Iím tempted to say that the G9 will be fine at ISO 400 in existing room light for producing screen size images but I actually havenít taken any shots that way myself Ė yet. Iíve had my G9 for two months but most of my indoor shots have been with external bounce flash and ISO 80. Iíll be at a little party tonight so will fire off a few shots at ISO 400 and see what happens. ....
At the party last night I set the G9 on Program mode, ISO 400 and turned the flash off. I also set auto focus to ďface recognitionĒ. Capture was set to raw plus jpg files with auto white balance. I took some pictures myself and also passed the camera around for others to take a few. All in all, most of the pictures turned out OK. As I thought, but didnít know, image quality using existing room light is acceptable to me on a 1200x1600 screen.
The party was actually our photo club exhibit at the local library. The gallery room was somewhat brighter than normal household lighting. The party room was slightly darker than the gallery room. At ISO 400 and in Program Mode without flash, most exposures were about 1/30 to 1/60 second in the general range of f2.8 to f4 aperture.
Comparing the raw images to the in-camera jpg and pixel peeping at 100%, there is certainly visible noise in the raw file but this was expected. The Canon noise reduction routine has acceptably (to me) squelched that noise in the jpg version. The ACR noise reduction settings previously mentioned do a slightly better job on the ISO 400 raw file than the Canon noise reduction in my opinion. (ACR noise reduction is significantly better on ISO 800 noise.)
I was amused to note that face recognition did not always lock in on faces -- often favoring other parts of the anatomy -- but generally worked well and quickly.
Automatic white balance was not particularly good. The lighting was entirely fluorescent and I could have set the G9 accordingly but didnít. Of course, the raw file white balance can be changed after the fact and, as a result, the raw images have the correct, and more consistent, color balance.
It has been very interesting to see the pictures that other people took with the G9. All the pictures I took came out OK. My operating procedure is to always push the shutter button halfway (thinking ďfocusĒ), see the confirmation, recompose if necessary and then finish pushing the shutter button. Obviously, most people using the G9 last night simply pushed the button. About half of those pictures are blurred from camera movement; strangely, many of those also seem a bit underexposed. The G9, like many (all?) of Canonís digicams, definitely exhibits shutter lag but, not being particularly quick myself, Iíve learned to work with it.