Night exposures / Noise reduction
The DSC-F717 now extends its automatic noise reduction for all shutter speeds slower (longer) than 1/25 sec. For long shutter speeds (such as 1 second or longer) the camera appears to implement a dark frame subtraction noise reduction, this works by taking an equally long 'dark frame' after the main exposure and using that to subtract 'hot pixel' noise from the image.
The DSC-F717 allows for timed exposures of up to 30 seconds with impressive results. There is no visible noise nor 'black pits' where the camera has removed hot pixels. Overall very impressive. I did do a couple of Night Shot tests of this scene but it is far too dark (even at ISO 800) to capture anything useful. Night Shot is really only useful where the Night Shot lamps can illuminate the subject.
|15 sec, F2.8|
|30 sec, F4.0|
Barrel and Pincushion Distortion
The F707's otherwise excellent lens did exhibit slight barrel distortion at full wide angle (38 mm equiv.), this isn't that surprising. At full telephoto (190 mm equiv.) pincushion distortion was measured as approximately 0.9% which is about what I'd expect of a 5 x lens and is actually a little better than the F505V.
|1.1% Barrel Distortion at wide angle||0.9% Pincushion Distortion at telephoto|
Purple Fringing (Chromatic Aberrations)
Like all long zoom lenses the F717 does exhibit some slight purple fringing (chromatic aberrations) but to be frank these are limited to shots taken at wide open apertures or long zoom. You'll need a strong bright object against a darker background too. In our experience the DSC-F717 didn't often exhibit easily noticeable chromatic aberrations.
|Some purple fringing lens artifacts at full telephoto at the edge of the frame|
|Our now standard chromatic aberration test shot, some moderate fringing|
Overall Image Quality / Specific Issues
The DSC-F717 repeatedly produced sharp, detailed images with great dynamic range and good automatic white balance (under natural light). Colours are definitely less saturated and more accurate than we saw on the DSC-F707 and for this Sony should get an extra Kudos. Colours are now accurate and still well saturated providing images which look good straight out of the camera with very little post-processing required. The F717's has a very good lens, this was clear when we reviewed the F707 and we're glad to see Sony has stuck with this great lens.
Unlike most digital cameras we review I had no specific image quality issues with the DSC-F717. Certainly we observed overly saturated reds on our pre-production DSC-F717 but I'm glad to report that these appear to have been addressed in the final production camera.