Scope repair Broadhurst Clarkson 3"

[lfulham]

I recently purchased a rather sad brass refractor on AltAz mount w tripod. The lens is broken and missing.

It is a Broadhurst Clarkson 3” “Advanced Starboy”. The mount is probably a modified Unitron from the early 50’s so I expect the scope dates from that time also.
I am happy with making a replacement lens for this scope, but am finding the original focal length hard to nail down. If anyone has a intact scope of this type, I would be very interested to know it’s focal length. (My estimate is 1100mm, f14.5)

Further, I have no knowledge of it lens design. Possibly it was a coma free design as there is no provision for collimation. (Fraunhofer or Littrow are probables)

If any one has specific knowledge, or actually owns one of these scopes I could examine, I would like to hear from you.

Len.

[Rainmaker]

Hello Len,

Send a PM to Mark (gts055) he has one of the B&C Advanced Starboys as well as a Watson&Sons version.

I believe they are both F15 Fraunhofer designs

Regards,

[lfulham]

Thanks Matt, PM sent to Mark!

[lfulham]

Quick follow up

I have had some good information from Mark's experience with his scope.

The lens is airspaced and probably f15 probably Fraunhofer design.
I also learned more about missing parts esp the finder style.

Attached a photo of the scope as bought - it will stay like this for a while yet!

Len.

Attached: Scope (Mount following)

[lfulham]

And the AltAz mount Pic: