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Old Wednesday 18th October 2006, 10:02   #1
Lehel
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WO 7mm UWAN eyepiece

Hi Everybody,

Does anybody use Wo UWAN eyepieces with pentax pf scope?
What is your opinion? What about CA, FOV etc...?

Thanks in advance!
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Old Wednesday 18th October 2006, 17:46   #2
eitanaltman
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Quote:
Originally Posted by Lehel
Hi Everybody,

Does anybody use Wo UWAN eyepieces with pentax pf scope?
What is your opinion? What about CA, FOV etc...?

Thanks in advance!
I've never used it, but I've read almost every eyepiece thread on cloudynights.com and astromart.com, and the UWANs are very highly rated eyepieces. My impression was that people seem to think they're comparable to the high-end ep's like the TV Radians and Pentax XF, though they lag behind the top-end like Pentax XW and TV Nagler.

The UWAN's are an ultra-wide angle design, with an 82-degree AFOV. That's more than the Pentax XW (70-degrees), but I'm not sure how much of that extra AFOV you'll be able to use if the image degrades on the edges. However, the eye-relief is much tighter, only 12mm (vs. 20mm for the XW or XF), so if you wear glasses it's probably a no-go.

The one thing I've found in my research is that with a high-end eyepiece, it's fairly low-risk to buy-and-try because you can almost always re-sell it on the classifieds at astromart.com. These astronomy junkies are way crazier about their equipment than birders!! If you buy it, and don't like how it feels, I'm positive you can re-sell it to someone who is looking for one. Even if you lose $20-30 on the deal, just pretend you rented it for a few months.

One final point -- I don't know which pentax scope you have, but that 7mm focal length is probably not going to work well on a PF-65. I can't speak for the 80 or 100mm scopes, but on the PF-65 you'd really be pushing the optical envelope at that magnification (56X) and it would probably look like crud unless viewing conditions were fantastic.

Hope this helps!
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Old Wednesday 18th October 2006, 20:29   #3
Sout Fork
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Quote:
Originally Posted by eitanaltman
I can't speak for the 80 or 100mm scopes, but on the PF-65 you'd really be pushing the optical envelope at that magnification (56X) and it would probably look like crud unless viewing conditions were fantastic.

Hope this helps!
I can (more or less)...
The problem is simple physics to a great extent-all else being equal multiply the magnification by 2 and you divide light by a factor of 4. In other words light transmission at 40x is 1/4 what it would be at 20x roughly.

Also Ultra Wide Angle EP's are highly corrected for field distortion which means they are very complex with many light robbing elements. Typically around 8. If you must try high power EPs stay away from the Wide Field ones and use simple good quality 4 or 5 element designs.

I have both the 80mm and 100mm Pentax and my expierience so far...

Max power:

80mm
wide field eps - 40x
simple 4 or 5 element eps - 60x (on a good day)

100mm
wide field eps - 70x
simple 4 or 5 element eps - 90x

This is based on comparing $300 Pentax XW Wide Fields to $100 TMB Planetaries. The TMBs outperformed the XWs at short focal lengths in all ways except FOV (60 degrees compared to 70 for the XWs). The trade off was a no-brainer for me.

One man's opinion and nothing more.
SF
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Old Wednesday 18th October 2006, 23:58   #4
eitanaltman
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Quote:
Originally Posted by Sout Fork
This is based on comparing $300 Pentax XW Wide Fields to $100 TMB Planetaries. The TMBs outperformed the XWs at short focal lengths in all ways except FOV (60 degrees compared to 70 for the XWs). The trade off was a no-brainer for me.

That's a very interesting observation -- I know that a lot of the astronomer folks love the TMB planetaries.

What were the comparisons you made? I'm assuming 9mm TMB vs. XW10 and 7mm vs. XW7?

I just picked up a used Pentax XL 10.5 (the precursor to the XW -- totally blows the doors off the XF 12mm as far as I can see), but if the TMB 9mm can do the job of "occasional high-magnification when I'm trying to ID a far-away gull or shorebird" better than the XW/XL, I'm all ears.

It does make sense though, since the planetaries are designed for maximum constrast and detail... just curious to hear you elaborate a bit on your thoughts on XW vs. TMB.

