Eye piece & remote control focus

[Jason71]

Hi every.

Could some one advice me on a good all round eyepiece for astronomy and a good remote control focus.

Looking for a eyepiece that will be good for deep space & planets but their is so much to choose from I haven't really a clue on what's good and not.

Thanks.

[Jason71]

Hi every.

Could some one advice me on a good all round eyepiece for astronomy and a good remote control focus.

Looking for a eyepiece that will be good for deep space & planets but their is so much to choose from I haven't really a clue on what's good and not.

Thanks.

Hi every one I mean. Lol.

It is early lol.

[Schorhr]

Hello Jason,

what telescope would this be for?

I quickly browsed through some of your posts and looked at your signature, but only saw your binoculars;

Depending on the telescope's focal length, aperture and aperture ratio, things like magnification, exit pupil and wether or not you can use inexpensive eyepieces, have to be considered.

Also how much per eyepiece do you want to spend?

What eyepieces do you currently own?

There is no all-in-one eyepiece, even the zoom-type usualy have flaws (either a narrow field of view on one end of the zoom, a high price, or both).

The rule of thumb would be to get one with

5-7mm exit pupil (eyepiece mm devided-by telescope focal ratio = exit pupil) for low magnification, overview, such as Plejads, Andromeda, n.america nebula, other larger objects

Depending on age/eyes ands light pollution (disturbed night vision) your iris may not open 7mm thus some of the light from the eyepiece may not reach your retina.

Think of the exit pupil of an eyepiece as a flash light beam that has to go through a small hole ;-)

You can see the exit pupil of your binoculars by the way, too, from afar you'll see that there are two circles/dots of light visible in the eyepieces.

Their diameter relates to the focal ratio, if you'd cut out cardboard to make the aparture opening of your bins smaller, the exit pupil diameter would change as well. Thus on higher magnification the image gets darker, so a larger aperture telescope will show more as the exit pupil is larger.

4-5mm (great for light poluted areas, slighlty smaller objects such as the orion nebula or pairs of clusters, galaxies)

2-3 mm exit pupil (gread mid range magnification, darkens the sky background, ideal exit pupil for many deep sky objects, nebulae, clusters)

0.5-1mm for planets, moon and double stars (but keep in mind magnifications over 200x are rarely possible due to our athmosphere, seeing)

Now keep in mind this is pretty generic and this "rule of thumb" can fail at very large telescopes. A 16" telescope may allready have 2mm exit pupil at 200x and allready 60x around the recommended lowest magnification...

[ronin]

Without knowing the scope difficult, although such minor problems have never prevented a good guess. :eek:

How about taking the f number of the scope and double it, whatever the number buy an eyepiece of that focal length in mm. :grin:

Gives a magnification equal to half the aperture, and a 2mm exit pupil.

Cannot advice on the focus remote, as I am stood at the eyepiece I just use fingers. As you will use your fingers for the remote anyway why not use them on the focuser direct? :rolleyes:

[Jason71]

Sorry. My fault. Beginners mistake lol it would be for a Skywatcher Skyliner 150P Dobsonian.

[Jason71]

Hello Jason,

what telescope would this be for?

I quickly browsed through some of your posts and looked at your signature, but only saw your binoculars;

Depending on the telescope's focal length, aperture and aperture ratio, things like magnification, exit pupil and wether or not you can use inexpensive eyepieces, have to be considered.

Also how much per eyepiece do you want to spend?

What eyepieces do you currently own?

There is no all-in-one eyepiece, even the zoom-type usualy have flaws (either a narrow field of view on one end of the zoom, a high price, or both).

The rule of thumb would be to get one with

5-7mm exit pupil (eyepiece mm devided-by telescope focal ratio = exit pupil) for low magnification, overview, such as Plejads, Andromeda, n.america nebula, other larger objects

Depending on age/eyes ands light pollution (disturbed night vision) your iris may not open 7mm thus some of the light from the eyepiece may not reach your retina.

Think of the exit pupil of an eyepiece as a flash light beam that has to go through a small hole ;-)

You can see the exit pupil of your binoculars by the way, too, from afar you'll see that there are two circles/dots of light visible in the eyepieces.

Their diameter relates to the focal ratio, if you'd cut out cardboard to make the aparture opening of your bins smaller, the exit pupil diameter would change as well. Thus on higher magnification the image gets darker, so a larger aperture telescope will show more as the exit pupil is larger.

4-5mm (great for light poluted areas, slighlty smaller objects such as the orion nebula or pairs of clusters, galaxies)

2-3 mm exit pupil (gread mid range magnification, darkens the sky background, ideal exit pupil for many deep sky objects, nebulae, clusters)

0.5-1mm for planets, moon and double stars (but keep in mind magnifications over 200x are rarely possible due to our athmosphere, seeing)

Now keep in mind this is pretty generic and this "rule of thumb" can fail at very large telescopes. A 16" telescope may allready have 2mm exit pupil at 200x and allready 60x around the recommended lowest magnification...

  

Without knowing the scope difficult, although such minor problems have never prevented a good guess. :eek:

How about taking the f number of the scope and double it, whatever the number buy an eyepiece of that focal length in mm. :grin:

Gives a magnification equal to half the aperture, and a 2mm exit pupil.

Cannot advice on the focus remote, as I am stood at the eyepiece I just use fingers. As you will use your fingers for the remote anyway why not use them on the focuser direct? :rolleyes:

Sounds like their is a lot more to it than I thought. Lol. Thank you any way.

[Schorhr]

Hello Jason,

sorry for the huge reply but as you wher enot specific I just wrote what to watch out for.

Go by those rule-of-thumbs. As you send me a message I replied to you where you can get the 66degree eyepiece that work well at f/8, but BST or TMB planetary eyepieces would be a tad better.