|
FPL53 is more expensive, than FPL52 or FPL51. You can achieve an equal degree of color correction with all three when given they are matched to suitable mating elements. The difference is that telescope using FPL53, will likely have a shorter focal length. A shorter focal length results in a wider field of view, as desired by imagers. Within each glass type, various grades of quality are availalable. Premium grade of any glass will be guaranteed to a specification regarding striae, bubbles, and clarity etc. Quality comes at a price.
Regards Mark
mmm, my post is late, that Cloudy Nights reference two posts above explains it nicely.
Last edited by gts055; 12-05-2008 at 09:51 AM.
Reason: added note
|