doublet question

I have an 80 mm doublet that was cemented but was designed as an airspace.
I can't explain why that happened but it did. How can I restore it back to
being an air-space as it was designed to be?

Mike wrote:
I have an 80 mm doublet that was cemented but was designed as an airspace.
I can't explain why that happened but it did. How can I restore it back to
being an air-space as it was designed to be?


Not to be snippety, but: cf. Fixing cemented doublet thread,
but don't.

On 2005-07-17, Mike wrote:
I have an 80 mm doublet that was cemented but was designed as an airspace.
I can't explain why that happened but it did. How can I restore it back to
being an air-space as it was designed to be?

Refer to the thread with the subject "Fixing a Cemented Doublet" for
information on uncementing a lens. Cemented objectives have to have
the same interior curves on the front and rear elements and so are
designed to be cemented. Air spaced objectives usually have different
interior curves on the front and rear elements to keep down interior
reflections and therefore can't be cemented. What tells you this was
originally an air spaced doublet?

How do you know it should be an air spaced doublet? Unless it was built as
an amateur lens, what you have really is what it should be.
The only way that you can get a lens pair to glue together is if the two
surfaces have the same ROC and when you do an airspaced lens, the two
surfaces are very rarely anywhere near close enough ot be gluaeable.

--
Why isn't there an Ozone Hole at the NORTH Pole?

"William Hamblen" wrote in message
...
On 2005-07-17, Mike wrote:
I have an 80 mm doublet that was cemented but was designed as an
airspace.
I can't explain why that happened but it did. How can I restore it back
to
being an air-space as it was designed to be?

Refer to the thread with the subject "Fixing a Cemented Doublet" for
information on uncementing a lens. Cemented objectives have to have
the same interior curves on the front and rear elements and so are
designed to be cemented. Air spaced objectives usually have different
interior curves on the front and rear elements to keep down interior
reflections and therefore can't be cemented. What tells you this was
originally an air spaced doublet?

I bought it as an air-spaced form Tele Hoon. I decided to clean it but
forgot to mark the orginal position.
I tolf this to Hoon and he told me to send it back and he would fix it.
I cam back cemented, marked and having three metal spacers between the
elements. I
just presumed he knew what he was doing but now I have my doubts.

I bought it as an air-spaced form Tele Hoon. I decided to clean it but
forgot to mark the orginal position.
I tolf this to Hoon and he told me to send it back and he would fix it.
I cam back cemented, marked and having three metal spacers between the
elements. I
just presumed he knew what he was doing but now I have my doubts.

The metal spacers hold more distance than it would glued. He may have glued
the spacers or some glue around the edges.

Clear Skies

Chuck Taylor
Do you observe the moon?
Try http://groups.yahoo.com/group/lunar-observing/

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On 2005-07-17, Mike wrote:

I bought it as an air-spaced form Tele Hoon. I decided to clean it but
forgot to mark the orginal position.
I tolf this to Hoon and he told me to send it back and he would fix it.
I cam back cemented, marked and having three metal spacers between the
elements. I
just presumed he knew what he was doing but now I have my doubts.

Metal spacers = air spaced.

My guess is he stuck the lenses together with a drop of cement on
either side of each spacer to keep it from coming apart. Don't
fool with it any more.

--
e-Harmony.com called the cops after I sent in my personality profile.

"William Hamblen" wrote in message
...
On 2005-07-17, Mike wrote:

I bought it as an air-spaced form Tele Hoon. I decided to clean it but
forgot to mark the orginal position.
I tolf this to Hoon and he told me to send it back and he would fix it.
I cam back cemented, marked and having three metal spacers between the
elements. I
just presumed he knew what he was doing but now I have my doubts.

Metal spacers = air spaced.

My guess is he stuck the lenses together with a drop of cement on
either side of each spacer to keep it from coming apart. Don't
fool with it any more.


ok