letter on ep's and their meaning ?

[vindictive666]

hello everyone

i was wondering if anyone explain or point me to the direction on what the letter on my ep's might mean ?

on my 20mm it has H20mm

on my 4mm it has SR4mm

on my 2.5mm it has H12.5mm



:confuse3: :D

[gbeal]

Hi Vin,
I'm not expert, so bear this in mind, but I do go back a few years.
"H" is for Huygens, a simple 2 lens design, with the focal point within the eyepiece, (between the two lenses). I have three Huygen eyepieces made by Zeiss, for the Zeiss scopes.
Ordinarily the Huygens is synonomous with cheap and nasty, sorry. (The Zeiss don't really fall into the C&N category though!!!)
One benefit of the Huygens is that they can be used for solar projection, as there is no cement used to join the lenses, this cement being vunerable to the heat build up when solar projecting.
The "SR" is a Ramsden derivative, and I believe the "S" is for symetrical. It is slightly better than the Huygens, and the focal plane is in front of the field lens. The SR and the H series were common in my earlier days, but mostly have been superseeded by the Plossl and orthos.
If they perform well, use them. There is a lot to be said for less elements as opposed to the multi element designs in vogue these days.
Gary

[vindictive666]

nah dont be sorry gary :)

i got the scope really really cheap as a (dont laugh) Supermarket type deal ive never owned a scope before and when this this scope cropped up i snapped it up it came with 3 eps 1 barlow and a erecting ep i realise its a so so scope however ive got an solar filter for it and i had and still have some great views with it a smidgin better than my 7 x50 binocs :)

at the moment trying to get my cash together for a 12 inch dob :) hopefully ill have it in time for the mars opposition next year

but as you know it a very very limited scope :)

better than nothing though :)

[gbeal]

Vin,
one of the worst things for folk new to this hobby is for some snob to tell them how lousy their gear is, and this is just what I was trying to avoid. The 7x50's will show you heaps, but eventually you will hanker for better.
If nothing else, learn from the failings of the Dept Store scope you appear to have. For Gods Sake though, avoid the solar filter, UNLESS it is a good quality fit over the objective model. Most C&N scopes come with an eyepiece solar filter, CHUCK IT.
If in doubt get advice, as astronomy relies on you being able to see. Sounds simple, but...........
As an aside, if you are handy with tools give some thought to building up a dob. I see a company called Antleers or similar advertising mirror sets, and reasonably priced too. Just an option, it isn't rocket science. There is plenty of knowledge to be had within this forum, so just ask.
Gary

[vindictive666]

nah dont worry :)
i jumped in with eyes fully open (i Paid a whole full 49 Aussie Dollars for it :))
and the solar filter is an celestron international solar filter (an Aperture one ) (done my home work as far as solar filters are concerned for the scope).

as i said this scope has given me good views of the moon, saturn and ive even seen the bands on jupiter and its four major moons :)

and the trapizium in orion

ive split the binary of castor or pollux cant exactly recall which one :)