how do decide which lens to use for a given shot

[stradibarrius]

When you decide to take a photo, how do you decide which lens in your bag to use? to be a bit more specific...ex. a table top shot where you could use a longer lens from a farther distance or a shot focal length and be closer to the subject.
You could use a 150mm at x distance away or a 300mm at x+ distance away.
Assuming both lenses are of equal quality, contrast, sharpness etc. I know that in portraiture shorter lenses will magnify certain features but subjects other than portraits.

[Will Frostmill]

The rule of thumb is in two parts:
1. The longer the lens, the further back you need to be to fit everything in.
2. The further back you are, the less difference you'll see in size between the things you are photographing. (This is a property of perspective, not lenses.)

So if you set up a bunch of identical bottles on a table for a still life, and frame it so that they fill the viewfinder/ground glass, with a "normal" lens, the bottles toward the front will seem a little bigger than the ones in the back. With a "short tele" lens, the bottles in the front and the ones in the back will seem to be the same height. This is why the convention is to use a short tele lens for portraits: you don't want to accidentally magnifiy someone's nose relative to the rest of their face. (This isn't always good advice.)

Another way to think about it is this: if you keep the framing the same, a shorter lens magnifies things in the foreground much more than a longer lens. The longer lens magnifies everything equally.

Using a longer lens can make some things look unnaturally flat and weird, particularly once you get beyond 200mm in 35mm film terms.

[Heroique]

When you decide to take a photo, how do you decide which lens in your bag to use?

Here's a great tool to help determine which lens is "best" for your image:



This is AA using his viewing card in The Camera – it’s from the "Basic Image Management" chapter. He calls it the cut-out card. He can be so literal sometimes.

Forum members here also call it the "viewing frame."

Me, I've taken fewer & better shots because of it. Yet, some of my best shots happened because I didn’t bring it, or I put it aside. (Never would this cause me to abandon its use.)

I'll just say that the frame, on one hand, is supremely useful in isolating elements in a scene by imposing borders roughly corresponding to the field of view of a particular lens. It makes choosing the best lens a lot easier.

On the other hand, its usefulness potentially blinds me to additional means of pre-visualizing. If I’m not careful, it monopolizes too much of my attention – w/o my awareness that it's doing so.

I made mine w/ a mat cutter and leftover piece of mat board, so I’ll add "cheap" to tiny, light, and useful.

[Old-N-Feeble]

1. What are the limitations regarding camera placement?

2. How to I want the main area of concern (foreground or background)... to relate to the other?

3. After 1 and 2 are answered: What kind of effect best suits the subject?

[Light Guru]

You choose the one that will give you the image you have in your mind.

[neil poulsen]

I first determine the camera position, depending on the object, direction, near to far relationships, etc. I append this process with a Computar zoom, viewing frame to frame and compose the image. I have marks on the Computar to determine which lens to use. It's pretty straight forward.

The Computar is kind of neat. It's an optical zoom, versus the Linhof viewer, which is a mechanical zoom. The computar was designed for a 3x4 ratio. But by opening it up and masking it a little more tightly, I get a good 4x5 framing tool. In focal length range, the Computar gives me from about 110mm to close to 450mm.

One can also use the Linhof viewer as well.

What I absolutely hate is trying to frame with the camera, putting one lens on, focusing, changing to another lens, back again, etc., and it's taken me fifteen minutes (or more) to compose the image.

[stradibarrius]

It seems "Will" understood the question more in line with the way my crazy mind works. To state the question another way for example I can use 150mm lens to fill the frame at say 5 feet...or I can use a 300mm lens which at a great distance, say 15 feet, will give me basically the same framing... how would you select a lens?

[Ken Lee]

A web search for "lens perspective" or "focal length example" will result in a lot of images which illustrate the change of perspective we get by selecting focal length and then moving closer or farther to retain subject size.

Here's a nice one from https://bakerdh.files.wordpress.com/...5/allsmall.jpg

[mdarnton]

Stand where you get the perspective you want, then choose the lens that will outline the boundaries of what you have decided you want in the photo, and will crop out what you don't want.

[Mark Sawyer]

Short answer: I consider how much I want to expand or compress the space.