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Author Topic: Problem with 5DmkIII sensor at high ISO?  (Read 6721 times)

CHpatent

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Problem with 5DmkIII sensor at high ISO?
« on: March 29, 2012, 09:07:54 PM »
Hi- My shiny new 5D3 just came in the mail a day ago and so, feeling giddy, I went off to start playing with it. I bumped into something though that has me worried. At ISO 51.2k and 102.4k, the lower right corner of all my pictures is a red/pink color. At first I though it was CA (coming from a 7D I never saw the extreme corners of my lenses), but I switched lenses and stopped them down to eliminate sources of error and the problem stays.

It is most visible against dark backgrounds but seems to be in all pictures. I know these are the expansion settings and reducing the ISO to 25.6k virtually eliminates the problem, but.....

A few sample images are here (they're awful pictures, but its really just about the lower right corner):
http://www.dropbox.com/gallery/11984962/1/5D3?h=dbe411

All are at 102.4K ISO and are either on a 2.4mm f/1.4 II or 85mm f/1.2 II stopped down to f/5.0. I should add that when taking pictures with the lens cap on at H1 and H2 ISO, I end up with a white lower right corner and otherwise the normal noise.

Am I being hysterical about my new baby or is the sensor really iffy/defective?

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Problem with 5DmkIII sensor at high ISO?
« on: March 29, 2012, 09:07:54 PM »

se7en

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #1 on: March 29, 2012, 09:32:59 PM »
Mine does it too, and I'm not concerned.

TrumpetPower!

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #2 on: March 29, 2012, 09:56:35 PM »
Curious.

I was going to suggest that it's a problem that a manual cleaning cycle (with the body cap on, not actually going near the sensor) might help -- and to send it back for a replacement if not.

Then I saw se7en's response and figured I should give it a try on mine. So, I turned on ISO expansion and took a shot in Av with the ISO set to H2 and saw much the same thing on the LCD playback. Covering the eyepiece doesn't change the results, so it's not light leakage from the viewfinder.

Changing to manual, 30", f/irrelevant, and ISO H2 causes it to do dark frame NR, which results in a picture that has uniform noise -- and a hell of a lot of it, to be sure.

So, my suggestion? Well, don't do that, then! That is, don't take ISO ludicrous-speed pictures of the inside of your lens cap and expect it to look pretty.

Just for giggles, I just took a quick snapshot of my cat sitting on the kitchen table, in the dark. 1/60, f/4.0, ISO 102,400. Not pretty, but he'd still be recognizeable in a lineup, which I'm sure is the point of H2. I could see the hot area in the lower right, but it's not really something I'd have bothered looking for if you hadn't brought it to my attention.

Cheers,

b&

CHpatent

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #3 on: March 29, 2012, 10:03:35 PM »
Then I saw se7en's response and figured I should give it a try on mine. So, I turned on ISO expansion and took a shot in Av with the ISO set to H2 and saw much the same thing on the LCD playback. Covering the eyepiece doesn't change the results, so it's not light leakage from the viewfinder.

huh. I wonder if we can take an unofficial poll here and see if other 5D3 users have the same bright lower right corner?


Orion

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #4 on: March 29, 2012, 10:11:54 PM »
I have that same "problem," too. I suggest you all not worry about it too much becasue it can be a simple firmware thingy later on. . . .

YellowJersey

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #5 on: March 29, 2012, 10:21:51 PM »
Meh, doesn't really bother me. I'm usually at 100 anyway... the only time I need a higher ISO is when shooting the Milky Way, in which case the highest I'll go is 12800. So this is really a non-issue for me.

Invertalon

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #6 on: March 29, 2012, 10:24:39 PM »
I have it, and many others do too... I think it is normal with this camera.

Here was my topic (with photos) over at POTN... Warning, people got a little nasty with me about it for whatever reason, but whatever.

http://photography-on-the.net/forum/showthread.php?t=1164623&highlight=glow


My theory is that there is some type of electrical component heating up inside the camera, causing this glow. But who knows!

I found out CS5 does a great job fixing it up with content awareness... Just lasso the red/magenta area and let it fill. Generally you only need 60-80% opacity and it does a great job.

No worries though... I have seen it on many examples at high ISO from many different people.

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #6 on: March 29, 2012, 10:24:39 PM »

justsomedude

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #7 on: March 29, 2012, 10:32:39 PM »
Uhm.  Is this a joke?

You're shooting at 102... THOUSAND ISO.   I'm not sure what you were expecting.

 :o

CHpatent

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #8 on: March 29, 2012, 10:40:53 PM »
Here was my topic (with photos) over at POTN... Warning, people got a little nasty with me about it for whatever reason, but whatever.

http://photography-on-the.net/forum/showthread.php?t=1164623&highlight=glow


We seem to be heading that way here too  ::)

TrumpetPower!

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #9 on: March 29, 2012, 10:52:36 PM »
So, for everybody else, like me, who has nothing better to do on a Thursday evening than to take out-of-focus high-ISO macro shots of the inside of your lens cap...

...turn high ISO noise reduction to ON, and compare a shot taken at 0"8 with one at 1". The former will have the magenta lower-right corner, but the latter will have more noise overall.

What will this demonstrate?

Why, of course, that you, like me, need to get a life. Or, at the very least, find (or make) some decent light to shoot in, and at least a marginally more interesting subject.

Hmmm...that bit of lint on the napkin looks interesting...I think I'll break out the MP-E, see what it looks like at 5x, wide open, slightly off focus, tilted at an odd angle, ISO 12,8000, handheld, by the light of my iPhone. Underexposed, of course, and then pushed five stops in DPP. Look out, Getty -- here I come!

