Tessar Coating Question

I recently got a quote to coat a Tessar - $700 if I'm figuring right. My
original idea was to coat the easily removable front and center elements
only. I would think the center element would be the most important element
to coat, assuming I'm using a proper lens hood and a coated UV filter up
front. The coating operation I contacted told me that in order to get a
visible result, I would need to coat 80% of the surfaces. In other words
every element of the Tessar - including the expensive separation and
re-gluing of the rear doublet. Does anyone agree with me that one or two
elements would yield a visible result or are they right in suggesting that
it's all or nothing.
Thanks

wrote in message
...
I recently got a quote to coat a Tessar - $700 if I'm figuring right. My
original idea was to coat the easily removable front and center elements
only. I would think the center element would be the most important
element
to coat, assuming I'm using a proper lens hood and a coated UV filter up
front. The coating operation I contacted told me that in order to get a
visible result, I would need to coat 80% of the surfaces. In other words
every element of the Tessar - including the expensive separation and
re-gluing of the rear doublet. Does anyone agree with me that one or two
elements would yield a visible result or are they right in suggesting that
it's all or nothing.
Thanks

Can't understand why separating and coating the doublet is necessary,
(Refractive indices of the glasses /balsam cement interfaces don't seem to
indicate this.) Could it be that their coating operation heats the lens
elements beyond what the cement can stand?
Good luck - hope the results are worth it. I've certainly noticed low
contrast when scanning Fuji transparencies taken with the f3.5 Xenar on my
Rolleicord Vb.

--
M Stewart
Milton Keynes, UK
http://www.megalith.freeserve.co.uk/oddimage.htm

wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right. My

I hope that was that a typo!

original idea was to coat the easily removable front and center elements
only. I would think the center element would be the most important element
to coat, assuming I'm using a proper lens hood and a coated UV filter up
front. The coating operation I contacted told me that in order to get a
visible result, I would need to coat 80% of the surfaces. In other words
every element of the Tessar - including the expensive separation and
re-gluing of the rear doublet. Does anyone agree with me that one or two
elements would yield a visible result or are they right in suggesting that
it's all or nothing.
Thanks

I don't think there is an point in coating the cemented surfaces. There
won't be much light lost in reflection at the interface due to the
balsam having a similar refractive index to the glass on either side.

"Malcolm Stewart" wrote in
message ...
wrote in message
...
I recently got a quote to coat a Tessar - $700 if I'm figuring right.
My
original idea was to coat the easily removable front and center elements
only. I would think the center element would be the most important
element
to coat, assuming I'm using a proper lens hood and a coated UV filter up
front. The coating operation I contacted told me that in order to get a
visible result, I would need to coat 80% of the surfaces. In other
words
every element of the Tessar - including the expensive separation and
re-gluing of the rear doublet. Does anyone agree with me that one or two
elements would yield a visible result or are they right in suggesting
that
it's all or nothing.
Thanks

Can't understand why separating and coating the doublet is necessary,
(Refractive indices of the glasses /balsam cement interfaces don't seem to
indicate this.) Could it be that their coating operation heats the lens
elements beyond what the cement can stand?
Good luck - hope the results are worth it. I've certainly noticed low
contrast when scanning Fuji transparencies taken with the f3.5 Xenar on my
Rolleicord Vb.

You are correct, the heat involved in coating will separate the doublet. I
wasn't going to send the doublet in at all. I was just going to send in the
two front elements, which are easier to remove and do not have to be
separated prior to coating.

wrote in message
ps.com...

wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right.
My

I hope that was that a typo!
No typo, in fact I might have under-estimated. The quote was for two
Tessars and it added up to $1400 based on my calculation. But they made it
sound like there might be extra charges too.

original idea was to coat the easily removable front and center elements
only. I would think the center element would be the most important
element
to coat, assuming I'm using a proper lens hood and a coated UV filter up
front. The coating operation I contacted told me that in order to get a
visible result, I would need to coat 80% of the surfaces. In other
words
every element of the Tessar - including the expensive separation and
re-gluing of the rear doublet. Does anyone agree with me that one or two
elements would yield a visible result or are they right in suggesting
that
it's all or nothing.
Thanks

I don't think there is an point in coating the cemented surfaces. There
won't be much light lost in reflection at the interface due to the
balsam having a similar refractive index to the glass on either side.

Read my earlier post - the coating process is too hot to leave the doublet
in a cemented state.

wrote:
wrote in message
ps.com...

wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right.
My

I hope that was that a typo!
No typo, in fact I might have under-estimated. The quote was for two
Tessars and it added up to $1400 based on my calculation. But they made it
sound like there might be extra charges too.


So why do it if it costs so much?


original idea was to coat the easily removable front and center elements
only. I would think the center element would be the most important
element
to coat, assuming I'm using a proper lens hood and a coated UV filter up
front. The coating operation I contacted told me that in order to get a
visible result, I would need to coat 80% of the surfaces. In other
words
every element of the Tessar - including the expensive separation and
re-gluing of the rear doublet. Does anyone agree with me that one or two
elements would yield a visible result or are they right in suggesting
that
it's all or nothing.
Thanks

I don't think there is an point in coating the cemented surfaces. There
won't be much light lost in reflection at the interface due to the
balsam having a similar refractive index to the glass on either side.

Read my earlier post - the coating process is too hot to leave the doublet
in a cemented state.

wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right.

Isn't that like gold-plating a turd? What's the point?

Etaoin Shurdlu wrote:
wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right.

Isn't that like gold-plating a turd? What's the point?

Well stated!

Bearing in mind that the Tessar is a fairly simple lens and better
lenses have since been made then it makes more sense to buy a camera
with a better lens. If contrast is the problem then bump it up using a
photo editor if scanning or use slide film which has more contrast.

If this person pays $700 to get a Tessar coated then the value of the
lens will only have increased by a few dollars.

"Etaoin Shurdlu" wrote in message
...
wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right.

Isn't that like gold-plating a turd? What's the point?

First of all I didn't say I thought it was a reasonable price, but secondly
people are spending far more than that on digital gear that will be obsolete
in months. Considering the prices in the digital world, I would hardly call
$700 "gold-plating". And I don't for one believe Tessars are "turds".

wrote in message
oups.com...

Etaoin Shurdlu wrote:
wrote:
I recently got a quote to coat a Tessar - $700 if I'm figuring right.

Isn't that like gold-plating a turd? What's the point?

Well stated!

Bearing in mind that the Tessar is a fairly simple lens and better
lenses have since been made then it makes more sense to buy a camera
with a better lens. If contrast is the problem then bump it up using a
photo editor if scanning or use slide film which has more contrast.

If this person pays $700 to get a Tessar coated then the value of the
lens will only have increased by a few dollars.

Did I say I was looking to increase the value of the camera? What collector
would have lenses coated? Yes there are better lenses than Tessars. Did
you consider that these Tessars are on a unusual body that has special
features, like rise and waterhouse stops for better bokeh?