Quote:
Originally Posted by daveb867
i was switching between the different presets to help me get exposure right, but when i check the settings on each one, the f-stop seems to be set at 2.8 regardless of which setting i choose, it only seems to be the ISO and shutter speed changing for each preset??
surely the f-stop will change aswell?????
but then again i have heard that i can leave the shutter and ISO at the same value and then just alter the f-stop????
and then i've heard i can adjust all three??
once again i'm confused 
with regards to my digital camera, the setting of f2.8 means my aperture is open quite wide therefore letting a lot of light in. but i also read that the lower the f-stop number then the blurrier the image will be, unless compensated for with the other values? |
Finally something I know about!!
The lower the f/stop the more light is let in, and the DEPTH OF FIELD is shorter. So, if you are shooting a photo of something that is very deep, or many of them, then some will be out of focus.
The lenses on ..er.. less-than-higher-end digital cameras aren't the best in the world optics wise, and the electronics aren't that smart either.
So if they make one variable ..er.. constant (i.e. keep the f/stop the same), then it'll help the camera figure out how to properly expose the scene.
Also, the majority of 'fun pics' are taken in dark settings - night time fire works, pubs, clubs, etc - so it helps to have the f/stop cranked as open as you can.
In the real world, the iris valve (f/stop) will open and close a whole lot. In the scene described above, the aperature would have been fairly open, but when he turned around it would have cranked closed a lot to stop most of the (excess) light from getting through.
In a film camera, you'd never vary the ISO - it's set by the film manufacturer!
Rule of thumb:
ISO 64 = outdoor
ISO 100 = outdoor
ISO 200 = indoor/outdoor
ISO 400 = indoor
ISO 1600 = indoor, in a dark closet, taking a photo of an ice cube with the lights turned off
Generally, I'd leave ISO alone (use the guide above), the shutter on 1/30 or 1/60 (1/30 is the de facto slowest you can go without a tripod or flash) and play with the f/stop. When you run "out" of f/stop, play with the shutter speed.
Hope that helps.