Don Pensack

I second Louis.

If you just use the defocused star test to see if astigmatism is visible in the defocused star image, you'll detect astigmatism down to about 1/2 the exit pupil in the TeleVue chart.

But if you evaluate astigmatism based on whether you see it in the focused star images, the TeleVue chart is very apropos.

My coma-corrected dob is f/5.75, and 11-12mm is almost exactly the point where I start noticing it in the in-focus star images.  I have 1.0 diopter of astigmatism in my observing eye,

and the chart suggests I should start seeing it at a 2mm exit pupil.  Bingo.

21 hours ago, Solar B said:

In response to the topic title I would say yes as you do get what you pay for 

But as ever they are subject (like any EP) to the laws of diminishing returns ...

My money would be on the Baader as you've got to go some to beat that , i normally 

use the Leica ASPH for everything now but would love to try the Pentax XL zoom  (not XF) 

Brian 

 

 

My advice: save your money.  The XL zoom is not very sharp, is very dark, and suffers from astigmatism in the outer 50% of the field.

The Baader Zoom is better in every way.

The 3-6mm TeleVue Nagler Zoom is NOT compatible with the DioptRx corrector.

Even if it were, it would reduce the eye relief to less than the depth of the pupil below the cornea of the eye.

The DioptRx sacrifices about 8mm of eye relief.  On an eyepiece with 10mm of eye relief, that's a No-Go.

46 minutes ago, scarp15 said:

I contacted by email most UK retailers Don and of those I contacted only the Widescreen Centre confirmed that they keep a stock of spare TeleVue caps. I do not think that any retailers even stock alternative replacement caps. These (alternatives) are available through Ebay UK vendors and I did place an order on some that seemed to match what I wanted, yet upon receiving, they were of a poor standard and to be honest I ended up returning them. Bolt cases are also not easily available in the UK either anymore, although again there used to be an ebay vendor that supplied a full range (when I got one for my 31T5). Sometimes the used market, I think astrobin have the odd one (boltcase) but again caps are of a lower quality. I got what I wanted from 'overseas' without problem, but to mention again; full credit to Widescreen Centre for stocking some surplus TeleVue caps, although I did not get as far as asking the cost.  

Try AgenaAstro.com in the US.  They ship to the UK and they carry a bigger selection of caps than anyone else I've seen.

1 hour ago, alan potts said:

I feel you may see a bigger difference when you use XW's in a faster scope. I had 8-5mm zoom with an 82 degree FOV, the name of which has completely gone from the dormant organ in my head. It was decent in the centre but at the edges the wheels feel off. Fully agree with the Nagler zoom. 

Alan

Speers-WALER

19 hours ago, scarp15 said:

A reference concerning TeleVue eyepiece caps, if you are looking for replacing a lost or damaged one. If you give them a call, the Widescreen Centre do stock them. Not listed on their website, need to ring or email. I had sourced some recently, not through the Widescreen Centre as they had responded to my email following arranging from elsewhere, would be best convenient for UK TV users. 

If you didn't care whether the cap had TeleVue stamped in it, isn't there a provider in the UK that sells a wide variety of eyepiece caps in different sizes?

The o-ring is there because, if I recall correctly, the same eyepiece was sold by several companies and the only difference was the outer barrel, which is just a sleeve threaded onto the upper section from the bottom.

The manufacturer just threaded different sleeves on the eyepieces to make different brands.

Zooms will be interesting to me when they go from 70° at the low power to 90° or so at the highest power.

The only one that even comes close is the Leica Aspherical Zoom 8.9mm-17.8mm which is 57°-78° (measured).

It is one of 4 expensive zooms, the others made by Nikon, Swarovski and Zeiss (which all need adapters to use in telescopes).

The Baader Mark IV 8-24mm is more of a mid-range zoom, while most of the others are of the inexpensive class.

All Zooms are fun to use, though, so even though I regard them as too much of an optical compromise, I still keep a Baader Zoom around for playing around.

It is a lot better eyepiece than the similarly-priced ones from other companies, especially from 12mm down to 8mm.

