PDA

View Full Version : FL question,,,,,,

BigSteveG
7-May-2008, 15:09
Best FL for shooting portraits on a 5x7 back. Any lens suggestions?

steve simmons
7-May-2008, 15:15
Studio portraits, environmental portraits, both ???

Not having any context I would say 240-300mm for studio, 125-180 or so for environmental portraits

just guessing.

steve simmons

BigSteveG
7-May-2008, 15:21
Steve,
Thanks for the reply. Those are the FL's I was considering as well. I'm after studio portraits for the most part w/ the goal of making contact prints using alternative processes. The camera I'm looking at now (Deardorrf 5x7 View) apparently only offers 24in of extension (according to K Hough's website), so I'm concerned that it may not be suitable. Why do you recommend a shorter FL for Evironmental work?

steve simmons
7-May-2008, 15:32
to get more of the person's surroundings if that is what you want. But I am just guessing.

steve

Darren Kruger
7-May-2008, 15:56
The camera I'm looking at now (Deardorrf 5x7 View) apparently only offers 24in of extension (according to K Hough's website), so I'm concerned that it may not be suitable.

24 inches is around 600 mm. I would think that would be plenty of bellows draw for the longer focal lengths suggested by Steve.

-Darren

BigSteveG
7-May-2008, 16:30
Darren,
Thank You!!! The question I had asked a few days ago was how to figure max focal length from a given bellows size. So what is the multiplication factor? approx x3?

Ron Marshall
7-May-2008, 16:44
Darren,
Thank You!!! The question I had asked a few days ago was how to figure max focal length from a given bellows size. So what is the multiplication factor? approx x3?

At life size, 1:1, the bellows extension is twice the FL. So with 600mm of bellows you could go to life size with a 300mm lens.

OD = object distance, ID = image distance

The thin lens equation: 1/FL = 1/OD + 1/ID

magnification = ID/OD

Mark Woods
7-May-2008, 17:04
A rule of thumb for millimeters to inches is: 25mm=1 inch. Approximately.