2 replies to this topic

[nic35]

In looking over various configuration options, I ran into a TS-optics 1.6 ( or 2.6 ) GPC.

 

Maybe it is the German to English translation, but their descriptions say the GPC reduces the light path of the binoviewer by 65 %  or maybe to 65 mm.  And their 2.6x eliminates the length completely.

 

I always thought these devices by pushing  the focal plane outwards - acting as a barlow.

 

What am I missing ?

 

john

 

[betacygni]

I think they mean reduced light path in the sense that you rack the focuser in by that amount, effectively compensating for 65mm of the binoviewers extra light path for example.

Pushing the focal plane out has the net effect of compensating for the physical length of the binoviewer.

Edited by betacygni, 13 January 2025 - 06:27 PM.

[ABQJeff]

betacygni is correct. Both statements are the same: reduce added optical path of binoviewer by 65mm or increase backfocus by 65mm (the latter matching your understanding). The point of the GPC is to give you more infocus travel range on a telescope so you can reach focus with binoviewers (or compensate for optical path length in an SCT to minimize induced aperture reduction and spherical aberration).