Eyepiece Doubts

[iPeace]

Perhaps there's a cool challenge in this for a future star party. Who can get the most impressive views with the cheapest setup? Has probably already been done, but it's a thought that occurred to me . "Scrapheap scope challenge"...?

In the mean time, I'm having too much fun with my gear to wonder whether I should spend less on eyepieces. Or more on aperture. Or whatever.

[iPeace]

Well, perhaps I do "wonder" a bit...enough to enjoy the prospect of acquiring new/improved gear...but I certainly don't "worry"

[alan potts]

I have read this thread with interest over the last few days and I always pay a great deal of attention to anything John has to say as he has a great deal of experience. Whereas i said the other day Cotterless was Mr Doubles, for me John is Mr Eyepieces. Now I have looked through a few different ones myself, mostly Televue and Meades but there have been others. Purely talking on axis I agree largely with John's findings however the further you move towards the edges the less I tend to see this as I am sure he accepts. I can clearly recall a poor edge performance of the Meade 24mm SWA (same as ExSC 24mm) which in my view only got worse when I was able to put it into an F4.3 scope for the first time, prior to this my fastest scope was F 5.26 and even here there were obvious faults to my eyes. In the F15 Mak it was almost as good as a Panoptic 24mm and then my own bias could be the difference.

I have a fair selection of scopes now from F 15 to F 4.3 and whilst as has been said there are not much in the way of differences on axis with eyepiece the outer field changes a fair bit as the steps get fasters. It is also worth noting that I and others with faster scopes opt for a Paracorr to keep the edges sharp with mega wides, I have always said why pay 500 pounds for an eyepiece only to let coma spoil the show and on these 100 degree eyepieces, here this becomes all the more important. It is one thing to view with an orthoscopic with a small but tight and well corrected field and completely another to use a Nagler or larger. I fully accept some are not bothered by coma but I really do wonder why, if and only if we are using premium brands, though understand that below about F5.4 coma is not really an issue at all. Going back to an eyepiece I tested some time ago a 40mm Super Plossl from the 60 degree Meade range, this was awful in my Sumerian, all I could do at the time was wonder what it would have been like in Calvin F3.9 although the exit pupil would be for the owl family near by to me.  

Having only TeleVue now I am content with my eyepieces, I have not bought one for almost 18 months, maybe longer, I did have many more but have moved them on with Derek's empty the eyepiece case fast plan for slimmers. I find that if you have reasonable scopes then it pays to try and get the best out of them as the eyepieces are a very important part of the optical system, which is maybe why we talk about them all the time.

[Mak the Night]

I acquired a pair of WO 9mm SWAN's not so long ago intending to use them as a bino pair. At virtually 60 quid each I wouldn't exactly put them in the 'cheapo' category. John did inform me that they had short eye relief and were not that sharp off-axis before I bought them. I didn't disbelieve him, but I supposed that they should be OK for lunar/planetary in bino's with an f/12.7 102mm Mak. They have a 72° FOV for an eyepiece which is about the size of a standard Plossl. I wouldn't say that I was terribly disappointed in them, but they were pretty soon replaced by a couple of 12.5 AH ortho's. I've had some decent lunar views using one in 'cyclops' mode on a little (90mm) highly portable Mak. I thought they would be perfect for the 90mm Mak along with my older Celestron Plossls. It's not so much that the WO SWAN and the Celestron Plossls were particularly bad, they weren't, it's just that even in my highly portable 90mm Mak I'm finding that I prefer my 18mm AH ortho and 8 & 11mm TV Plossls. The difference may be subtle, but it can be seen, even through what is to all intents and purposes a small spotting scope.

[estwing]

Yes Alan cheap ep's don't stay long in my focuser...big fast mirrors demand the best,why put up with anything less

[Mak the Night]

These Celestron eyepieces were what I was intending to use in my 90mm Mak. They are light and relatively decent quality and I've had many happy hours observing with them. They all essentially became redundant as I upgraded. Principally as they had rather aggressive undercuts and didn't play well with compression rings.

Ideal I thought for a little portable scope, enabling me, as a disabled person, to get some decent observing done without spending nearly an hour to set up. After some experimentation, particularly observing Jupiter (never the easiest) I ended up with a different set.

