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maybe you should think about the XW 3.5

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I borrowed a 10mm Delos from TV's John Rhodes last year at GSSP. I felt it gave great views; very similar to my Pentax eyepieces with one exception--finding the perfect eyepoint wasn't quite as easy for me compared to the Pentax.

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Just curious: You indicate you have an 8mm Delos; but did not throw that unit into the mix.

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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.

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I also wondered why Pentax went from a 10 to a 7 in their XW series. Why not a 10 to an 8?

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Then there'd be too big a gap between the 8 and the 5!

It seems Pentax was content to closely duplicate their XL series focal lengths and leave it at that. The 28mm 1-1/4" XL was replaced with the 30mm 2" XW to keep a common AFOV; a step in the right direction. The focal lengths follow a progression of approx. 70% FL increments.

Rich

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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.

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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?

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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.

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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.

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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

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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 , 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.

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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.

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

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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 , 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.

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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.

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Johnny,

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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 , 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.

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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

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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

Edited by Bob S. (03/18/13 05:54 AM)

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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

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Oh no-one more eyepiece to buy and try!

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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.

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