Image Size / Quality
The 990 offers an almost baffling array of different image sizes and quality settings. At the lowest end we have VGA (640 x 480) and XGA (1024 x 768) up to the full size of 2048 x 1536 there's also a 3:2 ratio image size of 2048 x 1360. All of these image sizes also offer three JPEG quality levels (Fine, Normal and Basic) plus an uncompressed TIFF mode (Hi) at 2048 x 1536 and 2048 x 1360.
Standard Test Scene
To give a good 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 downloadable for each, all images were shot within seconds of each other of the same subject. Please note that the TIFF images are VERY large (9.2 MB & 8.2 MB) please only download these images if (a) you really need to and (b) you have the bandwidth and intend to fully download the image, otherwise you're wasting bandwidth.
Camera settings: ISO 100, Aperture Priority, Metering: Matrix, F8.0, Focus Locked, Sharpening: Normal, White Balance: Cloudy, Measured light: 10 EV. Crops below have been expanded 200% for clarity (no resampling).
|Size / Quality
||Hi TIFF (1:1)||Fine JPEG (1:4)|
|2048 x 1536|
|9,287 KB (Zipped: 7,043 KB)||1,011 KB|
|2048 x 1360|
|8,231 KB (Zipped: 6,272KB)||901 KB|
|1024 x 768||n/a|
|640 x 480||n/a|
|Size / Quality
||Normal JPEG (1:8)||Basic JPEG (1:16)|
|2048 x 1536|
|667 KB||387 KB|
|2048 x 1360|
|595 KB||347 KB|
|1024 x 768|
|287 KB||161 KB|
|640 x 480|
|70 KB||50 KB|
What becomes obvious from these samples is that JPEG compression becomes less of an issue as image sizes increase. At 3.3 megapixels even high compression doesn't show up significant artifacts. For typical shooting you could easily use NORMAL mode, switching to FINE mode for the occasional special shot. TIFF mode is hardly distinguishable from FINE but may be useful in the studio.
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 it's price however and doing so also amplifies any noise that may be present. Below are three images, in order ISO 100, 200 and 400.
Camera settings: Aperture Priority, Metering: Matrix, F5.7, EV Comp +0.3, Focus Locked, Sharpening: Normal, White Balance: Cloudy, Measured light: 5 EV.
|ISO 100, 1.4 sec||ISO 200, 1.0 sec|
|ISO 400, 1/2 sec|
Putting the 990 in Auto ISO mode it will automatically adjust the ISO for low light circumstances. To my eye noise has been improved slightly since the 950, using higher ISO's in good light will give you high shutter speeds and good quality images, however using them specifically for lower light will still produce visible noise. That said colour rendition is still good and there are techniques for removing noise.
The 990 features a range of image adjustment which are applied after the image has been taken, the effect of the adjustment is displayed in the LCD preview before you shoot. Below are six samples representing the six possible Image Adjustment modes.
A note: I have heard from a reliable source that the Contrast and Brightness controls on the 990 are different the the 950. They are more like the S curves in Photoshop's Curves menu for brightness and more like gamma curves for contrast settings. This means that anything they do in camera is likely to NOT reduce the dynamic range of the saved image.
Camera settings: ISO 100, Aperture Priority, Metering: Matrix, F5.7, EV Comp +0.3, Focus Locked, Sharpening: Normal, White Balance: Cloudy, Measured light: 9 EV.
|Auto Image Adjustment
|Lighten Image (Brightness +)
||Darken Image (Brightness -)|
|Black & White
For me these effects are little too strong, there could have been an "effect level" setting. In this scene we can't see any significant difference between Auto and Normal mode. Personally I'd leave this in Normal and adjust the image later, but it could be useful for on-the-fly shots which won't be post-processed.