Proximeter filter

[jamaeolus]

In my daily scan of potential treasures I came across a lens fitted with a proximeter filter. What is it for?

[calvin83]

Used to correct the parallax error when using a close up lens.

[visualopsins]

https://en.m.wikipedia.org/wiki/Optical_proximity_correction

[jamaeolus]

Interesting. It seemed very strange. Was attached to a staeble color ultranit. This giant ring of clear optical glass like a halo. After searching for others on ebay I figured they must be like viewfinder attachments for rangefinders but for close up filters. Thanks.

[paulhofseth]

The Proximeter is NOT a filter, it is a device wih a close up-lens plus offsetting prismatic device to correct for the viewfinder and rangefinder offset in relation to the lens.

Probably well before the fashion of suing for trademark infringements, the term was used by Voigtländer for their system , with a rectangular window attached to a round achromat fitting in front of the lens. Cannot recall whether that was it sole fastening means or if gthere was another method. Canon had a vaguely similar system for use on their rangefinders, the circular prism type may be their solution.

p.