Fixed EP recommendation for PF-65ED (II) (1 Viewer)

stuprice68 said:

Others on this forum recommended the Baader Hyperion 13 and 17 eyepieces and I admit they look a good option.

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I've seen a number opinions on Astro forums that put forward the view that the XF fixed EP's are a better product than the Hyperion/Stratus EP's. See for example: http://www.iceinspace.com.au/forum/showpost.php?p=184451&postcount=2

The local pricing: Hyperion 12mm is $235AU, and the XF12 is $215AU. It does seem that the Hyperions have a slight price advantage in other markets.

Similarly the cloudy nights comparison puts the XF12 ahead of the TeleVue Radian ($345AU). I believe the Radians are significantly more expensive than the XF regardless of market.

Given that the Astro reviews of the XF EP's seem very favorable, and that Pentax designed the XF EP's specifically for the PF65 I suspect you'd struggling to find a better matched EP at that price point.

At the top end, the XW's are widely reviewed as being on a par with the Televue Naglers, sometimes ranked slightly better, and a hands downer winner if you wear glasses. XW14 retails in .au at $455.00, while the Nagler 13mm comes in at $419.00AU or 16mm at $489.00AU.

Obviously the relative pricing is going to vary depending on where you source the EP's from.

There is a wide range of pretty reasonable EP's priced below the XF: mentioned in this thread are Burgess Optics/TMB, Meade Series 5000 Plössl's which seem to have a similar level of performance, and seem to be pretty good value. When I purchased my Meade Plössl I also tested a couple of GSO and Superview EP's, which to my eye seemed a bit softer and lacked the overall image quality of the Meade 9mm.

cheers
Paul

Hi Paul. I'm happy with the XF12 but I wish Pentax made an XF eyepiece in the 15-18mm range. Sometimes 32x Mag is just a little too high.

stuprice68 said:

Hi Paul. I'm happy with the XF12 but I wish Pentax made an XF eyepiece in the 15-18mm range. Sometimes 32x Mag is just a little too high.

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I guess that's where the baaders et al have a role to play. I'd still go for a pentax as a main EP and use either a zoom or fixed EP to fill the gaps. It seems like reasonable compromise to spend a little less on an EP that will get less usage.

Just scored a Vixen LV Zoom eyepiece for $50 on eBay! Woo-hoo!

I will definitely look forward to comparing this to my current selection of eyepieces, especially the Celestron Deluxe Zoom 6.5-19mm I've got currently. The Celestron is very sharp, but beyond 9mm (45x or so) it gets pretty soft, and the AFOV is terrible. I think 8-24mm might be a better fit for the 65mm scope, providing a magnification range of 16-48x or so -- there aren't many times going above 50x is really necessary or even possible given the seeing conditions.

The fact that the low end is much lower than the Celestron means that at least I can at least have a true FOV (~2.45*) equal to the XL14 (~2.33*) if I need to pull back and scan. The low end of the Celestron provides barely half the true field of the Pentax, even though it is much lower mag.

Pentax zoom comparison

Paul asked about the SMC zoom EP and eitanaltman made a very good point regarding the apparent field of view for the XL14 (65 degrees), divide apparent FOV by power (27.86x) for the xl14 on a pf65-ed yields a real FOV of 2.33 degrees.

The apparent field of view for the SMC zoom is 38 to 60 degrees as the focal length is varied from 24 to 8mm (16.25 to 48.75 power on the PF65-ED), which yields real FOV of 2.34 to 1.23 degrees, respectively.

The SMC zoom is huge, it produces the same real FOV at 16 power that the XL14 does at 28 power (on the pf65-ed), you cannot close the padded, ballistic cloth, view-throught-case when the SMC zoom is attached, it is simply too big. Almost any time I use the zoom lense, I start at low power, find my target and then zoom in, I rarely use anything past the mid range (about 32x), so, it is just very convenient to leave the XL14 on the pf65 scope.

