what F for an 8" galaxy hunter

[Brian W]

There is way too much cloud cover so my mind is getting silly.

I own an 8" F6 Lightbridge and I love hunting faint fuzzies.

What suggestions would anyone have for making it a better faint fuzzy hunter?

Brian

[koputai]

Put a 1 in front?

Cheers,
Jason.

[Brian W]

Well yeah that's 1 solution but I have a major balance problem so if I did that I would need to dig a deep hole so that the ep was at eye hight and then there would be drainage problems and I would need an observatory over the hole and of course electricity and well you get the picture.

Brian

[tlgerdes]

Not much else is going to change the gathering capability. You could buy better mirrors and install them.

Have you ever collimated your scope?

[Terry B]

The "f" mostly doesn't matter for visual astronomy. Use a scope that is a comfortable length and eyepieces that give you a choice of widefield and higher power to find the smaller faint fuzzies.

[mental4astro]

Your f/6 scope is just fine for faint fuzzies, Brian. I've used both f/6 & f/4 8" scopes on faint fuzzies, and both work as well as the other. Sure, the image in an f/4 scope is 'brighter' than in an f/6 for the same aperture, ONLY if you are using the same eyepiece in each scope.

If you have the SAME magnification in each scope, the image brightness should be the same! For that, you'll need a longer focal length eyepiece in the f/6 scope.

Keep in mind that here the exit pupil of the eyepiece should dictate the longest focal length eyepiece you should use, that being 7mm for a 15 year old, :rolleyes:, but closer to 6mm for older eyes.

For your eyes, 6mm X f/6 = 36mm eyepiece.

As eyepieces vary in available focal lengths, the max. f.l. would be 7mm X f/6 = 42mm eyepiece.

So, a 40mm eyepiece would suit your scope to give you the max. image brightness.

With an 8" f/4 scope, this would be a 28mm absolute tops, with 30mm being the most widely available. And then, you may start encountering coma becomeing an unwelcome intrusion, along with any astigmatism that your eyepieces may have.

[pgc hunter]

Yup focal length doesn't matter one bit when it comes to light gathering for faint fuzzies. An F/4 and F/10 scope of the same aperture will yield images of identical brightness at the same magnification, all else being equal.

[Brian W]

Thats all good to know.

Yes indeed collimation and I are old friends. I learned on our f3.9, 4.5" Orion short tube reflector. The primary was not hard but my stubby fingers and the secondary had a fight or two.

I looked into premium mirrors but a gentleman by the name of Royce didn't think it would make much difference, at least for the primary but it was suggested a premium secondary could make a difference.

Certainly the flocking and the light shroud really help.

Brian

[wavelandscott]

My recommendations (some covered) flocking, shroud, dew shield (light blocking at the top)...and anything that can help protect your dark adapted eyes...from carrots, no alcohol, hood for your head, red glasses (when you are not observing)...reduce the use lights (even red ones).

Maximize the reduction of stray light...