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Amp glow

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Jadom View Drop Down
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Post Options Post Options   Quote Jadom Quote  Post ReplyReply Direct Link To This Post Topic: Amp glow
    Posted: 22 November 2023 at 10:29
Changing drained batteries in my A7M2 while our trip to Rome caused a huge problem.
My camera changed (or I've done it unwittingly) its settings to extremely high (20000) ISO. I (stupid me) haven't noticed it and continued taking pictures.
The result - as we could expect - very high noise and nasty color blotches in darker places on most of the pictures.
But it wasn't all. My all pictures have nasty magenta cast in lower left corner.
I've performed some web digging about it and I found that I am experiencing some common problem called "amp glow". I won't write about it here - you can google it on the web. But I have a few questions to Dyxum gurus in regards of it.
My questions are:
1. Has anyone experienced it?
2. Is this somehow fixable in camera (by firmware for example)?
3. Is it possible to remove it from a picture? If yes - how?
Anyone?
Jack

MOD EDIT: changed the post title from amp glove to amp glow.

Edited by stiuskr - 22 November 2023 at 12:28
Jack.SigmaDP1x,DP2M,SonyA7M2,Min: MC35F2.8, AF50F1.7, 70-210F, SL16-35F4, KironKine 80-200F4Macro, Promaster MC28F2.8, Rokinon 85f1.4, Samyang 14F2.8, Tamron: SP AF 28-75F2.8XR Di LD, 70-300 F4-5.6Di
 



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LAbernethy View Drop Down
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Post Options Post Options   Quote LAbernethy Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2023 at 12:15
I'm sure there is an AI generated fix as a plug-in with that popular photo editing software.
For me, over a certain ISO threshold I revert to B&W or convert to B&W. Then use digital filters to adjust the grain to taste.
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Post Options Post Options   Quote stiuskr Quote  Post ReplyReply Direct Link To This Post Posted: 22 November 2023 at 12:25
It was a common issue with the Konica Minolta 7D, most prevalent in long exposures and also in high ISO shots but most avoided high ISO as it got nasty very quick. Seems like 640 was as high as you could go cleanly and the only solution at that time with the available software was to just crop it out.
Rob Suits Jr.
a99M2 a99 a77 a700 KM7D|Min24/2.8 Min35/2 So50/1.4 So50/2.8 Min85/1.4G Tam90/2.8 Tam180/3.5|Tam17-50 CZ24-70G2 KM28-75D So70-200G1 So70-300G So70-400G1| SonyF60 AD200R2
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Jadom View Drop Down
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Post Options Post Options   Quote Jadom Quote  Post ReplyReply Direct Link To This Post Posted: 23 November 2023 at 09:25
Originally posted by LAbernethy LAbernethy wrote:

I'm sure there is an AI generated fix as a plug-in with that popular photo editing software.
For me, over a certain ISO threshold I revert to B&W or convert to B&W. Then use digital filters to adjust the grain to taste.


Thank you for your comment, Lee.
My post processing idea from very beginning (before checking all pics) was to make two copies of each picture. One in color, other in BW. And it fortunately works in this particular case. However I need more time to post process each picture because of using Topaz Denoise AI software.
But, thank to it, many of my pictures are saved regardless of noise and amp glow unwanted "effects".
Jack.SigmaDP1x,DP2M,SonyA7M2,Min: MC35F2.8, AF50F1.7, 70-210F, SL16-35F4, KironKine 80-200F4Macro, Promaster MC28F2.8, Rokinon 85f1.4, Samyang 14F2.8, Tamron: SP AF 28-75F2.8XR Di LD, 70-300 F4-5.6Di
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Jadom View Drop Down
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Post Options Post Options   Quote Jadom Quote  Post ReplyReply Direct Link To This Post Posted: 23 November 2023 at 09:39
Originally posted by stiuskr stiuskr wrote:

It was a common issue with the Konica Minolta 7D, most prevalent in long exposures and also in high ISO shots but most avoided high ISO as it got nasty very quick. Seems like 640 was as high as you could go cleanly and the only solution at that time with the available software was to just crop it out.


Robert. Thank you for your comment. I resolved this problem deleting really bad pictures, cropping bad areas (if possible) and converting to BW others.
I am pretty sure that experienced Photoshop or other post processing software user can fix this problem, but my skills in this matter are rather poor.
I was just guessing that perhaps there is some method (firmware fix for example) of avoiding this nasty effect in a future.
But it looks like there is nothing in this matter. However I am pretty sure that newer cameras are amp glow effect free.
I have learned one more lesson: to check my cam settings frequently.
Jack.SigmaDP1x,DP2M,SonyA7M2,Min: MC35F2.8, AF50F1.7, 70-210F, SL16-35F4, KironKine 80-200F4Macro, Promaster MC28F2.8, Rokinon 85f1.4, Samyang 14F2.8, Tamron: SP AF 28-75F2.8XR Di LD, 70-300 F4-5.6Di
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Post Options Post Options   Quote sybersitizen Quote  Post ReplyReply Direct Link To This Post Posted: 30 November 2023 at 16:57
Originally posted by Jadom Jadom wrote:

My questions are:
1. Has anyone experienced it?
2. Is this somehow fixable in camera (by firmware for example)?
3. Is it possible to remove it from a picture? If yes - how?

1. Yes.
2. Only if the exposure is one second or longer, in which case the effect can be reversed by using long exposure noise reduction.
3. Probably. The right way is to shoot a dark frame (lens cap on) with the same shutter speed and ISO when you take the original shot, and then use software to 'substract' the amp glow from the original shot. This might not work properly if your dark frame is shot in a different ambient temperature, though.

Google 'dark frame subtraction' for more info.
 



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