Something Odd!

Bryan Peterson described f/8 to f/11 as the “who cares” apertures. In good light I’ll shoot a lot of stuff at that setting, ony stepping up or down for creative reasons – need more blur in the background? Open up to f/5.6 and further.
f/8 is quite often described as the “sweet spot” of lenses. It’s that setting where you’ll get the sharpest image. It’s not the same for every lens but it’s a good place to start!
This thread on the Canon forum covers these issues and more ..

• Moving up and down the aperture settings affects your shutter speed. Some people use f/8, 1/250s when it’s bright enough, only adjusting the ISO to maintain the correct exposure. That’s handy to avoid camera shake, and if things are really dark then sometimes you have to stop down to lower settings.
• Why does every shot have to be “tack sharp”? A little DOF can add a lot to a photo.
• I use f/22 on occasion for those deep images, but I should read up on the diffraction effects that has on light.
• Here’s a depth of field calculator.

Opening RAW files in Photoshop CS2 looks a lot more involved than UFRaw & GIMP. Some things are the same so I’ll have a quick read of this later.

Here’s a small tutorial explaining how to remove the purple fringe that often occurs in high-contrast photos.
It’s Photoshop orientated but may be possible to do the same thing in GIMP even without adjustment layers.