I've a 35mm 3.5 Summaron. When the goggles are detached, I can't focus correctly. I learned that this lens must be used with the goggles. So, why are the goggles detachable? When do we need to detach the goggles?

Thanks in advance for your help.

-- WP Cheng (cwpcsl@netvigator.com), May 06, 2002

Answers

I had several of these lenses, and the later models (f/2.8 Summarons) had fixed eyes. They could be removed, but it involve using a screw driver to seperate the finder assembly from the lens. As you found out, this removal caused the lens to not be able to be focused via the rangefinder.

My only guess about the reason the first models were able to be quickly detatched would be either the fact that the structure was based on the DR 50mm Summicron lens which needed to have a way to add and remove the eyes depending on the focusing range, and / or it was easier to stow the lens in two pieces, rather than the odd shaped full assembly.

-- Al Smith (smith58@msn.com), May 06, 2002.

They may be detachable to facilitate easier repairs if needed.

-- Andrew Schank (aschank@flash.net), May 06, 2002.

and focusing cam is designed to work with goggles on, on any M body, bringing 50mm finder as 35 finder, originaly for M3 use, but can be used on any M body, without goggles is focusing useless.

-- r watson (al1231234@hotmail.com), May 06, 2002.

My guess would be what Andrew said about facilitating repairs is correct. It is also possible that having separate lens vs ocular units facilitated production. The same sort of thing happened with the early 135/2.8-RF Elmarits which had VF-RF units to magnify the image 1.5X to improve focussing accuracy. The earies 135/2.8 lenses had the VF-RF unit attached by screws, while the later lenses utilized a single heavy casting.

Leica never intended for these lenses to be unscrewed from the VF-RF units. If they had, they would have made them simply detachable like the 50/2.0-DR. But there are an unusually large number of tinkerers among use, proof of the law of unintended consequences.

-- Eliot (erosen@lij.edu), May 06, 2002.