So far, though, the only one that has truly rivaled separate fixed power eyepieces is the Leica.

I wonder how many of these are the same zoom in a different housing:

TeleVue is switching over to a new single-sided cap that fits very well and stays on.  It's a running change, though.

The Apollo, Delites, and a few others now come with the new cap.

Baader, however, did it right--they provide eyelens caps for the eyecup in both up and down position, and two diameters of field lens caps for the Zoom (which can be used both ways).

I grant you that many brands come with poorly-fitting caps.

Bolt cases are not the answer, though.  In the field, they're just plain inconvenient.

Opening a case to pull out an eyepiece and pull off the caps is chore enough.  Having to open another case to get to the eyepiece is just heinous.

Eyepieces I've bought that came with a bolt case had their bolt cases stored in the boxes, somewhere in the closet where all the boxes are stored.

If you use an eyepiece case, they are "as useless as teats on a boar", as my Dad used to say.

On 08/11/2020 at 13:12, Dantooine said:

Ive just ordered 2 tv barrel extenders from widescreen centre and 2 parfocal rings from 365. I’m hoping to get my 6 & 8 ethos focal points near to my 13e. Have I done the right thing? Will it work?  Winding the focuser back and forth going to wear it out 😬

The 13E as a 2" focuses (with the shoulder of the 2" barrel as reference) 0.3" above the focal plane of the scope.

The 6mm and 8mm Ethos, used as 2", focus 0.7" above the focal plane.

Ergo, you will need parfocalizing rings installed so that the 6mm and 8mm are parfocal with the 13mm because they need to be an additional 0.4" farther out.

It can be done.  It also means all 3 would use the same setting in the Paracorr--setting H.

The parfocalizing rings will tighten down in the safety grooves on the 2" skirts, so you will need to use 3-screw parfocalizing rings to center the rings and keep them from moving.

On 04/10/2019 at 08:09, Louis D said:

How about some discussion of the results?

I'm surprised by just how good today's step-up 60 degree eyepieces are relative to premium eyepieces from 12mm on down.  The HD-60 and Paradigm eyepieces are very good across their fields.  I was a bit disappointed with the field curvature of the 12mm Pentax XF by comparison.  I'll have to see if it has superior polish under the stars allowing for better contrast and dimmer details to be picked out to atone for its edge issues.

THE XF HAS A LOT OF LIGHT SCATTER INTERNALLY AS WELL.

I just can't get over how much SAEP some eyepieces have.  I always knew I had issues with some of them even with fully dilated pupils.  They're definitely easier to use under those conditions, but they're still fussy.

The AstroTech AF70 eyepieces are quite good for 70 degree eyepieces if you're on a budget and can pick them up used for a good price.

ALSO AVAILABLE AS ASTROMANIA, OMEGON, OLIVON, ETC--SEVERAL LABELS STILL AROUND.

The older Konig and Erfle wide angles are very sharp in the center, but fall off rapidly toward the edges.  They really make you appreciate modern wide angle eyepieces.

FOR SURE--MANY HAVE SEVERE EDGE OF FIELD ASTIGMATISM, EVEN AT F/10.

Those generic Kellners, the RKE, Plossls, and the zooms are really pretty good, all things considered.  Even the $10 Aspheric is decent.  The same can't be said of the reversed Kellner.  Thus, there are some good budget choices out there if you know what to look for.

Televue eyepieces are sharp across the field if you can get past the SAEP of some of them.  Only the 22mm Nagler is in my A-Team case, though.  The rest have been ousted by newer, better designs.

IT HAS BE EVOLUTIONARY WITH TELEVUE: NEWER DESIGNS LIKE ETHOS AND DELITES ARE TRULY BETTER THAN SOME OF THE EARLIER EFFORTS.  I'M WITH YOU ON THE 22MM, THOUGH.

ES-92 eyepieces are phenomenal eyepieces.  Given their size and price, they'd better be.  They ousted my 12mm and 17mm NT4s from my A-Team case.

IF ONLY THEY WEREN'T SO PORKY.  BOTH EXCEED A KILOGRAM.