The only Celestrons left are the 32mm Plossl and 15mm Kellner for low power wide viewing. As I'm more interested in lunar/planetary with the 90mm MightyMak I decided to go with a couple of apochromatic shorty Barlows and high end Plossls and an orthoscopic. Oh, and the 9mm WO SWAN with a Barlow element permanently threaded into it. I can carry them all out with the scope and range from around 31x to 182x. Not surprisingly, the TV's, AH and Antares (Japanese made) Plossl spend the most time in the Barlow/diagonal. My old Celestrons were great, but there is a difference for me.

[Mak the Night]

The first three 'shorty' Barlows on the top row are all Celestron. Out of them, the third is probably the best quality and has a removable element, it was from the AstroMaster Kit. It's sold by FLO as the 'Universal' Barlow and almost certainly Synta made. The two Barlows to its left are virtually identical and are probably Guan Sheng Optical (GSO). All three of them are fairly decent for the money. I bought the Omni thinking it would be better quality than the other two, it wasn't. The apochromatic shorty Omegon (possibly GSO) Barlow at the end has more or less replaced the Celestrons.

The bottom row has a TS Optics (GSO) 2.5x apochromatic shorty which I use in my little Mak as the TeleVues are too heavy and large in it. I had a lot of use out of my older Celestron shorties but the first quality Barlow I obtained was the 3x TV shown here. I was so impressed with it I bought the others eventually.

Those Celestron Barlows were pretty decent, especially compared to the Christmas cracker giveaway Barlow that came with my Explorer, but I can definitely tell the difference with the better quality pieces.  The difference may be slight, in many ways, but it can often make all the difference. I remember once viewing Jupiter's GRS with the 3x TV and a cheap Celestron Kellner. I'd never seen it that well at that magnification (180x) before.

[alan potts]

11 hours ago, estwing said:

Yes Alan cheap ep's don't stay long in my focuser...big fast mirrors demand the best,why put up with anything less

Calvin,

This in your few words was what I was trying to get cross. We know all along that F15 and even 10 can take cheaper eyepieces without much in the way of optical problems pretty much in the full FOV. I think it was only when I bought my second scope at F 7 I started to look more closely at edges, I can only imagine how the wheels come off at mirror speeds of F 3.9. I do sometimes use Panoptics with mine without the Paracorr but I can't put up with the edges of an Ethos in the same way. I think my biggest trouble is I worked in QA many years back and can find fault in almost anything, I was so good at spotting problems, it has never left me which has cost me many times in life. Still as i said, I'm content at the moment, now who mentioned Ethos 2 the other day.

Alan

[estwing]

Alan I am a man of few words to take notice of .....Nichol and ethos are two I recommend!

[Moonshane]

Above points granted can you see anything with an ethos that you can't with a supplied free ma or plossl?

[alan potts]

Shane,

In a very fast scope I have to say yes, there is a lot you can't see due to the poor edge control and other aberrations. Leaving a paracorr aside the edges of the two Meade SP from the series 5000 (60 degree)range I tested were awful in my fastest scope and that FOV I could live with for slight coma. I agree yes you can still see things but they just are not sharp, on axis they are much better but I still don't feel they are up to Pentax XW and TV standards. Personally I would like to see a stock eyepiece in my F 4.3 scope as all I have ever done is gift them to people believing them to be poor. Maybe I have wasted alot of money on the eyepiece cases, but I don't think so.

[spaceboy]

Yes the edge performance of a quality eyepiece is better corrected than that of a cheap ep. BUT as you say with out a paracorr or field flattener your always going to have irritating squibbles around the edge of view.

I know from previous threads (have no experience personally) that coma correctors can be fiddly to use or bring unwanted magnification in to the mix. If you put that aside I have to wonder why there are so many threads on eyepiece performance given even the most expensive ep's won't remove coma. If everyone was to ask what is the best and easiest coma corrector / field flattener on the market and we all took light of that then surely the question of ep's would be more relevant ?

