Wednesday, 24 June 2009

Hot pixels spoilt my day...

Last week I received my much anticipated Canon 5D Mark II camera body. As soon as I had the opportunity I eagerly unpacked the unit, attached my favourite L series lens (70-200 mm f2.8 IS L) and started playing. Let me say before I go any further this camera is simply incredible! the issues I have faced are specific to my unit and just bad luck. So first the good news...

The 5D Mark II is a 21M pixel full frame digital SLR that also supports full HD video capture at 1080p. The latest firmware (version 1.1) offers full manual exposure control over said video so this product now becomes one of the most useful and flexible image capture tools on the market. Now I'm a stills guy, I've never really explored video but the 5D Mark II will almost certainly change all that. From a stills point of view, it is a joy to use. The colour rendition is fantastic with a rich accurate palette, the sensor yields fantastic detail (when coupled with the right optics) and the high ISO noise control is simply incredible.

With my old 5D I would shoot at ISO 800 if the need arose but would never really consider ISO 1600 due to noise and the loss of detail that would always result in post production. With the 5d Mark II I set ISO to 1600, shot a few frames and was simply blown away by the cleanliness and usability of the frames, they were fantastic! I pushed the ISO up to 4000 and found I could still get perfectly usable results requiring very little post processing! This will revolutionise my wedding photography and the ability to capture those all important candids in low light situations. Simply amazing!

Now one check I always perform on a new camera body is the hot pixel check. The HP check is pretty simple, all you do is place the lens cap on your lens in order to exclude all light, set the ISO at a suitable mid point (I chose ISO 800) and take a longish exposure (30 secs). Now look at the captured image at 100% and it should appear uniformly black, at least on the 5D Mark II. On other cameras that don't enjoy the same high ISO performance as the 5D MK II some noise may be visible, this will take the form of faint mutli-coloured mottling but it should be pretty uniform across the frame, this is normal and not an indication of an issue. In my case, I was checking for "hot" pixels. These often result from small manufacturing errors in the production of the camera's sensors but can also indicate other more worrying issues. To my horror, when I examined my hot Pixel frame, I found somewhere between 8 and 15 instances where the pixel was glowing either white, red of blue. These pixels remain "hot" from frame to frame and could be visible on dark areas of an image, especially when attempting astro-photography. They can also be a problem on dark video scenes where the removal would represent a great deal of work. In the image below I have circled some of the most obvious pixels as they won't show up on the compressed image allowed by Blogger.

The Eight examples circled here were the eight brightest, you can see they are distributed uniformly across the frame.

So why should you worry? After all, 8 pixels in 21 million is a very low percentage, what's the problem? Well consider the following...
  • this is a £2000 camera body!
  • On normal daytime shots, these blemishes would be unlikely to show up. On night shots, Astro photography or video footage of dark scenes, they certainly would.
  • It's a real pain having to remove blemishes from every frame you ever shoot!
  • Blemishes of this type suggest a problem in the quality assurance stage from this manufacturing batch, there could be other hidden problems.
  • Errors in the production of the sensor could be a one-time problem but they could also indicate a sensor with degenerative problems leading to further, significant degradation.
  • When I contacted Canon to discuss the issue, they felt it was a problem and a replacement would be required
I should be receiving a replacement unit very soon. I believe I was just unlucky this time and can't wait to get my hands on this fantastic camera again soon. Once I have my working body I will publish my thoughts and impressions together with some examples of the miracles this camera is capable of.

1 comment:

  1. I so envy you! Hehehehe! I also have a Canon EF 70-200mm, but it's the f/4 L IS USM lens. I'm so excited for you! I want a 5D Mark II, too!