The Speers-Waler zoom is very sharp across the field.  Again, if you can live with the SAEP (which I find mild in use).

THERE IS A SPEERS-WALER SERIES 4.  THESE NEED TO BE TESTED BY SOMEONE........

The Morpheus eyepieces are very sharp across the field.  The 7mm Pentax XW is rather disappointing by comparison.  I may get the 6.5mm Morpheus the next time it goes on sale.

I'M WITH YOU ON THAT, THOUGH THE DECREASED EYE RELIEF OF THE 6.5MM AND 4.5MM MAKE THEM NOT GLASSES FRIENDLY.  WITH THE SMALL EXIT PUPILS LIKELY TO RESULT, THAT MIGHT ALLOW GLASSES TO BE REMOVED.

The Meade MA Astrometric is no replacement for the Celestron Ortho Astrometric.  The former is not sharp across the field.  What good is a wider field if it isn't sharp in a measurement eyepiece?

THAT WOULD BE MY COMMENT AS WELL.

The 15mm and up HD-60s and Paradigms are definitely not the in premium eyepiece category, but by comparison to Konigs and Erfles, they're not all that bad.  Again, they're good budget buys, just not great budget buys like the 12mm and below versions.

THAT WAS MY IMPRESSION AS WELL.

The 24mm APM UFF is a bit of a disappointment given its size, price, and hype.  The 30mm APM UFF really does live up to the hype by comparison.  It ousted my venerable 27mm Panoptic from its spot in my A-Team case.

THE 24MM IS A DIFFERENT DESIGN, AND FAIRLY GOOD IN A COMA-CORRECTED AND FIELD FLATTENED SCOPE.  IT ISN'T ON THE LEVEL OF A 24MM PANOPTIC, BUT IT IS GLASSES-FRIENDLY.

The 30mm Kasai Super Wide View, which was their $400+ copy of the 30mm Leitz Super Wide, is just awful by any measure.  It's not even as good or wide as the $50 Rini MPL.  The Agena UWA looks very usable by comparison.  Under the stars, I find the Agena UWA very sharp in the center 50% and very easy to hold the view with eyeglasses.  It just suffers from massive field curvature and some edge astigmatism.  The ES-82 is slightly less sharp in the center (compare the barcodes between the two).  Of course, it is very nearly sharp to the edge, just suffering from chromatism out there.

I ALSO NOTE A LOT OF EDGE OF FIELD ASTIGMATISM AND LIGHT SCATTER IN THE ES 30MM 82°--SOMETHING NOTED IN THE FIELD.

The Scopos is a real keeper.  It is very sharp in the center and holds most of that sharpness to the edge.  It is a huge and heavy eyepiece, so it had better do something well.  The Aero ED is a nice compromise on size and weight by comparison.  The military eyepiece show how far premium eyepieces have come over the last 50 years.

I THINK THE SCOPOS WAS DISCONTINUED BECAUSE OF WEIGHT AND PRICE, NOT BECAUSE OF THE IMAGE QUALITY.

The Meade 5000 Plossl while sharp in the center is a bit of a disappointment further out.  The 5000 SWA is a keeper showing a nice sharp field nearly from edge to edge.

YES, MEADE PUSHED THE FIELD TOO FAR.  THE S5000 PLOSSL WOULD HAVE BEEN A FINE 50° EYEPIECE.  THE S5000 SWA IS A CLOSE COPY OF A PANOPTIC, AND PERFORMS LIKE THE CURRENT ES 68°.

QUITE AN EFFORT.  WHEN THIS PANDEMIC THING IS IN THE PAST, IT WOULD BE GREAT TO EXTEND YOUR PIX TO A LOT OF NEWER EYEPIECES AS WELL.  PERHAPS WITH LOANERS FROM FRIENDS.

I FIND IT VALIDATING THE PICTURE RESULTS MATCH MY FIELD IMPRESSIONS.  THE CAMERA AND THE EYE MUST NOT BE TOO DIFFERENT IN THAT REGARD.

On 04/10/2019 at 06:16, Ruud said:

Louis, what an effort this must have been and what a great result you have here!

