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Old September 11th, 2010, 02:25 AM   #1
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CMOS S/N deteriorating with time?

Those reading my posts here and on the nanoFlash forum may think I've become paranoid with this issue, but it's my impression that the particular, fine noise in my EX1 is increasing with time...

I have just compared some clips, recorded at the same lighting, scene and PP - tow years ago and today, and I can bet the noise level is higher in the current recordings!

My knowledge on CMOS technology is very limited, so if anyone out there have noticed the same, and know how to explain it - I'm all ears.

The S/N may decrease over time and usage, and it may be irreversible - but perhaps some calibration could bring it back to what it was when new? Interestingly, the Black Calibration is greyed out (inactive) in my EX1 menu...
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Old September 11th, 2010, 06:03 AM   #2
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Quote:
Originally Posted by Piotr Wozniacki View Post
Those reading my posts here and on the nanoFlash forum may think I've become paranoid with this issue, but it's my impression that the particular, fine noise in my EX1 is increasing with time...

I have just compared some clips, recorded at the same lighting, scene and PP - tow years ago and today, and I can bet the noise level is higher in the current recordings!

My knowledge on CMOS technology is very limited, so if anyone out there have noticed the same, and know how to explain it - I'm all ears.

The S/N may decrease over time and usage, and it may be irreversible - but perhaps some calibration could bring it back to what it was when new? Interestingly, the Black Calibration is greyed out (inactive) in my EX1 menu...
You probably use your camera more than I do Piotr so I haven't noticed this problem. However, is there perhaps a filter on the front of the camera that you are using now that maybe you weren't using back then?

John
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Old September 11th, 2010, 06:41 AM   #3
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Thanks John, but no - it's not a filter...

As I said, I compared takes almost identical in every aspect.
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Old September 11th, 2010, 07:30 AM   #4
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can you upload two examplepictures in full-res?
i got paranoid too :D
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Old September 11th, 2010, 07:58 AM   #5
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can you upload two examplepictures in full-res?
Frankly? No, I will not post any pics. I've done my fair share of them in the past - the only outcome being people commenting how poor examples they were - JPEGs instead of PNGs, or that one cannot judge video using a still frame, blah blah... Finally, it all boiled down to the fact they were using 20" displays so they just couldn't see what I see on my 50-incher - but I've had enough :)

So, just an open subject for discussion: has anyone observed a noise increase with time on their CMOS-based cameras, and if so - can it be measured, or is it only subjective?

'Cause you know - once you become obsessed about something, it can become reality...
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Old September 11th, 2010, 10:33 AM   #6
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I don't recall seeing anything when I got the EX3 a year ago, but back in June when I was thinking about buying the Nano Flash, I started noticing mosquito noise in really busy shots, like trees and bushes that were rustling in the wind. I don't know if it was there before (I've got other things to do than go digging through old footage), but I notice it now.
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Old September 11th, 2010, 11:35 AM   #7
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No Charles - I don't mean the typical mosquito noise, if by that you understand the compression artifacts around contrasty edges / details. This is not a problem with the EX1, and even less so with the nanoFlash, when using higher bit rates.

Neither do I mean the typical low-light noise in the form of those largish "blobs", mainly present in shadows in most cameras of not-so-great sensitivity.

What I do mean is this typical for EX cameras, very fine & short, busy little "needles" that change their pattern from frame to frame, thus causing the shimmering - easily visible on larger displays. It tends to be present across the entire luma range, and is not restricted to just shadow and dark areas (though it's most apparent on those mid-bright, large areas of uniform color)...

I hope you know by now what I mean, in spite of my limited English :)
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Old September 11th, 2010, 11:44 AM   #8
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Hello Piotr,
I know that you are not joking with this. It has been a very long time since you started the thread at CD NF. But now you are observing the same thing directly from your camera and the logical question here is When was the last time you've serve your camera? It could give you a mind rest if nothing else...
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Old September 11th, 2010, 11:52 AM   #9
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Good point, Luben!

Believe me, I keep my rig in the best condition imaginable. Nevertheless, I have purchased a 1-year extension of my Sony Prime Support just before my camera turned 2 years old, and I'm going to send it in for an overhaul before it expires (which is in the coming January) - but before I do, just wanted to draw fellow users' attention to the noise issue.

