This attractive scene was especially arranged for purposes of testing G9 and G12 at high ISO. The G9 and G12 were tripod mounted and set for 2 second shutter delay to minimize camera shake. Cameras were set in Av mode at f4 and zoomed to produce roughly the same composition. The picture above was taken at ISO 80 with the G12 at 0.6 second exposure. The picture below is at ISO 3200 with the G12 at 1/60 second. All images in this post are from the in-camera JPEGs.
At first glance, the G12 ISO 3200 shot is nearly indistinguishable from the ISO 80 shot – especially for these reduced and compressed images. (Click on the images for an enlarged but not full size view.) The image below is from the G9 at ISO 1600 and 1/40 second.
As noted by DxOMark, the actual and indicated ISO are different for the G9 and G12. For purposes of testing, I decided to first use the G9 at ISO 800 and 1600 and then adjust the ISO of the G12 to produce the same exposure as the G9. The corresponding G12 ISOs were 1000 and 2000 but this turned out to have a relatively minor effect.
Yielding to the temptation to pixel peep, the image below is 100% crops at ISO 800 for the G9 and 1000 for the G12, click for a larger image.
Even though we know not to pixel peek, doing so shows that higher ISO produces noisy images. The noise is even worse at ISO 1600 for the G9 and ISO 2000 for the G12 as shown below.
From the 100% crops of high ISO images, one would think that prints would be terrible but I printed a full frame 8x10 of each shot and they were all surprisingly better than expected. I made a game out of guessing the camera and ISO for each print and included ISO 800 and 1600 for the G12. Although I sometimes confused G12 ISO 800 vs 1000 and G12 ISO 1600 vs 2000, I usually got the ISO order approximately correct and could always sort out the G9 prints from the G12 prints with careful examination. What I'm trying to say is that at first glance all the prints looked OK but there are differences. I suspect that a casual observer would not readily detect the difference between a G9 ISO 800, G9 ISO 1600, G12 ISO 1000 and G12 ISO 2000 print but I'd like to think that the ISO 80 and ISO 3200 prints would be noticed by most people.
So, what to make of all this? It is obvious to me that the G12 produces better high ISO images than does the G9; in fact, I'd say that the G12 is about one “stop” better than the G9. That is, if ISO 400 is OK on the G9 then ISO 800 is OK on the G12, etc. I'll try to stay at ISO 800 or less on the G12 but for casual snapshots even ISO 1600 is probably OK.
With the release of Adobe Camera Raw for the G12, I hope to make further reductions in noise by shooting in RAW – more later.