exosure compensation settings on s400...am i right on this?

[Alec006c]

I just got back from shooting a concert with my s400, and based on the shutter speeds and other info i can pull off the files, it seems to me like adjusting the exposure compensation in manual mode is like changing the f-stop on a regular SLR camera...is this right? i found that when i kept the iso at 200, and moved the exposure compensation from +1/3 to +2/3 the shutter speeds droped from around .7 seconds to around 1/6 or 1/8 of a second. Anyway for anyone whose curious about the results is posted on the the best pics that i got, (i did minor postprossesing in photoshop including darkening and bluring the backgroud to eliminate noise)

http://images.fotopic.net/?id=2565838&outx=600&noresize=1&nostamp=1

[Alec006c]

ps...shoud have proofread my own post...the end of the message should say the results are posted at....

[Tom W]

Actually, the ISO setting is designed to mimic the various film speeds available. ISO 100 roughly matches 100-speed film, ISO 400 matches 400 film and so on.

There are 3 camera variables that control the light situation on a camera. Aperture (or f/stop), shutter speed, and sensitivity. The ISO is the sensitivity. When you double the sensitivity, such as when you change the ISO setting from 100 to 200, your camera will automatically double the shutter speed, or stop down the aperture (note that the S-400 has a rather unique aperture function that isn't really a variable aperture at all) so as to create the same approximate image.

So, indirectly, changing the ISO does have a similar effect of changing the f/stop as far as light and shutter speed are concerned, but it doesn't change depth-of-field like an actual aperture change would do.

The end result is that in low light, use a higher ISO setting (just as you would use faster film in low-light conditions) and in daylight, use the lower ISO rating. Note that while the higher ISO gives you the ability to work in darker environments, it does introduce noise (or grain) to the picture.

BTW, that's a nice picture, especially since it was taken in a difficult environment.