When I try to ferret out the really faint fuzzies, I'm usually running
between 377 (7mm Pentax XL) and 881x (3mm Radian) on my 22"
f/4.1...especially if the galaxies are packed together such as the
Hicksons, Abell Galaxy Clusters and Shakhbazian galaxy chains
The eyepiece I use depends on the sky and the size of the object. If it
is really small and really faint, then I go higher. If I'm going for
Abell Planetaries, which many are faint extended ancient planetaries, I
usually ride between 155x and 293x.
Regards,
Alvin Huey
--- 22" f/4.1 Pegasus Reflector faintfuzzies.com tac-sac.org observers.org > There definitely reaches a magnification (or exit pupil) for me where > the background is sufficiently dark that no additional detection is > gained (or contrast) by boosting the magnification as the background > stays constantly dark from that point on. For small galaxies, I > generally reach this ideal contrast/detection magnification with an > exit pupil of ~1.6-1.8 mm. With an f/10 scope, this translates to a > 16mm-18mm eyepiece or 110x-125x but with my f/4.3 Starmaster, you're > talking closer to a 7.5mm eyepiece or ~250x. Of course, with small > high contrast objects like planetaries, much higher powers are often > useful. > > I think when folks use an exit pupil of 3mm or 4mm on galaxies (easily > computed by eyepiece focal length/f ratio) they're not maximizing this > contrast. Unfortunately, some guide books mislead by stating lower > powers = brighter images. Any other thoughts?Received on Mon Oct 10 21:53:53 2005