87 replies to this topic

[Tank]

Ive compared in a few scopes and they were nearly identical

[Starman1]

Yes. I've had both, and the Delos felt more immersive.

 

There was a discussion about this a year or so ago. Don commented on this, and the consensus was this was down to how the exit pupil was shaped + size of eye lens. I can't remember exactly but yes, certain EPs feel more immersive than others of similar FL and AFOV. 

 

The Delos + Pentaxes are good examples of this. The Delos to me, feels more immersive than the Pentaxes do. 

 

Richard likes to call the UFF 30MM a honorary Morpheus but I'm more of the thinking that the UFF 30 is more like a Pentax than a Morpheus. 

I agree.  The 30mm UFF feels very much like the 16.5mm Pentax XW85 except for apparent field.

The 17.5mm Morpheus feels very similar to the 17.3mm Delos in both field and eye relief.

In contrast, the 14mm-4.5mm Morpheus eyepieces feel noticeably wider than the Delos

 

There is a characteristic that is not quantified, nor even discussed, and it is the distance the image appears to be away from the eye.

I used to think it was simply a matter of apparent field--that wider eyepieces' fields appear to be closer than narrower eyepieces.

But the Ethos line changed my mind, as their fields of view appear to be different distances away from the eye.

 

I am aware, of course, that focus is at infinity in every case, yet, nonetheless, the image in some of the Ethos appeared closer to the eye than in others.

 

I have not been able to evaluate a fair number of eyepieces at one time to rank them as near the eye/medium/far.

I had a 40mm Plössl once whose image appeared to be far away, down a long tube, where the 32mm in the same brand appeared close to the eye.

It was true the focal plane in the 40mm was farther from my eye, but a few mm couldn't account for the perception of where the image was.

 

One other thing is how the image appears to the eye in terms of flatness.  Some eyepieces have flat fields, some have fields that appear to be concave, with the center away from the eye,

and others appear convex, with the center closer to the eye.  This cannot be purely geometric distortion, because some eyepieces with flat fields have pincushion distortion,

though every eyepiece I've seen with a convex field had noticeable barrel distortion.  I have, however, seen at least one eyepiece with barrel distortion that had an apparently flat field.

 

So there are some aspects of eyepiece design that influence our personal reactions to them, and I just don't think they are all described or quantified.

 

Any comments from others?  Have you seen the same things?

Edited by Starman1, 02 May 2024 - 03:21 PM.

[GeneT]

All in all, whether 3.5mm XW or 3.5mm Delos, I think you'd be happy when the seeing was good enough to use a 3.5mm eyepiece.

Excellent post! Very helpful.

[Kutno]

 

I had a 40mm Plössl once whose image appeared to be far away, down a long tube, where the 32mm in the same brand appeared close to the eye.

 

...

 

Any comments from others?  Have you seen the same things?

 

I have had the same experience using 40mm and 32mm Omni Plossls.

 

I am not sure whether this addresses any of the other things you bring up, but there are eyepieces - Naglers for binoviewing and Ethos in mono mode - that pull my eyes in to acquire more of the scenery.  (I do love getting lost in the scenery they provide.)

[areyoukiddingme]

I agree.  The 30mm UFF feels very much like the 16.5mm Pentax XW85 except for apparent field.

The 17.5mm Morpheus feels very similar to the 17.3mm Delos in both field and eye relief.

In contrast, the 14mm-4.5mm Morpheus eyepieces feel noticeably wider than the Delos

 

There is a characteristic that is not quantified, nor even discussed, and it is the distance the image appears to be away from the eye.

I used to think it was simply a matter of apparent field--that wider eyepieces' fields appear to be closer than narrower eyepieces.

But the Ethos line changed my mind, as their fields of view appear to be different distances away from the eye.

 

I am aware, of course, that focus is at infinity in every case, yet, nonetheless, the image in some of the Ethos appeared closer to the eye than in others.

 

I have not been able to evaluate a fair number of eyepieces at one time to rank them as near the eye/medium/far.

I had a 40mm Plössl once whose image appeared to be far away, down a long tube, where the 32mm in the same brand appeared close to the eye.

It was true the focal plane in the 40mm was farther from my eye, but a few mm couldn't account for the perception of where the image was.

