DVPhoto

Well earlier this week, the Canon EOS 50D information was leaked, and then quickly followed with the official announcement. It has many new features, but most impressive was 15.1 megapixels and a maximum ISO of 12800.

15 megapixels? I am still happy with 8! I’ve printed 36×24 inch prints with it and was quite pleased with them. Admittedly a pickier viewer might have complained they were not sharp enough… after practically touching the print with his eye. Do we really need it? I’m not the only one who thinks we should stop increasing megapixels.

Those calling for more resolution sometimes state large prints as a reason why they want the extra pixel, though more often these days is the claim of improved ability to crop. But how often is this actually the case?

At 15MP on a 1.6 crop sensor the diffraction starts to show up at and aperture of about f8 onwards. So from f8 onwards, the extra resolution is just showing the airy disk, and cropping becomes less and less of an option. Open the aperture up and the problem of diffraction is not longer noticable.

So now one has to ask how sharp your lens is. A brief look at the sample photos on the canon site shows us what lenses and apertures were used.

• EF600mm f/4L IS USM @ f/8
• EF-S17-55mm f/2.8 IS USM @ f/4.5
• EF50mm f/1.2L USM @ f/8
• EF16-35mm f/2.8L II USM @ f/8

A nice selection of very good lenses, and mostly stopped down to f/8 which should reduce chromatic aberrations. And yet when I viewed these images at 100% (pixel peeping if you will), I noticed CA immediately on several of the images. It was small, and wouldn’t be noticable in a normal print; yet already this limits just how much you can crop some parts of the image. These are all quite decent lenses, so consider how more mundane low end lenses might perform with this sensor; not well I would think.

Now this new 15MP sensor is managing an maximum ISO of 12800! Many people complain that such high ISOs are pointless since they only ever use lower ISOs themselves. Others claim the current autofocus doesn’t work properly in light which requires high ISOs. I look at it from the point of view of a user with a cheap lens in bad light. The lens needs to be stopped down to f/8 to provide good results, and thus the ability to up the ISO without sacrificing too much quality becomes quite important.

If Canon can squeeze ISO 12800 from a 15MP sensor, what could they do from a 10? ISO 25600, or even higher; clean 1600, very usable 3200 or maybe even 6400? Suddenly the poor photographer who cannot afford several thousand dollar lenses as well as a camera, can suddenly use his cheaper zoom in dim light.

The lower megapixels make problems with the lens less apparent, and the higher ISO allows greater flexibility in different lighting.

Of course that is probably the reason we won’t ever get the lower mega pixel high ISO camera; less reason to upgrade the lenses…

Tags: digital photography, ISO, megapixels, resolution

This entry was posted on Friday, August 29th, 2008 at 10:47 am. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.