Lens coverage question

[Peter Schrager]

I have a beautiful Wollensak Aprochromatic 15 inch lens in barrel and want to know the coverage of this lens...this is before I contact Sk Grimes about putting it into a shutter ....thank you in advance
Best, Peter

 

[John Kasaian]

Theres lots of links on the Large Format Photography Home Page to tables with lens data.

 

[jbbooks]

If you use the link and scroll down to the Wollensak brochures, you might find what you are looking for in one of them:

http://www.cameraeccentric.com/info.html

 

[Dan Fromm]

The general rule with process lenses is: if a G-Claron, 68 degrees, else if not engraved "wide angle", 45 degrees, else 68 degrees.

There are exceptions. For example, some users claim that Konica Hexanon GRIIs cover more than 68 degrees. And as can be seen here http://www.cameraeccentric.com/html/info/wollensak_2.html y'r Wolly probably covers even less. Remember that the circle covered at infinity is half the circle covered at 1:1.

 

[Alan Davenport]

Peter,

I understand these can be had pretty reasonably priced and used for general purpose large format work. The problem with published coverage figures for apo lenses is that they assume you are going to use them for critical process work. If you intend to use this for 8x10 contact landscape work you will find that the useful coverage is more than that published. I use a 210 mm Reproclaron for 5x7 landscape and for contact printing and it has way more useful coverage than advertised.

Your best bet is to put it on an 8x10 camera(if that is what you are going to be using it for?) and see where the vignetting occurs and see how far out the useful (sharp) field extends. How far towards the vignette does it lose its "edge". A 7x magnifier works well for this. I've done this on a couple of lenses for my 8x10. A 120mm SuperAngulon and a 16.5 cm Angulon. They gave sharp images farther out than expected.

Alan

 

[steven_e007]

I've noticed that when a lens is being sold the seller often boasts about a much bigger field of coverage than the manufacturer specified!

There is a difference between the size of the maximum circle of light you can see on the film (which will fall off progressively towards the edge) - the circle of light which falls off to an 'acceptable level' as defined by different manufacturers' criteria - and the circle of acceptable sharpness, again judged by some criteria relevant to the application - which can be quite tight for a process lens. Big Tessars, for example, often produce a circle of light much greater than the coverage quoted by the manufacturer, as the sharpness falls away long before the brightness does....

I'd stick your lens on the biggest camera you have, use cross movement or rising front to get as much 'edge' on the film as possible and take a picture with it. Decide yourself at what point the sharpness ceases to be acceptable.