x2 or x3 ?

[ianB (Ian)]

Hi All,

I want to order a Televue Barlow this week for use with my Nexstar 6SE f10.
I want to use it with my Philips Toucam 900NC webcam and was wondering should I order a x2 or x3 Barlow, I know the answer may be obvious ( x3 will give a larger image ) but maybe I am overlooking something? From your experience ( doing webcam imaging ) what would you suggest would be best for me to get.

Your thoughts are most welcome.
iB

[Merlin66 (Ken)]

Ian,
My rule of thumb for webcam imaging is x5 the pixel size (microns) = optimum focal ratio....I think you'll find this comes out close to f25.
Your f10 with a x2.5 Barlow/ Powermate would be very good.
Unless you experience fantastic seeing conditions, I'd go for the x2 rather than the x3.
Just my 2c

[ianB (Ian)]

Thank you Ken I appreciate those comments, I am only just starting to understand the pixel size thing so its good to hear from someone with knowledge about this.

iB