Archived posting to the Leica Users Group, 1999/06/23

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Subject: [Leica] Pradovit Color projector - in neeed of CLA?
From: "John Hudson" <>
Date: Wed, 23 Jun 1999 21:59:24 -0700

My 28 year old Pradovit Color with 2.5 / 90mm Colorplan lens has been
brought out of retirement after sitting idle in its original packing box for
about 15 years.

I removed the top casing and blew away as much of the residual dust as
possible followed by a short burst of canned air from about ten inches to
remove any trapped dust but avoiding any direct contact with the mirror
behind the projector lamp or the optical elements in front of the lamp. The
projector lens had been removed before using the canned air.

With the top casing removed and the lamp lit up I could see that the side of
the optical element nearest the lamp looks as if it was covered with tiny
tiny pin prick marks. With the top casing in place, the lamp lit up, and
looking obliquely though the lens as the slide changer worked I could see a
reflection of those very very small pin prick marks. The pin prick marks on
the rear elements were seen to be present before I used the canned air to
remove any trapped dust.

The images I projected today seemed to be as crisp and as sharp as were
images made and projected fifteen years ago. So, either the prick marks were
present fifteen years ago and the projected images are as negatively
impacted today as they were fifteen years ago, or the prick marks have
arisen in the last fifteen years and are of no apparant consequence today.

Is anyone able to surmise whether these prick marks are actually on the
surface of the optical elements and if so what they are and whether they
could spread, or whether they are being reflected off the interior casing of
the projector itself?

If in fact the pin prick marks are pit marks in the optical glass is there
any advice as to the economics of having the glass reground, or replaced?

Thanks in advance for any advice

John Hudson
Vancouver, BC