Re: Lubitel and zone plate

----- Original Message -----
From: "Paul Lowing" <plowing@blueyonder.co.uk>
>
> I am planning to mount a 75mm zone plate in a Lubitel 166B.
> I wish to mount it where the front lens element is currently mounted as
> apparently there is some requirement to focus a zone plate.

Altho ZP could be focused, most of us just mount it at the focal length they
were made for and leave them at that fixed distance.

> I have removed the rear two lenses held in place by circlips but am a
> bit stuck with the front lens and am unwilling to use brute force and
> ignorance in case I cause some damage.
>
> The lens seems to be held in place with an insert from the rear which is
> probably either threaded or a tight push fit.
>
> Has anyone removed this lens and could advise me on how to get the
> offending piece of glass out of the way?

You need to remove the whole lens assembly out of the camera's body. To do
so, unscrew the retaining ring at rear of the lens assembly inside the
camera. I used a screw driver to rotate the retaining ring counter
clockwise. If it is too tight, you may want to use a pair of long nose
pliers, like these ones:
http://www.leevalley.com/images/item/woodworking/assorted/25k6501s1d.jpg
alternatively, you could take a flat piece of metal and file or cut one of
its ends so it looks like this:
http://ca.geocities.com/penate@rogers.com/wrench.gif
that would work as a wrench you can turn with pliers.

Here is an image of one of my lubitels, I mount the ZP or Sieve instead of
the rear element (also held in place by a C-clip), this way the focal length
is in the order of 67mm:
http://ca.geocities.com/penate@rogers.com/pinhole/lubi.jpg
Here is the lens assembly when removed from the camera, its retaining ring
beside of it:
http://ca.geocities.com/penate@rogers.com/pinhole/lubitel5.jpg

Guillermo
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Received on Tue Apr 5 13:08:49 2005