A couple of unrelated Digital Photography Questions - fun, and informative.

[Sean Dempsey]

Questions build up in my head over time. And I like to come here to hear what others say. So here goes.

Question 1:
What is the technically accurate way to refer to aperture and changing aperture? Whether its in Tv or Av, or in M. For instance, if I am shooting something, and I want the little exposure compensator meter to move to the left (negative numbers), am I "stopping" up or down? Am I using a higher or lower aperture? Am I opening or closing?

And the same goes for moving the little exposure indicator to the right. I always say something different, and luckily my camera friends don't know any better. I know what it does to the image, I just want to know that if I am, say, wanting to overexpose someting a bit, what am I doing to the stops of light, and the aperture?

Question 2:
On the 10D, should 100 ISO be used as much as possible? Is it the most noise free? Typically I shoot everything at 100 ISO and use the IS or a tripod to overcome situations where the shutter is slow. Rarely if ever do I go above a 200 ISO.

Am I misguided in this? Should I be using the 200 and 400 ISO settings more often? Or if a shot can be acquired with 100 ISO, will that produce a higher quality image?

Thanks!

[another view]

Going from f8 to f11 (for example) is "stopping down". Going from f8 to f5.6 is "opening up". That's my slang, anyway!

Generally, just like with film, you want to shoot at the lowest ISO you can get away with. If you can get the shot with ISO100, then use it because it will be there will be the least noise in the file that way.

There are a lot of reasons you might use a higher ISO though - I often use up to ISO800 with my Fuji. For example, maybe you can't get a sharp shot handholding at ISO100 because the shutter speed isn't fast enough; you can get a sharp shot but have to shoot wide open and need more depth of field; need a faster shutter speed to stop action; need more distance from your flash; all kinds of possibilities. Be careful working with high ISO files in Photoshop though, sharpening the whole image can really make the noise stand out more - especially in dark areas.

[berrywise]

I always thought is was kinda messed up how when you stop down you actually go up to larger "numbered" f-stop.

Here is a good table dealing with what is going on with your aperature when you compensate either direction.

http://www.fineart-photography.com/fstop.html

[Michael Fanelli]

And the same goes for moving the little exposure indicator to the right. I always say something different, and luckily my camera friends don't know any better. I know what it does to the image, I just want to know that if I am, say, wanting to overexpose someting a bit, what am I doing to the stops of light, and the aperture?

Exposure compensation depends upon the mode. If you are in Av, you have chosen an aperture. The camera will change the shutter speed. If you are in Tv mode, you have chosen the shutter speed so the aperture gets changed. In manual mode, exposure compensation is useless as you have full control to change anything you want.

This may be obvious, but moving the exposure compensation to the "+" side lets in more light, that is, longer shutter speed or wider aperture. The opposite occurs when it is moved to the "-" side.

[Michael Fanelli]

I always thought is was kinda messed up how when you stop down you actually go up to larger "numbered" f-stop.

Simple! The f/stop number is the ratio of the lens focal length to the diameter of the aperture. Optics defined this and the definition pre-dated cameras. This means that the diameter of the aperture is an inverse proportion (the aperture diameter is on the bottom). As the bottom gets large, the entire fraction gets smaller.

[berrywise]

And that is why photography lingo was not made for the common folk I guess I should have stated that I understand why it is but to me it never has made it easy to explain to people who have asked.

Heres something to do, a photography quiz:
http://www.funtrivia.com/quizdetails.cfm?quiz=133168

[another view]

Heres something to do, a photography quiz

OK, I tried. 12 out of 15. Back to the books! Oh well. Some of the answers could be argued, like most of photography. That's my story anyway...