using the switar AR lenses on a REX

[james mcpherson]

in the UK we have pretty much one guy who sells bolex stuff, he's written a guide called the bolex bible . he mentioned to me that the AR lenses cannot be used on a REX-5 /reflex model bolex because the thread is deeper than the specifically designed RX series of lenses. this didnt sound right to me because ive read that ll c mount lenses have the same thread and you just meter AR lenses at 1/80th of a second on a reflex model

thanks

j

[Robert Lewis]

in the UK we have pretty much one guy who sells bolex stuff, he's written a guide called the bolex bible . he mentioned to me that the AR lenses cannot be used on a REX-5 /reflex model bolex because the thread is deeper than the specifically designed RX series of lenses. this didnt sound right to me because ive read that ll c mount lenses have the same thread and you just meter AR lenses at 1/80th of a second on a reflex model

thanks

j

 

Hello James.

 

As I understand it. the problem on which you have had advice is nothing to do with the diameter of the thread on an REX "c mount" lens, or metering. It is to do with the fact that the REX5 camera is a reflex camera and therefore has an "image splitter prism". This is mounted in the camera between the back of the lens and the shutter. The distance between the lens and the film plane is critical and this distance is different as between a non-reflex and a reflex camera because of the "image splitter prism" positioned in a reflex camera but not in a non-reflex camera. It will affect focusing and, depending on the depth of the threaded portion of the lens can limit the scope of the lens and even damage the "splitter" with serious implications. RX lenses take this into account, but AR lenses do not. Take it from me that the guy from whom you got the advice knows exactly what he is talking about.

 

Regards.

Edited January 31, 2010 by Robert Lewis