I have a question regarding kidney beaning.  Do you still have EXIF information for the images? It would allow calculating the entrance pupil (= camera lens effective aperture, "focal length / focal ratio used for the picture") for each photograph. Most of us use our astronomical eyepieces with observer pupils of around 5 mm or larger.

For an observer, a messy exit pupil causes kidney beaning mainly when the pupil of the observer is only slightly wider than the exit pupil of the eyepiece. Especially the Nagler T4 12 mm and the Meade 4K UWA 14mm both show severe kidney beaning in the second of the two images you post for each, which may have been caused by an entrance pupil that is only slightly wider than the exit pupils of the eyepieces. In that case, even the mildest SAEP would show as kidney beans. That being said, both of the first images for each of these eyepieces also show kidney beaning, though very much milder. I wonder how big the exit pupils of these eyepieces and the entrance pupils of the camera lens were for these four shots.

The Nagler T4 12mm and Meade 4K UWA 14mm may indeed have particularly messy exit pupils. I actually tried the NT4 12mm in a bright daylight test. From the dealer's shop it showed a strong tendency to kidney beaning so I decided against it. My pupil must have been pretty small at the time, but since it is also small when I observe the Moon I thought this eyepiece was not for me.

Thanks for the thread. I think it is epic and deserves to get pinned.

 

 

I've used nearly all of the eyepieces in question and found the same results at the telescope as his photos, i.e. SAEP in some of them, out of focus images at the edge of the field, astigmatism, etc.

Some of the eyepieces are so bad I wonder why they're being saved.

Yes, cell phone cameras don't require as much eye relief as DSLRs.

As for eye relief, I think I list almost every eyepiece here:

[I recently removed a number of discontinued eyepieces, even though a few may still be in circulation]

2020 Buyer's Guide to Eyepieces.xlsx

6 hours ago, Ruud said:

 

First I need to set something right: I never answered to OP's original question. I would choose the Delos 14. That's the only one of the three for which I've never seen any drawbacks reported. For other focal lengths than the 14mm I'm very fond of the Morpheus line (I have the 4.5, 6.5 and 17.5mm).

----

Indeed, the exit pupil is not an image of the sky.  It is a projection though, of the objective. Use a long focal length eyepiece, stick a heart to the objective, place your eye half a metre or so behind the eyepiece, and you'll see the heart on the exit pupil as well.

 

Sure you can! Every one who wants to use my animations can do so. This would be an honour. The more people who see the animations the better.

I have just one request: For use here please credit them to Ruud and for use elsewhere to Ruud, stargazerslounge.com
 

Don, did you spot these that explain the difference between blackouts and kidney bean shadows? Plenty members here found them useful.

   

I made a still to show how to recognise kidney beaning

I normally include vignetting because it kind of belongs to the same family

 

Those are good, too, though I have run into similar before on the web (maybe they were yours?)

The illustrations here are pretty good, too, though static:

https://www.handprint.com/ASTRO/ae4.html#SAEP

That is a fantastic illustration!!!

It easily displays how eyepieces are afocal, with parallel rays leaving the eyepiece, while at the same time explaining the exit pupil

and why light rays seem to narrow to the exit pupil and expand beyond it when you draw in the rays from both sides of the field.

Do I have your permission to borrow it for future explanations to people who don't understand how an eyepiece can be afocal and have an exit pupil at the same time?

On 30/10/2020 at 10:57, John said:

It's been a long time since I owned the 22mm T4 but I seem to recall that it was an easy eyepiece to see the full field with, maybe a touch easier than the 31mm T5 ?

Don Pensack might see this and comment - he probably has more recent experience of these two eyepieces than I do.

I believe that Don now uses the 22 T4 Nagler rather than the 21mm Ethos because he now finds the eye relief more comfortable and the optical quality comparable.

 

Basically because from 11mm up, I have to use glasses to eliminate visible astigmatism.

I recently sold my 21 Ethos and went back to a 22mm T4 Nagler.  It works well for me with glasses, and I have fairly deep-set eyes.

