Originally posted by Mark DeB Thank you, that explains it very well and is very clear! I appreciate it. I see now that it actually adds just one button push to the procedure, not complicated at all. Thank you for those references to the User Manual. I had seen the information contained on p. 182, but there it refers to the DOF preview and it is not explicit about what happens when you do it. Just curious, does DOF preview do the same thing as AE-L (in this context), or something different?
I don't have a *istDS2 specifically, so there's a slight risk things might be different, but with my cameras the DOF preview does just that, it provides a depth-of-field preview in the viewfinder for as long as you hold the switch in position.
It may also show a suggested (preferred) exposure reading and/or compensation in the viewfinder, but I it doesn't actually changes the shutter speed.
On later cameras the DOF switch can be configured to provide either optical depth-of-field in the viewfinder or Digital Preview on the rear screen, but this isn't an option on the *istDS2.
The AE-L button, on the other hand, closes the aperture just briefly to read the light but it then also changes the camera setting.
The two functions are similar in operation, but achieve different purposes, so best considered separately to prevent confusion
Once you get used to it, it really does become second nature quite quickly, but I still rely on my
"F A S T" mantra … just in case