 

One other thing is how the image appears to the eye in terms of flatness.  Some eyepieces have flat fields, some have fields that appear to be concave, with the center away from the eye,

and others appear convex, with the center closer to the eye.  This cannot be purely geometric distortion, because some eyepieces with flat fields have pincushion distortion,

though every eyepiece I've seen with a convex field had noticeable barrel distortion.  I have, however, seen at least one eyepiece with barrel distortion that had an apparently flat field.

 

So there are some aspects of eyepiece design that influence our personal reactions to them, and I just don't think they are all described or quantified.

 

Any comments from others?  Have you seen the same things?

I guess it ranges from "looking down a tube" through "I can hardly see the edges" to (perhaps) the field edges have melded with the top of the eypiece (28 RKE).

 

Seems to me that this effect is a good part of the reason that many people have favorable opinions on the Nikon HWs (only 1 mm extra eye relief than Ethos, but it feels like more), and the 92mm Explore Scientifics--the field feels much further away than (say) 82 degree eyepieces--at least to a degree that goes beyond the eye relief.

[Mr. Mike]

I own the 12mm and 8mm Delos EPs.  Love them and they are perfect for viewing with glasses.  I alkso have the Pentax 3.5mm XW.  Its also good for glasses but the eye relief is not quite as generous as my Delos EPs.  Both the Delos line and Pentax XWs are excellent quality EPs.  Whatever you choose you arent "missing out" on much by not buying the other if you get my drift, IMO.  The few degrees difference is negligible.  The slightly better eye relief of the Delos could be a factor some people.

Edited by Mr. Mike, 04 May 2024 - 05:07 PM.

[CrazyPanda]

I agree.  The 30mm UFF feels very much like the 16.5mm Pentax XW85 except for apparent field.

The 17.5mm Morpheus feels very similar to the 17.3mm Delos in both field and eye relief.

In contrast, the 14mm-4.5mm Morpheus eyepieces feel noticeably wider than the Delos

 

There is a characteristic that is not quantified, nor even discussed, and it is the distance the image appears to be away from the eye.

I used to think it was simply a matter of apparent field--that wider eyepieces' fields appear to be closer than narrower eyepieces.

But the Ethos line changed my mind, as their fields of view appear to be different distances away from the eye.

 

I am aware, of course, that focus is at infinity in every case, yet, nonetheless, the image in some of the Ethos appeared closer to the eye than in others.

 

I have not been able to evaluate a fair number of eyepieces at one time to rank them as near the eye/medium/far.

I had a 40mm Plössl once whose image appeared to be far away, down a long tube, where the 32mm in the same brand appeared close to the eye.

It was true the focal plane in the 40mm was farther from my eye, but a few mm couldn't account for the perception of where the image was.

 

One other thing is how the image appears to the eye in terms of flatness.  Some eyepieces have flat fields, some have fields that appear to be concave, with the center away from the eye,

and others appear convex, with the center closer to the eye.  This cannot be purely geometric distortion, because some eyepieces with flat fields have pincushion distortion,

though every eyepiece I've seen with a convex field had noticeable barrel distortion.  I have, however, seen at least one eyepiece with barrel distortion that had an apparently flat field.

 

So there are some aspects of eyepiece design that influence our personal reactions to them, and I just don't think they are all described or quantified.

 

Any comments from others?  Have you seen the same things?

I honestly think there are a lot of things about perceptions through eyepieces that aren't quantified, designed for, or even understood.

 

Why do I see radially symmetric tangential astigmatism in the 22N but not in the 21E?

 

Why is the exit pupil of the Docter so forgiving with respect to distance, but Delos requires exact placement?

 

Why is the 7XWA field stop easier to acquire and see than the 8 and 6 Ethos, as if there's something in the way in the Ethos that requires your eye to be at the exact position to see past (some internal baffle between the field stop and eye that isn't present in the XWA?)

[Starman1]

I honestly think there are a lot of things about perceptions through eyepieces that aren't quantified, designed for, or even understood.

 

Why do I see radially symmetric tangential astigmatism in the 22N but not in the 21E?

 

Why is the exit pupil of the Docter so forgiving with respect to distance, but Delos requires exact placement?

 

Why is the 7XWA field stop easier to acquire and see than the 8 and 6 Ethos, as if there's something in the way in the Ethos that requires your eye to be at the exact position to see past (some internal baffle between the field stop and eye that isn't present in the XWA?)

And add EOFB to the unknowns.

Computer modeling may figure all these things out, but visual astronomy will have to last another 50 years, and I'm not so sure it will.