Thanks!

Last edited by eitanaltman : Thursday 19th October 2006 at 00:04.
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Old Thursday 19th October 2006, 08:11   #5
Sout Fork
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Quote:
Originally Posted by eitanaltman
That's a very interesting observation -- I know that a lot of the astronomer folks love the TMB planetaries.

What were the comparisons you made? I'm assuming 9mm TMB vs. XW10 and 7mm vs. XW7?

I just picked up a used Pentax XL 10.5 (the precursor to the XW -- totally blows the doors off the XF 12mm as far as I can see), but if the TMB 9mm can do the job of "occasional high-magnification when I'm trying to ID a far-away gull or shorebird" better than the XW/XL, I'm all ears.

It does make sense though, since the planetaries are designed for maximum constrast and detail... just curious to hear you elaborate a bit on your thoughts on XW vs. TMB.

Thanks!
At the time I compared the XW 10 and 7mm and a Stratus 5mm
to
TMB 9, 7, and 5mm.

I bought the xws from EO and returned them for full refund after the
test. The same for the Stratus which I returned to Orion.

Simply put the TMBs outperformed the WFs in contrast, brightness and
resolution.

The most obvious difference was in contrast. The TMBs had a vividness in
contrast that was simply lacking in th xws. In my opinion contrast is
especially important in wildlife observation because of the superior
color detail this implies. On the other hand astro folks are, to a
great extent, working in a black and white environment compared to
birders. Color is not a big deal with the astro folks but for terrestrial
daylight wildlife observation vivid detailed color is the name of the
game. Contrast is the first quality that seems to be lost when trying to
push optics too far and hard such as when using a zoom at high power.

I also found the XW 10mm unsuited for birding for other reasons.
Normally the birder is scanning with binos or the naked eye. When a
distant target is found he goes to his scope. So you are constantly
going from your naked eyes or bins to your scope and back again. The "sweet
spot" (proper orientation of the eye to the ep) was difficult and slow to acquire
on the xw 10 to the point where I was missing identifications. This was
especially problematic when scanning for moving raptors or waterfowl.

BTW for a short time I had a Stratus 8mm which had a very easy sweet
spot to find compared to the XW 10mm. Strange that this would be so on
a ep that was both shorter in focal length and cheaper than the Pentax
ep. I returned it for a full refund to Orion when I got the 9mm TMB.

Also I have found the 60 degree FOV of view not to be a problem compared
to wide fields at high powers. When using a 7mm ep you are not normally
doing indiscriminate scanning but are trying to reach out to a discrete small
target at a great distance. Accurate aiming is much more important
than FOV for finding your target.

Its for this reason that both of my scopes are equipped with red dot gun
sights mounted on removable Weaver gun sight mounts. At high powers they
are quick, accurate and indispensable for sighting in on moving or very small
targets at a great distance. The difference between 60 and 70 degrees
makes no practical difference out in the field when using these sights
for long distance high-power observation.

SF

Last edited by Sout Fork : Thursday 19th October 2006 at 08:56.
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Old Thursday 19th October 2006, 11:53   #6
sandokan
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Many thanks for all info about using different EPs on the pentax scopes.
I own the 65ED and some LV vixens: 6, 9, 12.5 (the last one was made by vixen for soligor brand).

Vixen 6 is too soft and I'm selling it, 12.5mm offers an excellent view due to the relative low mag (31x) and the Vixen 9mm is on the edge of quality. Unfortunatelly the view through the 9 is lower quality than the 12.5, i.e. it is softer. I don't know is this due to the EP or the optical limit of the scope is reached at this mag (43x) ?

I am on the way to find some other 10 or 9mm EP, which will give the same level of quality as the 12.5 or longer EPs.
The eyerelief is not important, I can accept from everything from 13-20mm. I don't need wide ep, 60deg is enought. But I would like to get good sharpness and contrast. I think that I should buy some more $ ep, like the televue radian or pentax XW ?

I would like to ask you have you made some tests with the Pentax 65 equipped with the top EPs of 9 or 10 mm (televue, XW, XL)?
Can I get the better with them comparable with my current Vixen LV9 ?
Can I expect a better view with the Pentax XF 8.5, is it ''better'' than LV9 ?
Can I expect the TMB 9mm will give sharper view than the LV9 ?

