Quote:
Originally Posted by Astro_Bot
The rule of thumb is, "50x per inch of aperture", so 200x for a 100mm (4 inch) refractor is about right. You may be able to get more, but the advertiser is being conservative and that's a lot better than other advertisers who claim ridiculous magnifications for small refractors, notwithstanding the commonly-accepted limit of 300x due to the atmosphere. But see this:
Where does the 50x per inch limit on magnification come from? |
Thanks, but 50X per inch is for reflectors. High end APO refractors - which don't have a central obstruction that pushes light out into the diffraction rings - should typically be able to do much better than that.
I can understand the advertiser being conservative, but I think it extremely unlikely a 4" APO or ED refractor won't get a lot better high power performance than a 4.5" reflector.
Cheers,
Renato