Aw, damn. The cat just sat on the napkin. Guess I'll have to go look for a more interesting piece of lint for my Magnum Opus Maximus!

Cheers,

b&

se7en

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #10 on: March 29, 2012, 10:52:55 PM »
Welp, after further investigation it was revealed that this was only caused when shooting with a setting that I will literally never use again so i've determined it to be benign. Now where are the damn cappuccinos this thing is supposed to make?

RyanDavis200

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #11 on: March 29, 2012, 11:30:38 PM »
Wow, the amount of pixel peep-age dork-age around here is unreal.  It's 100k ISO!?!  Who cares, why are you shooting that high?? Stop spending 10 hours a week trolling forums about your pixels and buy a 2.8 lens.   

TrumpetPower!

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #12 on: March 29, 2012, 11:47:48 PM »
In all seriousness, here's how it'll play out

Some talentless hack somewhere with ego even bigger than his credit card limit will discover this and call up "his" personal CPS rep to bitch about it. The rep will smile and nod and promise to send it up the food chain, all the while praising himself for his remarkable self-restraint that allowed him to not once hint at the hack's crack dealer.

And the rep will, indeed, run it up the chain because he knows he'll never hear the end of it if he doesn't. Eventually it'll make its way to a software engineer somewhere, and she and everybody else before her will have proudly refrained from making wisecracks about crack smoking.

The engineer will spend the afternoon kludging together a quick hack to make it not quite so noticeable, and said hack will go out in the next firmware update.

Measurebators everywhere will simultaneously rejoice about the fix and whine that the update didn't also turn on in-camera IS (you know they could if they wanted to!), and the no-talent hack will be too stoned out of his gourd to remember how to open his email, let alone install a firmware upgrade. But that's okay, his agent has the CPS rep's number on speed dial, and the two of them can figure out all that messy tech stuff.

Meanwhile, real photographers will see the one-liner about ISO overdrive image quality improvements in the firmware update announcement and wonder about just how much crack you have to be on to even shoot at ISO elebenty brazilian, let alone worry about what it looks like.

Cheers,

b&

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #12 on: March 29, 2012, 11:47:48 PM »

Drewskers

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #13 on: March 30, 2012, 12:14:51 AM »
At ISO 51.2k and 102.4k, the lower right corner of all my pictures is a red/pink color. At first I though it was CA (coming from a 7D I never saw the extreme corners of my lenses), but I switched lenses and stopped them down to eliminate sources of error and the problem stays.

It is most visible against dark backgrounds but seems to be in all pictures. I know these are the expansion settings and reducing the ISO to 25.6k virtually eliminates the problem, but.....

This is colloquially known as "amp glow". Astro-photographers are well acquainted with this source of noise. The image sensor is surrounded by amplifiers ("amps") used to read the faint electronic signals off the sensor and send them to the A/D converters. These amps are necessarily in close proximity to the sensor, and the heat they generate actually heats the corners and edges of the sensor (the exact layout varies by manufacturer). This in turn causes the sensor sites near the amps to create more noise than the sites further away from the amps. That excess noise shows up as the pink stuff you are seeing. It will not only show show up in extreme ISO images such as your sample, but also in time exposures at even the lowest ISO setting. This is a serious problem for astro-photographers, in a sense it is the digital equivalent of reciprocity failure with film, since amp glow means you can't just take a longer exposure to capture the desired amount of starlight.

Astro-photographers deal with amp glow in several different ways, the most basic is allowing the sensor adequate time to cool down between  exposures and using fast glass to keep exposures as short as possible. They also use a technique called "image stacking" where several shorter exposures are taken instead of one long exposure; the celestial bodies are aligned either manually or with the use of special software, and then the images are merged. Sort of a form of HDR.

But the most effective solution is to modify the camera so the sensor is cooled by a Peltier device, this not only reduces amp glow but also reduces the overall noise generation in the sensor and this improves sensitivity. Also, astro-photographers usually have the UV and IR filtration removed from the sensor since much of the light from stars falls into these ranges and this radically improves the sensitivity of the camera to celestial objects. (There are companies that specialize in these modifications and most cameras can be completely modified for well under $1000).

The venerable 5D "classic" had amp glow in spades and it could easily be seen in twilight pictures taken at ISO 3200 around 1/8 of second or longer. The 5D MkII made a big improvement on amp glow and many people are eagerly waiting for reports as to whether the MkIII is further improved.

Congratulations on being inquisitive enough to experiment, astute enough to recognize something unexpected, and for asking the question! Those that have answered your post with the standard "pixel-peeping" and "measurebating" ridicule are demonstrating a high degree of intellectual immaturity (AKA ignorance).

Aglet

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #14 on: March 30, 2012, 12:26:06 AM »
.. At ISO 51.2k and 102.4k, the lower right corner of all my pictures is a red/pink color.
-clip-
Am I being hysterical about my new baby or is the sensor really iffy/defective?

In the testing I'm currently doing I've seen this exact phenomenon in more than one Canon DSLR when the iso is cranked to the max.  It becomes more noticeable if you also push the exposure in post.

it may be something to do with that part of the sensor being a little warmer or possibly some other reason for the inconsistency.

Not likely anything to worry about unless you really need that top-notch hi ISO setting to be clean.  If you do, then, uh-hmm...  There are other options. ;)

Might be worth trying again after letting the camera cool off thoroughly to see if it is a heat-related issue.


« Last Edit: March 30, 2012, 02:20:28 AM by Aglet »

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Re: Problem with 5DmkIII sensor at high ISO?
« Reply #14 on: March 30, 2012, 12:26:06 AM »