Thanks.
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Old Thursday 19th October 2006, 16:53   #7
eitanaltman
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Quote:
Originally Posted by sandokan
Vixen 6 is too soft and I'm selling it, 12.5mm offers an excellent view due to the relative low mag (31x) and the Vixen 9mm is on the edge of quality. Unfortunatelly the view through the 9 is lower quality than the 12.5, i.e. it is softer. I don't know is this due to the EP or the optical limit of the scope is reached at this mag (43x) ?
I don't think it's the ep, it's the magnification. As SF indicated above, when you increase magnification you lose brightness. You can't change how much light comes through the objective lens of the scope, so you're spreading the same amount of light thinner and thinner when you increase magnification. Also, as you zoom in, eventually you'll start losing resolution -- in other words, the pitcture is getting bigger but not more detailed. Going from the 12.5mm to the 9mm is a 39% increase in magnification, which is a pretty big step.


Quote:
Originally Posted by sandokan
I am on the way to find some other 10 or 9mm EP, which will give the same level of quality as the 12.5 or longer EPs.
The eyerelief is not important, I can accept from everything from 13-20mm. I don't need wide ep, 60deg is enought. But I would like to get good sharpness and contrast. I think that I should buy some more $ ep, like the televue radian or pentax XW ?

I would like to ask you have you made some tests with the Pentax 65 equipped with the top EPs of 9 or 10 mm (televue, XW, XL)?
Can I get the better with them comparable with my current Vixen LV9 ?
Can I expect a better view with the Pentax XF 8.5, is it ''better'' than LV9 ?
Can I expect the TMB 9mm will give sharper view than the LV9 ?

SF seems to have found that the simpler design of the TMB will outperform the complex 7- or 8-element designs of the WFs like XW, XL, Stratus. I think he makes a very good point that when you want that high magnification, you're not going to be scanning around, you're probably trying to get a little bit "closer" to that faraway bird to make the difficult ID. In this case, the brightness, contrast, and resolution on-axis (i.e. in the middle) is the most important thing.

I'm definitely going to give that 9mm TMB a try and put it up against the 10.5 XL for long-distance ID's.

I can tell you about my experience with the XF 12, and my recently purchased (used) XL 14 and XL 10.5. The XF isn't any less complex than the XL/XW, it's just smaller and doesn't use the high-end lanthanum glass. And my personal experience so far is that the XL's are just superior eyepieces to the XF's.

The difference in AFOV isn't that big (65 vs. 60), but the XL's are obviously brighter and maintain their crispness from edge-to-edge. I didn't notice it as much before I got the XL's, but the XF12 eyepiece starts to lose a lot of image quality on the outer 20% or so of the field. The quality in the middle is pretty close, but when I'm scanning a flock of shorebirds, being able to have the peeps on the edge of the field still be crisp and identifiable is a nice plus.

The amazing thing is that the XL 10.5 doesn't seem any less bright than the XF 12 (though it's only about a 14% increase in magnification), and it also beats the XF 12 in edge-sharpness. But, even the 10.5 (at 37X magnification) doesn't help when I'm looking at something far away and the heat waves are shimmering. In other words, sometimes it's the atmospheric conditions that are the limiting factor, and the magnification only makes it worse.

But if the conditions are nice and I'm not looking at something that's a zillion miles away, both the XF 12 and the XL 10.5 allow for nice, closer study of ducks and shorebirds at medium-to-long ranges.

I felt that the XL14, at 28X, was just about the sweet spot for the PF-65. Everything was bright and crisp, I wasn't pushing the limits of the scope at all, and the 65-degree widefield view was beautiful for scanning mudflats. I personally didn't have the problems that SF did trying to find the "sweet spot" when viewing -- once you get the eyecup screwed out to the right distance for the eye relief, I found it very pleasing to look through. The XW is supposed to be the same (or a teeny bit better) in image quality, with a 70-degree AFOV. I would imagine an XW14 paired with the PF-65 would be a fantastic combo for almost any situation.

