M101 using DSLR lens

[Prathab]

First image I'm posting here. M101 shot over 2 nights. Total integration time 4 Hrs 27 Mins from bortle 6 skies. Equipment used: EQ5 pro, SX-H9C camera, Tamron 150-600 lens at 600mm, Orion SSAG and guidescope, no filters. Processing: stacked in DSS, processed in Pixinsight and PS.  I got into AP in Jan this year and have been trying to get decent results without dropping a ton of cash into the hobby. I've been learning post processing with SiriL and photoshop in the past few months, but I'm struggling. So signed up for PI trial and have been poking around with my data. It definitely has helped with some of the frustration I was facing with SiriL, but still not able to get fine details to show up and the colours are messed up too. I'm posting the stacked TIFF file here as well. Please feel free to run it through your processing workflow and post the result here. It will help me enormously to understand if I have to improve on data acquistion or post processing. If you can't tell yet, i'm a total noob 🙂 and open to feedback. Thank you!

 

M101600mmcombostack.tif

Edited April 29, 2021 by Prathab
typo

[mackiedlm]

Hi there,

 

first off let me say I am far from expert, not much more than a beginner myself, so take all that follows with appropriate sceptesism - hopefully the real experts will correct me.

 

I have take a go at your data and produced this

My thoughts on your data;

 

Your stars are not the best - this is a AbberationInspector  mosaic from PI and you can see they are all flared on one side- right across the image. I'm not sure if this is poor guiding or if its optical - tilt maybe? whatever, I think this is the reason we cant get much detail or structure in the galaxy.

Then you have some pretty funky gradients and vignetting and its pretty noisy. Can you tell us, exposure duration, did you calibrate with darks, flats, etc and what was the sky like - moon, high haze ???

On the plus side, the camera is clearly very sensitive and I think if you can resolve the above problems you have a set up that can deliver great images.

I do hope this helps a bit. And, for what its worth, I always find M101 to be a complete pig to capture and process!

 

 

 

 

 

Edited April 29, 2021 by mackiedlm

[Prathab]

1 hour ago, mackiedlm said:

Hi there,

 

first off let me say I am far from expert, not much more than a beginner myself, so take all that follows with appropriate sceptesism - hopefully the real experts will correct me.

 

I have take a go at your data and produced this

My thoughts on your data;

 

Your stars are not the best - this is a AbberationInspector  mosaic from PI and you can see they are all flared on one side- right across the image. I'm not sure if this is poor guiding or if its optical - tilt maybe? whatever, I think this is the reason we cant get much detail or structure in the galaxy.

 

Then you have some pretty funky gradients and vignetting and its pretty noisy. Can you tell us, exposure duration, did you calibrate with darks, flats, etc and what was the sky like - moon, high haze ???

On the plus side, the camera is clearly very sensitive and I think if you can resolve the above problems you have a set up that can deliver great images.

I do hope this helps a bit. And, for what its worth, I always find M101 to be a complete pig to capture and process!

 

 

 

 

 

Thank you for taking a look and the feedback.  These are 3 min subs, attaching one here. This was shot on Apr 21st, so moon was not up till 4:00AM. My guiding is usually around 1-2" RMS and is usually pretty good for 2-3 min subs. No calibration files added on this stack. As a best case scenario, I'm also attaching a more recent 5 min sub of M82 and a stack of 23 lights, 40 flats and 40 bias for comparison. This was also done with exact same setup and the only difference is the calibration files added to the stack and had perfect guiding. Based on your feedback, I feel the lens might be the suspect. This is very helpful, atleast it doesn't look like this is just a PP problem.

L_2021-04-21_22-09-11_Bin1x1_180s__na.fit L_2021-04-25_22-11-36_Bin1x1_300s__na.fit Bodesstack.tif

Edited April 29, 2021 by Prathab

[mackiedlm]

On a very quick look at those, the star shapes are much the same in the 5 min sub compared to the 3 min which suggests this is not a guiding issue. So definitely look at the lens and also make sure there is no tilt.

I also strongly advise using darks in calibration that will help reduce the noise. I dont know ccd's very well (at all actually!), but if this was a cmos, like my own, I'd be saying to drop your exposure down, the 5 mins are showing big bloated stars and very bright noisy background with bad gradients - all suggesting your exposure is too long for those conditions.

Good luck, I look forward to seeing your next images.

[mackiedlm]

BTW @Prathab I think you mean "This was shot on Apr 21st, so moon was not up till 4:00AM" - the moon was bright that night, about 75% I think, and high in Leos head and therefore quite close to your target. This accounts, I think, for a lot of the noise and gradients in your image.  It is very difficult to capture broadband targets with that much moon in play and many imagers (myself included) will not even try. I had been planning to try the owl nebula with a L-enhance filter (narrow band) that night but as there was a high haze, the sky was very bright and the Oiii band tends to let some moonlight leak  I didnt bother.

Edited April 30, 2021 by mackiedlm

[Prathab]

6 hours ago, mackiedlm said:

BTW @Prathab I think you mean "This was shot on Apr 21st, so moon was not up till 4:00AM" - the moon was bright that night, about 75% I think, and high in Leos head and therefore quite close to your target. This accounts, I think, for a lot of the noise and gradients in your image.  It is very difficult to capture broadband targets with that much moon in play and many imagers (myself included) will not even try. I had been planning to try the owl nebula with a L-enhance filter (narrow band) that night but as there was a high haze, the sky was very bright and the Oiii band tends to let some moonlight leak  I didnt bother.

You are right about the moon and possibly one of the reasons for the gradient and noise. This small sony sensor apparently didn't need dark files as it has very little readout noise. But I'll definitely shoot some darks on my next outing. But now that you have pointed out, I can see out of shape stars everywhere 🙂 .  I also realize that the lens racks out of focus often, especially when tracking stuff near the zenith. I probably have to bite the bullet and get a APO scope.  Thank you for your input.