jlw
Rangefinder camera pedant
I've just bought an LTM mount 135/2.8 Komura lens from another RFF member.
As he warned me, this particular example has dreadful performance at large apertures, and still rather lousy performance even at small ones -- it barely forms an image at all! I couldn't believe that Komura would let such a turkey get out the door deliberately, so I took a very close look at it.
I'm now convinced it has a tipped element. Looking down into the barrel, I can see chipped paint and other possible signs of impact damage, and one of the elements in the rear group looks as if it might be sitting slightly cockeyed.
As further evidence -- You know how you can hold a magnifier (or another lens) at the back of a lens to look through it by eye, like a telescope? The magnifier "eyepiece" forms a nice, bright aerial image for your eye... usually. Well, in the case of this Komura, the aerial image looks terrible with the magnifier straight behind the lens -- but if I hold the magnifier off at a 20-degree angle in one particular direction, the image cleans up tremendously. That's another reason I think one of the elements is tilted in the barrel.
Anyway, to make my usual long story a bit shorter: the seller graciously expressed his willingness to take it back (thanks, Paul!!) but since it would be very useful if it worked correctly, I'd like to hang onto it and see if I can get it rehabbed.
It would have to be at a reasonable cost, though -- while this lens seems to be uncommon, it's not super-valuable, and it wouldn't make sense for me to spend hundreds of dollars to have it put right. So, I don't want to send it off to (for example) John Van Stelten of Focal Point -- he does beautiful work and can fix anything, but it would be pricey, and I'm not sure he even works on "off-brand" optics.
So, can anyone recommend a more plebian U.S. repair shop that might at least be willing to take a look at it and either advise me, "Yeah, we can fix it for X dollars" or "Forget it, it's beyond economical repair"?
[I'd almost be willing to tackle it myself if it weren't for the fiendishly complicated rangefinder coupling, which consists of two differentially-pitched helical threads -- I can all too easily imagine myself taking that apart and then never finding the one of innumerable possible start-position combinations that would get it correctly back together again!]
As he warned me, this particular example has dreadful performance at large apertures, and still rather lousy performance even at small ones -- it barely forms an image at all! I couldn't believe that Komura would let such a turkey get out the door deliberately, so I took a very close look at it.
I'm now convinced it has a tipped element. Looking down into the barrel, I can see chipped paint and other possible signs of impact damage, and one of the elements in the rear group looks as if it might be sitting slightly cockeyed.
As further evidence -- You know how you can hold a magnifier (or another lens) at the back of a lens to look through it by eye, like a telescope? The magnifier "eyepiece" forms a nice, bright aerial image for your eye... usually. Well, in the case of this Komura, the aerial image looks terrible with the magnifier straight behind the lens -- but if I hold the magnifier off at a 20-degree angle in one particular direction, the image cleans up tremendously. That's another reason I think one of the elements is tilted in the barrel.
Anyway, to make my usual long story a bit shorter: the seller graciously expressed his willingness to take it back (thanks, Paul!!) but since it would be very useful if it worked correctly, I'd like to hang onto it and see if I can get it rehabbed.
It would have to be at a reasonable cost, though -- while this lens seems to be uncommon, it's not super-valuable, and it wouldn't make sense for me to spend hundreds of dollars to have it put right. So, I don't want to send it off to (for example) John Van Stelten of Focal Point -- he does beautiful work and can fix anything, but it would be pricey, and I'm not sure he even works on "off-brand" optics.
So, can anyone recommend a more plebian U.S. repair shop that might at least be willing to take a look at it and either advise me, "Yeah, we can fix it for X dollars" or "Forget it, it's beyond economical repair"?
[I'd almost be willing to tackle it myself if it weren't for the fiendishly complicated rangefinder coupling, which consists of two differentially-pitched helical threads -- I can all too easily imagine myself taking that apart and then never finding the one of innumerable possible start-position combinations that would get it correctly back together again!]