I think we all agree that slow scopes rarely show any issues with even the cheapest of eyepiece. So if you remove the fast scope created coma with a corrector which cleans up the edges in even the cheapest of eyepieces then all you are left with is the aberrations brought to the mix by the eyepiece. In my mind the quality of the eyepiece becomes more the issue and where exotic and often expensive eyepieces would earn their money. I don't loose any sleep over edge performance as it stands as I tend only to look at on axis stars as I'm not a fan of coma and if the eyepiece brings any other aberrations to the edge they are blanked from my attention along with the coma. I'm not saying I don't take in the full view as I do. It is just that I don't allow myself to get hung up on it. If I had a paracorr and the edges were still mush then I would have some issues. 

 

Given most people seem to shy away from correctors I often wonder why there is so much interest in the performance of an eyepiece when your still left with distracting coma.

[John]

4 hours ago, Moonshane said:

Above points granted can you see anything with an ethos that you can't with a supplied free ma or plossl?

There are occasionally things that a fine quality eyepiece can show that a real cheapie can't. Faint planetary moons close to bright parent planets for example, splitting Sirius and resolving the finest lunar details are the examples I've come across. Most of the time it's aesthetic / presentational things such as darker background sky, reduced light scatter (which can show better contrast) and better definition in the outer parts of the FoV that the premium optics and price provide.

I'm not specifically referring to the Ethos here but generally the "top dog" eyepieces that we discuss.

 

 

[Paul73]

Great thread!

I did a test last winter with a variety of eyepieces of similar magnifications. The differences were most pronounced in the following areas. I was using a 10" F4.7 Dob under NELM 5.5 sky during steady transparent seeing (for the UK.....).

 - Observing Expereince

- Light scatter (Jupiter)

- Transmission (faintest star seen)

- Distortion off access

The only eyepieces that scored consistently well was the Baader BCO (18mm) and the Delos. Although, the Delos at 5x the price did go a touch deeper and the viewing experience was a more immersive. Surprisingly the others all scored well on Sharpness but failed noticably on at least one other category. Sadly, I did not have the, much recommended, Vixen SLV at that mag.

It seems to be the eyepieces that don't overstretch on FOV °/£ that provide the best views.

Paul

 

[Mak the Night]

I have a pair of Baader 18mm BCO's for my bino, from what I can tell, they are as good as my AH ortho's. The BCO's are quite superb considering their price.

[niallk]

14 hours ago, Moonshane said:

Above points granted can you see anything with an ethos that you can't with a supplied free ma or plossl?

Can't comment about an Ethos but one thing that I found noteworthy was the first night I tried my Nagler 13T6 in my 250px. Prior to this, I used a GSO 70° SWA EP that cost €45 on its own - I got it as part of a 'plossl' set. Anyway, that first view of M42 - wow I was taken aback: strong green colour, beautifully detailed crisp view. It was grey in the other EP and less detailed. M42 has been green ever since with the Nagler. I had spent more than half the cost of the Nagler on the plossl set: I haven't used an EP from it in ~6yrs, whereas the Nagler has been a firm favourite all this time. To me, that's why I've been very happy with the purchase. I don't have experience of the wide variety of eps like you guys. Without access to an active local second hand market, I've tended to buy a low number of eps that I hope to be 'good bets'.

I do use 2x of the stock 25mm EPs that come with the likes of a Skywatcher dob in my binoviewer for very nice full disc views of the moon or sun with solar film (I use a pair of TV 15mm plossls for higher power). With the binoviewer, I work to keep things on-axis for the sharpest views, and the brain's image processing gain helps a lot, and afov not as important for the chosen targets.

[Moonshane]

Sorry John yes me too. I just really meant to refer to the ethos as an example of a top notch ocular.

[Brasspoodle]

I'm sure this has been mentioned but in an undriven Dob AFoV does matter at higher magnifications. I tried my 6mm BCO in my 12" non-goto Dob (250x) and although the centered image (of Jupiter) perhaps showed even slightly more contrast than the Delos 6mm this view was quite fleeting (a matter of seconds). At the edge of my 6mm BCO (and I'd be generous saying this was the outer 20%) Jupiter turned into an out of focus blob. It was really not possible to get enough time to observe the planet in a satisfying way. A larger well corrected AFoV at high magnifications allows so much more time for planetary (or lunar) detail to emerge from shifting atmospheric instability. This is the rather 'hopeful' way I like to observe though: push the magnification up and catch the moments that come. On the ST120 the BCO has been fine however but the TFoV is much larger so drift time is less of an issue.

