Re: Coming to terms with *ist D lens mag factor?

[graywolf]

Hum? I figure that 127 is the equivalent of a 31mm on 135 camera. And the 105 is 
the equivalent of a 46mm. I have always found it strange that people do this 
stuff, because one works differently in different formats, one tends to use much 
closer points of view with a large format camera and thus shorter relative focal 
length lenses. Furthermore prior to the 70's when there was a 35mm explosion and 
it became the norm no one hardly thought in those terms. As Shel says it seems 
to be a dumbing down factor (I am ignorant of anything but 35mm make it 
understandable to me without my having to think).

For anyone interested the old Press/View Camera rules of thumb are:

Normal = diagonal of the film. Approximately 43mm on 135 format. 150mm on a 
press camera.

Wide angle = the short side of the film. Approximately 24mm on 135. 90mm on a 
press camera.

Wide field = the long side of the negative. Approx 35mm on 135. 127-135 on a 
press camera.

Portrait = the sum of the short and long sides of the film. Approximately 60mm. 
Usually 200mm on a press camera (that is almost exactly what you get from a 50mm 
lens on 135 cropped to an 8x10 print, BTW).

Telephoto = Twice (or more) the long side of the film. Approximately 70mm on 
135. 250-380mm on a press camera.

You will note that those are all shorter than we normally think of them in 135 
format, though the WA as gotten down to about right in recent years.

Once again manufactures's of P&S digitals started using 35mm equivalent focal 
length because there are no standards for sensor size which can vary from the 
equivalent of a Minox to an APS negative size from camera to camera. It is 
simply a way to compare the zoom lens equivalent between disparitent cameras. It 
has no optical meaning other than that.

--

Paul Stenquist wrote:

On Dec 23, 2003, at 8:19 PM, Shel Belinkoff wrote:

Y'know, it's funny how, when using other formats, rarely is it said 
that an 80mm
lens for a 6x6 is "equivalent" to a 50mm lens for a 35mm camera.  
When's the
last time you heard a 4x5 user ask "What's that lens in 35mm terms?"


Hi Shel,
I've heard that a lot, and I frequently use 35mm focal lengths as a 
mental point of comparison. For example, I know that my 127mm 4x5 lens 
is somewhere around 45mm in 35 terms and my 105mm 6x7 lens is 
approximately the same as a "normal" 35mm lens. I work in advertising 
and I've found that most art directors understand 35mm angle of view, so 
when working in other formats they frequently ask, "What's that in 
35mm?" The same is true on television shoots where 35mm lenses are 
closer to APS or the current crop of digitals in focal length vs. angle 
of view (because the neg is actually half of what we call 35mm.) The 
still camera 35mm focal lengths are a reference point for many working 
pros and their clients.
Paul


--
graywolf
http://graywolfphoto.com
"You might as well accept people as they are,
you are not going to be able to change them anyway."