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PeteMo
28-11-2006, 03:38 PM
I have a 25mm Plossl and Meade 12.4mm Super Plossl that came with my Optex 8" dob. I also use a GSO 2x Barlow.

What do all the eye piece names mean like Possls, Syntas, Kelners, Naglars etc? I'm guessing that the name refers to the arrangement of lenses and groups that make up the EP. What type of viewing are lens type best suited for? How do you know what lens to select for what job, as I see many people list the lenses they use.

What sort of lens ranges should I consider? I'd like to view planets as well as Deep Space stuff. I'm guessing that something like a 42mm, 17mm and 9mm would be a good range and complement my existing lenses. Would I be better off ditching my existing lenses and starting from scratch?

Is a 'Super Plossl' better optical quality than a 'Plossl'? I'd rather have a couple of good quality lenses than a dozen mediocre cheapos. Are GSO or Bintel Eyepieces any good? Also I hear that with the big names like Meade, Naglar, etc you are paying for a name so is it worth buying a Meade Super Plossl at $89 instead of a GSO Super Plossl at $49?

I did hear from someone that whatever I spent on buying my scope, I should budget at least half that amount again to get a couple of good quality lenses. I got my scope 2nd hand for $500 (previous onwer paid $850 and hardly used it)
So I should be looking to spend about $300-$400 on lenses. Is this approach correct?

Cheers

Sidewinder
28-11-2006, 05:10 PM
Well, the names usually refer to a certain way of construction, but they are also sometimes fixed product names (like TeleVue Nagler oder Panoptik), which, of course, also refer to a certain kind of construction.

For Deep Sky objects, in my opinion, a wide field of view is really necessary, it's the only way to really bring out the whole beauty of the objects. I'd go for wide angle (around 66° FOV), super wide angle (around 70° field of view) or ultra wide angle (around 80° FOV or more). This way you can see a lot more of the field surrounding the objects, which provides a more aesthetical view - at least that's what I think.
Those eyepieces can, of course, also be used at the planets, even though they're no planet specialists. For planets you can also use eyepieces with smaller FOV (around 40° or 50°), such as Plössels, for example, because what you are looking for is not a big FOV, but higher magnifications and good contrast. Pentax also provides great eyepieces for plantes, unfortunately,they're not the cheapest.

How much you invest, is another thing. You can get cheap eyepieces for 30 or 40 US Dollars, but you can also get really expensive ones, like TeleVue Nagler for example, which rank in the field of 600 or 700 US Dollars. This all depends on how much you are willing to invest and also what you want to view and what kind of telescope you own.
A f/8 telescope will basically "swallow" any eyepiece, no matter how cheap it is. Sure, better eyepieces provide better views, but it's not that critical. This is also the case with most f/6 telescopes. Once you get into faster ranges like f/5 or f/4, it's getting more difficult, those telescopes usually react highly critical to cheap eyepieces, so it's basically a good idea to get better ones, otherwise, viewing might be not so much pleasure.
When buying a telescope, you definitely have to think about the eyepieces, that's what beginners often forget, they get expensive telescopes, but then there's no money left for the eyepieces - and the best telescope is worth nothing with a bad eyepiece. Take that into account before buying.

I personally like Speers Waler a lot for the shorter focal lengths (i.e. higher magnifications), because they are still reasonably priced, work great even at f/5 or f/4 telescopes, plus the Speers Waler Zoom (5mm-8mm), is one of the moste genius things I've ever purchased, with a FOV of over 80° at all magnifications.
For the longer focal lenghts - 20mm upwards - there is no other choice for me, but Nagler, I can't help it. They're simply great.

Well, this is a highly subjective opinion, it's also difficult to cover the whole topic here. Others will supply their point of view as well - and for any questions: you can always ask!

Sebastian

mickoking
28-11-2006, 07:02 PM
If I have one piece of advice it would be to buy the best eyepiece you can afford. When you change scopes you will still have your eyepieces and good ones are with you for life.

Plossl v superplossl. Superplossls are not really plossl's at all; Plossls have 4 lens elements while super plossls have 5. Superplossls have a slightly better eye relief and compared to cheap plossls less distortion (aberations). A meade super Plossl will perform better than a GSO Plossl.

