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Equipment Discussions >> Eyepieces

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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
A Delos, Pentax XW Comparison
      #5735280 - 03/15/13 11:28 PM

A Delos, Pentax XW Comparison
Recently, I have rethought my needs, and updated my eyepiece collection. I would like to share some thoughts in the area of my decisions I recently made while moving into the ‘high power’ range of eyepieces. For the past two years, I have bought most of the new TeleVue Delos as they were released. I have posted on Cloudy Nights my appreciation for the production quality and outstanding views provided by this new eyepiece line.

I have also read several postings by owners of the Pentax Extra Wide eyepieces saying that these are among the finest eyepieces ever made in their range of specifications. When Cloudy Nights posters ask for their top 10 favorite eyepieces, the Extra Wides often show up in the listings.

It is important for me to have eyepieces that allow me to view while wearing glasses. With minor exceptions, long eye relief is the second or third most important criteria when I consider buying an eyepiece. For this, I need a minimum of 17mm of eye relief; 19 or 20 is even better. Both the Delos and Pentax Extra Wides have 20mm of eye relief, and 72 and 70 AFOV respectively. These are nice criteria for doing high power work.

In the ‘high power’ range, I had purchased the 8, and 6mm Delos eyepieces. I already owned a 4 Radian. I recently found and bought a used 5mm Pentax XO—in my opinion, one of the finest eyepieces ever made. There are no 7 and 5mm Delos eyepieces. Pentax offers a 7 and 5mm Extra Wide, and about a week ago, I purchased both of them. One of my viewing axioms is that I like having eyepiece focal lengths bunched up when moving below 10mm. I now can move in 1mm increments going from an 8, to a 7, to a 6, to a 5.

On Tuesday March 12th and Thursday March 14th, I did some comparison viewing with all four eyepieces. The telescope I used was my 12.5 inch, F5 Portaball. Here are the comparative values of the eyepieces; I did not use a Paracorr:

7mm/218X (Pentax XW)
17X inch
Exit Pupil: 1.5

6mm/254X (Delos)
20X inch
Exit Pupil: 1.3

5mm/305X (Pentax XW, XO)
24X inch
Exit Pupil: 1


I spent about two hours each evening viewing two objects: Jupiter and the Orion’s Trapezium. I viewed in about Mag 4.8 skies about 22 miles from my home. When making eyepiece comparisons I prefer to have Jupiter or Saturn in the equation. I selected the Trapezium because it gave me six stellar points to view—the four main stars, along with E and F.

The seeing was very good Tuesday evening, and excellent Thursday. I made these observations beginning about 9 p.m. central day light savings time. Both Jupiter and the Trapezium were well placed in the sky. I realize the one must extrapolate when comparing a 7 to a 6 and a 6 to a 5. However, experienced viewers learn to make the necessary adjustments to at least get it close. Delos does not make a 7 and Pentax does not make a 6 XW, therefore direct comparisons cannot be made. I also made some comparisons between the Delos 8 and Pentax 7 XW, and other eyepieces. However, my main comparisons are listed below.

Here are my conclusions: Jupiter—
The Pentax 5mm XO yielded noticeably more contrast and clarity on Jupiter than the 5 XW. The word I choose to use here is noticeably. If I were giving the two eyepieces a letter grade, I would give the XW an A and the XO an A+. The 5mm XW did provide excellent views of the planet. With both eyepieces, there was excellent delineation of the belt structure. On Thursday evening, the Great Red Spot was easily seen on the planet’s surface. On and off axis viewing was excellent in both eyepieces.


The Pentax 7mm XW was also an excellent performer on Jupiter. Going back and forth between the Pentax 7 XW and the Delos 6, I was surprised—it was a tie. Both eyepieces gave superb views of the Jupiter. Extrapolating from the 1mm focal length difference, I could not give one an edge over the other. Some people are ‘color’ conscious. It appeared to me that the Pentax eyepieces had just a little bit more of a brownish tone than the Delos. However, for me, that has never been an issue. I will agree that my Radians gave the moon a nice coffee tone, yet this colorization in no way affected the amount of detail I could see on any of the astronomical objects.

