Archived posting to the Leica Users Group, 1997/08/12

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: Re: Which Standard Focal Lengths ?
From: Dan Cardish <dcardish@microtec.net>
Date: Tue, 12 Aug 1997 07:27:58 -0400

At 05:39 PM 11-08-97 -0800, you wrote:
>Mon, 11 Aug 1997 15:30:17 -0400 (EDT)  Alf Breul wrote:
>
>>In einer eMail vom 11.08.1997  18:54:55, schreiben Sie:
>>
>>>I always thought that the "normal" lens was one [snip]

At the risk of beating a dead horse, for me a "normal" picture is one where
if I return to the actual scene of the photo, hold the photo up in front of
me, the subject pictured in the photo will exactly superimpose itself over
the live subject.  If the scence in the photo appears smaller than real
life, then the lens used to take the photo is (by definition) a wide-angle
lens.  Likewise, if the subject appears larger than life, then the lens
used was a telephoto (or long focus lens).  Obviously, the size of the
image in the photo depends also on how large I made the enlargement, and
how far from my eye I am holding the print or slide, hence the formula that
I posted here a week ago.

I have heard the view that the 50 approximates the human eye.  Well, maybe
my eyes are different, but my vision extends much further to the sides than
any 50mm lens I've ever encountered.  In fact, I can't imagine any camera
lens duplicating the effect of human vision.

The other explanation I have heard many times is the one concerning the
diagonal of the film equaling the focal length of the lens.  A nice, tidy
explanation, except for why?  How is such a lens "normal"?

The best alternative explantion of course is that a normal lens is one that
a photographer most feels comfortable with.  No arguments here.

Dan C.