which road shall i travel?

[estwing]

hello there i have a telementor 2 840mm focal length f13.3 a 25mm and a 16mm eyepiece in 0.965 flavor with a x2 barlow giving me about 105xmag very nice..just bought all the adapters to allow me to use 1.25 ep's so next step would be what?, 6mm to give me 140 or which type would suit my scope the best or am i entering a minefield..

[Chris H]

A 6mm ep would be a good choice as a high power ep as for the type that depends on budget but your F13 scope is slow so not demanding on eyepieces so you have plenty of choice.

[John]

There are loads of options as you have probably seen and most would work very well with your scope !.

Keeping faith with the supplied eyepieces, which were orthoscopics I believe, you could do a lot worse than a 6mm Baader Genuine Ortho. They are really sharp and contrasty - as good as it gets without spending masses more. The downsides of them are the usual ones for orthoscopics - small eye lens, tight eye relief (the distance you need to put your eye from the top lens) and a relatively narrow field of view. Budget around £72 new or £50 used.

There are other choices of course but personally I'd love to view though a Telementor with a fine orthoscopic

[estwing]

think i will stick with the ortho's..as i don't really know the difference between ortho,ethos,nagler,planetry,etc..and why is it slow? sorry me not know...

[estwing]

just read robin's eyepiece page on swindon stargazer's website...great read!

[John]

This primer from one of our members is good as well:

http://stargazerslounge.com/beginners-help-advice/80772-eyepieces-very-least-you-need.html

If you divide the focal length of a scope by it's aperture you get a figure which is known as the focal ratio. It's expressed as a number preceded by an F/. With your scope the focal ratio is F/13.3 (840mm divided by 63mm). By contrast I have a newtonian scope with a focal ratio of F/4.8 (1200mm divided by 250mm). Scopes with higher focal ratios are termed "slow" while those with low focal ratios are "fast". The differences between these types have significance in a number of different ways, one of which being that "slow" scopes don't need really well corrected (and expensive) eyepieces to work well.

Hope that helps a bit.

[estwing]

help's alot thanks john..

[AndyH]

This UK company sells the volcano shaped orthos.

Lyra Optic - Eyepieces

I used to have a full set and probably will get some again some day. I find them just as good optically as the flat topped style ones and are easier to see through due to the shape, especially in the 4, 5 & 6mm sizes.

I agree with John, regarding the use of orthos on your scope. An old but still an excellent design, giving crisp contrasty views. Sure, the field of view is small, but as you've got slow motion knobs on your mount, it shouldn't be a problem.

Andy.

[estwing]

look nice and the price is very tempting....dear santa....