Re: [ATM] Triplet

[Anthony Stillman <atmer@flash.net>]

Alfredo,

First, good luck.  Second, I am not trying to dissuade you.

The tolerances on a triplet are daunting.  Its not impossible for an amateur, but you will need patients and tools, a means to center, to measure CT, to test cave surfaces on axis, to test vex surfaces, to measure ROCs, the list goes on. On your budget, making them is your best bet.  Some of the testing vex surfaces problem can be built into the design by matching a cave radii (you want an oil spaced objective anyway) and contact testing, but you may still need to make at lease one proof plate (a separate piece of glass with a matching cave surface).  Triplets have a lot of degrees of freedom so coming up with a decent design that meets your requirements should be possible, but maybe not easy.  Perhaps Richard F.L.R. Snashall will help you.

Anthony



A R <gulgoz55@gmail.com> wrote: Hi All,

As my next Project I would like to make a 5" or 6" APO or semi-APO
triplet around F8. I am looking for advice on the design and glasses
to be used. I would like to use easy to get and work glasses, no
exotic ultra expensive  or no longer produced glass. I like the idea
of oil spaced since it means a lot less work. My budget is about US$
500 for the glasses. Any suggestions?

Regards,

Alfredo
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