I did mention I'm becoming paranoid, didn't I :)

PS Just for the records: my thread on CD nF Luben mentions is about the nanoFlash actually augmenting this noise, especially in high bitrate, Long-GoP modes.
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Last edited by Piotr Wozniacki; September 12th, 2010 at 03:23 AM.
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Old September 12th, 2010, 02:54 PM   #10
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Originally Posted by Piotr Wozniacki View Post
Frankly? No, I will not post any pics. I've done my fair share of them in the past - the only outcome being people commenting how poor examples they were - JPEGs instead of PNGs, or that one cannot judge video using a still frame, blah blah... Finally, it all boiled down to the fact they were using 20" displays so they just couldn't see what I see on my 50-incher - but I've had enough ..
You could just ignore the troll posters and show others who are more interested in seeing the problem and hopefully offering their findings or solutions.

I haven't noticed anything going downhill with my footage and I use my camera a lot. Maybe the "Rose Tint" for your camera has worn off. It's funny I never noticed a dead pixel on my Nikon D90, now every shot I take I look for it. It has always been there, but I never looked for it when I first got the camera.

Hope you solve the problem
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Old September 14th, 2010, 04:10 AM   #11
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I haven't noticed any issues with my EX3, and I've had it since 2007. I have started to become very picky over what is happening to the picture though through compression. I have noticed a lot of compression related issues with some shots. For example a rough river in harsh sunlight with a lot of trees really does kick the stuffing out of the codec. Keeping my eye on the Ki Pro Mini.
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Old September 28th, 2010, 02:48 PM   #12
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hey, I just had the chance to compare my ex1 ( about 400 hours in use) with a brand new one. i made a lot of test-videos to compare noise levels: i could not see any difference, even in extreme settings or extreme colorgrading.
so: No, the chip is not deteriorationg over time.
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Old September 28th, 2010, 05:44 PM   #13
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Quote:
Originally Posted by Piotr Wozniacki View Post
It tends to be present across the entire luma range, and is not restricted to just shadow and dark areas (though it's most apparent on those mid-bright, large areas of uniform color)...
The only type of sensor noise that fits that description is photon shot noise. The only sensor-based explanation for a change in photon shot noise is that the quantum efficiency reduced over the span of two years and conversion gain was increased to keep output levels the same.

While that might be theoretically possible, the likelihood is so remote that I'm certain the cause of what you're seeing lies elsewhere.

There are so many non-sensor (or external) factors that affect noise and its perceptibility that the most likely explanation is a gradual or marked change in one of those -- not the sensor itself. Here is a brief sampling of the possible factors:

* Sharpening

Sharpening increases noise visibility. Did you ever change your sharpening settings (in camera or in post) over the last two years?

* Saturation

Increased saturation can also increase noise visibility.

* White balance setting

Have you changed any of the methods you use in selecting white balance over the last few years? This can have a tremendous impact on noise visibility. For example, if you shoot in Tungsten light and allow a very reddish color cast, the noise wont be that bad. But if you use a typical white balance (that removes the color casts), it will often have more noise.

* Light

This isn't about absolute light levels (lux) -- obviously low light has more noise than ample light. But what I'm talking about here is how different types of light have different noise levels because of white balance. Magenta light has the last noise of all. Blue-defficient light such as Tungsten can be a lot noisier.

* Subject

Even your subject matter can greatly affect the perception of noise. For example, a highly detailed subject with lots of microcontrast does not look as noisy as a clear blue sky.

* Optical sharpness

Because of the preceeding factor, anything that reduces sharpness can increase the perception of noise. If the lens was bumped and no longer performs as well as it did brand new (e.g. decentration issue), then the lack of fine detail may increase the perception of noise.

Those are some of the factors that could be causing the issue you see. Hope that helps.
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Old September 28th, 2010, 05:50 PM   #14
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@ Thomas:

from a scientific point of view your test only reveals there is no noticable deterioration after 400 hours :-p
(When shooting a lot 400 hours can be reached within 10 weeks: comparing with 2000 hours would be more interesting.)
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Old September 28th, 2010, 08:27 PM   #15
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Quote:
Originally Posted by Piotr Wozniacki View Post
As I said, I compared takes almost identical in every aspect.
The "almost identical" part is a killer. There are so many variables on a camera like EX1. Are you using the identical profile with identical parameters? Can you reset the camera back to the factory defaults?
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