Why are some Wollensak lenses pritned backwards?

Okay, a trivia question (to which I do not know that answer...).

 

Why do some Wollensak lenses apparently have the writing around the

front of the lens barrel printed in reverse - that is, a mirror

image, so the writing is all back to front?

 

I just bought one of these off ebay - a 15" f10 Apo Raptar. And no,

it's not a Photoshop accident - check out the second image. I vaguely

remembered seeing this before - I think it is in Steve Simmons LF

book - 4 lenses in one photo, and the Wollensak has the writing on

the front (nowhere else on it) mirrored... weird huh?

 

http://tinyurl.com/a8hq

 

http://tinyurl.com/a8hm

 

 

tim

Tim: The important question is whether they make the image look right side up on the ground glass.

I assume since these are process lenses, you could easily read the labeling of the installed lens holding a mirror below it (e.g. in a vertical process camera) Just a guess...

I recently asked the same question of a flea market, sorry, camera show, vendor. His answer matched Arne's.

Process lenses were sometimes used with a gigantic prism or

a first surface mirror stuck on the front. Process cameras were

too bulky to rotate for mural prints or copying large originals, and

in any case, their tracking and other controls all relied on gravity

acting in a particular direction, so the solution was to use a

prism or mirror to turn the optic axis through 90°.

 

Another advantage of the prism/mirror is that the negative would

be a reversed image of the original, and could therefore be

contact printed emulsion-to-emulsion for the best sharpness

and highest contrast. Old time printers have told me this was

the best way to make copy prints from screened images and

keep the individual halftone dots/shapes looking good.

 

I assume the reversed writing is so that anyone looking through

the mirror box to see which lens they were holding could read

the text. For best results the prism/mirror had to be well-aligned,

so you wouldn't want to remove it just to read the front bezel.

I think these were used with a right-angle prism mounted on the front.

Yup, its a big mirror. Kodak Copying Ektanons have the same reversed print.

Big prism I meant... here is an example<div></div>

Some of them are mirror boxes, some are prisms. A prism is

more dimensionally stable, and less prone to getting dust or

other blemishes on the reflecting surface, but the long path

length through the glass can introduce spherical aberration, so

sometimes a mirror was preferred.

.srehpargotohp cixelsyd rof erew esehT

Perhaps you have the Russian version, a Wollensky Apo Raptovich.

Tim, I have two of the 15" Apo Raptars of which you speak. I think your question has been adequately addressed but will add the following: the reverse printing appears on the "Wollensak Rochester U.S.A." lens while the non reverse lens is simply "Wollensak U.S.A."

That lens originated from Wollensak-OZ. The coriolis force did it.

?sdrawkcab gnitirw htiw gnorw s'tahW

.esrever ni elddap ylno i esuaceb eciton t'nod elpoep tsom tub ,sdrawkcab detnirp si hcihw kayak a evah I