From: "Bojidar Dimitrov" <[EMAIL PROTECTED]>
> Hi,
>
> a question to the optical-formula gurus. Pentax describes the optics of
> this mirror lens as 6 elements in 4 groups. Looking at the diagram that
> they provide us, I see 8 elements. I will number them 1 through 8 when
> looking from left to right. 1 and 2 as well as 5 and 6 seem to be forming
> the two two-element groups (like the optical formula suggests), but what
> about the rest?
>
> I am thinking like this:
>
> - elements 2 and 3 must be mirrors, so they might not be counted towards
> the number of optical elements. Now we are down to 6 elements which
> agrees with Pentax. But the number of groups is now 5.
> - alternatively, element 8 is the screw-on filter, so that might not be
> counted. Then we are left with 7-5. Still doesn's fit.
>
> Your ideas are welcome. Cheers,
> Boz
>
>
Boz,
my interpretation :
first group of 2 elements, some schmidt/maksutov like corrector forms a
group with the secundary mirror.
Second group of 1 element is the primary mirror (maybe mangin mirror?)
light goes then to the already mentioned secondary mirror, and then back to
the third
group af 1 element, a negative lens.
Then the 2 element fourth group, some kitted achromat.
So, now we have 4 groups and 6 elements, although I have my doubts if it is
right to
consider the corrector/secondary mirror one group.
The last 2 elements, are the 2 filterwheels.
one for the color filters, and one for the ND filters
Probably not counted as elements.
George
-
This message is from the Pentax-Discuss Mail List. To unsubscribe,
go to http://www.pdml.net and follow the directions. Don't forget to
visit the Pentax Users' Gallery at http://pug.komkon.org .
