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Canon 5D Mark II:
Black Pixels around Uranus
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Canon 5D Mark II Black Pixels

What Black Rings? Around Who's Anus?
(Canon 5D Mark II, 10 seconds at ISO 400, 50mm f/1.4 USM at f/2.8.)

December 2008      Canon 5D Mark II Review        More Canon Reviews

07 January 2009 update: Canon's firmware version 1.0.7 for Mac (also windows) claims to have fixed this. This test was shot with the original firmware. We all can go back to sleep.


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Every time a new digital camera comes out, gearhead non-photographers do everything they can to try to break it.

Instead of taking pictures, they photograph every possible thing that might break the camera, and in every case, they always find something that any new camera won't do. They put it up lame photos of light bulbs in their mom's basement on the Internet, and scream about some vast Oriental conspiracy.

What these guys don't get is that every camera has its limits (especially digital cameras), and if these artifacts don't happen in real pictures, then just get over it.

For the Nikon D200 is was banding, which only happened if you pointed the D200 at the sun and expected to see the dark parts of the photo. It didn't matter to photographers, since we control our light better than that.

Just like the D200 banding, the only way you'll see anything like this from the 5D Mark II is if you're doing things that result in crappy pictures far more obvious than any of these very subtle effects, blown out of proportion by the still-living-with-their-parents video gaming crowd.

For the Canon 5D Mark II, the latest tweaker discovery is that if you're lame enough to point the Canon 5D Mark II at a very bright light source at night, and then look on the right edge between light and dark at extremely high magnification, that you just might see a pixel or two that's darker then the other dark pixels.

This is caused by a combination of ringing in the analog circuitry that captures the analog data from the sensor, and the 5D Mark II's sharpening algorithms. If you could see them, these dreaded dark pixels help to emphasize the brightness of the light source and make the image sharper.

You'll never see these dark pixels at any reasonable print size. If you can make them happen, which they don't except for extreme conditions, you'll only see them on your monitor at 100% magnification. This is the same as looking at a 56 x 38" print (150 x 100 cm) from as close as you see your monitor.

You'll never cause this issue with real photos. You'll only excite this if you point your 5D Mark II into sources of light in conditions that lead to very crappy photos, even without any of the mysterious dark pixels.

To cause these darker pixels, shoot a brilliant source of light in such a way that there is an extremely sharp transition from blinding to dark. It's tough, because the issue happens at the transition, and to excite this ringing, you need to go from blinding to dark in the space of a pixel or two. Most of the time, simple diffraction will dull this transition enough to prevent the artifact.

Let's look at the only photo I've made where I can see this, and I only can see it if I'm looking too darn close, and even though I can see it, I don't care.

Guide image

Guide image. Note red-lined areas cropped below.

Let's zoom in and look at some crops from this image at 100%. 100% on-screen is the same as looking at the image printed at 56 x 38" (150 x 100 cm), and looking at it this closely. I never print this big, and I shoot large-format film.

Black Pixels around Your Anus

Black Pixels around Uranus. Crop from 100% image (56 x 38" (150 x 100 cm)).

Can you see it? Can you see the black pip just on the right side of the point-spread of the bright dot? The dot is the evening star and planet Uranus, pronounced "your anus." (Some humorless science teachers tired of hearing the joke about the starship Enterprise being like toilet paper because it flew around Uranus looking for Klingons, and these dull sorts now try to teach kids to mispronounce Uranus as "urine us," which is still pretty funny.)

Anyway, I care more about the science jokes than the ringing (excess dark overshoot) on the right side of the planet. Do you have any idea how bright that planet is? It's so bright it's throwing an eight-pointed sunstar, even though I'm only shooting at f/2.8!

I'd never notice this until some dweeb, the same sort with the Star Trek jokes, points it out. Now that I have seen it, do I care?

Nope! I care more that the image is so clean, even at ISO 400! Film could never do this.

In case you can't see it, let's blow this up (like on TV) to 500%. Now we're looking at a section of a 24 x 16 foot (11 x 7.4 meter) print!

Your Anus at 500%

Crop from image at 500%. (24 x 16 foot (11 x 7.4 meter) print.)

Ooooh, now it's really scary! It's a black hole eating Uranus! Will it swallow the planet?

The light mark above Uranus is another star, accurately reproduced.

Let's look at two more crops, marked above in the lower left of the guide image

Sodium Light

Sodium Lights. Crop from 100% image (56 x 38" (150 x 100 cm)).

It looks fine to me. I almost can imagine some ringing on the right of one point source, but the brightest sodium (orange) lights look fine.

Tract Homes.

Tract Housing. Crop from 100% image (56 x 38" (150 x 100 cm)).

This again is the only other place in the huge image I can see anything at all. You almost can see some ringing (darker pixels which highlight the sharpness) on the right side of one of the windows. The interiors of those homes is nine stops brighter than the rest of the image.



The only photos in which I've seen these black rings demonstrated suck for far more reasons than the black dots.

Just get over it. It should be easy to fix by firmware or hardware if Canon wanted to.

I never see this. I had to look way too close in just this one image, and never saw it on any other similar ones.

If Canon offers an upgrade or recall for this, I wouldn't bother to send my camera in unless it was going for something else at the same time. I'm serious: for me, this is a non-issue.

I love the image quality of my 5D Mark II.

This is invisible. On other shots of the same thing made at different settings, it went away! See my ISO 25,600 shots, shot straight into the moon, where these are nowhere to be seen. In those shots, the moon is eighteen (18) stops overexposed!

I have zillions of shots of point-source and other lights on Christmas trees and you name it, and I've not seen this except in the shot of Uranus presented above, in which I can't see it either, except greatly enlarged beyond all recognition.

The real issue photographers should be discussing about the Canon 5D Mark II is the issue of differential textural smoothing as a result of noise reduction. I'm seeing that some areas are splotched over more than others, making the shot look digital instead of natural. Go experiment with this, something that matters but is too subtle to catch the eyes of the gadget tweaker crowd.

Now go out and take some good pictures! If this stuff bugs you, just shoot film, which has none of these problems.


Science Maturity Disclaimer: As you all should know, the evening star pictured is actually Venus, which is a whole lot brighter than my anus.



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