Details of Skywatcher Startravel needed please.

[keith5700]

I’m just designing my next binoscope, and can start buying stuff if/when I sell my 16” reflector binoscope.

I’m going to make a smaller setup, with 2 x 150mm f5 refractor lenses from Startravel scopes.

All I need at present is a couple of dimensions. Does anyone know the thickness of the 6” doublet lens, at the edge?

Just so I can order the material to make the bespoke lens cells.

Also, the 750mm focal length? Where is that dimension taken from? Is it from the rear of the lens, or the midpoint, or the front?

Thanks.

Edited September 12, 2023 by keith5700

[Albir phil]

The 750mm is from the front of lens are you using the original tubes to make the binos 

[keith5700]

Thanks. No, the only thing I need from the scopes is the objective lenses. Don’t even need the lens cells. Shame to waste the rest, but highly doubt I could just buy the lenses from anywhere.

[Peter Drew]

I've made several binoscopes using SW 150 F8 and F5 Startravel achromats.  The images show a F8 version.  I used the original cells so did not measure the edge thickness.      

[windjammer]

That's great!

[keith5700]

Wow, that’s a beast.

[keith5700]

I bought a couple of the scopes in the end. Lens is 31.6mm at the edge, if anyone ever needs to know.

I have another question though. I measures the internal baffles to see what the designers were thinking as to the light cone. ie what diameter of light hits the eyepiece. I was thinking at least 15mm dia.

drawing it all out, in a straight line, shows it has a 5mm dia light cone when it hits a 17.5mm Baader Morpheus, for example.

Surely this isn’t big enough, or am I missing something?