Re: wide-angle lens for 4x5

----- Original Message -----
From: "Shannon Stoney" <sstoney@pdq.net>
To: <pure-silver@freelists.org>
Cc: <alt-photo-process-l@sask.usask.ca>
Sent: Tuesday, October 18, 2005 6:37 AM
Subject: wide-angle lens for 4x5

> Hi, I am supposed to do some architectural photography in
> the coming month, and I am thinking about borrowing or
> buying a wider format lens than the one I'm accustomed to
> shooting with. Right now I have a 150mm lens. What would
> be a good length to look for? I will be shooting in a
> prison near Houston called The Walls.
>
> Also, I think I might have to learn to do the perspective
> correction thing. Any suggestions about web sites or
> books to look at?
>
> thanks,
>
> --shannon
>

   I think you have already gotten some good answers. The
choice of focal length is mostly dictated by the conditions,
that is, how far back you can get, or by the choice of
perspective.
   Schneider, Rodenstock, and Fuji all make excellent WA
lenses of comparable quality.
   A bag bellows has pleats in a special pattern that allows
much more lateral flexibility than a standard bellows. They
look like a bag, hence the name.
   I agree about the Steve Simmons book for learning about
movements. I don't know of a good web site for this although
there may be one. The best book on movements was a Kodak
book on large format work. Kodak books are now published by
the Silver Pixel Press, I have no idea if this book is still
available.
   For correcting perspective keep the lens board, film, and
subject plane parallel. Be careful of too much correction,
it can look unnatural. It helps me to visualize the image as
it is produced by the lens. Remember, the image of three
dimensional objects or spaces is also three dimensional, the
camera movements are so that you can put the film plane in
the right place for the part of the image you want to
capture.
   Another thing to remember is that the back focus of the
lens, that is the distance from the rear apex of the glass
to the film, is not the same as the focal length. The
distance from lens to film for infinity focus is the
distance from the rear principal point which for most common
WA lenses of modern design is somewhere around the back air
space, you can say approximately in the center of the lens.
The back of an extreme wide angle lens may nearly touch the
film.
   You can see what the coverage of any focal length will be
by cutting out a film size opening in a sheet of cardboard
and holding it at the focal length from your eye. For wide
angle lenses you can multiply the dimensions.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com