[rollei_list] Re: Bubbles in Schneider Lens!!!
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 27 Apr 2005 13:18:02 -0700
----- Original Message -----
From: "michael Sta. Maria" <littlwing5@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, April 27, 2005 9:54 AM
Subject: [rollei_list] Bubbles in Schneider Lens!!!
> Hello all,
> This is probably a stupid question, but I
> just won a bid on *bay for a 210mm symmar-s lens and
> now I am questioning whether I really want it. In the
> description there are bubbles barely visible between
> the lens elements if seen at an angle. Does this
> affect image quality? Where do these bubbles come
> from?
>
> Please have a look: Item number: 7508963819 on *bay
>
Its very difficult to see anything in the photo. However,
I think what the guy means is what appear to be bubbles
around the edge of the lens. This is the anti-reflection
paint on the edges of the elements flaking off. This seems
to be common on Schneider lenses for some reason. The seller
states this is the cement holding the element to the lens
mount but there is no such cement, its the paint. If this is
so its not serious and probably has no effect on the lens
performance. Bubbles in the cement for the elements would be
a problem because it indicates the synthetic cement has not
been cured correctly and is beginning to separate. Small
bubbles do appear in some type of optical glass but are very
rare in modern glass. They were fairly common in some types
of dense Barium glass in the very distant past because the
melting point of these glasses was so high and because the
technology to remove entrapped gasses had not been
developed. Glass making techniques changed during and after
WW-2 so such bubbles have become very rare.
The Symmar-S is an excellent lens. If this one is in
otherwise good condition, and if the "bubbles" are simply
places where the edge paint has separated, its a safe buy. I
have no idea what these are worth on the used market so I
can't comment on value.
Get a right of return on the thing so you can really
inspect it.
Look it over for any sign of mechanical damage;
indications of being dropped or banged hard, etc. Look
through it with a strong light and at the surfaces with both
transmitted light and grazing reflected light using a
magnifer. Scratches do matter and lenses with many scratches
should be rejected. "Cleaning marks" are scratches and, if
there are many, will diffuse the image just like ground
glass. They also show carelessness in handling.
Good luck.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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