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Old 06-03-2013, 07:18 PM
swannies1983 (Dan)
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Canon 30D banding

I have been imaging with a modded Canon 30D and would like some advice regarding banding issues at high ISO (1600 in my case). I generally only do 5 min subs but have had recent success pushing 10 mins with my RC8.

My latest attempt is Thor's Helment. I have attached a raw 10 minute sub and a stretched version. They both clearly show large horizontal bands. Dark files don't appear to get rid of them. I have only noticed it as a real problem after imaging for 10 mins @ ISO1600. I thought it was perhaps Ha data but I don't see a lot of Ha regions surrounding the helmet in other pictures.

I know some of the early models do show banding, but generally it's much thinner. Just wondering if what I'm seeing is normal or not?
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Old 06-03-2013, 08:28 PM
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MrB (Simon)
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I see some banding with the 60Da too when I've pushed subs to 10mins or more. I think it's just par for the course with a DSLR?
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Old 06-03-2013, 09:13 PM
DJT (David)
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Do you have a memory card in there? This might seem a bit odd but I have a 30D, had exactly the same issues on longer exposures, which stopped when I removed the card. I use BackYard Eos and download direct to pc without the card in the camera. I believe electric type artifacts get introduced somewhere in the storage process.

I would habitually do 10 to 20 min subs so it was a big issue, now resolved
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Old 06-03-2013, 09:14 PM
swannies1983 (Dan)
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So how do you fix this? Can you process it out? Do you bother imaging at ISO1600 when doing 10min subs?

After looking at some older data, the banding doesn't appear to be much of a problem at ISO800, even with 10min subs so I think I won't bother with imaging at ISO1600 when doing long subs.
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Old 06-03-2013, 09:16 PM
DJT (David)
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So the fix was not to use a memory card. I would image at 400ISO and still have the same problem. No card, no issue.
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Old 06-03-2013, 09:18 PM
swannies1983 (Dan)
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Quote:
Originally Posted by DJT View Post
Do you have a memory card in there? This might seem a bit odd but I have a 30D, had exactly the same issues on longer exposures, which stopped when I removed the card. I use BackYard Eos and download direct to pc without the card in the camera. I believe electric type artifacts get introduced somewhere in the storage process.

I would habitually do 10 to 20 min subs so it was a big issue, now resolved
Yeah, I do have a memory card in. I generally record on both card and PC. The reason is that one of the USB slots is a bit loose so there have been instances when the USB cable disconnected and I lost a sub. So I record to card just in case this happens but I should try and fix the USB slot.

I will give your suggestion a go. I could try this by doing just a dark as the banding is present in them as well. I'll keep you updated. Thanks
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Old 06-03-2013, 09:19 PM
DJT (David)
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Originally Posted by swannies1983 View Post
So how do you fix this? Can you process it out? Do you bother imaging at ISO1600 when doing 10min subs?

After looking at some older data, the banding doesn't appear to be much of a problem at ISO800, even with 10min subs so I think I won't bother with imaging at ISO1600 when doing long subs.
By the way, I never imaged at 1600. At these temperatures, and with the length of exposure and imaging from Sydney. it just wasnt worth it.

Flow at the moment is ISO 400 (800 for something really faint) 5 to 6 minutes subs and a lot of them.
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Old 06-03-2013, 09:20 PM
swannies1983 (Dan)
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So the fix was not to use a memory card. I would image at 400ISO and still have the same problem. No card, no issue.
My previous reply was to MrB. I didn't see your first post before I posted mine
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Old 06-03-2013, 09:23 PM
swannies1983 (Dan)
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By the way, I never imaged at 1600. At these temperatures, and with the length of exposure and imaging from Sydney. it just wasnt worth it.

Flow at the moment is ISO 400 (800 for something really faint) 5 to 6 minutes subs and a lot of them.
What are you imaging with though?

I'm now imaging with a RC8 so f/8. Thor's Helmet is the faintest object I have imaged. I'm up to 6 hrs of 10 min subs but it needs a lot more. However, the banding is very annoying so I will hopefully be able to salvage the data I have now.
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Old 06-03-2013, 09:48 PM
DJT (David)
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Originally Posted by swannies1983 View Post
What are you imaging with though?

I'm now imaging with a RC8 so f/8. Thor's Helmet is the faintest object I have imaged. I'm up to 6 hrs of 10 min subs but it needs a lot more. However, the banding is very annoying so I will hopefully be able to salvage the data I have now.
Am imaging with an ED100 refractor and a Tak60fs. Basically I sort of know my limits with the setup so try to avoid objects that will cause frustration.

One way around the banding is not to stretch the data so much, but then you have to have good quality data to get to that point. With a DSLR, to me that means a lower ISO and its only recently I have reduced sub lengths ( but increased the number of subs) to take into account LP which was not helping processing.

Jury is out on how this is working though. I do need to try some more objects but weather is not helping.
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Old 07-03-2013, 01:45 AM
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Quote:
Originally Posted by swannies1983 View Post
My previous reply was to MrB. I didn't see your first post before I posted mine
Sorry, posted from my phone at work and have only now got home.
I never solved the problem, to be honest I never even tried, would just shoot shorter subs.
I went thru all my shots trying to find a 10 min sub at 1600, but could only find this one at 400.
There is one strong band at the bottom and hint of another one just above it.

I will be giving David's suggestion a try tho
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Old 07-03-2013, 09:14 PM
swannies1983 (Dan)
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I tried your advice David but it didn't appear to fix the problem. Apparently, this looks like the "dark river effect" that was common with the 20Da. You can process this out using ImagePlus but I don't have this program.
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Old 07-03-2013, 11:15 PM
DJT (David)
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That's a bit of a sod. Good luck with processing that out. Maybe a ground loop related thing. If you are using an ac supply for the camera can you keep it separate from your other power cables/circuits ( he says, now clutching straws and hoping someone else pops up and provides a better suggestion as he is fast running out of ideas but swears blind it worked for him!)
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