Saturday, 25 April 2009

Competence and the consumer

I had a nasty shock the other day. There is a snake's head fritillary on my balcony that was looking rather nice, and I took a picture of it. The image was out of focus. Now, my digital camera is both sophisticated and perfectly capable of handling the conditions, so I wasn't pleased. But I forgot about it until I saw this post on DIY auto focus adjustment.

It looks a bit tricky, but actually it isn't. After an hour, I had recalibrated my Pentax's AF, and it is now much sharper. But what shook me - almost stunned me - was how far out the camera was. 260 microns. That's like trying to get to the Tower of London and ending up in Milton Keynes. My naive assumption that a piece of high end consumer electronics would be properly calibrated out of the box was obviously very foolish.

Of course, by the time I had got this done, the fritillary flower had fallen, but here's a 100% crop from an image of some blossom, taken with the newly calibrated AF:
I wouldn't say the focus is absolutely perfect, but it is an awful lot better than it was, and close to the best that is achievable without lab equipment.

It is interesting that things like my camera are limited not by their maximum performance, but by the competence of the factory and distribution system. Given that these problems get much harder for higher resolution cameras - see here for an extended discussion of calibrating medium format digital backs - you might want to pause before buying a camera with more than 10M pixels. It might be fine out the box, but it might well not be, and if it isn't, extracting the performance that the camera is capable of can be a tedious business.



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