When to use different lenses?

[Tim Davison]

Sorry for the obvious question but, when using prime lenses, is it simply a case of what focal length is required? (i.e. if in small space use a small wide angle lens (e.g. 28mm) and if far away from subject use an 85mm lens?)

[Jean-Philippe Archibald]

Not just that, the differences in angle of view and depth of field caracteristics allow for differents compositions depending of the lens used.

[Tim Davison]

Thanks for your reply. Could you elaborate a bit on what you mean by 'angle of view' and 'depth of field characeristics'? Do you know any links that show comparisons between shots that can be achieved?

[Bob Hart]

It is a whole craft on its own.


Quick stuff :-

A "normal" lens approx 50mm for 35mm stills image and approx 30mm for motion picture image (DPs please smite me if my onfo is wrong and post corrections) confers the "normal" human field of view and perspective. - Far objects appear as far away as if seen directly by the eyeball. Close objects appear as close. Motion of subject towards and away appears normal. Motion of camera itself toward or away from subject appears normal.

A wide lens approx 24mm for 35mm stills and maybe 17mm for movie frame makes distance away from the camera appear longer than it is. Motion towards and away is accentuated or looks faster. Close-ups on faces confer a distorted look with length of face from nose to outline accentuated (longer), sometimes used for a surreal effect, ie., the POV of another persons face by a madman.

A long lens approx 85mm for 35mm still and 70mm for movie frame makes distance away from camera appear shorter. Motion towards and away seems to be slower, (classic shot with even longer lens of stumbling man perishing in desert, makes a lot of footsteps and no apparent progress, car on a dusty road, throwing up huge dust yet making slow progress ), motion of camera towards or away from subject appears slower. Close-ups on faces confer a distorted look with length of face from nose to outline appearing shorter, the face appears flatter.

Genuine DPs and camera-ops, please feel free to correct me in these comments as I am not in the full knowing of this craft by any means.

[Tim Davison]

Thanks once again Bob, really appreciate the response. Do you know of any videos which show the differences

[Bob Hart]

That is about my lot for the knowing (or lack of knowing).

I have only picked up scraps of info here and there and joined the dots, sometimes wrongly and played with the lenses to see what happens.

I have done no formal study in this craft. I don't know of any actual videos to refer you to. Others who know much more than I, may add their piece here sooner or later.

On this page

http://www.dvinfo.net/forum/let-us-d...extreme-4.html

All of the frame grabs except one were done with a Sigma-for-Nikon 14mm f2.8 at about f3.5 - f4.

Frames are :-

1 2
3 4
----
5 6

Frame 3 was done with a Nikon 58mm f1.2 prime, also at about f4. You will observe if you look closer that the same rocks have more of a cut-out-of-cardboard look to them than the higher wide shot with the 14mm which seems to make bumps and hollows look deeper.

In Frame 1, I have sort of composed the shot similarly to Frame 3, but to get the big granite hump in background to be just that little bit off sharp in the available light and to put it where I wanted it to be - far away, I chose the 14mm.

With the 58mm, the only other lens I dragged up the hill that day, it just did not look right because I had to lower my camera position and the hump was brought closer and the edges were cropped out of frame.

A zoom would make it all a lot easier, but also make a person lazier to fire off the shot and move on without trying the variety of camera positions a prime lens forces you to do. The green moss was only about 10" or 270mm from front of lens.