I find it sharper than I remembered from 1998-2010, probably because I had some uncorrected astigmatism then and viewed without glasses.

Now I have fully-corrected vision and find the star images tiny little points.  Amazing what you see when your eye's aberrations are corrected.

I always loved the 22mm, but never thought it was as sharp as some other eyepieces, thinking that was in the eyepiece.  Oops.  Well, live and learn.

Did I mention it's a comfortable eyepiece to use.  I experience no finicky eye positioning, either.

The 31mm is also usable with glasses, but it's a little harder with glasses on.  It might have less eye relief, but I can't be certain.  Sometimes, it's just the design of the eyepiece.

On paper, the 11mm Apollo 11 eyepiece, at 85°, has even less eye relief than the 31mm Nagler, yet the 11mm is much easier to use with glasses.  Sometimes you just have to try

an eyepiece to know.

One thing I might mention about glasses and an eyepiece with such a large eye lens: you might see the rims of your glasses in the field, and bifocals don't work if you ever look down at the bottom of the field.

Long eye relief eyepieces with large eye lenses, used with glasses, sort of require very large-lensed eyeglasses (as were really popular in the '80s).

Fortunately, there are a lot of makers of just that kind of eyeglasses.

That would put the frames outside the field of view, and allow bifocals to be used (as you might need them to read your notes, star atlas, or tablet).

22 hours ago, pete_81 said:

So, with a 1200mm focal length scope, high magnification is relatively easy but not recommended with the atmospheric conditions, lower exit pupil, etc etc...

When I look at calculating TFOV's from eyepieces, I can use a 52º_30mm, or 68º_24 and get the same TFOV.
Obviously there's a 20% difference in magnification (40x or 50x) but what are general reasons for the purchase of either EP?
The 52 is likely cheaper, but is the 68 more 'useful' with same TFOV but higher mag?
Is a 52 easier to use in that the observer doesn't need to move head around EP to see full image, so lower magnification is more preferential to see the full field in one go? Wider FOV is nice to get the 'immersive' experience but equally at the expense that isn't a necessity?
For instance, the Pleades occupy 1º51', which will be fully visible in the following EPs with the 1200mm FL
52º 40mm (30x),
68º 34mm (35x),
82º 30mm (40x)

The higher magnifications are better for splitting double stars, etc, but what factors/reasons do folks have for different EPs?
I do like the wide field but budget wise and coming up to winter observing (and Christmas), looking at a larger TFOV EP. Those observant may also note my scope is f/4.8. Explore Scientific are likely my choice (hence the list of EPs above too).
What's the ES70 like - they never seem to be recommended to the 68, and the 52 seem to have very good reviews throughout also...

What others have said is very true, but another reason for not going lower in power than the 24mm is simply that 50x is a low enough low power to frame large objects well, and see improved resolution of objects compared to the

lower magnification of a 32mm.  I advocate for 50x steps in magnification, which would be focal lengths of 24mm, 12mm, 8mm, 6mm, 4.7mm to make a complete set.

Make the 24mm an 82° 2" if you want a wider field of view than a 1.25" eyepiece will yield.

The Pleiades really look best when the field of view exceeds 2° and even better at 3°.  This is the realm of the short focal length refractor (480-750mm focal lengths).  It's pretty close to the only object that large that you might care to look at, and it is fantastic at 15x in a short 80mm refractor.  I wouldn't plan my eyepieces around that object when 99.99999% of all objects you're likely to view are smaller than 1° and probably 90%+ are smaller than 1/2°.

If you really love large fields, look into a pair of large binoculars or an 80mm refractor.  Either makes a great complement to a 10" scope.

I reviewed these eyepieces and binoviewer a while ago in the context of a small refractor review:

https://www.cloudynights.com/articles/cat/cn-reports/telescope-reports/cn-report-william-optics-zenithstar-80-st-r1390

I encourage owners of them to utilize another brand of OCA to enable the focal plane to extend backwards sufficiently, or to eliminate the OCA entirely

if the scope has enough focuser travel.  And to use other eyepieces.  These do not perform well.

