View Full Version here: : Eyepiece Preferences - Why do you like it?
01-10-2006, 03:10 PM
Just a quick poll...
I am curious...
What you find most important in terms of characteristics of eypieces?
You can choose as many as you want of the choices or suggest alternatives too.
I am most interested in your written comments...
01-10-2006, 03:21 PM
I prefer eyepieces with a wide field of view, sharpness and not so big physically...
As an undriven Dob owner, I like the wide field of view and the ability to let the object drift across my field of view. I also don't like eyepieces that are so big that they through out my scopes balance...
I desire many of the other characteristics listed too but these are my (personal) preferences, for instance I will give up some eye relief and I am willing to spend a bit of money (although it would be nice no to)...your opinions will most likely vary.
01-10-2006, 03:35 PM
I bought and sold EPs for all of the reasons listed. Yes, including peer pressure, which is why I bought my first TV Plossl, and little later a Nagler, to see what all the fuss is about. Both EPs have since been sold for other reasons listed. :P
My four picks match the top four so far..... (contrast, eye relief, sharpness, transmission). Love my TV Plossls...... :love:
02-10-2006, 12:36 AM
I have become convinced over my years of observing that the fewer optical elements in an eyepiece the better. I chose sharpness, contrast, brightness, eye relief, weight and cost. I rather like plossls, the 50deg FOV is usualy adequate and the on axis images are cool and sharp but the best eyepieces i ever used were some orthoscopics owned by a mate of mine.
I do sometimes appreciate a wide FOV and own 2 such eyepieces but I don't regard a wide FOV essential, I'm also not bothered by lack of edge of field sharpness provided it is not gross; the on-axis image is what counts for me. Now, this is only my opinion but i'm afraid Naglers don't cut it for me, have used them but would never wish to own one----I know, I'm weird but there's always one isn't there! :screwy:
Well that's my quidsworth
Cheers to all
02-10-2006, 12:39 AM
You could have expanded the "sharpness" criteria to "on-axis" and "EOF" as two separate items IMO, to make it a little more complete. Specifically for the reason that "on-axis" sharpness is the single most important criteria to me but off axis sharpness, particularly near the EOF is not such a major concern.
In addition, three other criteria you could include would be.
1) lack of off axis astigmatism.
2) lack of rectilinear distortion
3) Ability to cope with a steep light cone, ie to work in a fast F-ratio telescope
I opted for the same four criteria as Lee and in no particular order.
CS- John B
02-10-2006, 12:55 AM
This is a very good point. I think far too many people place too much emphasis on sharpness right to the EOF. This is particularly so of new observers who take one look through a Nagler, for the first time, with it's 82 deg AFOV and usually sharp right to the edge and become mesmerised and spellbound by it's wide flat field. Consequently they do not pay enough attention to other important issues concerning eyepiece performance, particularly what's going on "straight up the guts".
02-10-2006, 01:56 PM
Fair point as to other factors in eyepiece selection...I had an even longer list of characteristics originally and shortened it down to 11...mostly in an effort to make the poll somewhat useful.
I think the main point I wanted to make with the poll is that there are several factors that have an influence and that there is no single eyepiece that can possibly meet every single requirement...It is all about compromise (I think I read a mention on another website ;) JB paraphrase)
While there are some things that might always be in common with a preferred eyepeice (good fit and finish, high quality control) the "perceived value" of these attributes will be subjective...
While the "fact" that an eyepiece has field curvature or sharpness on-axis etc. will be a consistent characteristic of an eyepiece, the viewer's preference for that characteristic I believe is subjective.
Yes, your preferences may change over time with age and/or experience (or scope type), I still contend that these are just additional factors in determining the subjective preference for certain eyepiece characteristics.
One of the strengths of the forum here is that people still ask a few questions before blurting out "buy a Pentax or Televue (insert any brand name you want)"...
I am becoming of the opinion that in some ways eyepiece preference is a bit like selecting wine...while it is generally easy to seperate the truly awful...the range from average to top shelf is getting pretty tricky...for many people it is hard to seperate out a $15 bottle from a $50 bottle...
So, what do I do...I go into a bottle shop I trust and ask for the things I like (characteristics) and describe what I want to accomplish with the wine (I leave this to the imagination)...my point being the combination of "factual" characterisitics + my preferences = enjoyment...
I think this recipe holds for eyepeices too...
02-10-2006, 08:00 PM
Lee, I voted exactly the same way as you....great minds...;)
I only have the one eyepiece at the moment, a Meade 5000 26mm Plossl which I find to be a very capable eyepiece. My main criteria is field of view.
