Aperture on Cameras pt. 2

Chris Lane / Camera parts, Training / / 1 Comment / Like this

Used to be…

Minolta X-700 with lens
Older SLR (single lens reflex) cameras, pre-digital info screen, had aperture adjustment on the lens itself. The image shows an example from my Minolta X-700 with a 50mm f/1.7 lens, made in 1983. This camera does, however, have a full auto setting, so that it can adjust the aperture for you. Unfortunately, you cannot tell what it is adjusting to without the digital screen that the somewhat more modern film Canon Rebels had. Through the viewfinder, the only display is the light meter and a little mirror that shows the aperture setting on the lens. Also notice on the lens, the adjustment is in full stops.

Now-a-days

Top View of the Canon 40D
With modern SLRs the adjustment is all done in camera. The easiest route is to go with full-auto or A-DEP (auto depth-of-field) but I recommend against this. Because it is automatic, you have no control over what the aperture is doing and thus no control of the depth-of-field. A-DEP doesn’t really seem to work, in my opinion, as you can see in the following images. These are all of the same subject and the A-DEP came back with a variety of different aperture settings.
A-DEP examples

In this image, I changed the shot angle thinking maybe that would give me a different option. Either way, the A-DEP always came back with far too high an f-number. One other problem with A-DEP is that you cannot choose the focus point. The image on the right is what I wanted. Which do you prefer?
A-DEP vs. Manual aperture setting

The next route is using Av (aperture priority). This is where you can set your aperture manually and the camera will set the shutter speed and ISO automatically. This is a pretty good choice for beginners trying to work with aperture or anyone needing quicker adjustments (opposed to full manual) when they are only concerned about the aperture setting.

Finally, M (full manual) setting gives you full control of everything the camera is doing, in particular, the aperture.

Whether you use Av or M at this point, it doesn’t really matter. I almost always use full manual because I like the control, though this is at times slower, especially if you don’t know the camera really well. Just keep in mind if you are using Manual, you will have to keep an eye on the exposure indicator as well as your aperture and adjust accordingly.

If you read my last post, you already know that modern camera apertures depend on the lens attached and just move up from there in 1/3 stop increments, such as f/2, f/2.2, f/2.5, f/2.8 and so on. And also remember that the lower the number = the wider the aperture (or hole) = the shorter depth of field. I made this diagram to try help with the concept; whether it helps or not I’m not sure.
aperture diagram

Aperture Preview

Another thing to keep in mind, when you are looking through the viewfinder of your SLR, which is a through-the-lens (TTL) viewfinder, the aperture is in the full open position, or f/whatever your lens rating is. After you set your aperture to anything else, f/8 for example, there is a button on the side of the camera next to the lens mount that gives you aperture preview. This way you can see the depth of field that the photo will have, once taken. The problem with this, however, is that the lens will allow less light to enter the camera and the preview will get darker as the aperture decreases, becoming quite dark and rather useless once you hit f/22 or so.
aperture Preview button

A lot of times I shoot at a very low aperture; quite often the lowest I can go with a particular lens. With this, I have to be careful that my focus is right on, and if the aperture is large enough, make sure that my subject doesn’t move, effectively moving the focus at the same time. But it changes depending on the subject matter I am shooting.

A very short depth of field is quite effective when you want the focus of the viewer to go directly to a particular place, such as the eyes of a person, or a single person in a crowd. A long depth of field is important when taking landscape shots and things of that nature. I will go into depth of field particulars in another article.

Point-and-shoot cameras

Unless you have a higher-end point-and-shoot camera, such as a Canon Powershot SX10, you often can’t directly change the aperture. If it can, then you can just follow the direction in the same manner as SLR cameras. Most point-and-shoot cameras generally shoot at a fairly high or mid-range aperture, probably between f/8 to f/16. In researching this article, I found that my wife’s Olympus FE-330 said it was shooting at f/3.5 and f/4, which shocked me because the depth looked more like f/16. This is why you can almost always tell when a cheaper camera is being used, far too much is in focus in the photo.

One way that you can make your point-and-shoot camera look like it is taking a shot like a more expensive camera is by shooting in Macro or Super-Macro mode and getting really close. It also helps to have any background elements as far away as possible. Obviously, this is rather limited, though.

One more point, that I will go into more in the future, is that pin-hole cameras, which are simply boxes with a tiny hole in the end and film on the other, always have a very narrow aperture, usually much smaller than a typical camera lens. They give an incredibly long depth of field that is almost eerie.

What kind of camera do you use and what do you set your aperture to typically? What is the lowest f-number lens that you own? If you have any other comments or questions on this topic, leave them below.

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