JPEG/TIFF Image Size & Quality

The Pro90 features ten different resolution / size combinations. In RAW mode you shoot only at 1856 x 1392, in JPEG you can choose from compression settings of Super-Fine, Fine and Normal at sizes 1856 x 1392, 1024 x 768 or 640 x 480.

Standard Test Scene

To give an impression of what each combination of image size and quality produces the table below is a cross reference of image size against quality with an original image available for each, all images were shot within seconds of each other of the same subject. We've resaved the RAW shot as a TIFF for the purists out there who want to see what a RAW file would look like up-close, we have made the original RAW file (.CRW and .THM) available if you wish to manipulate the RAW file (you can use the downloadable G1 or D30 TWAIN modules they appear to work fine with these RAW files).

Sections below are 200% magnified crop of a 240 x 100 area of the image.

	1856 x 1392
RAW	Acquired and saved as 8-bit TIFF (4,686 KB) / CRW and THM
SUPER FINE	1,471 KB
FINE	787 KB
NORM	372 KB
	1024 x 768
SUPER FINE	535 KB
FINE	282 KB
NORM	144 KB
	640 x 480
SUPER FINE	235 KB
FINE	129 KB
NORM	69 KB

Difference between Super-Fine JPEG and RAW? If you simply import the RAW files as is (using the camera settings) it'll be extremely difficult to see any difference between Canon's excellent Super-Fine JPEG (very light compression) and RAW. However, RAW provides lots of flexibility you can't get out of JPEG, you can alter the white balance, contrast, sharpening or saturation settings before importing, something impossible with JPEG. That's because the RAW files are simply that, raw data which has come directly from the camera's imager (CCD) before any in-camera processing has taken place, this can be seen as the true "digital negative".

For more information on RAW files read the page I wrote for the G1 review (everything written there applies to the Pro90's RAW files).

ISO (Sensitivity) Adjustment

ISO equivalence on a digital camera is the ability to increase the sensitivity of the CCD to allow for faster shutter speeds and/or better performance in low light. The way this works in a digital camera is by "turning up the volume" on the CCD's signal amplifiers, nothing is without its price however and doing so also amplifies any noise that may be present and often affects colour saturation.

As with the G1 the Pro90 offers a cleaner, slow ISO of 50, it obviously requires well lit situations and enables the use of large apertures (small F number) in even very brightly lit situations. Below are crops from four samples, in order ISO 50, 100, 200 and 400.

ISO 50, 1/10s, F2.8

ISO 100, 1/20s, F2.8

ISO 200, 1/40s, F2.8

ISO 400, 1/50s, F3.5

As we saw on the G1 there's a progressive (expected) increase in visible noise from about ISO 100 upwards, ISO 50 being very clean (but only useful in good light). I'd say there seems to be a little more noise at ISO 400 than on the G1. If you use AUTO ISO the camera will automatically choose either ISO 50 or ISO 100 depending on available light.