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ES 82 Degree 11mm VS Pentax XW

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#1 jm510227

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Posted 19 August 2013 - 10:26 PM

Hello All:

Have any of you compared the ES 82 degree 11mm eyepiece against the Pentax 10.5mm XW?

What I am looking for is comparison of color fidelity, sharpness and contrast.

Thanks in advance.
Jim Miller/Tulsa, OK

#2 Rick Woods

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Posted 20 August 2013 - 12:49 AM

Boy, that doesn't seem like it would be a fair contest!
It'll really say something if the verdict comes in favorably about the ES. (Although, I'm sure it will be relatively favorable anyway - ES seems to make some good stuff!)

#3 csrlice12

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Posted 20 August 2013 - 07:11 AM

Don't get me wrong, the ES 82* 11mm is one of my favorite widefields and eyepieces.....but it's not an XW......The XW is much a much more "inviting" eyepieces. The ES delivers a great view, like looking thru a picture window....The XW's immersiveness is like being thrown out the window...it invites you outdoors. Hard to really describe in technical words....it really is more of an emotional reaction.....an emotional reaction of what you experience in the eyepiece. Maybe that's the best way to put it, you don't use an XW, you experience it........ oh, and its a 10XW, the 10.5 is an XL (another really nice eyepiece).

#4 Redshirt

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Posted 20 August 2013 - 07:29 AM

Hi Jim - my main gripe with the ES82-11 is scatter. I did some testing on Saturn back in June...the ES was easily bested by a 12mm Konig on-axis. My other (minor) gripe with the ES is a fuzzy field stop.

It is probably a marvelous deep-sky eyepiece, but would not be a suitable choice for planetary imho.

#5 Messyone

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Posted 20 August 2013 - 09:10 AM

A while back I did my own ES v XW for 11 ES v 10 XW, 6.7 ES v 7 XW and 4.7 ES v XW 5 and every time the XW wasn't just better it was miles ahead, The XW's showed more of everything it was chalk and cheese. One example sticks in my mind and that was the Trapezium, The ES 6.7 showed the E star but not the F star...drop in the XW 7 and there is the F star clear as night.
It convinced me that the XW eyepieces are worth the dollars.
Matt

#6 dobsoscope

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Posted 20 August 2013 - 09:46 AM

How does the Pentax XW perform planetary-wise?

#7 Starman1

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Posted 20 August 2013 - 10:26 AM

How does the Pentax XW perform planetary-wise?

There have been many posts over the last few years that tout the virtues of both the XWs and the new Delos eyepieces for planetary use.
Hardcore planetary observers still think they have unacceptable light scatter, but I think it is a matter of taste. When the details are super-sharp and as small as the seeing will allow, having the ultimate in blackness around the planet doesn't matter one iota to most observers.
In which case a 70 degree widefield eyepiece on this level could do for viewing everything in the sky, including planets and Moon.
And the Delos are getting great write-ups in lab tests. The French magazine Ciel et Espace just said the 10mm Delos became their reference standard, and they did resolution and actual wavefront error lab tests as well as field tests. In fairness, in another set of lab tests from the same magazine, the 14 XW scored high.

#8 Tank

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Posted 20 August 2013 - 12:21 PM

How does the Pentax XW perform planetary-wise?

Does very good however I find simple great ortho or plossl will beat it but in terms of the whole package WF/Comfort/glass you cant beat a XW.
I assembled a workhorse WF set and includes a few XWs
5XW on the way
7XW
10XW
14 UWA
20T2 Nagler
28 UWAN
40 TV WF

The ES 11 is a very good EP but not a XW but for the price hard to beat! Heck you can get 3 ES 82 for the price of one XW! If you can save up get the XW thou!

#9 Starman1

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Posted 20 August 2013 - 01:29 PM

For the planetary observer, the Delos and XW lines may be complementary.
Delos comes in 3.5, 4.5, 6, 8, 10, 12, 14, 17.3
XW comes in 3.5, 5, 7, 10, 14, 20
Other than the 3.5, the shorter focal lengths are different.
Here is a lab test of 10mm eyepieces:
http://www.cieletesp...laires_10mm.pdf
Use Google or Babylon to translate.

#10 jm510227

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Posted 20 August 2013 - 01:39 PM

Wow!

I was expecting one or two replies, but feel like I hit the mother lode. Thanks to all for much useful information.

Jim Miller/Tulsa

#11 Scanning4Comets

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Posted 20 August 2013 - 02:07 PM

I am more of a deep sky observer myself, but I have sat at the telescope for countless hours observing fine detail on Jupiter, and looked at Saturn waiting for that hairline ring structure, Cassini Division and have seen nice detail on Mars.

For these observations, I always used a Pentax XL or XW....and sometimes used a barlow for more mag. The XW's and XL's are excellent planetary performers and even on globs stars just "POP".....

They just have that instant focus snap that other eyepieces kind of slowly gurgle through if you know what I mean. My 9mm ES 100 has that focus "POP" like the XW's. I don't know what it is with that eyepiece, but I get XW-like performance out of it, except for the edges of course. If I were just studying planets, I'd get myself some more XW's because the comfort, matched with the overall sharpness and focus POP is worth staying at the eyepiece for hours & hours instead of squinting through an Ortho or Pentax XO which I couldn't use due to eye fatigue.

Like Don says, scatter around the planet itself is of no concern as long as the detail on the planet itself is really sharp. Factor in other things such as a fan at the back of the reflector with a baffle, good seeing, a bit of "haze", flocking in the tube, excellent collimation and I am good to go.

#12 JustaBoy

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Posted 20 August 2013 - 02:17 PM

*scatter around the planet*

Splitting hairs here, but if there is scatter that you can see around a planet, it is also there across the disk. It's just that the disk itself is too bright to see the scatter, but it has to be doing something very subtle to the contrast - No?

