Richard:
I recalled the list does not accept attachment afterwards,
however I can see it in my cellphone, it is a statue in a park and looks
good.
Carlos
El jue., 6 de feb. de 2020 00:34, `Richard Knoppow <dickburk@xxxxxxxxxxxxx>
escribió:
What I mean by bubbles is clear separation. I think it would
take a lot of heat to cause synthetic cement to let loose.
Certainly excessive heat can damage Canada balsam but it takes a
lot.
I don't know about the effect of moisture on synthetics, I
would doubt its a major problem. It is with balsam. Usually the
edges of cemented lenses are sealed, often with the same paint
that is used for anti-reflection at the edge. I have thought that
the quality of the seal may determine how resistant the cement is
to separation. Not all lens edges need anti-reflection paint
because there is not a condition of total internal reflection at
all of them.
There is no attachment, I don't think this list accepts them.
On 2/5/2020 5:27 PM, Don Ferguson wrote:
A couple of years ago I purchased a tele rollei that actually
belonged to a man that used it shooting stills for Disney back
in the 1960's. The viewing lens is fine, but the taking lens
has some separation that comes in
about 20 to 25%. I don't see yellowing, nor bubbles not
crystallizing, but just a clear separation. The son of the man
that used it said it was in a storage shed for about 5 years in
Georgia - so hot. My understanding
is that could also cause the lens to separate - probably the
humidity didn't help either. I use it all the time for b&w and
see no negative affects at all. I can't speak to what others
are experiencing, but that's mine.
I didn't buy it as a collectible piece, but to use and it
hasn't disappointed. Attached is an image taken with it.
Hope this helps
On Wed, Feb 5, 2020 at 7:27 PM `Richard Knoppow
<dickburk@xxxxxxxxxxxxx <mailto:dickburk@xxxxxxxxxxxxx>> wrote:
I think Zeiss had some problems with cementing using
synthetic cements. Actually, there were several types of
cements,
some heat curing, some with UV light. If the lens surfaces are
not absolutely clean and if the baking is not done
correctly the
cement will separate with time.
Canada balsam usually separates because moisture
penetrates
at the edges. That causes the balsam to crystalize. The usual
symptom is yellowing at the edges, which has little effect
if it
does progress far. Eventually, the balsam crystalizes.
Synthetic
cement seems to separate as large bubbles between the cemented
surfaces. Ruins the lenses. I don't know what causes this
other
than faulty cementing. I have a Wollensak copy of a Zeiss
Convertible Protar where all the surfaces separated. I
tried to
recement it but without success. I have also seen Kodak lenses
with bubbles. The only Schneider lenses I've seen with
problems
were cemented with balsam and have the typical yellow ring. I
once saw a Contaflex kit at a camera show with four or five
lenses, all separated. What a shame.
It is possible to recement lenses but its important that
they be centered correctly. While some say that clamping the
edges is enough that probably does not suffice and is not
possible for some types of lens. A real centering machine is
needed. Its an expensive procedure, some lenses are worth
it but
many are not.
On 2/5/2020 3:20 PM, wayne pinney wrote:
> Wow! in pursuing Tele-Rolleis, I note that a significant
number of cameras being offered for sale have developed
problems with lens separation. I think it is more than my
imagination. It seems like at least half of owners indicate
the problem with their camera.
>
> Is this truly a bad problem with this model of camera, or
is it a case of the camera being so collectible that only
flawed cameras are offered for sale.
>
> What about examples of the camera that have not yet
developed the problem?, is it likely they will not develop
problems with lens separation?
>
> I bought a pristine example at a very reasonable price,
about 60 or 70% of the cost of a nice F. Already shot a
roll through it and really like it. Wondering if there are
some things I should do in storing and/or using it to
prevent the problem from cropping up.
>
> Best,
>
> Wayne---
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WB6KBL
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