The Trapezium—
The Pentax 5mm XO yielded just a tad more granularity in the stellar components compared to the
5 XW. However, the differences on the stellar points were not as marked between the two eyepieces as were the clarity and contrast in the views of Jupiter. The Trapezium’s four main stars were tack sharp in both eyepieces, as were E and F. On and off axis views were excellent. I am not sure of the reasons why the 5 XO did not provide a more significant difference when compared to the 5 XW. However, I remember reading that the Pentax 5 XO was designed to be a first rate planetary eyepiece. It truly is. One conclusion I drew from this is that when doing work on stellar objects, the Pentax 5 XW will get most of the use in that range—the 70 AFOV and 20mm of eye relief makes viewing much less challenging.

The Pentax 7mm and Delos 6 also were outstanding performers on the Trapezium. All the stellar points, to include E and F, were nice and sharp, on and off axis.

Some final thoughts:
If you own the Pentax XW’s, would I recommend that you sell them, for the new Delos? Definitely not! I was really surprised that the Pentax XW’s provided as good a views as the new Delos. The XW’s came on the scene about 10 years ago. Along the way, did Pentax improve the polish, coatings, and possibly make some improvement tweaks to their lens configurations for their more current rendings? I don’t know. Is the XW of 10 years ago as good as the current ones? I don’t know. Maybe someone else can answer that through some A B comparisons.

I was surprised how these comparisons came out. I thought that the Delos would be noticeably better than the XW’s. After all, the Delos emerged from the design methodology learned from the excellent Ethos series. The Delos drew on the lessons learned over the past 10 years when the XW’s emerged. What I thought I would be doing was to make these comparisons, and that the Delos would be the clear winner. I then was going to sell my Pentax 7 and 5 XW’s. No way—I am keeping them both!

If you own neither the Pentax XW’s or the Delos, and would like to pick up some with these characteristics (they are very similar), which ones? You could just flip a coin—and you will be a winner either way. They are both excellent eyepiece series. You could calculate and decide if, in the high power range, a Pentax 7 and 5 combination, or a Delos 8 and 6 combination, or possible a Delos 4.5 or 3.5, would best serve your telescope type, and your viewing habits. If you want a new Pentax XW, I would check with various venders to see if they have the one you want. There is some question of Pentax plans to continue the XW’s. The Pentax XW’s are dribbling in by ones and twos. There is plenty of product in the Delos line. Does one need a 7, 6, and 5mm eyepiece? (I also own a 4 Radian.) Probably not. However, as I noted above, when moving through the high power ranges, I like to have shorter stops between eyepieces. In the wide angle range, I make wider sweeps—going from a 31 Nagler to a 22 Nagler, to a 14 Delos. As we all know, seeing dictates how much magnification we can use, as does collimation and mirror cool down. But, when the gods align, one can keep moving to more and more magnification. This become important when doing double star work, and when seeing planetary detail, and other objects. I rarely use the Radian 4—so that is the shortest mm eyepiece I own.

Lastly—I recommend you beg, borrow or steal (no—just kidding; never steal ) a Pentax 5mm XO if you want to max the potential for seeing planetary detail.
GeneT


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Stephen S
professor emeritus
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Reged: 08/21/07

Loc: Evansville, IN
Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5735329 - 03/15/13 11:57 PM

Thank you for sharing this info. This is consistent with what I've read in other posts and with my own brief experience.

I really like TeleVue stuff. I have the full set of 1.25" Pentax XWs. I seriously considered making the change. I purchased a 10mm Delos to see if I might want to make the change. After comparing the Delos head to head with my 10mm XW, I had a tough time calling one a winner over the other.

I like (am used to) the ergonomics of the XWs. I've already have a full set of XWs and they are cheaper. I'm sticking with the XWs for now. That said, I'm thrilled to see that TeleVue has come up with a comparable line of eyepieces. Great time to be in the hobby!

