Originally Posted by Pawel Kwiecien
One of the early lessons you will need to understand in LF photography is the importance of lens coverage.
I do not know either of the lenses being offered, so thus do not know if they will cover the diagonal for the 4x5 format (or 5x4 as you would know it in the UK). The diagonal for 4x5 is around 165mm (163mm actually).
If you think of the image coming out of the back of the lens as a cone with a circular image circle, then the image circle will be smallest when the lens is focused at infinity. To focus closer, we move it away from the film / back. This is how we can use shorter focal length enlarging lenses for macro work, as although they have small image circles at infinity that do not cover the format, when we focus closer the image circle gets bigger.
Now to increase the constraint on our lenses, we also change the camera through "movement" where we might shift the front or back of the camera parallel relative to the other end for composition, or change the angle to change the plane of focus.
Bottom line is that lens coverage may become extremely important depending upon the type of photography you do.
Might want to do a little reading before reaching fo the wallet. Another god source is the LF Photography forum. Have a look at the articles and reviews on the LF home page there.
Good luck in your efforts,