celestron CR achomat lens : HD, ED... ?

Hi,

A question addressed to Celestron achromat users.

On their website C. does not tell what lens quality they use today to made
their achromat lenses (e.g. in CR-6 f/8)

In the past (a couple years ago) their ED lens was qualify of very good
quality and even recommended.

Some users told me that currents lens are HD now...

What are the current quality, always ED or a real mix including HD and other
dispersions ?

Any info on the Internet or review about them is welcome to update an
article.

Thanks in advance.

Thierry
http://www.astrosurf.com/lombry/rapp...berrations.htm

Any info on the Internet or review about them is welcome to update an
article.


HI Thierry:

To my knowledge, this has never featured ED glass. It is a plain old acrhomat
made by Synta.

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

"Rod Mollise" wrote in message
...

Any info on the Internet or review about them is welcome to update an
article.


HI Thierry:

To my knowledge, this has never featured ED glass. It is a plain old
acrhomat
made by Synta.

Still worse than expected ;-)
Remain the chromacorr, even though..

Thanks.
Thierry

Peace,
Rod Mollise
Author of _Choosing and Using a Schmidt Cassegrain Telescope_
Like SCTs and MCTs?
Check-out sct-user, the mailing list for CAT fanciers!
Goto http://members.aol.com/RMOLLISE/index.html

peopel throw the term "ED" around like it was cheese. Any excuse and its
ED. Not too many years ago its was "quartz". Then "digital". Anyone care
to nail down users of "diffraction limited"? You will get 20 experts testifying
what it means or comes close to meaning, or should mean ... its like speed
limits signs everyone knowswhat theyare but nobody drives them!



Thierry wrote:

Hi,

A question addressed to Celestron achromat users.

On their website C. does not tell what lens quality they use today to made
their achromat lenses (e.g. in CR-6 f/8)

In the past (a couple years ago) their ED lens was qualify of very good
quality and even recommended.

Some users told me that currents lens are HD now...

What are the current quality, always ED or a real mix including HD and other
dispersions ?

Any info on the Internet or review about them is welcome to update an
article.

Thanks in advance.

Thierry
http://www.astrosurf.com/lombry/rapp...berrations.htm