As to some of your other ep questions, I'll relate what I've read:

From my reading, the Vixen ep's in general (LV and LVW) are very highly rated, and I doubt you'll see an improvement going to the XF. I also read a technical review of the TV Radian 12mm vs. the XF 12mm, and it was basically a tie. I think that the Radian, XF, and LV are all very comparable, and the difference between them is largely personal preference.

I think that the Pentax XW/XL (considered to be among the finest ep's out there) are a definite step up in overall quality -- but not in a way that is necessarily going to allow you to comfortably have 50X magnification on a small scope like the PF-65. Pentax XW's are most often compared to Naglers and Panoptics, but I don't know if those are as suitable for birding (way less eyerelief).

Vixen LVW's (from which the Orion Stratus and Baader Hyperions are cloned) get extremely good reviews, and the LVW or Stratus are pretty much the consensus "best-bang-for-the-buck" widefield ep's. I actually thought the Stratus 13mm was better than the Pentax XF 12, but I couldn't zip the PF-65 case closed with the Stratus attached.

Anyway, that's all very long winded, but here's some brief suggestions:

1. The classifieds at www.astromart.com are a great place to buy/sell eyepieces.

2. Before you spring $300 for a shiny new XW, try out other options like Stratus 8mm or TMB 9mm. You could spend less than $200, buy a couple of different used ep's, and then keep the one you like the best. Keep your eye on the classifieds at astromart and you might find a used option at a good price.

3. I would sell your LV 6 (way to powerful for the PF-65), but maybe hang onto the LV 9 for now and see for yourself how it stacks up to other options. You can always sell it later if you like something else better.

4. The bottom line is that you have to see what works for you -- ep's are very much a personal preference. And, again, with quality ep's you can always recoup 70-80% of your money selling them used on astromart or eBay. These astronomy guys have collections of 5-10 or more ep's and they like to swap and sell and try different ones out.

Hope this helps!

Last edited by eitanaltman : Thursday 19th October 2006 at 17:02.
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Old Thursday 19th October 2006, 18:34   #8
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Speaking of used eyepieces....

As an FYI, I just noticed that gr8fuldoug (who sells a lot of nice optics) is selling an XL-14 and an XL-21 on eBay right now. The XL-14 has a $199 buy-it-now option, which is pretty much market value.

I know the XL-14 is a fantastic ep for my PF-65, and both would likely be great on any Pentax scope. At around $200, they're a solid value compared to shelling out $300 for the XW for a little more AFOV.

And the XL's consistently sell for $180-200 on astromart, so if you don't like it it's a pretty low-risk investment.
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Old Thursday 19th October 2006, 22:11   #9
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Many thanks eitanaltman
Of course that your post will be usefull not for me only, but for many other pentax owners and potential buyers too.
A big thank you for the gr8fuldoug offer info, I think that XL for 199 (or less) will be the great buy for somebody. If it was xl10.5, I would buy it.
Now I really want a little higher mag than the 14 gives (I know the gr8fuldoug too, they are excellent sellers).
No, I am not the birder. I bought the PF-65 body some months ago for occasionally wild live observating, for holidays, for sea watching etc. The birds are not my primary target. I got 65 body on ebay, new for 399$. My first ep was the vixen made but 'soligor HP'' named 12.5mm and it gives the best images of my EPs. I still have it.

Yes, I bought the new Baader Hyperion 8 in July and compared it with the LV9. They have very simmilar quality of view, of course much bigger FOV with Hyperion. I noticed a little less cromatic abberation with the LV. But, man, Hyperions (and Stratus) are VERY big and heavy, and I also ''couldn't zip the PF-65 case closed with the Hyperion attached''. I sold Hyperion 8 with a minimal money lost.

I don't have any top rated scope to be able to compare it with my PF-65, but I joined the European Day of Birdwatching some days ago.
I had a chance to look through the Zeiss 85 and KOWA TSN-61X (ED version, angled) with a zoom. I must to say that despite of the zoom attached and despite it is only 60mm scope, the view was very good, even at the higher mag. I didn't compare at the moment (I didn't take my scope with me), but what I remember it was very good and sharp image, even at higer mag (50x for example) on the 60mm KOWA. KOWAs EP was small, relative narrow and with shorter eye reliefe than 20mm er from Vixen&co. This Kowa is more expensive than PF-65, but anyway I would like to know why they can offer such a good view. Maybe due to the simplified design and less EPs lens. I would like to find sometnig simmilar (but fixed) for the PF-65 and this is why I said the eye relief is not the most important for me. I prefer sharpness and contrast against the
eye relief.

