Choosing the aperture

[480sparky]

........

My (many many) questions now are:

• How would you/do you choose your aperture?

My default first option will be the sharpest aperture the lens will give me (at a given focal length if it's a zoom).

•Do you almost never use your lens wide open because you (probably) don't get the sharpest image? If so: did you just test what's the sharpest image?

I test every lens I buy myself, and determine how each aperture performs. Knowing THE aperture the lens will perform best is a starting point. As I know the sharpness characteristics of the various aperture settings of each lens I own, I know which which setting to start out with for best results, which settings will give me acceptable results, which settings will give me so-so results, and which, if any, settings to totally avoid.

• If you use a prime lens like the 50mm f/1.4 which aperture do you use to get a narrow dof? Since there's a kinda wide range of apertures which lead to a narrow dof (1.4, 1.8, 2, 2.2, 2.8,...).

Depends on the situation. If I'm shooting a static subject, I can afford to take my time. But if I want a shallow DOF and the subject is moving rapidly (sports, for instance), I may choose to close the aperture a stop or too to maintain focus. This may bring the background closer to being in focus, but that's a fair trade to make sure the subject isn't blurry.

• Or do you "know" which aperture is best for the current situation?

Pretty much.

• Do you make a lot of pictures and compare later?

No. Not for DOF, at least. I may bracket for exposure or focus, but not for DOF.

• What if you have to be quick? If I want to take a foto of two persons and I want both to be in focus but still separated from the background, which aperture should I use?

Too many unknowns here to answer. 50mm? 28mm? 200mm? How far am I from the closer subject, and how far away is the other? And how far to the background?

• If I don't really need a narrow dof (like when the object doesn't have depth, like a wall), which aperture should I use?

The known 'sweet spot' aperture.

• If I want a wide dof, which aperture should I use?

What is 'wide' dof?

 

[cynicaster]

I try not to overthink it. Practice makes things come pretty naturally after a while, and every little shoot you do, you learn something from the results.

How would you/do you choose your aperture?

I know it's crude, but I normally think of DoF in the (admittedly vague) terms of deep, shallow, and medium. Normally, selecting one of these vague concepts for a given shot will suffice, at least for me. As quick examples, I'd use "deep" for most landscape shots, "shallow" for a portrait of a single person, and "medium" for a shot of 2 or more people that are at slightly different distances from the camera. Experience using my lenses tells me what the aperture needs to be in order to get what I want. The trickiest part of this is that you have to get a feel for how DoF varies with distance of the focal plane from the camera.

Do you almost never use your lens wide open because you (probably) don't get the sharpest image? If so: did you just test what's the sharpest image?

I never shoot wide open, as the lack of sharpness bugs me, at least with the cheap-o lenses in my bag. I'll only do it if it's the only choice that will allow me to get a photo--for example, if I'm hand-holding in low light and flash isn't allowed or isn't practical.

If you use a prime lens like the 50mm f/1.4 which aperture do you use to get a narrow dof? Since there's a kinda wide range of apertures which lead to a narrow dof (1.4, 1.8, 2, 2.2, 2.8,...).

See my comment on deep, shallow, and medium. There are too many variables to simply "know" what the DoF is down to the inch, so just focus on developing an instinct for what is needed. I have the nifty-fifty, and when I use it, I try to stop it down at least one full stop, maybe 2. In my experience, there is a noticeable bump in sharpness over f/1.8 by doing this.

Or do you "know" which aperture is best for the current situation?

See above

Do you make a lot of pictures and compare later?

Best way to learn!

What if you have to be quick? If I want to take a foto of two persons and I want both to be in focus but still separated from the background, which aperture should I use?

I struggled with that question too, and kind of still do, to an extent. If light permits, I'll go to f/8-f/11 but I've had good results with f/5.6 as well. Again, depends on how close the people are to being on the same "plane", how much light you have, whether flash is being used, and how far away they are from the camera.

If I don't really need a narrow dof (like when the object doesn't have depth, like a wall), which aperture should I use?

Set it to the "sweet spot". The best way to determine what that is would be to set up an experiment yourself, but in lieu of that, do a bit of research on the net for your particular lens. Most "non-pro" lenses seem to be at their best somewhere between f/8 and f/11. Not only that, but the zoom lenses also have a sweet spot in the zoom range. For example, I keep my 18-55 kit lens to 35mm all the time and use my feet to move in and out, unless that is simply not possible.

If I want a wide dof, which aperture should I use?

This question is unanswerable in a general way, but I'll say this: it might be tempting to crank it down to f/22 or something, but you might be surprised at how much DoF you can get at f/13, depending on the situation.

 

[ktan7]

You will really need to test out each 1.2, 2.0. 2.8. 3.2... to see which works best for you. For objects, try to use the highest aperture to isolate your subject. Usually, you would like a smaller aperture (ie. greater than 4.0) for a group shot.