High ISO test with the EOS 40

On the DPReview forum there was a lot of discussion on the higher ISO capability of the EOS 50 (introduced in August 2008) than the EOS 40. There were lots of pictures posted with both cameras so I decied to test the capabilities of the EOS 40 with super high ISO values up till 25000. I set the ISO value to "H" (3200) , set the exposure to two (12500) or three (25000) stops underexposed, took the pictures in RAW (or sRAW), processed them with Photoshop CS3 and CS4 (Adobe Raw 4.5 / 5.0) and set the 'Exposure value' to +2 resp. +3. At first the pictures were rather grainy/noisy when I set to 100% view. All I had to do was set luminance noise reduction to high value and a little bit lower contrast. The result was somewhat grainy but for postcard size prints or 15" screen view is is OK. Far better than (noise reducing poocessed) 1600 ISO pictures with the Powershot G9. The latter contain far more chroma noise which the 40d nearly lacks even at ISO 12500. Moreover the pG9 pictures have far less contrast.
The explanation is possibly that the sensor os the G9 is far smaller (7.6x5.7mm compared to 22.2x14.8mm). A full frame SLR will even show better results. The Nikon D700 and new Canon EOS 5 have native sensitivities up till ISO 25000 and can probably be pushed to 50000.
I did not test this on astrophotography yet, but I don't expect much as the sky background may be very grainy (see the flashed picture left above the roof of the building. But 3200 ISO gives good results.

In June 2011 I tested with ISO 200 000 by taking pictures of the garden in deep twilight, the camera recommended 3 sec @ F/4 @ ISO 3200. But I selected 1/20 sec and the pictures appeared nearly black. I processed them in Photoshop CS5 and pushed them to +6 stops. The RAW version (with Adobe Raw) couldn't be pushed more than four stops. And the qualiry of the processed RAW is even worse with a lot of false color. Of course this cannot be used for serious photography, but those are at least usable newspaper quality photos.