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View Full Version here: : Eyepiece Selection - 254mm Newtonian F4.7


guru_meditation
10-02-2007, 10:13 AM
Hi,

New to these forums, and would like some advice on a set of three eyepieces which would be optimal for my f4.7 254mm Newtonian (1200mm FL)

I have some standard Plossl eyepieces, but I would like to discount them for the purposes of this exercise. Mainly because they are not that great for viewing, apart from one of them which has a nice wide field.

So, I am looking for three quality eyepieces, which would give me a good range for DSOs and some planetary observations. I did think of the Antares Speers-Waler 5-8mm, but it seems to be quite bulky. I would also like a quality barlow to give me the extra range. My viewing conditions here in Perth vary, but I do like to take the scope on trips. (yes a 10inch Newtonian :D ) so I can get to some nice dark skies on occasion. However, most of the use would be backyard type viewing. This probably limits the useable magnification to about 250-300x for my scope with current conditions.

Also, some recommendations on where to purchase the eyepieces, even overseas stores.

Any takers for this little exercise?

Many thanks

Simon

chunkylad
10-02-2007, 10:42 AM
You will get many and varied answers to your question, as there are lots of newtonian owners on this forum. You need to think about what you want from your eyepice collection. For example: for your planetary viewing, do you require a wide field, or are you more interested in contrasty views? For your DSO viewwing, what focal lentghs are you interested in, and how much are you prepared to pay?. I'm afraid that at f4.7, widefield eyepieces which are crisp from the centre to the edge of field don't come cheap.

I have just taken delivery of a 5mm and 7mm Burgess Optics/TMB Planetary eyepieces. AT f5, they are widefield, contrasty and crisp to eof. Frontier Optics have a 3 for 2 deal atm. IMHO, they represent great value in higher powered eyepieces, especially for my 'unguided' dob.

Cheers and good hunting

wavelandscott
10-02-2007, 11:18 AM
How much money are you willing or able to spend?

As mentioned earlier, in a fast scope like yours good sharp widefield views may not come cheaply...

janoskiss
10-02-2007, 11:46 AM
:welcome: Simon! Why so blue? :( Cheer up! :)

Best medium budget / lightweight set IMO would be Pentax XF 12 and 8.5mm (fr Frontier Optics), 24mm Panoptic and a Televue 1.8x barlow if you can find one (no longer made, I got one from AEC) or a TV 2x (from current line), or 2x Orion Deluxe 1.25" barlow (fr Sirius Optics). All you'd need and then some. :)

It is hard to overstate the performance and value for money of the XFs. These EPs are truely premium performers. Stratus and Hyperion are similarly priced and probably more would recommend them because they are better known. Optically they are not in the same league as the XFs though.

If money is no object 5, 7, 10mm Pentax XW, 26mm Nagler T5, 4 & 6mm Radian or Burgess Planetary, and something to go between the 10 and 26mm - maybe a 2" Orion Deluxe barlow for the T5. (you will need to rebalance the scope for the heavy T5)

On a tighter budget UO HD orthos are your best bet - these are relatively narrow FOV EPs but excellent performers. TV plossls might be nice also - never used them at f/4.7 though.

guru_meditation
10-02-2007, 11:50 AM
Hi again,

Budget is not a real issue for me. I have money to spend if it is a quality eyepiece, this includes Pentax XWs which I have also considered. Wide Field and crisp views are the most important characteristics.

Thanks

Simon

wavelandscott
10-02-2007, 02:33 PM
Okay then with a wide open budget I'd jump into the Pentax XW line and the Televue Nagler line...


My 2 cents...Pentax XW in any focal length 10 mm and less will be very very hard to beat...(I've got the 7 and 10)...and I'd go with Nagler above 10 mm...(I've got the 11 T6 and the 16 T5 and a 24 Pan too)...pick up a Televue Powermate (like a barlow) and you are in business...

Both XWs and Naglers will give you nice wide field views in your faster scope and should be pretty good to the edge...there are many "personal" preferences that come in to play as to which of these two lines are the best.

Another option that you might think about would be a Televue Parracor (sorry if I spelled it wrong)...many people in faster scopes say these are the "cat's meow"...

In all cases there is some "serious" money involved but consistently folks with fast scopes would list these two lines at the top...I would encourage you to try them before you buy them.

As far where you can buy these...the Televue line can be found at Bintel (I think they are on sale now) and Pentax can be purchased at Star Optics (I know there are some others here in Austalia that sell them too)...

ausastronomer
10-02-2007, 05:03 PM
Knowing what I know, having used what I like and owning what I like :) If it was me I would do the following.

