Questions about XENOTAR 135mm f/3.5 lenses

hello all,

i have a question about a 4x5 xenotar 135mm lens. i have 2 of these lenses,

they are a bit different, and have different shutters. the lens elements

itself are the same size.

#1 TECHNIKA 135mm xenotar mounted in a LINHOF shutter serial# 983XXXX

#2 (regular) 135mm Xenotar mounted in compur shutter serial# 790XXXX

is there a big difference between the two lenses in optical quality? the

reason i ask is because on my Technika Xenotar it has a small mark on the rear

element. I was thinking swapping out the rear element for the other one. is

that ok to do?

thanks for you help in advance!

-peter

It is very likely that each set of elements is a matched set. It's very hard to control the exact thickness of lens elements, although the curvature can be well controlled. So lenses are often selected of sets of elements that are "self-consistent".

Thus, mixing and matching the groups could very well results in two sub-optimal lenses.

Small marks are generally irrelevant, except for collector value on Leica lenses.

It is well established that Linhof would test their lenses and reject the poor ones, so you can bet that it performed up to par *when it was tested*. On the other hand, there is no guarantee after 50+ years of use (and a bruised bottom) that it STILL performs well, or that it would perform better with another lens's rear element.

I have a handful of 150mm f2.8 Xenotar lenses, and from my experience found that the regular (not-Linhof) Xenotars perform as well as the branded ones.

In any case, were I you, I would run a few quick tests to see which of the lenses I preferred, and while you are at it, you might as well test to see how well the swapped rear element performs.

Although a Technika marked lens does indeed mean that it was tested by Linhof, it does not necessarily mean it is better than an unmarked lens, only that it was acceptable to Linhof. Lenses are all unique and there are good lenses and not so good lenses of the same type in the marketplace, so the unmarked Xenotar you have as is might actually test out as the better of the 2 lenses or they might not show any difference in a test.

I would also say to go ahead and try swapping the rear element, it can't hurt anything as you can always put the elements back the way they were originally. You might end up with a lens better than what you have now or you might end up with the lenses performing worse or the same.

I did this same thing several times when I was testing lenses ( 300mm & 360mm Schneider Componons ) while working at an engineering camera maunfacturer in the last century. When I had 2 lenses that tested poorly, I would swap the rear elements and often would end up with a better lens than before, so it never hurts to experement.