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Canon 6D what should I expect!?


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Ive been a bit fed up recently as Ive not been able to use my main set up for a while but lets be honest its been pretty cloudy! I have managed to get out a couple of times with my travel set up but since upgrading from my Astro modified 600D to a 6D I feel I'm going backwards with my data not forwards. Attached is a DSS stack from last night during finally a clear night!. Canon 6D with Pentax Takumar SMC 28mm - 1hr 15mins of 90 sec subs at f4 iso 1600 in half decent bortle 4 skies, stacked with Bias and Darks.

I would have expected better so just seeing if I'm missing something!? User error, stacking error etc, if any one feels the stack should be better than this in terms of how the stack seems with no processing and how the data processes for the data gathered and what it produces. I have to admit I find this kind of data difficult to process, its probably not helped by the lack of flats! I used to use filters with my 600d and that helped, i feel everything is just get's washed out with out filtration! I think some haze has ruined this data aswell!

Also, I tried stacking with and with out calibration frames and the stack appears exactly the same, should this be?

4thJan28mmOrionCaliFrames.TIF

Edited by Rustang
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It is actually very good with exception of:

1. stars - that is due to lens and sensor size. Edge stars are really astigmatic

2. lack of flats

If you start to stretch it - you start to get glimpse of Orion molecular cloud complex:

image.png.b37227acbbe7c04ecab735f6d4b38670.png

With proper flats - this image can be properly stretched and will reveal much.

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Posted (edited)
11 minutes ago, vlaiv said:

It is actually very good with exception of:

1. stars - that is due to lens and sensor size. Edge stars are really astigmatic

2. lack of flats

If you start to stretch it - you start to get glimpse of Orion molecular cloud complex:

image.png.b37227acbbe7c04ecab735f6d4b38670.png

With proper flats - this image can be properly stretched and will reveal much.

I was hoping it would be something like that. I know the lens isant the best but I can only afford cheap right now. Il look to get some flats done. Is it about what you would expect then with the above info mentioned!? Also, as said, should a stack with Darks and bias look the same as a stack with just lights!? 

Edited by Rustang
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1 minute ago, Rustang said:

I was hoping it would be something like that. I know the lens isant the best but I can only afford cheap right now. Il look to get some flats done. Should a stack with Darks and bias look the same as a stack with just lights!? 

It turns out that you really should avoid darks with Canon DSLRs. They apparently perform internal dark calibration on each sub (which is good as it avoids temperature issues).

Use bias and flats. Bias should be used instead both darks and dark flats.

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1 minute ago, vlaiv said:

It turns out that you really should avoid darks with Canon DSLRs. They apparently perform internal dark calibration on each sub (which is good as it avoids temperature issues).

Use bias and flats. Bias should be used instead both darks and dark flats.

Ok thanks, do you feel for the above info that the stack is looking about what it should be then!? Just keep going and use flats and bias? I really need a lift in this hobby and it's been a while since that's been the case. 

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Don't need darks with the 6D. It has low noise and very low thermal noise. I used to take temperature controlled darks (peltier cool box) and found they did very little to the end result. As vlaiv has said, just use a master bias for your flats and lights. Dithering also helps. I've had my best results with my 6D on the end of a scope, never had much luck with lenses apart from a Samyang 135. Always used a filter. 

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17 minutes ago, david_taurus83 said:

Don't need darks with the 6D. It has low noise and very low thermal noise. I used to take temperature controlled darks (peltier cool box) and found they did very little to the end result. As vlaiv has said, just use a master bias for your flats and lights. Dithering also helps. I've had my best results with my 6D on the end of a scope, never had much luck with lenses apart from a Samyang 135. Always used a filter. 

I'm regards to filter, is that when you used a lens? If so which did you use? I thought not having any kind of filter would hinder and it seems so! 

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I've got some nice images using my stock Canon 6D, admittedly with some nice Canon glass🙂 No darks, flats or filters, it's a great camera.

Comet 2020F3 NEOWISE, 70-200mm f4L zoom and 1.4x extender, 26x20s, ISO3200. Light polluted NW England.

image.thumb.png.394b39487c2049a2e659dc36b370d99f.png

Cygnus, 100mm f2.8L, 22x120s, ISO1600, Isle of Skye, so cheating😉

image.thumb.png.fa9bc78aa3a7bc52d007e0f569f5e838.png

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2 hours ago, fireballxl5 said:

I've got some nice images using my stock Canon 6D, admittedly with some nice Canon glass🙂 No darks, flats or filters, it's a great camera.

Comet 2020F3 NEOWISE, 70-200mm f4L zoom and 1.4x extender, 26x20s, ISO3200. Light polluted NW England.

image.thumb.png.394b39487c2049a2e659dc36b370d99f.png

Cygnus, 100mm f2.8L, 22x120s, ISO1600, Isle of Skye, so cheating😉

image.thumb.png.fa9bc78aa3a7bc52d007e0f569f5e838.png

Lovely images 🙂

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16 hours ago, Rustang said:

I was hoping it would be something like that. I know the lens isant the best but I can only afford cheap right now. Il look to get some flats done. Is it about what you would expect then with the above info mentioned!? Also, as said, should a stack with Darks and bias look the same as a stack with just lights!? 

Look at some 50mm Canon F1.8, can get one for 50-70 quid second hand. Not got one myself but heard good things about it, and at F1.8 you can collect a lot of data very fast, perfect for few and far between clear nights with British weather :).

16 hours ago, david_taurus83 said:

Very limited for choice with a 6D. Personally I use an Optolong L Pro clip in if using a lens. If using a scope I use my IDAS D2.

