Barlow - which one?

[andrews5040]

Hi,

Thanks for the welcome to the site, loads of useful information out there but I haven't found much obvious relating to this.

I have an 8" Meade LX90 and a Coronado PST.  I am looking to purchase a barlow that will suite both these but am confused as to whether to get a short or standard length one!  Have seen much discussion on cheap vs expensive, is there anything else I should consider?

Cheers,

Alan

[YKSE]

Both your scopes are F10,which means the most used EP for them will be around 8mm to 24mm (exit pupil between just under 1mm and over 2mm) in addition to a wide field EP for LX90.

Barlow is used most together with the mid and short focal EPs, in your case, if you have 24mm, 20mm, 18mm 16mm EPs, with a 2x barlow, you'll get 12mm 10mm, 9mm and 8mm when combined with the barlow. It'll meet most of your observation needs.