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Old 10-10-2015, 11:51 AM
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ReaPerMan (Paul)
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A7S Banding

I have had a lot of success with my A7S and it's ability to take pictures and it's sensitivity and low noise at High ISO are great. I have successfully taken some nice pictures with stacks of 40+ subs totalling 10 minutes of exposure. The other night I pushed it further and took a number of targets based on 15 second exposures at ISO 3200 totalling 240 subs (1 hour). I was surprised after processing in Pixinsight to see artefacts that I had never seen before. To highlight these here is an example of the High Pixel rejection from the DBE process it shows these 'bands' in remarkable clarity. Anyone have any ideas as to why they should be present?

All the best

paul
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  #2  
Old 10-10-2015, 12:36 PM
glend (Glen)
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Perhaps you picking up a reflection off a nearby structure that has been at such a low level it was not captured at lower ISO rates. That's a pretty aggressive ISO setting. Have you shot darks and bias offsets at that ISO and compared them?
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Old 10-10-2015, 05:53 PM
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Quote:
Originally Posted by glend View Post
Perhaps you picking up a reflection off a nearby structure that has been at such a low level it was not captured at lower ISO rates. That's a pretty aggressive ISO setting. Have you shot darks and bias offsets at that ISO and compared them?
Thanks Glen,

No reflection as these pics were shot at five different targets from West, South and NE at varying elevations. ISO 3200 is not aggressive for an A7S and previous stacking has not required darks. I will try to eliminate these bands with Bias etc but that's not the issue that I have, it's that it's even there in the first place and I have not seen it manifested in any other pictures until I have stacked this many of them together. I am concerned that there is a hardware issue or that My A7 is faulty.

all the best

Paul
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Old 10-10-2015, 09:07 PM
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You'd be better off posting this at the Sony Full Frame forum at DPReview.
Do you have the latest firmware in your Sony?

Greg.
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Old 11-10-2015, 03:53 AM
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Quote:
Originally Posted by gregbradley View Post
You'd be better off posting this at the Sony Full Frame forum at DPReview.
Do you have the latest firmware in your Sony?

Greg.
Thanks Greg,
Yes I have the latest Firmware installed.

I have posted it to Sony Support but I'll have a look at DPReview

Last edited by ReaPerMan; 11-10-2015 at 04:16 AM.
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Old 11-10-2015, 08:26 AM
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Never seen that in my A7s Paul, though I've never taken as many subs!

After using the camera for awhile, I most definitely recommend using darks. A big difference in results.
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Old 11-10-2015, 08:57 AM
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Did you use Silent Shutter or EFCS? If so try using those turned off.

There are a number of posts that silent shutter can cause banding in some artificial light.

ECFS, Silent Shutter and Bulb mode all output to 12bit not 14bit. I don't know if that is an issue though.

Also how did you take your darks? Did you use silent shutter for them?

Greg.
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Old 11-10-2015, 04:03 PM
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Quote:
Originally Posted by gregbradley View Post
Did you use Silent Shutter or EFCS? If so try using those turned off.

There are a number of posts that silent shutter can cause banding in some artificial light.

ECFS, Silent Shutter and Bulb mode all output to 12bit not 14bit. I don't know if that is an issue though.

Also how did you take your darks? Did you use silent shutter for them?

Greg.
Thanks Greg,

Yep silent shutter was on... I hadn't seen any of those posts. I didn't take any darks with these pics so they haven't had any reduction applied. I will take some reference darks tonight and see if they have the ability to remove the problem. I still am more concerned that the banding is there rather than what is necessary to remove it from the pictures.

Paul
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Old 12-10-2015, 06:27 AM
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I've only seen references to banding and the silent shutter when its used with indoor lighting. I presume fluoro lights that oscillate.

Darks probably would remove it but turning it off will should stop it also.
Are you worried about shutter shake? See the latest review of the A7rii on DPreview. Silent shutter also increases noise.

Greg.
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