Any trick to choosing the right aperture??

Joined: 03 Aug 2006 Posts: 254

Hey everyone...

I'm fairly new to photography but I've read numerous instructional articles about F-Stops and Shutter speeds and even saw the calculator...but I somehow never choose the right aperture for my pictures...

I usually am taking portraits and just end up going with whatever aperture will accommodate the quick shutter speed in that lighting. But my photos are missing that sharpness.

I am using an 18-55 lens on the Nikon D50...

Is there any "trick" to choosing the right aperture..??

Joined: 14 Jul 2004 Posts: 374 Location: Georgia

Well this could be a long tutorial but Ill try to give you something in a few sentences. The aperture, like the shutter, controls how much light hits your film or sensor. So a smaller fstop number (like f5) lets more light in than say an f22. The aperture also controls depth of field which is sort of the amount that is in focus in your picture (read more on that). A smaller fstop number like f5 will have less DOF where as a larger will have a more depth of field (f22 would cause most everything to be in focus like a pinhole camera). Hope this helps somehow.

Joined: 03 Aug 2006 Posts: 254

Thanks for the response, but I know all that...

I still can't seem to choose the right aperture on the spot. I never know what will work.

Posted: Thu Nov 08, 2007 9:58 pm

Sharpness is not a factor of f/stop. In short, your focus point will be sharp regardless of the aperture. What will vary is how much is in focus in front and behind the focus point or plane. In other words, if you focus properly, then the image should be sharp.

Now to the choice of f/stop. Like anything, the f/stop and shutter speed are always a comprimise. You always have to play one against the other. How to pick the right aperture comes with experience. In short, you have to decide what is more critical to get the shot right, shutter speed or aperture. For example, if I want to shoot with a shallow DoF then I set a wide aperture with a long lens. If I need to bring the shutter speed up, I add light. eg. with flash.

In the end, if your shot is not sharp there can be various causes but aperture is not one of them. Here is a shot that was shot at f/10, if memory serves. The reason it's sharp, however, is not the aperture. It's the fact that the shot was well focused on the eyes and that the photo was properly sharpened in post process.