One last thing the expensive eyepieces like Televue Naglers and Panoptics are well worth their money (and they are expensive). With your telescope they will work a treat :thumbsup:

Merlin66
28-11-2006, 08:31 PM
When I started with a 6" f8 reflector, my eye wasn't trained, and almost any eyepiece was Ok. Great views thru a 1/2" Ramsden ( Ramsden???...google to find out!) Many years later I found a UO Orthoscopic I think 18mm FL, wooow
the moons of Saturn looked great so I collected another two or three.
When eventually I built a 12" f5 I began to realise that distortion, field of view actually could impact on the limiting magnitude and amount of detail that could be observed; I tried other members eyepieces and listened to the BS about the "lastest and best" eyepiece designs. I went for TV Plossls ( about 25 years ago!) and still have them today. Sure, I've added a Nagler ( wide field) but the plossls have never let me down.
SO, I suppose I agree that if you can buy a good set, three or max four eyepieces they will stand you in good stead..... unless you get suckered in to the latest BS and can't live without the latest " ultra wide angle super corrected, 15 element computer generated laser guided, multi coated ( for all wavelengths)" eyepiece, on special, for this week only at $99,999,99, drive away no more to pay!

Lee
28-11-2006, 09:08 PM
I mainly observe DSO's - my favourite EP is my 20mm Televue Plossl.... simply beautiful.... so my vote is with the TV Plossl - reasonably priced too ($140 or so)....

janoskiss
28-11-2006, 09:13 PM
Generally, you get what you pay for when comparing prices between eyepiece of similar design, but you pay big bucks for a well corrected wide FOV without gaining anything in on-axis performance over less expensive but good simpler designs (e.g., ortho, plossl).

PeteMo
29-11-2006, 02:00 PM
Thanks everyone.
Whilst I have an understanding of the physics involved with telescopes and eyepieces, that is no substitute for actually using them. Initially I looked a tprices and wrongly concluded that Plossl EP's were optically inferior to just about everything else.

My eyes are not that wel trainied, but I could differentiate between the cheap lenses that came on my first scope a Tasco 375 500mm 4.5" Newtonian and the same design Plossls of my son in law's Plossl EP's.

I'm presently looking at getting either a TV Plossl, Meade Super Plossl or Orion Stratus, but don't yet know what focal lengths to get.

I know not to get a 20mm and a 10mm since the 20mm will effectivelty be a 10mm when Barlowed. But if I were to get 2 or 3 lenses to complement my existing 25mm Plossl and Meade Super Plossl 12.4mm (seems an odd focal length), what focal length should I consider? I intitally thought 9mm, 15-20mm and 40mm (in 2").

from what you've all advised, I should go for a high magnification EP for viewing planets, and low magnification Wide Angle for DSO.

skies2clear
29-11-2006, 02:57 PM
Hi Pete, you haven't said what f-ratio your dob/scope is, but assuming it's less than f7, say f6 or f5, I would forget about purchasing a 40mm ep for low power use. The exit pupil will be too large for your eye to accomodate, in other words, you are wasting light your eye can't take in. The longest focal length ep you should consider is 30 or 32mm max.
There's no substitute like getting experience yourself and looking through other scopes and eyepieces to find out what you really like and want. Everyone is different....some like ultra-wide fields, some like super-wide fields, some aren't bothered how wide the view is. Some people zero in on sharpness, again, this varies. How sharp and over what part of the visible field, ie centre, extreme edge. And so on it goes.
The point is, listen to other peoples opinions, but try to find out for yourself what is really important to you. It may take some time and going to public viewing nights/ star parties, etc, but it's worth it. That way, your purchases will stay with you for a long time, and you won't end up with a huge box full of eyepieces, most of which you never want to use.
All the best.

PeteMo
29-11-2006, 05:12 PM
Hi skies2clear
My scope is an f1200 so I get an f ratio of 5.77. I have only used other scopes at observatories or night viewing sessions with Starry Nights here in Perth. BTOW have viewing nights every thursday so I may drop and and check out some eyepieces.

I also have to remember that when I get a 12" dob that the magnifications will increase when I use the same eyepieces in both scopes.

Thanks Again