[Bill Barlow]

A few months ago I owned both these eyepieces and did a side by side comparison in my Stowaway.  This focal length gives a magnification in the 92mm Stowaway of 175X.  I own both Pentax XW's and Delos eyepieces and like them very much.  I filled in the gaps between the XW's with some Delos (12mm, 8mm and 6mm).  Having all these shorter focal length eyepieces gives me some more magnification options with my shorter focal length refractors and smaller SCT's.  

 

So after comparing the two 3.5mm eyepieces on some double/triple stars, open clusters and Jupiter, I preferred the views in the Pentax XW.  It just seemed a bit sharper than the Delos.  But someone else might prefer the Delos.  It was close but that is what my eyes saw.  The Pentax was also a bit smaller/lighter in size as well.  Anyway that's my take.

 

Bill

[oatmeal]

I just got the Delos to compare against my XW, and I'd be lying if I said I could meaningfully split the two performance wise. Spent a while last night & tonight comparing their performance on Izar; briefly in my 12" Dob and 102EDL, and for a bit longer in my XT8. During passing windows of Pickering 6-7 seeing tonight at 340x, they both put up a stable, easily defined split, with clear central star points and sharp diffraction rings. Both pieces exhibited just a bit of chromatic aberration in the last 10% of the field or so. Colors were excellent in both, maybe a little cooler in the Pentax, which I slightly preferred. The Delos might have been just a hair tighter - maybe? - but near as makes no difference, and moment-to-moment variations in seeing might have been a bigger factor. The Pentax, for its part, was a smidgen more comfortable, though neither were challenging or uncomfortable to use. In my 12" collapsible, which is a bit more sensitive to vibrations, it seemed the Delos image was a little more "bouncy" and took bit longer to settle after adjustment pushes than the XW. This might be due to the fact that the Delos is ~70g heavier (despite a similar morphology between the two) and focuses a bit farther out.

 

Waiting til the next 1st quarter moon to compare their lunar performance, and may hang onto them both until planets are high again in the fall to compare them there too.

[CrazyPanda]

Waiting til the next 1st quarter moon to compare their lunar performance, and may hang onto them both until planets are high again in the fall to compare them there too.

 

You'll definitely want to compare on bright extended objects and not stars. The diffraction patterns of optical point sources are crude and do not reveal the fine details and structure that the eyepiece has to render to the eye. You're probably still going to have a hard time separating XWs from Delos, but the planets and the Moon will be better tests of comfort, focus snap, color rendition, and general level of detail shown.

[cst4]

I owned both of the 3.5 Delos and XW for about a year and compared them several times.  The aim was to find a high power piece to add to my Morpheus set.  I liked them both but ended up keeping the XW.  It just fit in better with the Morpheus line, being parfocal and lighter weight.  There is a difference in color tone between the two, which some may have a preference, but I never really saw a difference in view quality. 

[25585]

My 3.5mm Vixen LVW is as good as the XW.

[happycamperjohn]

I like what Don is saying about the almost intangible differences between otherwise equally good EPs.

I think with these two exceptional eyepieces (xw,delos) it may come down to how you react to it in the field.

I remember having most of the xw’s (and a fair few televues) at one point and buying a 17.3 delos to see how it compared. I was fully prepared to open my wallet to a new line of eps, and technically, for me, there was nothing really in it. However, over the two years that i had it, for some intangible reason i just didn’t bond with the Delos. I can’t really explain why either. Perhaps it was the well-known bias that you get when comparing two things and the first one has a greater chance of being preferred over the second. But for whatever reason, it wasn’t as satisfying as the xw’s (both 14 and 20) in my refractors. These human factors just can’t be explained…

I’m wondering if the OP has the ability to access a club to try them out themselves? I know it’s not the answer you want, but for me it was immediately obvious which EP I preferred on the night.

Good luck!
John

[f74265a]

Own 3.5 Delos and xw and T6. Agree the T6 is not quite as sharp. But I like its wide field and compact size. It’s really easy to use. I can’t really distinguish between the Delos and xw in 3.5. Pretty much equal and very good. All the above said, my strong preference in this neighborhood is the 3.7 ethos. It is what I use most of the time now. I know it is significantly more expensive but it is super impressive and in my opinion worth saving for. In comparison, the 3.5 Delos and xw are like looking through a straw. The ethos is as sharp, if not better, and immersive. I understand the televue “looking through a porthole” when I use the ethos.

