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Old 22-11-2017, 07:58 PM
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The_bluester (Paul)
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Quick camera question

So, had a quick crack a couple of weeks ago at using my wife's Nikon D3 (Unmodified) for AP to see how it goes, this is a stack of 42 frames of 10 seconds (From memory) at 6400ISO, unguided. A quick and dirty result here as I am not after comment on the framing, focus, composition, vignetting, processing, the obvious internal reflection artifact or anything like that, I just have a question below.

What I am curious about is the banding that is evident as soon as you stretch the data, this is visible in all the subs. The EOS350D I bought cheaply to have my first crack displays even more obvious banding though it seems less consistent. Is this an affliction I can expect to see with most DSLRs? With guiding I might be able to help stack it out a little by dithering but I see it much the same way as we do undesired traits when breeding ponies "If you don't want it out, don't put it in"
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Old 22-11-2017, 08:14 PM
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I have a Nikon D700 which has the same sensor as the D3 and noticed the same issue on the same target with the same exposure time and same ISO about 6 years ago!!!

I have found that this largely goes away with much longer subs but I also have a feeling it may be a part of the high ISO. I found that at ISO1600 it wasn’t as pronounced. With 60s exposures at ISO 1600 there is still SOME banding but it is largely gone.

As for why? No idea. Just worth mentioning that it is the sensor that is the culprit and not your camera alone.

I haven’t noticed anything in my much newer D7200 however.
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Old 22-11-2017, 11:54 PM
raymo
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It certainly isn't a general DSLR problem; I have never had a trace of it at
any ISO with the Canon 350D and 1100D that I used for AP.
raymo
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Old 23-11-2017, 06:53 AM
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Quote:
Originally Posted by The_bluester View Post
So, had a quick crack a couple of weeks ago at using my wife's Nikon D3 (Unmodified) for AP to see how it goes, this is a stack of 42 frames of 10 seconds (From memory) at 6400ISO, unguided. A quick and dirty result here as I am not after comment on the framing, focus, composition, vignetting, processing, the obvious internal reflection artifact or anything like that, I just have a question below.

What I am curious about is the banding that is evident as soon as you stretch the data, this is visible in all the subs. The EOS350D I bought cheaply to have my first crack displays even more obvious banding though it seems less consistent. Is this an affliction I can expect to see with most DSLRs? With guiding I might be able to help stack it out a little by dithering but I see it much the same way as we do undesired traits when breeding ponies "If you don't want it out, don't put it in"
Hello B,

Sorry to hear of your woes. The issue could certainly be with the sensor or possibly a light leak, which might be being amplified when you stretch/push the exposure in post.

You never know / Longshot - TRY the following.

Put a body cap on the camera. Set the camera to the same exposure settings you were using for your images.... 10 seconds at ISO 6400 and take one image with the eyepiece shutter OPEN and one with the eyepiece shutter CLOSED in a brightly lit room. Now go in to your editor and stretch/push both images the same amount you did previously and compare. Maybe even try a 30 second shutter speed too.

Were the original images taken with the eyepiece shutter OPEN or CLOSED ?

Out of interest post your results if they're conclusive.

Best
JA

Last edited by JA; 23-11-2017 at 07:13 AM.
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Old 23-11-2017, 07:23 AM
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ZeroID (Brent)
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I have 450D and 1200D and never had banding but then I am on a guided mount so longer exposures and less processing push and amplification ( ISO6400) to contend with.
I suspect your high ISO is part of the problem. Normal recommendation is about 800-1600 max. You may have to do more exposures to collect more photons but the result should be more accurate and cleaner.

Also what was the ambient temperature while you were shooting ? The hotter it is the more noise and other issues occur.
How bad is Light Pollution from your imaging site ?
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Old 23-11-2017, 01:04 PM
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Quote:
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I have 450D and 1200D and never had banding but then I am on a guided mount so longer exposures and less processing push and amplification ( ISO6400) to contend with.
I suspect your high ISO is part of the problem. Normal recommendation is about 800-1600 max. You may have to do more exposures to collect more photons but the result should be more accurate and cleaner.

Also what was the ambient temperature while you were shooting ? The hotter it is the more noise and other issues occur.
How bad is Light Pollution from your imaging site ?
Time for guiding methinks to be able to cut the ISO and up the exposure time. Ambient temp was not too bad, somewhere between long sleeve shirts and time for a jacket. LP is also pretty good from home, we are about 50KM away form the outskirts of Melbourne and 6KM out of a smallish town so about as good as it gets without going out to a proper dark sky site.

A fair few of Andy01's images are shot from my place.
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Old 23-11-2017, 03:22 PM
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PixInsight has a script called "CanonBandingReduction". I think the implication is that banding is not uncommon with DSLRs...
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Old 23-11-2017, 03:50 PM
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I have a feeling it is a different kind of banding :/
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Old 23-11-2017, 03:59 PM
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I noticed that script when I looked at PI, quite different effects between the D3 and 350D though.
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Old 23-11-2017, 04:14 PM
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Originally Posted by Atmos View Post
I have a feeling it is a different kind of banding :/
Here's a before and after from applying the script to the original image. I haven't attempted to tweak parameters and see if the result could be better, but the banding is certainly reduced.
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Old 23-11-2017, 06:13 PM
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Certainly seems to help. I am wondering about a combination of reduced ISO, longer exposure time, guiding and dithering between subs to help stack it out as noise. Then processing to help with what is left.
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Old 23-11-2017, 10:33 PM
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I have used four different Nikon DSLRs (D80 / D7000 / D7100 / D750) and never had any similar banding when stretching images.

Pretty sure that banded images I seen from elsewhere have had the banding running vertically - not horizontally.

Chris
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Old 24-11-2017, 02:16 PM
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I think Colin is on the right track. I have seen banding, but this is quite different.
raymo
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Old 24-11-2017, 03:09 PM
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I would presume it is there in all images taken with the camera, but anything involving daylight overwhelms it.

To simplify processing I have been letting the cam do it's own darks by way of long exposure NR (Basically it shoots a light frame, then a corresponding dark which it subtracts form the light frame, the result being what you get)

I will try shooting a separate dark and if I can get the conditions right, flats and stretch them both to see if it shows up there. It is just too regular for me to think readily that it might be anything external to the camera (Noise wise)
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