The same KUO XWA eyepieces have been sold under several labels, including William Optics, Stellarvue, Lunt,  APM, Sky-Watcher, etc., though outer barrels have differed.

The upcoming 7mm (due at the end of December) is, as far as I know, unique to APM.

Other focal lengths available: 20mm, 13-13.5mm (depends on vendor), 9mm, 4.77 (labeled 4.7mm or 5mm depending on source), and 3.5mm (also labeled 3.6mm)

Yes, look for a long eye relief eyepiece so your camera lens can pick up the field.

18 hours ago, John said:

I wonder if I could fit something similar to my ES 92 / 17mm ?. I've grown to like the eyepiece but what would really clinch it would be having the eye cup just a few mm further out.

 

 

 

I don't think there is a commercially-available eyeguard extender for that size.

However, there are a couple of things to investigate:

--Camera step-down or step-up rings.  These are available in a plethora of sizes to adapt camera lenses.  You could find one to press-fit to the lip under the eyecup and attach the eyecup to the outside of it.

--a custom-machined adapter.  You likely have machine shops in the UK that could easily do this and make it any length you prefer.  Here in the US, we have preciseparts.com basically an on-line machine shop for astronomy adapters.

And, you could make yourself a custom eyecup out of a bicycle inner tube that would work:

https://www.cloudynights.com/topic/389173-replacement-eyepiece-rubber-cups/?p=4981064

You can make it any length you want and get a hundred samples out of one inner tube.

4 hours ago, Jiggy 67 said:

What @Barry-W-Fenner said......It’s important to note that the Morpheus eye relief is around 20mm (I think) but can be increased with the supplied spacer ring which I’ve done with all mine. I’ve got the full range and, like Barry, I’m very pleased with them

Eye relief of an eyepiece is a fixed quantity.  Adding the eyeguard extender to the eyepiece doesn't change the eye relief--it's still 20mm--but it pulls the eye back and makes it easier to acquire and hold the exit pupil when glasses are not worn.

4 hours ago, globular said:

On FOV:
Using manufacturers published field stop to calculate AFOV I get Morpheus at 77, XW at 72 and Delos at 71. 
And in my scope that's TFOV of 0.51^o, 0.47^o and 0.47^o respectively.

So Morpheus is 8.5% larger - but Louis says the last 15% suffers a bit - so maybe the sharp area of the XW and Delos are a little larger than the Morpheus?  Albeit smaller overall.

I really wish I could try before I buy 😢

It depends on the scope.

  In my 12.5" with coma corrector, the 14 Morpheus is sharp to the field stop.  The CC flattens the field slightly and eliminates coma, something many mistakenly confuse with astigmatism.

When I wear my glasses, I see zero astigmatism in that eyepiece in the f/5.75 (CC corrected) scope.

The AT AF70 22mm is no longer available, but the eyepiece is still available as the Astromania 22mm 70° SWA and several other brands (e.g. Omegon Redline, Telescope Service Expanse, etc.)

I think it's fairly inexpensive.  I clculate a 26.9mm field stop, though.  How did you get 28.4mm?

I like it too but it isn't compatible with binoviewers, and some people get the 24mm APMs for binoviewer use with glasses.

The 24mm APM UFF had a 63° apparent field in the flashlight test (+/-)

Most on-line retailers are claiming the field stop is 30.2mm, but it is not possible.

Even the engineering diagram shows something in the mid 27mm range.

27.3mm is more likely to be the correct figure.

I did some crude timings of stars and got 27.3mm +/- 0.1mm, which is close to your figure.

4 hours ago, parallaxerr said:

Thanks for the info @Louis D, I've seen your posts like this on CN and they're very helpful!
 

By way of an update, I ordered the OVL 27mm Extra Flat as it seems to strike a nice balance between price and FoV, hopefully it will be comfortable enough to use for extended sessions. I'm hoping it will be of similar performance to that APM 24mm, nice and flat.

JUST BE AWARE THAT THE 27MM IS A 53° APPARENT FIELD.  THE 24MM APM IS 65° (CLAIMED, 63° MEASURED).