I am currently saving for another two of the Meade Ultra Wides though which two is yet to be determined.
04-10-2006, 09:03 PM
Sharpness and contrast are paramount but absence of "kidney-beaning" is also a must for me. That just drives me crazy!
04-10-2006, 09:54 PM
Couldn't agree more. And there is one to be had for a bargain price on ebay right now!! :eyepop: :whistle:
It's all about compromise! If I could not get sharpness I get in modern widefield EPs, I'd stick with narrow FOV EPs. If I could not get the brightness and contrast with long eye relief I'd go with shorter eye relief. But if I had to sacrifice some contrast to allow my eye to lift a few mm off the glass, then I'd opt for eye relief over contrast. ...etc..
With modern EPs the way they are, we are so lucky to be able to pick and choose from so many desirable attributes and make only marginal compromises along the way (other than $$$$$$). Best compromise EPs for me are the 7 and 10mm XWs. In FLs outside that range I am still looking for what will work best for me and my scopes (fast Newts mainly).
ER isnt so improtant to me atm so i didnt pick it. i went for 5 of them: sharpness, flatness, cost, contrast and weight/size.
I can choose to dob it or track so i am not worried too much about FOV :) of course if anyone wants to throw me nagler then i wont say no ;)
05-10-2006, 12:49 PM
I chose eye relief and field of view, but thats assuming other characteristics of the eyepiece are at least average. I rarely get the chance to use magnification much above 100X, so I'm most interested in deep sky and the more field I can see framing the object the better I enjoy the view. It follows that ample eye relief is needed to enjoy the wider AFOV. I once owned a 8.8mm UWA which to me showed very nice images, but I sold it due to the 9mm eye relief - I don't like squeezing up to the lens to see most of the field of view.
At this point I have to make a confession - I snagged the 27 Panoptic and 22 Nagler off astromart on the weekend(I hear gnashing of teeth), these being my first Televues. Now I won't have to go outside to observe; I can just put these on the coffee table, sit down and watch them. Maybe even lean over and touch them.
05-10-2006, 08:45 PM
Sharpness, contrast and eye relief for me. I must admit the view through the couple of Tv Ep's I've looked through is impressive, but I'm satisfied with the EP's I have for now.
05-10-2006, 09:54 PM
Sharpness, Contrast, Light Transmission, Eye Relief, and cost.
Although I love widefields, I also like to get as extreme a close up of Galaxies as contrast and light transmission will allow me. I found when I used a Takahashi 7.5 LE that even at high mag with good contrast and light transmission you also get sharpness! And they have great eye relief.
Cost is a big factor for me until I start working again. That's why I am stuck with Series 500's, GSO's and 1 widefield Erfle (which is magic!).
06-10-2006, 12:22 PM
How does your Erfle go in the 2" barlow, Ken? I just found out that LVWs and the clones (hyperion/stratus) are nothing more than barlowed Erfles!
06-10-2006, 12:58 PM
Where did you read or hear that, because it's not correct :shrug:
The Erfle design, both the 5 element and 6 element versions, uses a Bi-convex lens for the eye-lens and an internally facing positive meniscus doublet as the field lens. The difference between the 5 element and 6 element versions is that the center lens element is a bi convex single lens in the 5 element version and a bi convex doublet in the 6 element version.
The 8mm Vixen LVW, which is the one I looked at the lens schematic for, certainly uses a barlow at the base but the body of the eyepiece is completely different to an Erfle. The eye lens is an internally facing positive meniscus doublet and the field lens is also an internally facing positive meniscus doublet. Between the eye lens and the field lens are two plano convex lenses with the meniscuses facing each other. The 8mm Vixen LVW is similar to the Zeiss Astroplanar (developed in 1955) in terms of the field lens and eye lens, but the astroplanar uses a bi convex single lens in the center.
06-10-2006, 01:23 PM
John, I read it on the Baader Hyperion brochure or "data" (uhm advertising) sheet:
which says that if you remove the barlow bit, the negative achromatic doublet, you end up with a 6-element Erfle.
06-10-2006, 02:01 PM
You're correct, that is exactly what the Baader information sheet says, unfortunately it's not correct IMO. I will say there have been several variants of the Erfle design since the original and these have been termed "modified Erfles". Maybe they are referring to one of these later modified variants. I couldn't find a similar variant in my searchings BTW.
Here is a link showing two of the Erfle variants, including the original.
You can see that they are clearly different to the configuration of the Hyperion, shown in the link you provided.