The second ''small'' scope is the 60mm Nikon FS III. Again the only 60mm objective, but I have read some reviews which say that the image is very good even at the higher magnification too (especially when equipped with the new zoom).

In short, I think that both 60mm Kowa and 60mm FS III perform better than the 65mm (!) PF-65. Why?
I have noticed that nikon and kowa have much less eyereliefe and due to this are ''more simple'' designed than Vixen and their clones. It this the reason? Or the scope quality, which is hard to understand, since the Pentax makes the world top eyepieces and they sure know how to made the top scope body too...

In short, I don't want nothing special, I only want to find the fixed EP for my PF-65, which will give the simmilar quality as the kowa or nikon equiped with the zoom (yes, yes, they are both much more expensive than Pentax, and I agree that the PF-65ED has better value than the other two). On the other hand it is hard to accept the fact that I have to live with 65mm Pentax and the ''only'' 28-30x magnification, because I have read reviews which say that the new, smaller, lighter, more portable Nikon ED50, gives the excellent picture with the 28x wide EPs (in the sunny days...). So: 50mm vs my 65mm ?

1.25'' eyepieces with lower eyerelief and better transmission, contrast and sharpens at higher mag, where are you ?
I will buy the 9mm TMB first and compare it against the LV9.
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Old Thursday 19th October 2006, 23:06   #10
eitanaltman
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Quote:
Originally Posted by sandokan
1.25'' eyepieces with lower eyerelief and better transmission, contrast and sharpens at higher mag, where are you ?
I will buy the 9mm TMB first and compare it against the LV9.
Well, I am very happy with the 10.5XL, which is very similar to the 10XW, and if Sout Fork believes the TMB 9mm beats the pants off the XW, I think that's probably your best bet. As soon as I get back from my upcoming vacation in a few weeks that's the next ep on the list.

If you do get it, I'd love to hear how it stacks up against the LV9.

The only ep's that I know of that will give better transmission and contrast at high-mags are simple ep's like plossls and orthoscopics, but I have heard that they are absolutely unsuitable for day-time viewing through a spotting scope. I know you are willing to accept less eye relief, but these ep's have absolutely miniscule eye relief at high mags.

As to PF-65 vs. Nikon EDIII 60mm and Kowa 61x ED.... I wonder how much the quality of the eyepieces has to do with these reviews. I'd absolutely love to see a review where they do a "shoot-out" between the compact scopes, like the 60-65mm version of Swaro, Zeiss, Leica, Kowa, Nikon, Pentax, etc. The last major scope review (from Cornell) was a few years ago, and a lot of these scopes weren't out yet. I'm curious just how big the differences are....
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Old Friday 20th October 2006, 06:59   #11
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Eitanaltman, you have both XLs, 10.5 + 14. Please let me know how they compete in terms of quality view, are they equally sharp ?
The 10.5 is enough for me, unfortunatelly it is hard to find this discontinued product on the used market. I would like to buy it too.
Thanks in advance.
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Old Friday 20th October 2006, 10:42   #12
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Just a few thoughts on this thread so far...

High-power long distance viewing is a rather specialized thing.

On most days, in my part of the world, viewing much over 1/4 mile becomes
problematic no matter what equipment you may have.

Total optical system:

1 Ambient lighting at any given time and place

2 Size and visual quality of the object being observed

3 The amount (distance) and quality of the air between your target and
the objective on your scope.

4 The angle of view. Often it makes a great difference if you are
observing the same target at the same distance if its from a high bluff
looking down on the target rather than at ground level looking through
a mile of air turbulence 5 feet above grade.

5 The light path through the two to five elements in the objective
cluster of your scope and then through the prism and out the back end
of the scope.

6 The light path through the 4 to 8 elements in the ep.

Finally the two most idiosyncratic and problematic elements in the total
system...

