XW14 v Morpheus 14 v Delos 14

[globular]

I've just looked at a video of the Delos eyecup adjustment.  While it does indeed look like a two handed (and possibly out of the scope) adjustment, it looks like it would be quicker than adjusting the XW if a lot of travel is needed. 

It takes quite a while to screw an XW eyecup from one extreme to another - but small adjustments are fast and easy.

The Delos slides as little or as much as you need in about the same time - but the twisting at the start and end is a little fiddley.

Overall on the eyecup adjustment front (which is important to me and my wife) I think the Delos has the edge.

 

[John]

Another plus point for the Delos eye cup adjustment are the calibration marks etched on the eyepiece barrel. Once you know where you like them and where your wife likes them, it is much easier to get the position spot on. With the XW you have to sort of remember how many twists.

This image is from Matthew Hodgson's great review:

The full review can be found here:

http://alpha-lyrae.co.uk/2014/05/04/televue-delos-eyepiece-review/

[Paz]

I use Delos eyepieces with a C8 and they work very well.

[Don Pensack]

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.

[Don Pensack]

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.

[John]

54 minutes ago, Don Pensack said:

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.

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.

 

 

 

[Louis D]

3 hours ago, Don Pensack said:

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.

I'll go back this fall/winter and have another look at the 14mm Morpheus in several different telescopes.  I'll try them out in my new to me 90mm TS APO as well.  I have a TSFLAT2 dedicated to it as with the 72ED.  I'll even rotate my head around to make sure it's not my eyeglass prescription causing it.

Sometime over the last couple of years, I distinctly remember going back and forth between the Pentax XL and the Morpheus to determine which would be in the A-Team case.  Even in my field flattened 72ED, there was curvature in the Morpheus and slight astigmatism (racked on both sides to confirm tangential/radial swap at best focus) as compared to the XL which had stronger curvature but zero astigmatism, none, once refocused.  In the end, I decided that the larger field and milder curvature of the Morpheus were preferable to the XL's stronger curvature yet perfect edges once refocused.  I even increased the TSFLAT2 distance by attaching it to the end of the original diagonal nosepiece and pulling the eyepiece and 1.25" adapter upward out of the diagonal to vastly increase the flattener's working distance to over-correct the scope's field curvature.  The Pentax XL eventually was perfectly flat and corrected across the field.  It was magnificent.  It's a shame Pentax didn't add a dedicated field flattener somewhere in the design to achieve this same result.

Lest you think the scope was causing the curvature, my 17mm ES-92 wasn't showing any curvature, nor was my 10mm Delos or 9mm Morpheus.  I can't recall if the 12mm ES-92 showed any curvature or merely a tiny bit of edge astigmatism.  I do distinctly remember that the 12mm is slightly disappointing compared to the 17mm.

[Don Pensack]

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.

Edited October 29, 2020 by Don Pensack

[Louis D]

29 minutes ago, Don Pensack said:

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.

There's also the possibility of a rubber lens hood with the lens-end inner diameter similar to the widest part of the ES-17's upper barrel.  That would allow it to be slid up or down somewhat to adjust the height.  Once fitted, it could be cut down to custom fit the hood to the user's facial shape including wing shaped.

[Ruud]

Here is an animation for both exit pupil and eye relief. Parallel bundles of light are focused onto a point in the objective's focal plane. Here an image is formed. The eyepiece turns this image into parallel bundles again. The eye focuses on the bundle and brings the light to a point on the retina.

Objective and eyepiece together make the bundles narrower and increase their  angle with the optical axis. This way they increase the amount of light that can enter the observer's pupil and provide magnification.

Ideally, after leaving the eyepiece the light bundles all pass through a well defined zone. This is the exit pupil: the place where the observer should position his own pupil. The distance from the exit pupil to the objective is the eye relief.

[Don Pensack]

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?

 

[Ruud]

 

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).

----

18 hours ago, Don Pensack said:

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

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.

18 hours ago, Don Pensack said:

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?

 

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

 

[globular]

Thanks Ruud - both for your recommendation and fantastic animations.

I wonder why 14mm seems to be a hard focal length to get right?  It seems to be a weak link in many EP ranges, especially those with long eye relief. 

Thanks everyone for your contributions.
I think Delos has won the argument for me - the lack of reports of aberrations and the easy adjustment between glasses / non glasses winning over the slightly narrower FOV and higher price. 

Still very tempted by the XW14 for £190 though while they still have one in stock..... 

Or maybe I'll get ES92 17mm and ES92 12mm and skip 14mm altogether.....   

Edited November 1, 2020 by globular

[Louis D]

7 minutes ago, globular said:

Or maybe I'll get ES92 17mm and ES92 12mm as skip 14mm altogether..... 

I rarely use either of my 14mm XL or Morpheus eyepieces in favor of my 12mm and 17mm ES-92s.  The exception would be in 1.25"-only usages.  That, or where a light weight eyepiece is necessary.  I know, many folks don't consider 12 to 13 ounces light weight, but it is in comparison to the ES-92s.

[Louis D]

@Ruud Your next animation should be to explain chromatic aberration of the exit pupil, and how it causes the ring of fire in the 31mm Nagler and 30mm ES-82.

[Don Pensack]

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