Recommended Eyepieces for my scope?

[IXTL]

Hi everyone.

I just thought I'd ask for your opinions and advice on purchasing some eyepieces for my scope. I've used the supplied EP's for a few years now, but after reading the difference a quality EP can make I would like to buy some and see.

The focal length of my scope is 500mm, the aperture 114mm. F4.3.

I like to view the obvious: Planets, DSO's, clusters etc.

So which EP's would you recommend? Also, it may seem a newbie question, but how do I work out the maximum magnification of my scope, and how much magnification different sized (eg 10mm/17mm etc) EP's would give?

Thanks very much,

IXTL

[brantuk]

With UK seeing conditions any magnification much above 200x to 250x is not going to be practical (though the scope may be capable of much more).

The magnification is worked out as EyePiece length (in mm) divieded into Focal Length of scope (in mm). So a 5mm ep yields 100x mag in your scope

Edit: I'd suggest you borrow some ep's at your local astro soc to try out and you should see the differences in quality.

[IXTL]

Thanks very much for your quick response!

Ahh, that is very easy to work out - simple when you know how..

Edit: Yes, that sounds like a logical step to see which types I prefer. I'm not sure there is an astro society in my area, but I'll do some research to find out if there are any within a respectable driving distance.

[brantuk]

You'll find (like I did) that if you start with supplied ep's then go up to fifty or sixty quid ep's the difference is quite marked. As you go up into the £100-£200 bracket it's even more significant too. But over £200 the diferences start to get smaller and depend more on type and make. (Talking generally here about new prices).

You should think about differences between narrow field high power for planets, and wider field low power for dso's. There's also a difference between 1.25" and 2" and number of elements.

I'd suggest a good read of Andrews Primer on ep selection - will post a link in a min

Edit : http://stargazerslounge.com/primers-tutorials/63184-primer-understanding-choosing-eyepieces.html

[IXTL]

That link you posted is so useful! Thanks very much indeed brantuk

Going to start looking for some good quality Plossls and Orthoscopics, do you recommend any makes in particular?

Thanks again! You have been very helpful.

[IXTL]

Apart from the obvious of FLO, do you recommend also any retailers on the internet who deal in good quality EP's?

[BenM]

You didn't mention the type or quality of the scope's optics. I'm guessing that it's a mass-produced refractor or a low quality Newtontian. I'm not wanting to disparage it at all, but you'll get the best result from being realistic.

My experience is that only the best optics can achieve anything useful at 200x with that aperature. That's on a resolution target, not counting the atmosphere. A typical 114mm scope is most suited to 20 to 100x.

I would suggest the following eyepieces from Tele Vue:

Panoptic 24 (20x for good wide field of view)

Nagler 17 (30x with only a slightly smaller TFOV and better eye relief, generous AFOV)

Radian 8mm (62.5x) with comfortable eye releif, good AFOV and little dispersion -- probably one of the best higher power eyepieces for this scope.

You could also try a Radian 6mm but you might be better off using a 2x barlow or 2.5x Powermate with your collection of longer focal length eyepieces.

It's costly, but a good alternative to consider is a Leica WW aspheric zoom eyepiece. It gives you 9 to 17.9mm and everything in between with at least 60 deg. AFOV, very generous eye relief, and good optical performance in all respects. It should give awesome wide field performance as good as anything else, and up to 55x which is the best range for this scope. Going a lot higher and you're going to get worsening false color with a fast refractor like this that probably has no corrective elements (like ED glass or flourite crystal), not to mention spherical abberation and half the field by diameter out of focus. If it's a reflector, it's really a fairly small aperature owing to the central obstruction and at f4.3, you'll see bad coma particularly if you try to use extreme eyepieces. The Leica zoom is a good alternative to a collection including a Panoptic or Nagler, and a Radian. It's the price of three eyepieces but will do as much and with less fiddling.