[eblanken]

Hello HellsKitchen & All,

 

RE: How does the Delos compare to the XW?

 

Yes. I've had both, and the Delos felt more immersive.

 

There was a discussion about this a year or so ago. Don commented on this, and the consensus was this was down to how the exit pupil was shaped + size of eye lens. I can't remember exactly but yes, certain EPs feel more immersive than others of similar FL and AFOV. 

 

The Delos + Pentaxes are good examples of this. The Delos to me, feels more immersive than the Pentaxes do. 

 

Richard likes to call the UFF 30MM a honorary Morpheus but I'm more of the thinking that the UFF 30 is more like a Pentax than a Morpheus. 

 

I've met TayM57. I now own the entire set of Pentax XW eyepieces that he used to own. I respect his preference for the Delos.

 

Ive compared in a few scopes and they were nearly identical

 

 

Excellent post! Very helpful.

1+ for GeneT's comment about the thread.

 

So, realize that the choice really comes down to you and your preference, HellsKitchen.

 

Thanks for a Great Thread !!!

 

I would advise you to buy the Delos (based on my preference for the "equally good" Pentax XW.

 

Just saying,

 

Ed (aka eblanken)

 

P.S. To all: I respect your corporate wisdom & experience. Thanks for the wonderful posts !!! Very informative !!!

Edited by eblanken, 29 May 2024 - 01:18 AM.

[oatmeal]

All the above said, my strong preference in this neighborhood is the 3.7 ethos

This is a fair consideration. I did briefly trial the Lunt 3.5 XWA against the other two last night. The Lunt 3.5 is my favorite on the Moon; when I last compared them the Lunt was seemingly sharper than both the XW 3.5 and a 3x barlowed XW 10. The 110° field is definitely luxurious compared to the 68-73 of the XW/Delos, especially at long FL with a manual Dob. Last night, though, I felt the Lunt wasn't quite as clean in its star images across its entire field as the XW & Delos (though the central 70° was quite good) & it didn't render colors quite as well. I'd need to repeat that test a few more times before forming a concrete opinion though. And I'm sure the Ethos is at least a half-step ahead of the Lunt.

[helpwanted]

 

There is a characteristic that is not quantified, nor even discussed, and it is the distance the image appears to be away from the eye.

 

I am aware, of course, that focus is at infinity in every case, yet, nonetheless, the image in some of the Ethos appeared closer to the eye than in others.

 

I have not been able to evaluate a fair number of eyepieces at one time to rank them as near the eye/medium/far.

I had a 40mm Plössl once whose image appeared to be far away, down a long tube, where the 32mm in the same brand appeared close to the eye.

It was true the focal plane in the 40mm was farther from my eye, but a few mm couldn't account for the perception of where the image was.

 

Any comments from others?  Have you seen the same things?

Absolutely. I recently hesitated in buying a 40 mm Plossl because of memories years ago of using a Sirius 40mm and not liking how far away the field stop seemed, like it was down at the bottom of the very long tube. In fact, I returned the eyepiece. but while doing my homework, I noticed the length of the TV 40 was 1 inch less than the Sirius, so I took a chance and ordered the TV.
Completely different experience using the TV, in fact the field of view does not feel small at all because everything appears closer to the eye lens. It’s not like I’m looking down a long tube at all, I love the TV 40. 

[25585]

I honestly think there are a lot of things about perceptions through eyepieces that aren't quantified, designed for, or even understood.

 

Why do I see radially symmetric tangential astigmatism in the 22N but not in the 21E?

 

Why is the exit pupil of the Docter so forgiving with respect to distance, but Delos requires exact placement?

 

Why is the 7XWA field stop easier to acquire and see than the 8 and 6 Ethos, as if there's something in the way in the Ethos that requires your eye to be at the exact position to see past (some internal baffle between the field stop and eye that isn't present in the XWA?)

Because some eyepieces' optical designs are different enough to affect their viewing use experience, more than is assumed.

 

I find those said to have more AMD, are friendlier in use, and those designed with less AMD, and are said to be more corrected for astronomical use, are more difficult. The above is too cut and dried an analysis IMO.

 

My Noblexs are wonderful, but so are my ES92s, Morpheus, and various others I keep and use. It is what is used most that counts though. 
 

