View Full Version here: : EP for the moon.
20-05-2012, 09:19 PM
Wow people, so much information!!!!
Ok what I am after is an EP for mainly looking at the moon useing my 8" Dob, must be a 2".
After some trial and error with other equipment I will make this my last buy for a while. I do have a very fine Meade series 5000 15mm and a WO 12.5 mm one for my #.5" Orion and the other for use with my Lunt and I am happy with them.
Now I want to concentrate on the moon so I figure I need 2" Planetary EP of about 10 to 15mm.
What does everyone think?
Cost obviously is important and so TV are not really even close!
20-05-2012, 10:19 PM
I don't think many eps that size come in 2in I might be wrong though
Andrews have a wo 9mm 72' swa (super wide angle) that will give you 130x
Just under a hundred
Or a 2in 2x barlow with a 1.25 adapter that will double your eps ! Can pick them up pretty cheap
Hope this helps
21-05-2012, 09:15 PM
thanks, yes it does help.
I do already have a 2" Barlow and a 1.25" adapter along with a selection of suitable 1.25"ep's.
I had thought that the way for best ever planetary viewing would be via a 2" short FL EP.
That is good that I can carry
on with the gear that I already have.
8" DOB, 2"barlow with a 1.25" adapter and a selection of short focal length 10,12,15mm EP's.:thumbsup:
22-05-2012, 12:21 AM
Unless you cannot use a 1.25" eyepiece, or dislike using the adapter, there is no point. For any planetary eyepiece the 1.25" eyepiece will not limit what you can see. Honest! See here (http://www.saharasky.com/saharasky/formula.html#2) for the maths (see 2.2 and 2.3)
Maximum field stop in a 1.25" is about 27mm, and in a 2" about 48mm. You only need the latter with wide fields. Roughly, for 8"F6, the crossover point for 1.25" to 2" is about 32mm with AFOV of 50 degrees, or 16mm with AFOV of 100 degrees. So for say a 30mm 68 degree eyepiece you would need a 2" eyepiece.
So pick your poison - maybe somewhere in the 6mm range will be as far as you want to push it, a wide field will allow more time to watch it drift by.
22-05-2012, 12:15 PM
I have a GSO 32mm Kellner 2" which is excellent for wideviews but would not be much good for planets. Not enough mag to discern details. It also weighs a tonne !!
22-05-2012, 03:16 PM
Paul rini has some 2" ep's in lower sizes - but there isn't real advantage to have a big ep in shorter f/l.
you might also want to search for Russell 2" eyepiece, surplus shed also carry some 2" ep's - i had a 12mm 2' once which gave good views
in the mid range explore scientific have a 18mm 2"
22-05-2012, 04:16 PM
There are also eyepieces that fit both 1.25" & 2" focusers. These include Badder Hyperion, Orion Stratus, and Celestron Ultima LX series. All of these are not overly expensive & very good EPs.
23-05-2012, 08:42 PM
:) I love my TV Nagler 13mm T1 , I got it here at IIS for a really good price , its higher magnification and 82 degree field is spectular :eyepop: perfect edge to edge , its a pity these are not made any more but they do pop up 2nd hand from time to time ..( they are heavy mind )
I dont think I will ever sell mine .
I would go for the Andrews planetary eyepieces , made by the same Long Perng factory that make William optics ( same eyepiece sans the name and box) .
I have the 3mm and its awsome in my smaller refractors , easy to use with its 20mm eye relief . The 9mm - 12.5mm or the new 14.5mm would suit your scope well , and only $99 .
01-06-2012, 06:01 PM
Best to buy a 1.25" adapter and a 6mm TMB Planetary.
The TMB can be got for less then $60 and the 1.25"adapter will open up more focal lengths.
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