7 The Human eye

8 The Human brain

I guess all I'm trying to say is don't define the problem of long
distance viewing only in terms of hardware. There is many a day when my
35 year old 60mm Spacemaster at 20x is as good or better than my 100mm
at 90x. I believe them when someone says they are happy with their
no-name Chinese scope and a 25 buck ep.

On the other hand yesterday I had both the 100m at 90x and the 80mm at
40x setup. I was trying to view a raft of waterfowl at about a mile
with muddy poor quality images while the person with the 80mm was trying
to identify small passerines at no more than 1/8 of a mile out on an
island.

The 80mm at 40x just wouldn't cut it. So I turned the 100mm on the
island to see if that would help. The difference was stunning. The 100mm
at 90x at this distance was like standing on the island observing with
the naked eye. Sharp, clear, bright (enough) and crisp with enough
detail and scale that it was easy to see the difference between a
Goldfinch and a Yellow-rumped warbler at this distance. We also had a
botanist in the party and she used the 100mm to do a quick and dirty
survey of the plants along the shoreline of the island. The difference?
By turning the 100mm from the raft of ducks far out in the main channel
of the river to the island I got rid of a mile of air turbulence.

Also I didn't mean to say that the TMB "beats the pants off the XW".
Only that there was, to my eyes at least, a noticeable, practical,
real-world difference in optical performance between the two especially
with respect to contrast and brightness. No more no less.

I think there is a tendency, which I am also guilty of, to do a lot of
anal-retentive optical navel gazing in these forums.

Try before you buy.

Good birding

SF
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Old Friday 20th October 2006, 16:48   #13
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Quote:
Originally Posted by sandokan
Eitanaltman, you have both XLs, 10.5 + 14. Please let me know how they compete in terms of quality view, are they equally sharp ?
The 10.5 is enough for me, unfortunatelly it is hard to find this discontinued product on the used market.
The 10.5 is a high-quality ep, it's extremely bright and sharp edge-to-edge. There is definitely a slight but notable increase in brightness going from 14mm (28X) to 10.5m (37X), but that's to be expected with the increase in magnification.

But SF makes an excellent point above -- if the conditions are bad, like trying to observe ducks or shorebirds far away in the middle of the day with heat shimmer, the extra magnification isn't going to help see anything better because it's not the limiting factor.

If conditions are good, the 10.5XL is a great long-range viewer. But, I think when you're around 40X and higher, the limiting factor in the optical chain when trying to resolve something really far away will be air quality and that 65mm objective, and not the eyepiece. Simple physics dictates that the 65mm objective won't be able to gather as much light as an 80mm or up, so the further away something is, the more that will hurt the image.

But, as with SF's example about the passerines on the island, when I'm not trying to look at something 1/4 mile away, the 10.5 is fantastic. For example, if I'm looking at a mudflat 100 yards away and I want to get in there and identify the peeps and plovers, the 10.5 is great, nice and crisp out to the edges.

So I guess in short, if you're trying to get a closer look at something that's not too far away, the 10.5 works great. But the further away you are, the more the viewing conditions become the problem, and no eyepiece can overcome bad conditions (low light, heat shimmer, haze, etc.) no matter how great.

XL's are hard to find used, but there are plenty of ep's like the TMB, Televue Radians, Siebert Ultras, etc. that are out there and will offer similar performance. Like I suggested before, keep that 9mm Vixen LV for now and then experiment and compare with other ep's, and sell the ones you like the least.


Quote:
Originally Posted by Sout Fork
Also I didn't mean to say that the TMB "beats the pants off the XW".
Only that there was, to my eyes at least, a noticeable, practical,
real-world difference in optical performance between the two especially
with respect to contrast and brightness. No more no less.
Didn't mean to overstate your claim there, SF... just using a little rhetorical flourish. Obviously, I understand that these differences are often quite subtle. Mea culpa.


Quote:
Originally Posted by Sout Fork
I think there is a tendency, which I am also guilty of, to do a lot of
anal-retentive optical navel gazing in these forums.
Of course, you're absolutely right... but isn't that half the fun of being an obsessive hobbyist?
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Old Saturday 21st October 2006, 06:46   #14
Sout Fork
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Quote:
Originally Posted by eitanaltman
isn't that half the fun of being an obsessive hobbyist?
Touché

SF
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Old Sunday 22nd October 2006, 01:13   #15
mayoayo
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Quote:
Originally Posted by eitanaltman
Speaking of used eyepieces....

