P. ANGENIEUX PARIS, F.35 1:2,5 RETROFOCUS TYPE . This lense is actually created for what mounting? please help.

-- alfred (cnka@pacific.net.sg), March 15, 2002

Answers

Alfred:

If I recall, it was the first 35mm lens for SLRs with a mirror box that prevented rear elements from projecting back into the camera so the 35mm focal length actualy applied. They needed to use different rear elements to shift the focus far enough back to allow the lens rear elements to clear the swinging mirror. That is what the word "retrofocus" means. Again, if I recall,it was for an Exacta mount that I think was shared with Contax then.(???)

One of the reasons Leica M lenses are so good and small compared to similar FL lens for SLRs is just that: they do not need extra elements to shift the focal plane back. They can therefore use fewer elements resulting in less flare, better contrast and smaller size.

It can not be used on a Leica, because it does not have a focus cam, and the FL is all wonky for the flange to film distance on a leica.

If I am not 100% right on this, a REAL expert will set me straight, I am sure.

Cheers

-- RICHARD ILOMAKI (richardjx@hotmail.com), March 15, 2002.

Richard exaggerates a little I think although this is a commonly held belief: most of the current M wides are retrofocus, and Erwin Puts shows in his book that having a retrofocus lens usually makes it easier to correct aberrations, since otherwise you have to fill up the interior of the body with the optics - and there is only so much room to do this. He also makes the point that the required small size of M lenses is often a constraint in design not necessarily a design advantage. Retrofocus lenses often do have some advantages - low distortion is one.

-- Robin Smith (smith_robin@hotmail.com), March 15, 2002.

Robin:

You are indeed correct about teh new lenses, but in the early 50s, the Angenieux knocked everybody's sox off. Now it is easy to match it for SLRs or RFs

THX

-- RICHARD ILOMAKI (richardjx@hotmail.com), March 15, 2002.

Richard

Quite right; in the 50s and 60s the retrofocus approach was the only way to go. I like Angenieux lenses - the R series lenses they produced were very good. The latest set os R zooms (mid-late 80s?) were very good, but looked awful!

-- Robin Smith (smith_robin@hotmail.com), March 15, 2002.

Robin: I think that retrofocus lenses introduce distortion, rather than reducing it. I don't think they can make a distortion-free retro. Where the retrofocus excels is in uniformity of illumination-- greater freedom from corner falloff.

-- Bob Fleischman (RFXMAIL@prodigy.net), March 15, 2002.

Yes sorry Bob, I got my sentence garbled up. I meant "non-retrofocus lenses often do have some advantages - low distortion is one."

-- Robin Smith (smith_robin@hotmail.com), March 18, 2002.