30mm Pentax XW

Televue 2" 2X Powermate

10mm Pentax XW
7mm Pentax XW

That covers just about any option you need covered, with that scope. Alternatively you could go with a 26mm Nagler T5 and the 10mm and 7mm Pentax XW's. At the top end of town (Pentax XW's and Naglers) there isn't much between them; and it comes down to little things. They each do some different things a little better than the other. My 1st choice would be as indicated above but you could also go for something like a 31mm or 26mm Nagler T5 and the 11mm and 7mm Nagler T6's as opposed to the Pentax XW's. IMO the Pentax XW's are a tad sharper with better light throughput and longer eye-relief, hence a little more comfort, particularly if you or anyone else using the scope wears glasses. The Naglers have a wider FOV by a tad. You need to work out what aspects of eyepiece performance are likely to be the most important to you. The Vixen LVW's are also very good but you are limited here in appropriate focal lengths IMO.

FWIW I have 3 Televue Naglers (31T5,17T4 and 12T4), a 27mm Televue Panoptic, 5 Pentax XW's (5,7,10,14 and 20) and 6 University Optics HD orthos (5,6,7,9,12,18);as well as 3 good barlows and a paracorr. In addition to what I have, I have used most other eyepieces you're likely to consider. I use these in a 10"/F5 dob and an 18"/F4.5 dob.

I will conclude by saying this: The eyepiece is 1/2 the optical system and if you can afford high quality eyepieces buy them, you won't regret it and they always hold their value pretty well. You may ultimately upgrade your telescope, but it's likely you will keep top quality eyepieces for a long time to come.

CS-John B

MarkN
10-02-2007, 05:42 PM
Interesting as ever to read your posts John.

Would like to know your views about Barlows in various combinations of scope and ocular design that you've tried. Are there some "marriages" which just don't work and are there some that do?

Mark.

GrahamL
11-02-2007, 06:14 AM
I find a 27mm pano a 13 and 7 (smooth barrel) nagler gets plenty of use
in my 10 " ..seems to cover most bases

ausastronomer
11-02-2007, 06:41 PM
Hi Mark,

I do have some thoughts on barlows.

Let me say two things for starters. In the last 15 years, barlows have improved immensely. Historically, even the best, most expensive barlows could cause serious image degradation and in many cases, vignetting. The modern top quality barlows are very good and that brings me to the second point, "buy the best barlow you can afford". Like most things astronomical you get what you pay for. Another generalisation you could make is that a "long" barlow will always be better optically than a "short" barlow. However, it is not physically as convenient and easy to use, compared to a short barlow. This particularly applies to scopes necessarily using a diagonal like refractors. SCT's and Maksutovs. I will also add that with these scopes you can change the amplification of the barlow by using it "ahead" of the diagonal, as opposed to "after" the diagonal. A 2X barlow used "ahead" of the diagonal will give an amplification of 2.5X to 3X. You can also achieve this "additional" amplification with an extension tube in any of these scopes, as well as in a newtonian. It's also worth mentioning that a barlow with a greater clear aperture will have less tendency to vignette than a barlow with restricted clear aperture. This particularly applies to longer focal length eyepieces which naturally can have a tendency to vignette, like long focal length plossls. Any traditional barlow will increase the eyepieces native eye-relief. In most cases with eyepieces having inherently short eye-relief this is an advantage. For this reason many people prefer medium focal length orthos and plossls in a good barlow for high power planetary work as the native plossls and orthos have very short eye-relief. This eye-relief extension becomes a dissadvantage when using eyepieces having long native eye-relief. It is actually extended "too far" in many cases making it more difficult to hold the exit pupil, particularly for less experienced observers.

My preference is for the Televue Powermates as they preserve the eye-relief in all cases. Optically they are very good, albeit a tad behind the best barlows optically. the reason I like them is because they preserve the eye-relief and are transparent in use. You don't notice that "something else" is in the optical train which you usually do with the very best barlows. The powermates just "disappear" on you.

The very best barlows that I have used are the following, in no order:-

1.25" Televue 1.8X barlow (no longer available FI. I owned 1 and foolishly sold it)
1.25" Televue 2X barlow
1.25" Vernonscope Dakin Barlow. (The company that makes Brandon eyepieces for Questar telescopes)
1.25" Televue 2.5X Powermate
2" Astrophysics 1.7X Barcon
2" 2X Televue Big Barlow
2" 2X Televue Powermate

The best "value for money" barlows I have used are the Orion Ultrascopic, which I believe is now sold under a different name and the Orion Shorty Plus/Celestron Ultima. Two barlows which some rate highly that I have issues with, are the University Optics 2.8X Klee and the Meade #140 APO Barlow. The Klee whilst excellent on axis, can vignette with some eyepieces and I have seen odd samples of the Meade #140 noticeably dim the image.

CS-John B

MarkN
12-02-2007, 08:47 AM
Thanks for that John,

I had often wondered about the ER and exit pupil bit and whether some eyepieces would be rendered useless.

Mark.

guru_meditation
18-02-2007, 07:16 PM
Thanks everyone for your input, and for taking the time to assist me.

Cheers