Eyepiece use

A place to hang out and chat about astronomy

Eyepiece use

Postby christo » Thu Feb 23, 2006 8:10 pm

Hi all,
Have just purchased a set of five eyepieces plus barlow lens (Celestron set) to go with my 8 inch Celestron reflector. The sizes are 4mm, 6mm, 9mm, 15mm and 32mm. Could anyone provide advice about which size to use for what type of observations. Also have light filters as well. Looking forward to using my new kit once (if ever!) this cloud cover clears!!
Cheers v. much,
Chris
christo
 
Posts: 393
Joined: Mon Feb 13, 2012 6:22 pm

RE: Eyepiece use

Postby gammalog » Thu Feb 23, 2006 8:43 pm

Hi Chris

The size of eyepiece that you use depends on several factors, such as the 'seeing' conditions, the Field of View (FOV) required, and the object you are trying to view.

You would normally only use your higher magnification lenses (the smaller numbers) on the planets, but this is very dependent on the 'seeing'. It is unfortunatley, not too often that the atmosphere steadies enough for use high magnification. Under poor 'seeiing' the planet will be seen to be 'boiling/shimmering', and the higher the magnification the worse the effect.

If are lucky, and keep looking for a while, you may find the atmosphere will steady for a few seconds, revealing lots of surface detail. With planetary imaging, it is not uncommon to 'dump' up to 95% of a sequence of frames taken over a relativley short period.

Your 32mm eyepiece will be very useful for wider file views, of many 'deep'sky' objects, which will appear much brighter at lower magnification.

You have a nice range of eyepieces available to you, and the best advice would be to experiment with them and get a feel for where each is best suited for what you are trying to observe.

You will probably find that as you go up in magnification (down in eyepiece focal length), the amount of eye relief (the distance between the eyepiece and your eye) will decrease. With some eyepieces, this can make for uncomfortable viewing. A way around this is to use a Barlow lens. For example, a x2 Barlow used with you 15mm eyepiece, will turn it into a 7.5mm eyepiece, while retaining the eye relief of the 15mm.

Hope this helps.

Dave
gammalog
 
Posts: 840
Joined: Mon Feb 13, 2012 6:21 pm

RE: Eyepiece use

Postby deeds » Sat Feb 25, 2006 12:13 am

Hi Chris

I use a set of Vixen Lanthanum eyepieces. I find these better than any other eyepiece I have used (Plossls etc). I have a 42mm Wide angle (2" fitting ) as well as a 25mm, 15mm, 10mm, 4mm, and 2.5mm all of which have a 31.7mm fitting.
These eyepieces are not cheap as they average at £110 each but they are worth every penny - no more squinting through tiny holes as every eyepiece has 20mm eye relief !!!
deeds
 
Posts: 135
Joined: Mon Feb 13, 2012 6:21 pm

RE: Eyepiece use

Postby christo » Sat Feb 25, 2006 2:06 pm

Cheers you two, appreciate alll your tips and guidance.
Just to comment on one of your other threads Gammalog I agree that people should comment more and make others feel at 'home'. As a selfish point I have gathered so much useful and valuable information from this forum that has enabled me to move my hobby on with confidence. Although, I have no doubt that I have only just begun to scrath the surface. Will atempt to make a greater effort to contribute my rather amature comments and ideas to others. You have made good points about the survival and success of the forum, although I do appreciate that people (including myself) can be a little nervous about posting comment until they become confident with the forum.
Anyhow thanks again for the tips,
Chris.
christo
 
Posts: 393
Joined: Mon Feb 13, 2012 6:22 pm

RE: Eyepiece use

Postby gammalog » Sat Feb 25, 2006 2:06 pm

Hi again Chris

Glad that Tim and I have been of some help to you.

I'm sure people can be a little nervous about 'posting' on the forum, but as I said, it doesn't have to be technical and just 'popping up' and saying hello is a good start.

I've only been in this hobby for a little over 5 years, and at that time, knew little or nothing about astronomy. I only wish that something like this forum had been around when I started out.

Dave
gammalog
 
Posts: 840
Joined: Mon Feb 13, 2012 6:21 pm

RE: Eyepiece use

Postby geoff_p » Mon Feb 27, 2006 10:13 pm

what very useful answers to this question, in particular the Barlow eye relief thing is not something i have read before, i think i'll go and buy one right away. in fact eye relief in general rarely seems to get a mention - i was aware that my higher mag eyepiece was not as 'comfortable' to use, now i understand.

cheers

geoff
geoff_p
 
Posts: 1
Joined: Mon Feb 13, 2012 6:22 pm

RE: Eyepiece use

Postby christo » Mon Feb 27, 2006 10:30 pm

The Barlow trick does seem to be a top idea. Haven't had chance to use the new eyepieces yet but this idea to get around the problem of the eye relief is a very good one. Its amazing what tips you can pick up on this forum. Shame I haven't had chance to use any with the continual cloud cover - and now its just started to snow!
Chris
christo
 
Posts: 393
Joined: Mon Feb 13, 2012 6:22 pm


Return to General

Who is online

Users browsing this forum: No registered users and 4 guests