Ok, to help complete my telescopes and suggested equipment for beginners article, I want to include barlows (or powermates).
Given most guys are getting 8", 10" or 12" dobs and there seems to be always a 6mm or 9mm eyepiece floating around to start with, I want to advise what barlow / powermate to get for non tracking and then tracking. Also lets say you will get a few great nights per year and the noobie will want to have a really good view of the planets in as higher magnification as practical.
My conclusions from reading the excellent info from the threads
- When you first get a dob, a 2x barlow (orion shorty plus) is the limit that is practical. Any higher magnification (aprox 300 x to 400x) is too hard to manage as the view will zip across the screen.
- If you have tracking, then a 5X would be the best option.
Barlows seem to mean planets for most guys, so would i be right in saying that if you get a 5x then saturn, jupiter, mars will be very large in the field of view? Is there any need for a barlow at 2.5 or 2x if you have a 5.
Is the 5x only able to be used in very rare perfect seeing? What is the practical limit for magnification for a 10" 1250 fl dob?
I want to produce a summary shopping list, no list will be perfect for all, but by the repetive response we all give, then a common list would be very useful