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A Delos, Pentax XW Comparison

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#26 coutleef

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Posted 16 March 2013 - 04:53 PM

What i find unfortunate with the pentax is that the progression of available FLs corresponds to using a barlow 2x. 20-14-10-7-5-3.5. Using sligthly different FLs would have allowed more diversity.

#27 Ava

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Posted 17 March 2013 - 07:43 AM

I must admit as a pentax user that the variety and selection of FL of the delos is superior to that of the pentax however.


The Delos followed the Pentax XW's. Maybe they built that into the equation to be more competitive regarding their focal length offerings. However, I also wondered why Pentax went from a 10 to a 7 in their XW series. Why not a 10 to an 8?


I guess since they are geared toward Pentax spottings scopes, with those not having very long focal lengths that big of a gap is not a problem.

In a way it is fortunate, since it is now possible to acquire a near perfect series of 20-17-14-12-10-8-7-6-5-4.5-3.5 1.25" 70ish degree eyepieces by mixing in the 20xw, 7xw and 5xw into the Delos line (for 10mm either line seems great going by popular opinion). The 4mm is missing unfortunately. Add a 24mm pan and you may have the perfect 1.25" wide field set unless you want 100 degree views.

#28 russell23

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Posted 17 March 2013 - 08:03 AM

Great report Gene! I've enjoyed reading about your progression from Radians into the Delos/XW land. It seems as if in that higher magnification range the differences are "too close to call" and one might just pick the FL that best fits their needs. If cost is an issue a used XW is cheaper than a used Delos.

Dave

#29 russell23

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Posted 17 March 2013 - 08:11 AM

Thanks for the nice review and comparison.

After reading several threads on delos versus pentax i had come to the conclusion that pentax users would find the pentax sligthly better and delos users would find the delos slightly better. Meaning that these EPs were equivalent.


I'm also interested in the variation across different FL. I personally like the 20mm XW more than the 17.3mm Delos. But I thought the 10mm Delos was just about the closest thing to perfection of any eyepiece I ever looked through. I did not feel that way about the 17.3mm Delos.

Dave

#30 johnnyha

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Posted 17 March 2013 - 01:19 PM

Still hoping for a high quality, wide FOV zoom eyepiece that has long eye relief. Were such an item to appear in the market, I'd be one of the first in line to order. Until then, I will gladly pack my XWs as my go to grab and go eyepieces.

Thanks! Steve S


Steve, I am surprised you have not heard of the Leica ASPH Zoom. It zooms from 60* at the low end (17.8mm) to 80* at the high mag end (8.9mm), has 18mm usable eye relief, barlows beautifully, and get this - it is comparable in optical quality to the ZAO-IIs and arguably better than the XW/Deloi. No joke, this has been confirmed by many respected users on this site and owning the zoom, the ZAO-IIs, and the XWs - I wholeheartedly agree. Screwing a Barcon element on the end turns it into a 12mm-6mm zoom eyepiece, a 2X barlow makes it 9mm-4.5mm... and with a barlow or Paracorr it is sharp to the edge even in a fast dob. I suggest you do a search and check out the reviews, they are plentiful at this point.

Gene - superb review thanks! I have held on to my Pentax XWs and resisted the urge to get the Delos. I was going to get the Delos 8mm and 6mm to fill in my XWs :lol:, but I ended up with the Leica ASPH Zoom and I could NOT be happier. Along with a nice barlow it is a suitable replacement for ALL of these eyepieces.

#31 johnnyha

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Posted 17 March 2013 - 01:20 PM

What i find unfortunate with the pentax is that the progression of available FLs corresponds to using a barlow 2x. 20-14-10-7-5-3.5. Using sligthly different FLs would have allowed more diversity.


Simple. Use a 1.6X barlow or better yet, a 2.5X Powermate. ;)

#32 Sarkikos

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Posted 17 March 2013 - 01:51 PM

Johnny,

Steve, I am surprised you have not heard of the Leica ASPH Zoom. It zooms from 60* at the low end (17.9mm) to 80* at the high mag end (8.9mm), has 19mm usable eye relief, barlows beautifully, and get this - it is comparable in optical quality to the ZAO-IIs and arguably better than the XW/Deloi. No joke, this has been confirmed by many respected users on this site and owning the zoom, the ZAO-IIs, and the XWs - I wholeheartedly agree. And screwing a Barcon element on the end turns it into a 12mm-6mm zoom eyepiece, a 2X barlow makes it 9mm-4.5mm... and with a barlow or Paracorr it is sharp to the edge even in a fast dob. I suggest you do a search and check out the reviews, they are plentiful at this point.