[Charic]

On 18/03/2016 at 10:27, John said:

......... the differences between the really expensive eyepieces and the much cheaper ones were just so subtle. There were no details on the Moon or Jupiter that I could not see in the low cost eyepieces. 

Has anyone else experienced this sort of thing ?

Hi John, this has sort of been my remit since day one of my observing experience! Why should I buy a £300 eyepiece over a £9 eyepiece, when to all intense and purpose, to my eyes alone, the actual images I see look the same, using my scope, regardless of eyepiece brand given the same focal length ?

I know the why's for having  premium  eyepieces, and I'm certain  that one eyepiece can always work better for you/us under the right conditions,  in the right telescope?  and having recently bought some Delos EPs and still with so  little observing time ( check my count?) I still favour  my  BSTs for their value and image quality. Even my cheapest Revelations are a dream to use, so it looks like my TeleVue and my Meade Plossl's could be the first to go if deemed surplus to my requirements, and as for the  72° afov over the 60°, more testing is required, however with Spring/Summer around the corner, I need dark skies, and they just don't exist up here during the following Months. I'm sure my Delos would  be well suited to a faster scope, and just plain sailing for what I have now, which might be the reason I don't see any difference excepting the field of view. Perhaps my eyes are just not up to it any more?

Your eyes, the eyepiece, the telescope,  the seeing conditions and the final target all have a part to play. Getting this right is what its all about, this take time. At present, for my eyes,   with an f/6 reflector,  local street lighting, it's the best I can achieve for now. 

 

[Joves]

I certainly don't think there is as big a difference in the view through stock EP's vs the more specialised brands as there is in the cost difference, particularly if purely trying to find/tease out extra detail in the object being observed. I do find the "overall" view a lot more pleasing in the more expensive counterparts though. Perhaps it is purely my mind playing tricks on me and WANTING to see a clearer image in order to further justify the investment, but there does seem to be quite a pronounced clarity of image, darkness of surrounding background sky, and obviously a much wider field of view, when viewing through an Ethos vs, for example, a Vixen LV (which are very good ep's and weren't overly cheap in their own right).

It would be interesting to know if you were initially picking out fine details in the cheaper eyepieces and then replicating the view in the more expensive ones, or vice versa, John. It's funny how much easier things are to "see" when you know they are there and exactly where to look, irrespective of quality of glass.

[Mak the Night]

I've been observing the Moon earlier with my 90mm Mak as there was a bit of a break from the clouds and I wanted to give my new 15mm Antares UPL Plossl a good session. I deliberately compared it with a 15mm Celestron Omni, the Plossl I originally intended to use with my portable scope.

The Omni is a nice eyepiece with a fold up eyecup and rubber barrel grip. It's ergonomically pleasant to use with a nice eye lens size and gives a good image. It cost me about 20 quid. The Antares has orthoscopic like contrast and is noticeably brighter and sharper. It cost over four times the price of the Celestron. It was worth the money.

[Mak the Night]

OK, after much experimentation, these five eyepieces and two apochromatic Barlows are what goes out with me with my portable 90mm Mak:

After trying various combinations of both new and old eyepieces, these now cover the lunar/planetary targets for the little Mak (f/l 1000mm, f/11.3) . I've chosen the *five eyepieces (not including the apochromatic Barlows) for their weight, ergonomics, performance, clarity, brightness and sharpness. I can range in magnification from 55.5x to 182x with a nice spread of magnifications around the 100x mark with certain Barlow/EP combinations. The bottom row of eyepieces are all Japanese made, each one cost at least £80 or above. I honestly don't believe I'd get the same performance with cheaper pieces.

*18mm AH Orthoscopic, 15mm Antares UPL, 11mm TV Plossl, 10mm Baader Eudiascopic, 8mm TV Plossl.