Vixen ED114SS


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Subject: Re: vote by xxx.xxx.134.49
By: Anonymous (xxx.xxx.93.16)
In Reply to: Anonymous (xxx.xxx.134.49) (Original Vote)
Date: 10/24/2003 12:21:28 pm PDT
>No ED-doublet refractor should ever be called "apochromatic"! Not even the fluorite-doublets are! True apochromatic refractors are of true triplet or quadruplet design - which for example excludes doublets with additional field flattener lenses...

The above is a political statement more than a rating of the product. With modern glass and lens design it is possible to build an APO in a doublet configuration. The ED114SS review in S&T (5/02) called it an APO and compared it to other APO scopes.

Some quotes from the article:

"Jupiter looked neutral white when sharply focused, with no surrounding halo of blue light, remarkable for such a fast-foca-ratio refractor."

"Bright 1st-magnitude stars appeared clean white, with no halos from chromatic aberration."

This is not a fluke, many Tele Vue scopes are doublet APOs also.


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Subject: Re: vote by xxx.xxx.134.49
By: Anonymous (xxx.xxx.74.5)
In Reply to: Anonymous (xxx.xxx.93.16) (Original Message)
Date: 11/20/2003 09:31:18 pm PDT
"This is not a fluke, many Tele Vue scopes are doublet APOs also."

As are the Takahashi FS series. The modern definition of Apochramatic from the TMB website:

"An objective in which the wave aberrations do not exceed 1/4 wave optical path difference (OPD) in the spectral range from C (6563A - red) to F (4861A - blue), while the g wavelength (4358A - violet) is 1/2 wave OPD or better, has three widely spaced zero color crossings and is corrected for coma."

As you can see, it has nothing to do with whether it's a doublet, triplet .... all reports so far rate the Vixen EDs as apochromatic.


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