Canon 7D noise observations

[adamdoesmovies]

I finally got my 7D, and it's an amazing camera. Upgrading from my still-pretty-amazing old 30D(inosaur). Pretty much everything that can be said about using this camera has likely been said on this forum.

One thing I haven't found anywhere online is a detailed description of the 7D (or indeed pretty much any other DSLR) in the way that noise is physically perceived by the sensor. In my obsessiveness, I spent about a half hour looking at 10x enlargements of hi-iso live-view and video. I noticed that almost all of the pixels have a specific style of unpredictability which is, well, predictable. Certain pixels only glow varying shades of blue (Partially an artifact of the 4:2:0 processing?) while others flash red and blue, or others go dark with intermittent flashes of white.

The important thing I noticed is that the behavior of the pixels is consistent - one that flashes off-blue-white will always be in one of those three states, and won't flash red/green if it wasn't already predisposed to do so. Same for the dull blue ones, which stay in various modes of that state, or, if they have the disposition, flash red. This seems to indicate nano-scale "flaws" or slight differences in the way each pixel lithographed, but I'm not entirely sure. Sensor noise is caused by random electrons/charged particles striking the pixels, so the structure of each pixel might be different in such a way that some are more predisposed to being affected.

I understand that in stills, there is a fairly effective noise reduction algorithm based on a "dark frame" of this noise, but given the consistency and placement of noise activity across the sensor, shouldn't it be possible to create a more advanced noise reduction algorithm based on the fact that each pixel has its own specific, fairly predictable noise signature?

 

[bvukich]

It's probably an artifact of the demosaicing process that converts the raw output of the bayer type sensor to RGB pixels as we know them.

http://en.wikipedia.org/wiki/Bayer_filter
http://en.wikipedia.org/wiki/Demosaicing

 

[acoll123]

It could be a loose shim on the image sensor's trans-nebulizer - probably caused by the higher than normal gravity we have recently experienced from the "super moon". It should settle back into place in a few days.

 

[AJ]

Sometimes when we look at review sites that show graphs depicting noise, we are missing a critical element: the quality of the noise.

You've spent some time looking at it. So have I.

My first DSLR (300D) produced really "clumpy" noise. These were blobs of chroma noise many pixels (say 10) in diameter that were especially noticeable in shadow areas. These blobs would really show in prints. I've found no good way to deal with it in processing. On top of this was the more random-like pixel-by-pixel luminance noise.

I like the noise of my 7D much better. At 1600 iso the noise is almost filmgrain-like, and color is still pretty good. Noise is pretty even between shadow and highlight, which IMO gives it a more slidefilm-like look. At higher iso you start to see some clumps and the pixel-by-pixel noise goes sky-high. Still works out better in prints, though.

 

[bvukich]

It could be a loose shim on the image sensor's trans-nebulizer - probably caused by the higher than normal gravity we have recently experienced from the "super moon". It should settle back into place in a few days.

Is that a single exposure?

 

[acoll123]

It could be a loose shim on the image sensor's trans-nebulizer - probably caused by the higher than normal gravity we have recently experienced from the "super moon". It should settle back into place in a few days.

Is that a single exposure?

Yes, with a 7D . . . It was late-afternoon a few days ago. I did use Aperture to increase the contrast and saturation. Shot with a 300/2.8 on a monopod. Aperture was f/3.0, shutter was 350, ISO was 160. I just got lucky with the timing . . . we've had some great sunsets recently in this area.

 

[Kimberly Cher Photography]

Mine was so incredibly noisey at 100 - 400, then I skipped to 800 and it was XCACTLY the same amount on the 400 ISO/ASA. Also had focusing issues, with all 12 lenses, even in manual focus. Yes, the diopter was FINE, and I set all my settings in 900 different ways people 'suggested' all over the net. I also spoke with Canon for over 2 hours trying to fix the noise problem, couldn't fix and couldnt fix focus issues. My 50D was NEVER a problem -

Shot at 1/300 and went all the way up to 1/1200 (around there) and a guy gliding on a kite board was still blurry. Even where the AF point was 'beeping', it was supposed to be in focus and it was not. Not one part of any image was tack sharp, even when shooting a motionless.

I then googled noise and focus problems 7D on google and it is a KNOWN problem with many, many people. Canon repair in Irvine has it now - but some people them back perfect, some have to send them back 2, 3, I guess the 3rd time, Canon issues a refurbished unit. I DONT WANT A REFURBISHED.. I want and deserve a NEW camera that WORKS.

I contacted the original seller and he extended the 14 day return policy to 30 days and says if they cant fix it, that they will send me a new camera.

Now, I was on the phone with the 'right' people at Canon, I spoke with Michelle in the 'escalated issues' department and she agreed to overnight me a 7D and send me a label to ship mine to Irvine overnight. They are expediting my case too - she is doing this as a one time courtesy. As I had no clue about CPS - which I am buying after I recover from the costs of this 7D purhcase. I pray my OWN camera comes back soon - even though I have a loaner, I still want to put my hands on the 1479$ that I spent for this camera.. *yes, I got it while the rebate was still going on!!!*

 

[neuroanatomist]

Even where the AF point was 'beeping', it was supposed to be in focus and it was not. Not one part of any image was tack sharp, even when shooting a motionless.

Here's an image with a 100% crop from my 7D. I was outside doing some static shots of water lillies in a marsh, playing with the wide aperture of my new EF 85mm f/1.2L II (and comparing it to my Ef 85mm f/1.8 which I subsequently sold), when I heard the distinctive scraw of a grackle. I raised the camera and grabbed this shot with autofocus - and bear in mind that the 85L is known for it's 'ponderous' AF speed... This was at ISO 2000 for a fast enough shutter speed. As you can see, even with the slow AF of the 85L, the 7D locked focus on the flying bird.

