to only capture about 100 mins (max) per panel in Ha (either 5 x 1200s or 10 x 600s), which won't give me enough subs to take advantage of it. Did your stars look significantly better after you drizzled? I'm currently at 8.4" and i was a little worried beforehand that they might come out a bit blocky, but i think they look decent enough. Not the best of course, but good enough for a big mosaic, where the focus will be on large-scale nebulosity. 

Nice image btw 😎

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Hi Ciarán

With a 60 image stack, drizzle definitely improved stars and brought out a bit more detail out in the nebula (below is Drizzle at 5''/px vs Standard at 10''/px enlarged in Photoshop). I found about 20 images would normally be required to make drizzle work well. I'd guess the main drawback in say 10 images for drizzle is that you'd get a lot more noise than a standard stack and that you'd want to be more careful to get dither working between frames (in PHD).

I think you'll be fine with differential flexure (my setup was substantially more botchy than yours). If you do get a problem, flex is a lot less of a problem with objects nearer the zenith! (when the camera is hanging vertically down)

DrizzleExample.gif

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5 hours ago, SamK said:

Hi Ciarán

With a 60 image stack, drizzle definitely improved stars and brought out a bit more detail out in the nebula (below is Drizzle at 5''/px vs Standard at 10''/px enlarged in Photoshop). I found about 20 images would normally be required to make drizzle work well. I'd guess the main drawback in say 10 images for drizzle is that you'd get a lot more noise than a standard stack and that you'd want to be more careful to get dither working between frames (in PHD).

I think you'll be fine with differential flexure (my setup was substantially more botchy than yours). If you do get a problem, flex is a lot less of a problem with objects nearer the zenith! (when the camera is hanging vertically down)

DrizzleExample.gif

Thanks Sam. The drizzle is definitely making a difference for you. Good to know that 20 subs is around what it takes. 

I'll probably have to forego it myself though. With the 8300 chip being quite noisy, I need to do fewer longer subs, rather than a higher number of shorter ones. I could of course just shoot more subs, but I'm going to have to be pretty strict on limiting the exposure per panel, to have any chance of finishing the mosaic. 

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