Canon have just announced a “sister” model to their 40D, the 50D.

It is essentially a 40D 1.6x cropped sensor dSLR with 15mp instead of 10mp, an upgraded LCD to a hi res VGA LCD, and a few added features including:

contrast detect AF in live preview mode with face detect – much the same as Olympus E420/520 models

four levels NR instead of just On/Off – similar to Olympus E410/420/510/520/E3

AF microadjustment for up to 20 lenses – similar to Canon 1DMIII

four levels auto lighting adjustment not just On/Off – ie. Shadow adjustment

ISO extendable to 12800 – will be interesting to see noise vs loss of detail

new 3.8mp sRAW2 file save mode – not sure who would want to use this mode

peripheral illumination correction (vignetting) for 26-40 lenses – Olympus don’t need this as they use telecentric lens design

new Creative Auto exposure mode

minor changes to burst speed (6.3fps not 6.5) and 60 jpegs not 75.

HDMI output

Digic 4 image processor

While most of the changes are improvements over the 40D as to be expected, I am very concerned about the increase in photosites from 10 to 15mp and thus reduction in photosite size to 4.7 microns.

This would usually mean that the price for increased spatial resolution on the sensor should result in MORE image noise at higher ISO and LOWER dynamic range, although Canon seem to say changes in sensor technology have counteracted this – time will tell how much of an impost the increase in megapixels will be to image quality.

Another concern of this increase in megapixels is that it will be much more demanding on the lenses.
Canon discovered that at 16mp with the full frame Canon 1DsMII, even the L series zoom lenses struggled to maintain adequate resolution to make the most of the sensor and that sensor was much larger than the one in the 50D.

At 15 megapixels on a 1.6x crop sensor, this gives the same spatial resolution per mm as a 38 megapixel full frame or a 10 megapixel Olympus sensor.

I suspect Canon’s lenses will struggle to make use of the 15mp and you may just be creating 10-12mp detailed images but at 15mp file sizes.

Nikon have realised this problem and have embarked on creating new higher resolution lenses in anticipation of their presumed 25mp full frame.

Olympus realised long ago that these sensors need much higher resolution lenses than 35mm film cameras required and hence their ZD lenses have far greater resolution than their OM film lenses.

So the big questions are:

how will the increased megapixels impact the noise and dynamic range profile

will Canon’s lenses be able to extract more than 10mp detail in a cropped sensor?

Finally, I worry that Olympus will feel forced to keep up with the megapixel race which I thought should be over? I hope they stay with 10-12mp and target more dynamic range and less noise, NOT more megapixels. PLEASE.

dpreview.com have a preview here