Tuesday, June 7, 2011

The Cost of Mistakes

Photography is expensive in many ways.  Not the least is the cost of mistakes.  I have my share of costly mistakes, and most of them were made because of not knowing enough.  Case in point, Kern-Paillard (Bolex) c-mount lenses.  Obviously, there are at least two versions of their lenses that I didn't know of: the AR and RX.  I have two AR lenses which won't focus to infinity.

Wide Open -- NEX-5 & Switar 50mm f1.4 @ f1.4.  Click for larger.

Both AR and RX are c-mount lenses.  You would think that a c-mount lens is a c-mount lens.  It's a standard, right?   Well, if everyone makes everything to the exact standard, the world will be a much nicer place.  Alas, the AR and RX lenses share the same mount, but different lens to film register.  My Switar 50mm f1.4 can focus to about 3 meters wide open, and the Switar 25mm f1.5 is about the same.  They are still usable, just not to infinity.  Until someone makes a special c-mount to accommodate the difference, these AR lenses will be much less useful than they really should be.

Another one wide open -- NEX-5 & Switar 50mm f1.4. Click to see larger.

I wouldn't feel so bad if these lenses are mediocre, but they are nice little lenses, especially the 50mm f1.4.  I really like the bokeh of this lens, although it may be a bit weird to some.  The image quality reminds me of the Switar 25mm f1.4 RX that I used to have, and still regret to this day that I sold it.  The 25mm f1.4 has very severe vignetting even on the Panasonic G1, but the 50mm f1.4 has only very slight vignetting on the NEX-5.

Re-post, because this is one of my fav -- NEX-5 & Switar 50mm f1.4. Click for larger.

I am sure I will continue to make this kinds of mistakes in the future.  There are just so much that I don't know.  Was it Socrates that said  "The more I learn, the more I learn how little I know"?  Well, that about sums it all up.


  1. I made the same mistake with a MIR 37mm f2.8 M39 lens. I thought it would work great on my LTM Leica...until I got back the film and all shots were way out of focus. Turns out early Russian SLRs were M39, and soon after went to M42, which has a much greater mount to film plane distance than a Leica rangefinder.

  2. Hi,
    There is two standards : C Mount & CS Mount. Same thread but different register flange. No infinity with CS Mount, period, and often, you can't trust sellers on this. AR lenses in both mounts. No adapters are possible (well, in a normal way...), only an extra flat register flange camera. Cheers Phenix jc

  3. Hi,
    Some misunderstanding (from my side?). I have switar 50mm 1.4 AR and RX. Distance to plane is the same with both lenses.
    AR Mount does not screw as deep into adapter as it should (but there is some adapters that work with AR).
    RX lenses produce wide open some 'glow' (which I prefere in portraits and flower shots). This is because those are designed for Bolex Rx cameras (some glass between lens and film plane...from which comes misundersanding that they have different flange distance).
    brg Isto
    ps. but there is RX8 c-mount lenses, which really have different flange distance (shorter)