Having used the GF1 for over a week, I am quite satisfied with its image quality. But frankly, the major IQ (image quality) improvement for this larger MFT sensor over the tiny sensor fitted in my GX200 is the dynamic range. See for yourself by comparing the jpeg and Raw files of the GR1 and GX200 posted in the previous post here.
As for high ISO images, If you're hoping that the GF1 affords a much supreme quality, adjust your expectation a bit.
For me, I have no complaint about the GF1's IQ at even ISO 800. But at full-screen size, the ISO 1600 images are obviously smeared and the ISO 3200 ones more smudgy. Surely, they are better than those of the GX200, which is not known for good high ISO image quality.
I have briefly compared the ISO images of the GF1 to those of the CX1 and the Canon 500D (with a 50mm equiv. f1.8 prime lens). Generally speaking, at full-screen size, CX1's ISO 800 images are a little worse than GF1's ISO 1600 ones, while Canon 500D's fare better.
So, the high ISO IQ is not really ace for the GF1 but unless the high ISO values are used a lot, it is certainly not a deal breaker. And in prints, I doubt if this will make an issue.
The following full-sized images were taken at various ISO values for your reference:
If you're are struggling between a larger- or smaller-sensor serious compact to fatten up your camera cabinet (and flatten your wallet), you should yet factor in other considerations:
-- the GF1 gives a regular (shallower) DOF making it less desirable for street photography, for which the technique of using a large aperture to achieve a higher shutter speed (and to avoid a high ISO setting) becomes not fitting;
-- the mirror-less GF1, to my surprise and its disadvantage, gives a very audible mechanical shutter sound when the shutter release is fully pressed (3 clicks here), rendering it less suitable than a small-sensor compact for doing candid pictures. Your subjects can certainly hear the loud "click" which cannot be turned off;
-- the GF1 is heavier and "bulkier" and, despite of a grip, requires two-hand operation;
-- at least to me, the main idea of a serious compact is doing good photos in a snappy way, without the burden of a regular DSLR. Well, IMO, the fact that GF1 requires changing lens aligns it closer to a DSLR. If the GF1 is not a loan item but my acquisition, and on account of such a camera's vulnerability to dusts, I would certainly have been more conservative about changing lenses under a lot of circumstances. Take for example, the sky showers lightly; on a dusty street; under the dark sky when changing lenses become very clumsy and risky as one item or two can be more likely dropped. Well, then, I would have missed lots of shots.
I am not putting these up to say that GF1 is not a good camera; it is. But the small-sensor serious compacts have their own advantages especially if street photography is your cup of tea. And for this reason, you may not wish to buy one at the expense of the other.
If you are using a small sensor camera and don't have a proper large sensor camera or are fed up with the regular heavy gear, the next one you need is a camera like the GF1 – without shedding the small sensor camera maybe.
Apart from giving the photographer a fuller photographic experience, the GF1 has some well thought-out functions to my liking. I'll write about them in the next post.