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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mgwhittle
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Reged: 08/24/11

Loc: Chattanooga, TN
Re: A Delos, Pentax XW Comparison new [Re: Stephen S]
      #5735355 - 03/16/13 12:12 AM

I notice you didn't do any comparison of light throughput of the Delos versus the Pentax. From what I keep reading, that is an important strength of the Delos line. Maybe a follow up test on that?

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Scanning4Comets
Markus
*****

Reged: 12/26/04

Re: A Delos, Pentax XW Comparison new [Re: mgwhittle]
      #5735408 - 03/16/13 01:11 AM

Nice report Gene! Very thoroughly executed and a real enjoyable read.



Cheers,


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dcoyle
professor emeritus


Reged: 10/11/05

Loc: Turbulent but dark skies, N.M.
Re: A Delos, Pentax XW Comparison new [Re: mgwhittle]
      #5735419 - 03/16/13 01:19 AM

Thanks for writing that up, Gene.

Do you take your glasses off for the 5.1 XO? I find the eye relief tight without glasses. I ask because if you do, that could account for some of the enhanced contrast effect.

Dan


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Roswell_UDSO
journeyman
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Reged: 06/03/12

Re: A Delos, Pentax XW Comparison new [Re: dcoyle]
      #5735711 - 03/16/13 09:08 AM

Nice write-up - Thanks.

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t.r.
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Reged: 02/14/08

Loc: Upstate NY
Re: A Delos, Pentax XW Comparison new [Re: Roswell_UDSO]
      #5735857 - 03/16/13 10:13 AM

Gene, I have followed your process of inquiring and acquiring these eyepieces from the onset. If anyone is objective, I think it is you. Great report on your findings and not surprising to me. LLegee and myself compared the proto-type, first 10 Delos to my 10XW awhile ago in a TEC180FL and AP130GT and posted our findings here which mirror yours. We observed comet Garradd near M71 and Jupiter for a variety of detail. I however, found the Delos warmer than the XW, while Luke saw no difference in tone. We'll chalk that up to individual eyesight and color perception which is known to vary highly in individuals to say the least. But, for the most part, I think the data points are in agreement that no difference can be seen in these eyepieces. Thanks for the write-up and continue to compare and contrast that lineup!

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Damo636
sage


Reged: 08/16/11

Loc: Co Fermanagh, Northern Ireland
Re: A Delos, Pentax XW Comparison new [Re: t.r.]
      #5735917 - 03/16/13 10:34 AM

Great write up Gene

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catboat
sage
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Reged: 12/01/09

Loc: Maine
Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5736031 - 03/16/13 11:23 AM

Thanks, Gene. That's a clear, thoughtful, and very useful review.

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Sarkikos
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Reged: 12/18/07

Loc: Suburban Maryland, USA
Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5736075 - 03/16/13 11:40 AM

Quote:

Lastly—I recommend you beg, borrow or steal (no—just kidding; never steal ) a Pentax 5mm XO if you want to max the potential for seeing planetary detail.
GeneT




+ 1 The Pentax XO 2.5 is not too shabby, either.

If you liked the XW 5 and 7, maybe you should think about the XW 3.5. It's my favorite eyepiece for high-power views of planets or doubles when I want more FOV for my Dob than the XO's will provide. I had a great look at Saturn last weekend through the XW 3.5. Nice detail and color in the rings and globe.

So far the XW's have seemed neutral-toned to my eyes. If the Delos are cooler than the XW's, than the Delos must truly be ice-cold!


Mike


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MRNUTTY
Carpal Tunnel
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Reged: 11/22/11

Loc: Mendon, MA
Re: A Delos, Pentax XW Comparison new [Re: catboat]
      #5736090 - 03/16/13 11:48 AM

I found exactly the same non-differences between XW's and the Delos. I also like to have small increments in FL especially under 10, where I want 1mm, ans closer under 5mm.

I would be interested in a XW to Nagler comparison, if there is one, across the whole range. I know of a few like the 31nag vs 30XW.


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Rich V.
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Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: A Delos, Pentax XW Comparison new [Re: catboat]
      #5736135 - 03/16/13 12:05 PM

Gene, nice report. Did you notice a difference in "ease of view"?

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.