Here are couple more on the 7D, with a lens that's more suited to birds:


EOS 7D, EF 100-400mm f/4.5-5.6L IS USM @ 400mm, 1/1600 s, f/6.3, ISO 800


EOS 7D, EF 100-400mm f/4.5-5.6L IS USM @ 400mm, 1/1600 s, f/6.3, ISO 1000

 

[AJ]

Interesting shooting birds with a 7D 85/1.2 neuroanatomist

The 7D makes me rethink where the weakness of AF lies. I used to think it was mostly the lens, but a good camera makes a huge difference.

The other day I was shooting skiing action shots with my 7D and 55-250 IS. Yes, the lowly kit lens. The lens had no trouble at all keeping up with the action. It performed flawlessly in AI servo and one-shot. Mind you the light was strong and contrast was high. But still I was very impressed. I've had similar experiences with my 50/1.8 and Tamron 17-50/2.8, two lenses that aren't particularly renowned for AF performance.

Anyways, please excuse the AF thread drift. Please carry on with the noise conversation.

 

[unfocused]

Mine was so incredibly noisey at 100 - 400, then I skipped to 800 and it was XCACTLY the same amount on the 400 ISO/ASA. Also had focusing issues...I pray my OWN camera comes back soon - even though I have a loaner, I still want to put my hands on the 1479$ that I spent for this camera.. *yes, I got it while the rebate was still going on!!!*

Kimberly, I'm not trying to be rude, but a lot of what you are saying just doesn't add up.

You apparently received a defective camera. Okay. That can happen to anyone. So why didn't you take it back to the dealer immediately? I don't understand why anyone would send a brand new camera to Canon for repair, instead of just taking it back to the dealer and getting a new one.

That seems especially strange since you said the dealer told you they would replace the camera if Canon couldn't fix it. That seems a little backward. Most people would exchange the camera first.

You say focus and noise issues are a known problem and you found lots of examples on the internet. I Googled the terms you suggested and found only a handful of discussion board mentions. In several of those cases, the full discussion reveals either user error or subjective differences of opinion based primarily on pixel-peeping.

You say all of your lenses failed to focus properly with the 7D, but did with the 50D. You might want to read the Canon Rumors article by Roger Cicala from LensRentals.com. You may have a micro-adjustment issue.

You mention the diopter setting. You are correct in that the diopter would have nothing to do with autofocus. It simply compensates for our own eye issues and affects the viewfinder only, not the focusing of the lens (unless of course, you are focusing manually).

You say Canon issues a refurbished unit when you send in a camera for repair. I find that a little hard to believe. Has anyone else on this forum ever heard that?

You say not one part of an image was tack sharp, even when shooting a motionless subject. That also seems really hard to believe. But, what do you consider "tack sharp?" Is that based on prints or on looking at the image on a monitor? Are you shooting jpegs or RAW and what sort of sharpening are you applying?

Finally, you say you want to put hands on the $1,479 that you paid for the camera. If that's the case, again why didn't you just return it to the dealer for refund.

Again, I really am not trying to be rude or to pick on you, but your experience seems so out of character with what almost everyone else who owns a 7D has experienced (including myself) that I'm trying to make sense of it.

 

[awinphoto]

In regards to Kimberly,

I just had a few questions/comments. I have 2 50D's and 1 7D that I work with in both my office's and out on the field. On my 7D, at 100% pixel view, it is clearer than the 50D in every ISO across the board. I have done product shots with the 50D and even at ISO 400 the ISO for magazine shots are getting dicey for when I'm expecting buttery smooth images. The 7D, for me, is cleaner in every aspect. With that being said, you claim your 50D was better regarding noise. Would you care to post images of like images at like settings and exposures and subjects? (when you get yours back and if you're still unhappy?). I hate to be skeptical, however I find that people expectations what one person finds acceptable at 1000 others wont. So without images to show what your referring to, it's hard to decipher what your expectations are and what you are getting so people can make their judgements as whether you're asking too much of the camera. A month ago I shot at a concert venue at night and got very usable images shooting at 2500 ISO. Then again when I realize I could never have gotten these shots with film cameras even 6-10 years ago, I have a better expectations.

Regarding to AF, I will admit the 7D has one heck of a learning curve. Keep in mind I've been using Canon DSLR exclusively for about 8 years and when I got the 7D, it took me about 30 min to an hour to learn the AF modes, how to change the AF modes, and find ones I like and love. On my 7D, I find that I did not like it on the full zone AF which it defaults to on P mode... On manual mode I found the + zone AF (forgive me, the select AF mode where you get the 4 immediate points around the central point), and the single spot and single percise spot to be the most predictable and accurate. But now that I've mastered the AF and got the settings the way I like it, it focuses as well as I could have ever hoped.

This is another thing where you may want to post pictures however this is more of a technical issue. At the worst you can send your canon lens and camera to canon and they can calibrate them together. I noticed the 7D and my older sigma telephoto wasn't working too well... the lens was too slow... guess what, my sigma is gone and i picked up a 70-200L. Sometimes it can be the lens, especially when shooting fast action where you need the lens to catch up.

Lastly, for canon CPS, if you qualify, they do send out loaners for you to use if you send a camera in that would be there an extended period of time (longer than their average turnaround). For non CPS members, you have to contact them and see if they can make an exception. I highly recommend CPS for any professional who needs it and has a high investment in canon products.

Anyways I hope this helps and feel free to contact me if you have any more issues.