Gene - superb review thanks! I have held on to my Pentax XWs and resisted the urge to get the Delos. I was going to get the Delos 8mm and 6mm to fill in my XWs :lol:, but I ended up with the Leica ASPH Zoom and I could NOT be happier. Along with a nice barlow it is a suitable replacement for ALL of these eyepieces.


The Leica ASPH has been in the back of my mind as a possible alternative path for quite awhile now. I've seen the usefulness of a Zoom eyepiece for deep sky even more so than for planet/lunar.

So one of the uncertainties which has kept me from acquiring the Leica, is how its light transmission compares with other eyepieces. I have heard that the XW and Delos have excellent transmission, and that the Delos are somewhat better and the ZAO's the best according to Alvin Huey. Granted the Leica compares favorably to ZAO's as far as overall optical quality. But how do they compare in terms of light transmission? Personally, for deep sky, I think light transmission is more important than a somewhat wider AFOV and longer eye relief, and may even be more important than overall sharpness of the image. After all, unless we're looking at stars and star clusters, DSO - faint fuzzies - are fuzzy to begin with.

Also, I think if many observers - myself included - were to go the route of the Leica ASPH, they would need to sell many eyepieces in order to afford it. I would have to think hard about which eyepieces I would need to give up. I don't know if I'd want to let my XW's go if the Leica's light transmission is not as good.

Mike

#33 Stephen S

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Posted 17 March 2013 - 06:25 PM

Steve, I am surprised you have not heard of the Leica ASPH Zoom. It zooms from 60* at the low end (17.8mm) to 80* at the high mag end (8.9mm), has 18mm usable eye relief, barlows beautifully, and get this - it is comparable in optical quality to the ZAO-IIs and arguably better than the XW/Deloi. No joke, this has been confirmed by many respected users on this site and owning the zoom, the ZAO-IIs, and the XWs - I wholeheartedly agree. Screwing a Barcon element on the end turns it into a 12mm-6mm zoom eyepiece, a 2X barlow makes it 9mm-4.5mm... and with a barlow or Paracorr it is sharp to the edge even in a fast dob. I suggest you do a search and check out the reviews, they are plentiful.


Wow, this is great info. I had heard of the Leica zoom but had no idea at such a large field of view. I am definitely going to have to do some more research on this. Thanks so much for sharing this info with me.

Thanks! Steve S

#34 Sarkikos

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Posted 17 March 2013 - 06:53 PM

A large FOV is only one factor to consider - at least for me.

Mike

#35 Roy McCoy

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Posted 18 March 2013 - 01:14 AM

Hi Gene,

A very enjoyable read!

I was able to compare the Pentax and Delos eyepieces as well and agree with your findings. I found that there were a few focal lengths that I liked the view in the TV better and a few that I like the Pentax better.

The differences were not large enough for me make any changes in my line up. (I have the full set of XW's.)

I would recommend either brand or a mix of both without reservation.

When I look through the TV’s I see more of a “weak RKE like” view or more of a 3d depth which I enjoy.

In the Pentax’s, the views have always been flatter to me - which I also enjoy very much.

As I mentioned above, I liked both types of views, but sometimes the type of view seemed to be a better fit for a given object. (This was a while ago and it escapes me as to which object matched which view.)

Anyhow, I am curious to know if you noticed such a difference in depth (3d) vs. flatness?

Regards,

Roy

#36 Bob S.

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Posted 18 March 2013 - 04:38 AM

Johnny,

Steve, I am surprised you have not heard of the Leica ASPH Zoom. It zooms from 60* at the low end (17.9mm) to 80* at the high mag end (8.9mm), has 19mm usable eye relief, barlows beautifully, and get this - it is comparable in optical quality to the ZAO-IIs and arguably better than the XW/Deloi. No joke, this has been confirmed by many respected users on this site and owning the zoom, the ZAO-IIs, and the XWs - I wholeheartedly agree. And screwing a Barcon element on the end turns it into a 12mm-6mm zoom eyepiece, a 2X barlow makes it 9mm-4.5mm... and with a barlow or Paracorr it is sharp to the edge even in a fast dob. I suggest you do a search and check out the reviews, they are plentiful at this point.

Gene - superb review thanks! I have held on to my Pentax XWs and resisted the urge to get the Delos. I was going to get the Delos 8mm and 6mm to fill in my XWs :lol:, but I ended up with the Leica ASPH Zoom and I could NOT be happier. Along with a nice barlow it is a suitable replacement for ALL of these eyepieces.


The Leica ASPH has been in the back of my mind as a possible alternative path for quite awhile now. I've seen the usefulness of a Zoom eyepiece for deep sky even more so than for planet/lunar.