Putting my eye up to my Pentax EPs, the full FOV just naturally pops into place, with the old XLs just a bit easier than the XWs. The Delos reminded me a bit of my Ethos eyepieces; it's "perfect" eye position was a bit finicky to find; less so than the Ethos, though.

I know we all have our personal preferences in how an eyepiece "feels" to us and I'm wondering if you noticed any difference in this regard.

Rich


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JayinUT
I'm not Sleepy
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Reged: 09/19/08

Loc: Utah
Re: A Delos, Pentax XW Comparison new [Re: Rich V.]
      #5736194 - 03/16/13 12:30 PM

Gene,

I really enjoyed reading your post. Well written and fun. Both are great eyepieces. Thanks for the write up and again, well done and a pleasure to read.


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Kutno
Pooh-Bah
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Reged: 08/17/09

Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5736322 - 03/16/13 01:38 PM

Thank you, Gene, for your writeup.

Just curious: You indicate you have an 8mm Delos; but did not throw that unit into the mix. If you ever intend to do one, I would be interested to learn the results of a similar comparison between that Delos and the 7mm XW.


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coutleef
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Reged: 02/21/08

Loc: Saint-Donat, Québec, Canada
Re: A Delos, Pentax XW Comparison new [Re: Kutno]
      #5736550 - 03/16/13 03:53 PM

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.

You demonstrated great objectivity as you are a delos user and found both equivalent

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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Mike B
Starstruck
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Reged: 04/06/05

Loc: shake, rattle, & roll, CA
Re: A Delos, Pentax XW Comparison new [Re: coutleef]
      #5736575 - 03/16/13 04:17 PM

Thanks, Gene, for a fine write-up! Enjoyed reading it very much

Having recently jumped into the fray with a 10mm XW, i've been wrestling with the thot of trying the 7xw- but felt the mags produced might render it less useful for my situation. Your efforts have helped me focus on the possibility of an 8mm Delos as a "perfect" higher-mag compliment to the 10xw in my scope.


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Tank
Carpal Tunnel
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Reged: 07/27/09

Loc: Stoney Creek, Ontario, CANADA
Re: A Delos, Pentax XW Comparison new [Re: coutleef]
      #5736584 - 03/16/13 04:22 PM

From what ive experienced i think if you like more the immersive feeing the delos might be a better pick if you like the more the seeing the FOV easier a bit backed out and framed the XW is for you.
So far what ive seen i like the XW but its just what i like others may have a different take.


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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: mgwhittle]
      #5736611 - 03/16/13 04:34 PM

Quote:

I notice you didn't do any comparison of light throughput of the Delos versus the Pentax. From what I keep reading, that is an important strength of the Delos line. Maybe a follow up test on that?




Good question. I don't pursue very often dim fuzzies that task the limits of my mirror. This would be an important question for those who do.


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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: dcoyle]
      #5736615 - 03/16/13 04:38 PM

Quote:

Do you take your glasses off for the 5.1 XO?




Yes I do. Also, I am careful not to blink too often because the XO's short eye relief causes it to get dirty easily. My XO does not come out at star parties or outreach events.

I should have reported that I tested all these eyepieces both while wearing glasses (except the XO) and with my glasses off. In other words, I went from the XO to the XW back and forth with glasses off.


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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: t.r.]
      #5736620 - 03/16/13 04:41 PM

Quote:

I however, found the Delos warmer than the XW, while Luke saw no difference in tone. We'll chalk that up to individual eyesight and color perception which is known to vary highly in individuals to say the least.




I agree. Years ago when I joined the Air Force, a doctor told me that about 15 percent of those who would like to become pilots could not because they could not pass the color blindness part of the eye exam. Even those who can pass, we will see and process color differently.


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GeneT
Ely Kid
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Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: Sarkikos]
      #5736623 - 03/16/13 04:42 PM

Quote:

maybe you should think about the XW 3.5




I would--but I rarely use my Radian 4 and decided not to invest in a new eyepiece in that range.


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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: Rich V.]
      #5736627 - 03/16/13 04:45 PM

Quote:

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.




