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TAL 200K Telescope Televue and Vixen eyepieces

Televue and Vixen eyepieces



Choosing a set of eyepieces

I started off with the two TAL eyepieces and the TAL 2x Barlow lens, provided with the 200K. In the last two years I expanded my eyepiece collection with a Televue 32mm plossl and a series of Vixen Lanthanum's (25, 20, 15, 12, 10, 9, 7 mm).

Building a good collection of eyepieces, is very important. You might switch to one or more other telescope(s) at some point in your life, but the eyepieces will probably stay with you for a lifetime. They can be used with different telescopes; eyepieces are a long-term investment!

For the beginner the large number of different high quality eyepieces from which to choose can be very confusing. There are a lot of different designs, and no single eyepiece is best for every target you want to observe. It’s up to you to decide which eyepieces to buy.


Vixen Eyepieces

There are however two general advices I would like to give:

  • Read, read and read. There are many articles on eyepieces available on the Internet, but also in the popular astronomy magazines (Astronomy and Sky and Telescope). By reading all this information, you will gradually build op some basic knowledge about all the different aspects you have to think of while choosing a set of eyepieces, like magnification, eye-relief field of view, different type’s etc.

  • Join a local astronomy club, visit friends who already own a telescope, or go to some star-parties. Talk to people about their equipment, and most important, look through as much different telescopes and eyepieces as possible. Doing this you will learn what objects you like to observe, and most important, which equipment is best for observing your favorite objects.


Here are some links to articles that I found very helpful when choosing an eyepiece-collection.

- How to start an introductory eyepiece collection on $50.00 by Allister St. Claire

- Eyepieces & Choosing an eyepiece Set by Jay Michaels

- Eyepiece Review Pitfalls by Bill Brady

- Choosing your telescope’s magnification by Al Nagler



How did I choose my set of eyepieces?


After the initial phase of gathering some basic knowledge about eyepieces, I started talking to others, looking through different eyepieces at the local astronomy club etc. and I decided to go for the Vixen Lanthanum's. This is how I came to my decision:

Because I suffer from astigmatism, I have to be able to wear my glasses while observing. The number of eyepieces that I found useful for observing with glasses narrowed down very quickly. I found out that only eyepieces with an eye-relief around 20mm would be suitable. Basically, there where two series of eyepieces that fitted my need, the Televue Radian’s and the Vixen Lanthanum's. For me, the choice between these two was very easy: budget, the most limiting factor again. For the price of two Radian's I could buy five Lanthanum's.
(I never tested the Radian's, so I can't compare them to the Lanthanum's!)

So I started out with buying a 20mm and a 12mm Vixen Lanthanum. In combination with the TAL 200K they delivered very satisfying views of the moon, the planets and the deep sky, and I could observe using my glasses! From time to time I added an eyepiece, and at the moment I have seven Vixen Lanthanum's.

My favorite eyepiece however is the TeleVue 32mm plossl. This eyepiece has an even bigger eye-relief and with it's apparent field of view of 50 degrees, it gives me a nice "window" into the night sky, even with my glasses on. I compared this eyepiece to the 42-degree 40mm plossl from Televue, the 42-degree 40mm Vixen Lanthanum and the 40mm TAL plossl.


Vixen Lanthanum eyepieces
Televue 32 mm plossl



I couldn't get the 40mm Televue into focus. The 40mm TAL had some nasty "kidney bean" or darkening effect. I liked the Vixen 40mm best (of these three), but the 32mm plossl from Televue had a 50 degree field of view, and the True field of view (46.5 arc-minutes with my 200K) was slightly bigger than with the 42 degree Vixen 40mm. Also the 32mm Televue plossl proved to be even more comfortable to look through than the Vixen 40mm, wearing my glasses.


Basic data on my eyepieces


Here is some basic data on the eyepieces I own at the moment (all eyepieces are 1.25"):


M
FL
NOL
MAG
ER
FS
AFOV
TFOV
TeleVue plossl
32
?
62.5
22
27
50
46.4'
TAL plossl
25
?
80
?
21
50
36.25'
Vixen LV
25
5
80
20
?
50
?
Vixen LV
20
6
100
20
?
50
28,.75'
Vixen LV
15
7
133
20
?
50
22.5
Vixen LV
12
7
167
20
?
50
18'
Vixen LV
10
7
200
20
?
50
15'
Vixen LV
9
7
222
20
?
50
12
Vixen LV
7
7
286
20
?
45
9.4'


Legend:

M

Model

FL

Focal length in millimeters

NOL

number of lenses (from http://www.astronomieservice.de)

MAG

magnification (with my F10 2000mm TAL 200K)

ER

eye-relief in millimeters

FS

field- stop diameter in millimeters (unknown for the Vixen LV's)

AFOV

apparent field of view in degrees

TFIV

true field of view in arc minutes (measured using the star-drift method, so it is possible that they are not 100% accurate!)


If you want to read some reviews on these (and a lot of other) eyepieces, please visit the following links:

- Cloudy Nights Telescope reviews

- Todd Gross' Weather and Astronomy site

- The telescope review site by Ed Ting

- Excelsis eyepiece reviews



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