22T4 is an old design, 21E is newer. Neither of those, no Delos or Ethos are good for me. If I was given an Apollo, I would sell it, or swap it for a Noblex or Nikon HW right away. My 22T4 is in a landfill. I will take any Nikon SW & some Pentax XWs over a Delos.

[John Huntley]

..... My 22T4 is in a landfill....

Really ???? - you actually threw it away ????

 

You could have sold it for £100 (bargain for someone) and given the proceeds to charity. Anyway, it was yours to do what you like with I guess 

 

Back on topic, I have owned the Pentax XW 3.5 for quite a few years now. Before it I had the Nagler T6 3.5mm. For a couple of years I also had the Ethos SX 3.7mm and often compared it with the Pentax XW 3.5mm (and likewise the Ethos SX 4.7mm with the XW 5mm). 

 

I eventually concluded that the optical quality of the shorter XW's and Ethos SX was, for me, very, very similar. I liked them both so was happy to hold onto both in both those focal lengths.

 

Lately I've been gradually downsizing my eyepiece collection and I have parted with the Ethos SX's and held onto the XW's. It was a tough decision though. I still have similar decisions to make in the mid-focal length ranges which won't be easy I'm sure.

 

At one point I did have the 17.3 and the 14mm Delos but I found the 17.3, though very competent, somehow not an eyepiece that I "warmed" to so I let that go. I still have the 14mm Delos though as well as the 13mm Ethos. Maybe another tough choice to make ?

 

These are all great eyepieces - the differences are more about subtle characteristics rather than any flaws as such.

 

I don't wear glasses when observing by the way. 

Edited by John Huntley, 30 May 2024 - 07:08 PM.

[oatmeal]

It was the excellence of my 14 Delos, rather than any deficiency on the part of the 3.5XW that made me curious as to how the two would compare.

[Bill Weir]

Really ???? - you actually threw it away ????

 

You could have sold it for £100 (bargain for someone) and given the proceeds to charity. Anyway, it was yours to do what you like with I guess 

 

Ask him about Radians.

 

Regarding the original question get the one you can at a price you can live with. Between them you’d be splitting hairs although in all fairness that seems to be the point of the eyepiece forum. When I wanted to go for highish power I was pleased when a friend offered me his 3.7mm Ethos at a great price. I grabbed it. I use it in all of my scopes. A couple of nights ago I was using it in my f/8 6” dob on globular clusters and it behaved fabulously. I’m lucky to live in an area where the seeing often supports more  power. On great nights the 3mm Radian comes out.

 

Bill

[HellsKitchen]

Own 3.5 Delos and xw and T6. Agree the T6 is not quite as sharp. But I like its wide field and compact size. It’s really easy to use. I can’t really distinguish between the Delos and xw in 3.5. Pretty much equal and very good. All the above said, my strong preference in this neighborhood is the 3.7 ethos. It is what I use most of the time now. I know it is significantly more expensive but it is super impressive and in my opinion worth saving for. In comparison, the 3.5 Delos and xw are like looking through a straw. The ethos is as sharp, if not better, and immersive. I understand the televue “looking through a porthole” when I use the ethos.

 

I've considered the Ethos, especially as it weighs the same as the Delos. That bothers me. New price is not an option.  I just put out a wanted ad, you never know, you're not gonna catch any fish if you don't cast the line. I also have a wanted ad for a 3.5mm Delos, but no bites so far in 3 weeks.  The Ethos would make a sensible progression to my Morpheus with its FOV. 

[SeattleScott]

I've considered the Ethos, especially as it weighs the same as the Delos. That bothers me. New price is not an option. I just put out a wanted ad, you never know, you're not gonna catch any fish if you don't cast the line. I also have a wanted ad for a 3.5mm Delos, but no bites so far in 3 weeks. The Ethos would make a sensible progression to my Morpheus with its FOV.

The XWA are cheaper than a new Delos and perform very similar to Ethos in most focal lengths. I get the impression some prefer the 7XWA to the 6/8 Ethos.

That being said, the 3.5XWA might be a weak link in the series.

Edited by SeattleScott, 31 May 2024 - 07:45 AM.

[HellsKitchen]

The XWA are cheaper than a new Delos and perform very similar to Ethos in most focal lengths. I get the impression some prefer the 7XWA to the 6/8 Ethos.

That being said, the 3.5XWA might be a weak link in the series.

 

I've done my research on that aswell, and by all accounts it is the weak link, and image quality degrades out towards the edge of the field compared to the Ethos. I've eliminated it from the running.