I found both eyepiece series easy for me to find the exact place to place my eye to obtain the best view--both while wearing glasses and with them off.


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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: Kutno]
      #5736631 - 03/16/13 04:48 PM

Quote:

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




I did throw the 8 Delos into the mix. I did some back and forth between it and the Pentax 7 XW. As with the 7, the Delos 8 performed superbly. However, I decided for this writeup to focus more in the high power ranges going from the 7 to the 6 to the 5's. I agree that in most cases, an 8 does live in the high power range.


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GeneT
Ely Kid
*****

Reged: 11/07/08

Loc: South Texas
Re: A Delos, Pentax XW Comparison new [Re: coutleef]
      #5736638 - 03/16/13 04:51 PM

Quote:

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?


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Rich V.
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Reged: 01/02/05

Loc: Lake Tahoe area, Nevada, USA
Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5736734 - 03/16/13 05:46 PM

Thanks, Gene.

Quote:

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




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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coutleef
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Loc: Saint-Donat, Québec, Canada
Re: A Delos, Pentax XW Comparison new [Re: Rich V.]
      #5736756 - 03/16/13 05:53 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.

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Ava
sage


Reged: 11/30/11

Loc: Sweden
Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5738175 - 03/17/13 08:43 AM

Quote:

Quote:

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.


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russell23
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Reged: 05/31/09

Loc: Upstate NY
Re: A Delos, Pentax XW Comparison new [Re: Ava]
      #5738225 - 03/17/13 09:03 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


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russell23
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Re: A Delos, Pentax XW Comparison new [Re: coutleef]
      #5738234 - 03/17/13 09:11 AM

Quote:

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


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johnnyha
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Reged: 11/12/06

Loc: Sherman Oaks, CA
Re: A Delos, Pentax XW Comparison new [Re: Stephen S]
      #5738722 - 03/17/13 02:19 PM

Quote:

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 , 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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johnnyha
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Re: A Delos, Pentax XW Comparison new [Re: coutleef]
      #5738725 - 03/17/13 02:20 PM

Quote:

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.


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Sarkikos
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Re: A Delos, Pentax XW Comparison new [Re: johnnyha]
      #5738791 - 03/17/13 02:51 PM

Johnny,

Quote:

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.




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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Stephen S
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Re: A Delos, Pentax XW Comparison new [Re: johnnyha]
      #5739464 - 03/17/13 07:25 PM

Quote:

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


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Sarkikos
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Re: A Delos, Pentax XW Comparison new [Re: Stephen S]
      #5739525 - 03/17/13 07:53 PM

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

Mike


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Roy McCoy
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Re: A Delos, Pentax XW Comparison new [Re: GeneT]
      #5739992 - 03/18/13 02:14 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


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Bob S.
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Re: A Delos, Pentax XW Comparison new [Re: Sarkikos]
      #5740127 - 03/18/13 05:38 AM

Quote:

Johnny,

Quote:

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.




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

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


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GeneT
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Re: A Delos, Pentax XW Comparison new [Re: Bob S.]
      #5741019 - 03/18/13 03:57 PM

Quote:

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!


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Starman81
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Re: A Delos, Pentax XW Comparison new [Re: Roy McCoy]
      #5741327 - 03/18/13 06:13 PM

Quote:


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.


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MRNUTTY
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Re: A Delos, Pentax XW Comparison *DELETED* new [Re: Starman81]
      #5741712 - 03/18/13 08:50 PM

Post deleted by MRNUTTY

Edited by MRNUTTY (03/19/13 10:44 AM)


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csrlice12
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Re: A Delos, Pentax XW Comparison new [Re: MRNUTTY]
      #5742027 - 03/18/13 11:16 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.

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Roy McCoy
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Re: A Delos, Pentax XW Comparison new [Re: MRNUTTY]
      #5742157 - 03/19/13 01:22 AM

Quote:

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



Yes.


Quote:

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.


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Rick M.
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Re: A Delos, Pentax XW Comparison new [Re: Roy McCoy]
      #5742678 - 03/19/13 11:09 AM

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

Rick


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