Thanks,
-Chuck

#13 howard929

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Posted 21 August 2013 - 08:53 AM

Between a 11mm eyepiece with very good quality glass and a 10mm of equal quality I'd be most surprised if the 10mm wasn't said to be just a bit sharper and provided a tiny bit bigger view. In my limited experiences with a manual 8" dob, more FOV means less nudging = more enjoyable since I'm not doing serious science here, I'm just looking. "miles ahead"... being "thrown out the window"... funny stuff. YMMV.

#14 Starman1

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Posted 21 August 2013 - 11:41 AM

*scatter around the planet*

Splitting hairs here, but if there is scatter that you can see around a planet, it is also there across the disk. It's just that the disk itself is too bright to see the scatter, but it has to be doing something very subtle to the contrast - No?

Thanks,
-Chuck


Contrast is defined as the difference between a light and dark adjacent area.
If there is general light scatter, as from the background sky, it brightens both the bright and the dark areas, and contrast between those areas remains the same.
That, of course, assumes the light scatter is uniform across the visible spectrum, and it might not be. And it also assumes a uniformity to scatter, area-wise, that also might not be. If the light scatter throws light out of a brighter area into a darker area, there could be a reduction in contrast by lowering the brightness of the brighter area and brightening the darker area. On the other hand, if there is sufficient contrast, a slight lowering of contrast won't make enough difference to make something invisible that was visible before. Assuming the focus is good enough and seeing is good enough, and all the other factors.

In practice, a bright target like a planet causes a reduction in the sensitivity of the retina not only in the small spot occupied by the planet, but also in an area around it. The effect, when viewing, is to make the background near the planet darker while peripheral vision may see a lightening of the background sky farther out in the field.

It's an interesting effect. It is a reason why faint moons are hard to see immediately adjacent to a planet, since the reduction in retinal sensitivity will reduce the ability to see a faint moon. I had always wondered why I could see a star of magnitude 17, but had a hard time with a moon of Saturn that was 2-1/2 magnitudes brighter--especially when the background near the planet appeared quite black--until someone pointed out this reduction in retinal sensitivity.

#15 Lamb0

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Posted 21 August 2013 - 03:40 PM

Between a 11mm eyepiece with very good quality glass and a 10mm of equal quality I'd be most surprised if the 10mm wasn't said to be just a bit sharper and provided a tiny bit bigger view.



:idea: Then perhaps a 12mm Delos vs. 11mm ES82 is a better comparison - though I'd still favor the Delos in that match-up. A 14mm Delos vs. 11mm ES82 is a bit of a mismatch, though. :thinking:

#16 howard929

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Posted 22 August 2013 - 08:41 AM

Pitting a 70 degree eyepiece to a 82 degree eyepiece yields IME varying results. I'm new at this and find it hard to separate the noise of wide fields when viewing planets and comparing 2 eyepieces of similar focal lengths when one has a 82 degree AFOV and the other is a BGO. Sometimes I prefer one and at other times, the other with no clear cut winner. Possibly it's because I'm too new to this but apples to apples and peaches to peaches seems to work best with eyepiece show downs IMVHO.

#17 ausastronomer

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Posted 23 August 2013 - 05:45 AM

Hello All:

Have any of you compared the ES 82 degree 11mm eyepiece against the Pentax 10.5mm XW?

What I am looking for is comparison of color fidelity, sharpness and contrast.

Thanks in advance.
Jim Miller/Tulsa, OK


Hi Jim,

If they are the only criteria you are interested in; and FOV is not critical, it's a bit like taking a knife to a gunfight. That having been said if you are not a critical observer and do not push your equipment to the limits, you would be more than happy with the ES82 at its lower price point. It's a very decent eyepiece. A bit like comparing a Hyundai with a Mercedes. The Hyundai will get you there and do a good job of it, but a Merc it aint.

Cheers

#18 Sarkikos

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Posted 23 August 2013 - 08:02 AM

In practice, a bright target like a planet causes a reduction in the sensitivity of the retina not only in the small spot occupied by the planet, but also in an area around it. The effect, when viewing, is to make the background near the planet darker while peripheral vision may see a lightening of the background sky farther out in the field.

It's an interesting effect. It is a reason why faint moons are hard to see immediately adjacent to a planet, since the reduction in retinal sensitivity will reduce the ability to see a faint moon. I had always wondered why I could see a star of magnitude 17, but had a hard time with a moon of Saturn that was 2-1/2 magnitudes brighter--especially when the background near the planet appeared quite black--until someone pointed out this reduction in retinal sensitivity.


I think there are two kinds of retinal sensitivity involved here. The brightness of the planet will decrease sensitivity of the retina to faint objects, such as dim satellites, especially when they are near the bright planet. But this same brightness of the planet will increase sensitivity of the retina to fine surface details, contrast, and color range. Viewing faint satellites and fine planet surface detail involve different faculties of the eye.

Personally, when I'm observing a planet, I'm all about the surface detail on the planet itself. (In this case, the brightness of the planet can only help. Ambient white light can help even more.) I'm not really concerned about how many faint satellites I can see. It does seem that there would be a problem trying to do both. Maybe using tracking to keep the planet's disk out of the FOV is the best that can be done when trying to locate its fainter moons.

Mike

#19 gunfighter48

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Posted 23 August 2013 - 11:20 PM

At $300+ for the Pentax, I sure hope it would do better than the $99 ES. I would be very disappointed if I bought the Pentax XW and it didn't out perform the ES!!! For me this is like comparing a Sirius Plossl to a TV Plossl! I really like my ES eyepieces (I now have 7 of them) and while they are great eyepieces for the $$, there are better ones out there at considerably more money.






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