Oh Canon
I’ve had my 50d for about 5-6 weeks now, but for the last 2 1/2 weeks, it’s been at the Canon service centre. I was browsing some images in Aperture and noticed a bright green spot on one. I zoomed into the image and yup, it was a hot pixel. I then scanned the rest of the image and found 2 more. OK, could be a one off, so I scanned a number of other pictures and they all had them. So I narrowed down the parameters that could be affecting it, by looking at my images with different apertures, ISO, shutter speed (This is usually the culprit) and voila! Exposures from about 1/2 a second or greater exhibited these pixels.
“Hmm” I thought, “This is a bit of a bummer”. While screen size viewing often hid the issue due to scaling and 100% view was required to see it most of the time, it was still visible at normal viewing occasionally and nonetheless the camera was only 3 weeks old so I felt that it should still be in primo condition. So, I popped it into the Canon service centre after ringing the retailer and like any good software engineer entering a defect, I gave them all the tests and parameters on how to reproduce the problem. What ISO, shooting format, shutter speed and I even gave them pixel locations of the hot pixels. No way were they not going to find the issue – a week or so later and I’d have a nice sexy clean camera!
So, skip ahead about 13 days and I ring them to see what’s up. “Camera has been checked and no problems found. But we cleaned the sensor.” was the reply. Followed by “High ISO will result in noiser images.” – I had to chuckle.
“You sure they tested it right, you need to do this and this and this?” I remarked.
“I’m sure they did, the camera will come down to pickup in a couple of days. We’ll ring you when it’s ready.” – I hang up, very very confused as to why they couldn’t see some blatantly bright green pixels at the locations I specified.
Now where is that green pixel?
“Wait a minute! I wonder if they shot JPG!” which essentially nukes the image so bad you can’t see the problem. Another phone call and this time he said he’d ask the technician….couple of hours later.
“I have talked to the technician and he shot ISO 3200, RAW, 8 second exposure, Auto WB blah blah”. All OK it seemed but how could he not see the problem?
“He did clean the sensor” the support guy said “so maybe wait and see if that’s helped.”
“Well, that doesn’t produce hotpixels as far as I know, but OK” – hang up again.
“Ah ha I then think again! I can provide them the crops which display the problem plain as day!”, so I call them and suggest it.
“No need, just wait.”
“OOOOOOK, I said but I have no faith it’s fixed and all I want to do is avoid having to come back.”
So today I get another call, they go over the results yet again, I pick up the camera, walk downstairs, fire off a few shots at 4s exposures, load into Aperture, go to the pixel locations and blow me down, there are green pixels there – who’d have ever thought that!!
Of course the next step if I’m not satisfied is to go back and try and get them to see what I see and agree that it’s a problem, which is possibly harder than you might think for a number of reasons.
Hot pixels are a very debated topic. Manufacturers try and tell you it’s part of owning a digital camera, but of course not everyone has them and if you do, it sucks. When I bought my first dSlR, a used 300d it had no hot pixels for sometimes before they appeared. Essentially lasting about 5-6 years before showing a problem.
Some software tries to mask it, often successfully. Sometimes some pixels don’t appear on my images because Aperture has found and squished them. This isn’t infallible however and I still need to check all my images.
Turning on Long Exposure Noise Reduction in the camera can often remove it. Downside is that it takes twice as long to take the shot (30s for a 15s exposure) because the camera takes another black exposure of the same length to use as it’s base for subtraction.
And as I said before, printing at a small enough size or viewing at monitor size often doesn’t show it up at all.
So I’ll go in tomorrow and see where I get. I don’t want another camera or major repairs and I’d be more than happy to have them just mask the pixels out. My main concern is not having to post process all my images that might have a slightly long exposure of a second or two and end up missing one and handing over someone a print with a bright green dot on someone’s forehead.
If I forget to Photoshop out one of Uncle Billybob’s extra fingers, then that’s my fault, but if my camera is adding rubbish to my images that shouldn’t be there, I’m not happy.