So one of the uncertainties which has kept me from acquiring the Leica, is how its light transmission compares with other eyepieces. I have heard that the XW and Delos have excellent transmission, and that the Delos are somewhat better and the ZAO's the best according to Alvin Huey. Granted the Leica compares favorably to ZAO's as far as overall optical quality. But how do they compare in terms of light transmission? Personally, for deep sky, I think light transmission is more important than a somewhat wider AFOV and longer eye relief, and may even be more important than overall sharpness of the image. After all, unless we're looking at stars and star clusters, DSO - faint fuzzies - are fuzzy to begin with.

Also, I think if many observers - myself included - were to go the route of the Leica ASPH, they would need to sell many eyepieces in order to afford it. I would have to think hard about which eyepieces I would need to give up. I don't know if I'd want to let my XW's go if the Leica's light transmission is not as good.

Mike


Johnny and Mike, Thanks for adding the Leica ASPH in the conversation. I own the complete set of Ethos and all of the Pentax XW's other than the 14mm starting with the 20mm XW down to the 3.5mm XW. I was one of the relatively early adopters of the ASPH and at the time also owned a set of ZAO-II's. With a 6.3" f/7 Apo as the primary test instrument, I ended up concluding that the Leica ASPH could keep up with an occasionally exceed the performance of the Zeiss glass which is almost a heresy. This has also held true for my 20" f/3 and 12.5" f/5 Newtonians with either a Paracorr I or II, SIPS, Powermates or Barcon.

Over the past several months, I had bilateral cataract surgery which allowed for significantly greater light throughput due to the clear monofocal lens implants. Since returning back to doing astronomy, my first selection of an ep for planetary work is the Leica ASPH for the following reason. Gene hit the nail on the head when he described wanting tight increments between ep's in the sub 10mm range. I think this is because there is a point based on seeing where just the right amount of magnification shows you the most visual information. This is where the Leica placed in a 2" TeleVue Powermate runs away from my XW's or Ethos ep's in that I can set just the right amount of power for the given seeing conditions (8.9mm - 4.45mm variably). In other words, I am able to dial in the perfect magnification for a particular scope, the seeing conditions and my own personal functioning at that moment in time.

Because of the versatility and overall performance of the Leica ASPH, my Pentax XW's and even Ethos ep's have spent a great deal more time in their respective ep's boxes. The ASPH has spoiled me so much that I wonder how I ever put up with fixed focal length ep's. Of course the answer lies in the fact that I never had a zoom before that could keep up with the best fixed focal length ep's until the ASPH. Mike, I have not specifically looked at light throughput comparisons. I am so mesmerized by the perfection of the views based on the perfect mag and relatively wide FOV's that light throughput is down the list of critical attributes especially now since I have so much more personal light throughput. Bob

#37 GeneT

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Posted 18 March 2013 - 02:57 PM

Because of the versatility and overall performance of the Leica ASPH, my Pentax XW's and even Ethos ep's have spent a great deal more time in their respective ep's boxes. The ASPH has spoiled me so much that I wonder how I ever put up with fixed focal length ep's. Of course the answer lies in the fact that I never had a zoom before that could keep up with the best fixed focal length ep's until the ASPH. Mike, I have not specifically looked at light throughput comparisons. I am so mesmerized by the perfection of the views based on the perfect mag and relatively wide FOV's that light throughput is down the list of critical attributes especially now since I have so much more personal light throughput. Bob


Oh no-one more eyepiece to buy and try! :grin:

#38 Starman81

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Posted 18 March 2013 - 05:13 PM

When I look through the TV’s I see more of a “weak RKE like” view or more of a 3d depth which I enjoy.


Yes! I too noticed this RKE-like effect to a certain extent when I had the 10mm Delos. It did cause the exit pupil to be a bit more sensitive to head movement but it did also add the novel effect to the view.

#39 MRNUTTY

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Posted 18 March 2013 - 07:50 PM

Post deleted by MRNUTTY

#40 csrlice12

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Posted 18 March 2013 - 10:16 PM

Odd, I have found the XWs to have a 3D view to them. The ES appear more "flat", like looking at a picture, the XW is like watching Star Wars in 3D.

#41 Roy McCoy

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Posted 19 March 2013 - 12:22 AM

What does "weak RKE" refer to; the 28mm floaty thing?

Yes.


The ES appear more "flat", like looking at a picture,



I find the ES to be more "flat or picture like" than the Pentax as well. But I see more of the floating effect in the TV's than I do in the Pentax.

#42 Rick M.

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Posted 19 March 2013 - 10:09 AM

I'd like to see a comparison of the 10mm. eyepieces.

Rick






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