As an FYI, I just noticed that gr8fuldoug (who sells a lot of nice optics) is selling an XL-14 and an XL-21 on eBay right now. The XL-14 has a $199 buy-it-now option, which is pretty much market value.

I know the XL-14 is a fantastic ep for my PF-65, and both would likely be great on any Pentax scope. At around $200, they're a solid value compared to shelling out $300 for the XW for a little more AFOV.

And the XL's consistently sell for $180-200 on astromart, so if you don't like it it's a pretty low-risk investment.
Hello..i actually own the pf65ed and i love the scope...i have used a variety of EP on it from cheap ,and medium to pentax xf (zoom) and my only piece at the moment,the old astro style 7.7 -23.1 swarovski zoom....i was going to actually trade the zoom with a person ,through astromart,for a XL14,after i decided that i wolud prefer the wider field of view of the fixed better than the versatility/power of the zoom,,,but i changed my mind and backed up the trade,because the owner of the xl,(he also uses a pentax scope),told em that he doesnt reach infinity focus with his scope.....what is your experience with that issue????? i have a little of problem reaching focus at infinity with the lower power of the zoom and im concern that maybe my scope is defective...i am sending it to pentax for service anyway ,so i should now more after that....AH TALKING ABOUT USED EYEPIECES...IM SELLING MY SWARO ZOOM FOR 225$,,,ANY TAKERS...?
THANKS
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Old Friday 3rd November 2006, 10:46   #16
Lehel
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Hi All!

Thanks for your replies!
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Old Saturday 4th November 2006, 16:13   #17
eitanaltman
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Quote:
Originally Posted by mayoayo
i was going to actually trade the zoom with a person ,through astromart,for a XL14,after i decided that i wolud prefer the wider field of view of the fixed better than the versatility/power of the zoom,,,but i changed my mind and backed up the trade,because the owner of the xl,(he also uses a pentax scope),told em that he doesnt reach infinity focus with his scope.....what is your experience with that issue?????
Sorry for the delayed response, I've been travelling out of the country for a couple of weeks....

I have zero focus problems with the Pentax XL eyepieces, and considering the PF series scopes were designed to work with the XL/XF/XW eyepieces, I don't see why you would. I can't imagine why the XL would have problems with a Pentax scope.
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Old Friday 10th November 2006, 07:19   #18
Lehel
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Quote:
Originally Posted by Sout Fork
I can (more or less)...
The problem is simple physics to a great extent-all else being equal multiply the magnification by 2 and you divide light by a factor of 4. In other words light transmission at 40x is 1/4 what it would be at 20x roughly.

Also Ultra Wide Angle EP's are highly corrected for field distortion which means they are very complex with many light robbing elements. Typically around 8. If you must try high power EPs stay away from the Wide Field ones and use simple good quality 4 or 5 element designs.

I have both the 80mm and 100mm Pentax and my expierience so far...

Max power:

80mm
wide field eps - 40x
simple 4 or 5 element eps - 60x (on a good day)

100mm
wide field eps - 70x
simple 4 or 5 element eps - 90x

This is based on comparing $300 Pentax XW Wide Fields to $100 TMB Planetaries. The TMBs outperformed the XWs at short focal lengths in all ways except FOV (60 degrees compared to 70 for the XWs). The trade off was a no-brainer for me.

One man's opinion and nothing more.
SF
Hi Sout Fork
I have seem that the TMB oculars are available in our country. You Maybe I will try it but before I wonder what about TMB's CA in comparison with the XW?

Thanks in advance
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Old Sunday 12th November 2006, 09:31   #19
Sout Fork
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Quote:
Originally Posted by Lehel
Hi Sout Fork
I have seem that the TMB oculars are available in our country. You Maybe I will try it but before I wonder what about TMB's CA in comparison with the XW?

Thanks in advance
CA seems well controlled on TMBs. No fringing that I can see.
Don't really remember how the XWs did with CA now that you mention it.

SF
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