I also checked the Erfle configuration in Telescope Optics, Rutten and Van Venrooij and it is consistent.
06-10-2006, 02:35 PM
Last night, with the 21mm Hyperion in the WO 80mm, the FOV was pleasantly sharp all over. When I unscrewed the (1 ¼”) Barlow, making the 21mm Hyperion it a (2”) 42mm, the view was only sharp in the central half of the FOV. Outside that circle, the stars were quite fuzzy. This was all through a WO 2" Dielectric diagonal.
Its worth noting that I am not a visual observer by nature, so my review of eyepieces would tend to be relatively unsophisticated and not supported by lots of hard experience.
06-10-2006, 02:44 PM
Thanks John. Yes, that Erfle looks very different to the Hyperion.
06-10-2006, 09:49 PM
It works quite well Steve. It's like having a 'head in space' view at 16mm. No distortions or seagulls.
The thing to remember with Erfles though is 'black-spot'. That alone often turns people off them. Doesn't bother me. Only takes about 1 minute to learn how to get rid of black-spot, and then the views are great!
And good 2" 32mm Erfles are still relatively cheap. :thumbsup:
06-10-2006, 11:41 PM
ATM I put cost as my main reason. I have seen ep's worth more than my scope and the view is fantastic, but the view through my ep is always the best as it's the one I'm most used to and the one I get the most enjoyment with. I have a $400.00 Dob and $40.00 ep's and still see the same things as everyone with all their mega bucks gear. The money I save on ep's goes on my kids education and with one in year 12, one in year 11 and one in year 9 it's money well saved at least for the next three years.
07-10-2006, 12:21 AM
Well said Gazz! Indeed $40 spent wisely these days buys a very capable EP that shows everything a $400 EP does. Anything beyond good but inexpensive FMC plossls is a luxury. But if you buy 2nd hand and at good prices, you could at least temporarily enjoy a premium EP collection that would be the education fund for your kids. ;)
07-10-2006, 12:33 AM
LOL Steve you are a very bad man trying to tempt me...
07-10-2006, 04:00 PM
I chose Cost, Sharpness, Eye Relief and Field of View.
19-10-2006, 03:24 AM
Very Good info John,
Thanks for the link.
30-10-2006, 09:51 AM
For high mag work, this has to be the best!! Tight focus, hi contrast and great image.
05-11-2006, 12:38 AM
Compromises abound with this sort of priority indexing.
I am willing to give away a little field curvature and outer field 20-30% for pin sharp mid axis viewing with 65-80 degree EP's at F5 in a Newt.
But then the only Nagler's i use are borrowed.:rolleyes:
14-11-2006, 10:36 PM
Then my most favourite EP's are 6mm and 9mm UO Orthoscopics, bugger all fov but they make up for it by giving you everything else.
Not a lot of fun in a manual scope though..
Minimum field curvature,
Good light transmission, not a heap of elements,
As few white birds around the field stop as is possible
Decent threads in the barrel extension, unlike my 8mm Stratus which droped a UHC into the OTA on its first night out:mad2: Wasnt impressed with its optics either, it was a dud that was replaced pronto.
Just my 2 cents worth, again..
23-11-2006, 09:43 AM
I go for contrast, sharpness on axis, wide field of view, cost and light transmission. I like looking at nebulae and for them contrast is important and a large field of view especially for things like NGC 1499 and 7000. On globulars, galaxies and planetary nebulae sharpness, high power and transmisssion are more important.
24-11-2006, 06:28 AM
I'm surprised focal length was not a criterion listed separately.
First I choose the appropriate focal length (=/- a mm), then I look for
the other characteristics. I don't care how good any 3mm eyepiece is, because I can't use it, as a simple example.
26-11-2006, 04:38 PM
An interesting comment...when I developed the poll I just took the focal length as a given (any focal length) and for that focal length what characteristics do you look for...as in, for a 12mm focal length I prefer/desire...eye relief etc.
I do normally pick the focal length first and then move into the characteristics...
08-07-2008, 07:56 PM
My sentiments I love this eyepiece.
I just swap between the 26mm and the 2x barlow.
Next will be a 13 or 14mm with apparant 82`field of view.
Also this 7mm Orthoscopic cause i got told to get it.
Like aperture i like field of view for my very casual observing.
11-07-2008, 07:49 PM
Very old thread I know ... DESIGN is a good starter
Useing an f 6 scope as a gauge slower /faster examples would greatly influence your eyepiece choices before considering other factors imo?
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