Question How do I know what the right aperture setting is?

Nov 14, 2019
I mean, I sort of know what aperture is, but I don't really understand how to tell if I've set it right?
Nov 18, 2019
I'm sorry no one has replied to your question.

Have you learned about the exposure triangle and the three main ways to control exposure? How your aperture and shutter speed and ISO all work together?

Besides helping to control exposure, your aperture also controls the depth of field in your image. The smaller the F number (the larger the opening) then the shallower your depth of field will be. The larger your F number (the smaller the opening) the greater your depth of field will be.

Example, you're photographing a portrait and you want them to stand out, you want the background to be out of focus. Then you might use something around F2.8 for your aperture.

Another example, you're photographing a cityscape, and you want as much as possible in focus. Then you might use something around F22 for your aperture.

So how do you know you've set your aperture correctly? I say it's when you get the exposure and depth of field you want for your image. How do you learn all of this? Some people read, some take classes, some play around with their camera settings until they understand how they all work together. With a digital camera, you'll get instant results and can experiment. If you have Live View it's even more instant! :)

Have fun learning! :)
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Nov 19, 2019
^^^^ Great answer :)

In a nutshell - you're not paying for film. So once you have the basic knowledge - experiment! I learn best by doing.
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Nov 18, 2019
Another example, you're photographing a cityscape, and you want as much as possible in focus. Then you might use something around F22 for your aperture
Generally speaking you should avoid using a such a small aperture. Diffraction will start noticeably softening the image around f13 on crop, f16 on full frame.

Best practice for a standard shot is to avoid going over f11. If you happen to have something close to the camera that falls outside the depth of field then focus stacking is the way to go.

Generally speaking there are a couple of rules of thumb. Avoid shooting wide open, because your depth of field will be ridiculously shallow and few lenses are at their best that way - stopping down a little gives sharper results while maintaining a shallow depth of field that's useable.

Avoid closing past f16 for the reasons mentioned above, unless you're doing something specialised like a long exposure. (Even then I would only use the f16+ shot for the blurred part and composite in a shot taken at a sharper aperture).

Otherwise it's just a matter of remembering that smaller f-number = smaller depth of field and vice versa.
Mar 2, 2020
HI,i too am a beginner, and have learnt the following.
1. Learn the exposure triangle and learn how Aperture, Shutter Speed and ISO all relate to each other (change one and it impacts the others)
2. Choice of aperture then depends on the amount of the frame you want in focus, eg. Portraits you may use an aperture of 2.8 - 4, where you are looking to have the face in focus. Landscapes maybe f11 so more of the frame is in focus. (Depth of Field)
3. Remember the smaller the aperture number the bigger the actual aperture. So a 2.8 aperture lets more light in than an f11 for example.
4. Shoot the same scene using different apertures and this will give an understanding of how it works.

Happy Shooting.
Jul 23, 2020
Based on your needs. Portrait - small aperture value. If you want to see all the details, the aperture should be 8 or more.