Any reason you don't use an IDAS in the lens? Just asking because I had some weird purple and green reflections when using my IDAS in the Samy135mm, but not when using the ZS61. Never found an answer for it, always just assumed the lens was just too fast for it.

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20 minutes ago, Grant93 said:

 

Any reason you don't use an IDAS in the lens? Just asking because I had some weird purple and green reflections when using my IDAS in the Samy135mm, but not when using the ZS61. Never found an answer for it, always just assumed the lens was just too fast for it.

Sorry, should have been more clear. The D2 clip in for Canon 6D was discontinued when I tried to order one, so the closest I could get in terms of bandpass was the L Pro. I have a 2" D2 which I use with my scope.

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18 hours ago, Rustang said:

Takumar SMC 28mm - 1hr 15mins of 90 sec subs at f4 iso 1600

Hi

With the Takumar 28mm, you need to be f8 or smaller. maybe better with 2 panes and the 55mm Takumar which performs well at f5.6.

It seems that the lens isn't square with the sensor. Have a look at this adapter which gives you a bit of wiggle room. On some old Takumars the auto pin bears against the flange causing tilt. A three square file or a flange-less adapter is your friend there. Or simply file off the pin;)

Otherwise, the 6d is a fine low noise camera. It's just a matter of finding something which will cover it. 

Had a go at the vignetting and edge stars in StarTools' lens module, but not much we can do without flat frames.

Cheers and HTH

4thJan28mmOrion.jpg.6de050f438164eeac424a4c95590960e.jpg

Edited by alacant
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Posted (edited)
31 minutes ago, alacant said:

Hi

With the Takumar 28mm, you need to be f8 or smaller. maybe better with 2 panes and the 55mm Takumar which performs well at f5.6.

It seems that the lens isn't square with the sensor. Have a look at this adapter which gives you a bit of wiggle room. On some old Takumars the auto pin bears against the flange causing tilt. A three square file or a flange-less adapter is your friend there. Or simply file off the pin;)

Otherwise, the 6d is a fine low noise camera. It's just a matter of finding something which will cover it. 

Had a go at the vignetting and edge stars in StarTools' lens module, but not much we can do without flat frames.

Cheers and HTH

4thJan28mmOrion.jpg.6de050f438164eeac424a4c95590960e.jpg

Thanks, the lens is a pentax mount but I can look for simular adaptors or do as you say. It performed better on my 600D. Thanks for the advice, it seems you also managed to tame the high thin cloud/haze in the data also!.

Edited by Rustang
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Posted (edited)

Thanks everyone for the advice and help. I think I'm understanding my doubts/frustrations now. The not so great lens choice mostly, light pollution and no filtration, experience and understanding which goes with naive expectations and correct calibration frames. These are things I can work on but affording a decent lens is the most annoying and possibly un-reachable right now. I'm going to hold off buying any other cheaper lens for now. Onwards and upwards, or slightly sideways!

Edited by Rustang
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1 hour ago, Rustang said:

not so great lens choice

If you want affordable, wide and reasonable correction, try the older m42 Takumar 55mm. At f5.6 it will just about do corner to corner over ff. Don't expect telescope quality though.

Cheers

Edited by alacant
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Hi, does using bias frames only deal with defective / hot pixels?

My camera has a few of these, especially when exposing for several minutes. I've tried using a defective pixel map in Astroart, but it doesn't fix them perfectly, still get some faint trails without dithering. Dithering does help, but it's a bit annoying as I'd like to use my 6D with portable mounts without dithering.

 

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Just now, thomasv said:

Hi, does using bias frames only deal with defective / hot pixels?

My camera has a few of these, especially when exposing for several minutes. I've tried using a defective pixel map in Astroart, but it doesn't fix them perfectly, still get some faint trails without dithering. Dithering does help, but it's a bit annoying as I'd like to use my 6D with portable mounts without dithering.

 

No it does not. You do need hot pixel map or dithering and sigma rejection. Could get away with good cosmetic correction algorithm, depending on your working resolution and star FWHM (algorithm needs to distinguish stars from hot pixels).

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Thanks Vlaiv. 

Do people have an opinion whether my camera has too many defective pixels? This is a 1min dark, ISO800, screenshot of the raw file, showing about 1/4 of the frame. Taken at room temperature, no stretching applied.

 

 

Screenshot 2022-01-07 at 15.26.30.png

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46 minutes ago, thomasv said:

Do people have an opinion whether my camera has too many defective pixels? This is a 1min dark, ISO800, screenshot of the raw file, showing about 1/4 of the frame. Taken at room temperature, no stretching applied.

I don't think that is a lot.

If you think about it - even if there is like 100 hot pixels in that image, so about 400 total - your camera has about 20 million of them, and 400 out of 20,000,000 is not a big percentage - it is something like 0.002% :D. I'd call that small percentage.

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Posted (edited)

Out of this Ive got a good understanding now of what I need to do to improve. I have made a start in regards to one area and that's processing. I have downloaded Siril and with the help of Alacant I have produced my first image from that software.

The images below arnt great, what has killed the data is the high thin cloud, or haze that wasnt noticable by eye but is on each sub, it has caused the cloudy looking patches in the final image. The lens defects have also killed it and obviously the lack of data gained but its a promising start and something I look forward to improving on. Time to save for a better lens! 

Thanks again everyone for your help.

 

First image with Siril and PS, second DSS and PS

OrionSiriltest2peg.jpg

TestM42Stretchpeg.jpg

Edited by Rustang
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9 hours ago, Rustang said:

I have downloaded Siril

Yep. Well done. You're on your way now:)

Green? Use Image Proicessing -> Remove Green Noise

It's as easy as that.

Edited by alacant
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