Having said that, my daughter frequently uses the SMC zoom on the pf65. Atmospheric conditions permitting, the full power of the zoom can produce spectacular viewing, and of course whenever the distance is short, there is little atmosphere between you and the subject. Keep in mind that the SMC zoom delivers 60 degrees apparent FOV at 8mm, which is not bad by comparison to the XLs at 65 and the XWs at 70 degrees. The zoom lense offers flexibility and a maximum exit pupil of 4mm, which will allow early and late twilight viewing.

Also, be aware that the SMC zoom can be obtained at very good discount (about $150) when it is purchased with a scope -- as can the XW EPs. I wrestled with the decission to buy a XW10 or a zoom when I bought my PF65-ED. I already had a XL14, a SMC zoom and a PF100-ED.

SoutFork was not very impressed with the XW10, too much distortion, the problem is worse with the 82 degree apparent FOV Nagler EPs. I wonder how the XL10 at 65 degrees would compare.

It seems that we want to strech our dollars and the laws of physics to the limit, just when I think they have pushed the limits to the max, new engineering techniques are developed. You never know, our present glass could become obsolete overnight, just like computers.

Hi Jeepnut,

thanks for your comments on the SMC zoom.

one point I'd raise is that your comment re: sout fork disliking the xw10 due to distortion doesn't seem to backed up by his posts to the forum- of course i may have missed something.

In a recent thread on the xw10 sout fork mentions that he had "target acquisition" issues with the EP, and sold it for that reason.

Back in Feb 2006 Sout Fork made some very postive comments regarding the sharpness of the XW10, which he may have retracted elsewhere.

cheers
Paul

PaulJacobson said:

Jeepnut,

Thanks for your comments!

The PF65-EDa II's have apparently arrived in the country as of Thursday, so I'll hopeful be collecting mine on Monday :t: It does seem like the XW14 is the way to go. The distributor was waiting on stock of the XW14's last time I checked, but they hopefully have arrived too.

cheers
Paul

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Hi Paul,

do you have contact info for that distributor?

thanks

Willem

Perhaps a misquote

I cannot find the SoutFork post regarding the XW10 EP -- I may have misquoted -- if so I apologize. It was his comments that caused me to quit seeking to obtain a XW10 especially after reading about his experience with Naglers.

distributor

willemjacobusse said:

Hi Paul,

do you have contact info for that distributor?

thanks

Willem

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try [email protected] or go to www.cameralandny.com (tell them jeepnut sent you)

Happy Trails, jeepnut

jeepnut said:

try [email protected] or go to www.cameralandny.com (tell them jeepnut sent you)

Happy Trails, jeepnut

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Willem was looking for a Pentax retailer in Perth, Western Australia.

for the record the Australian distributor is C.R. Kennedy: http://www.crkennedy.com.au

Sout Fork also made some remarks about finding if difficult to find a sweet spot when viewing thru the XW10 in this post:
http://www.birdforum.net/showpost.php?p=707770&postcount=5

which seems to be part of the target acquisition issue.

I'm pretty certain none of the XW's are perfect - but then what eyepiece is? When looking a backlit bird in the late afternoon using the XW14 I'm able to see some colour fringing from about 70% out. The field curvature is also apparent as a slight softening of focus near the edges but for all practical birding purposes this is outside the portion of FOV that is used and seems to be a non-issue.

cheers
Paul

XW10 "sweet spot"

Paul,

Thank you for finding the original Sout Fork post. When he speaks of "sweet spot", I take that to mean getting the target into the focus depth of field while staying whithin the eye-relief limits of the EP and of course as power increases, eye-relief becomes more critical, and also as power increases, depth of field suffers or in other words focus also becomes cirtical.

Increasing field of view increases distortion (look at a fisheye lense). I believe that the increased distortion also decreases depth of field and hence the "sweet spot" suffers -- or in other words the effective target aquisition is slowed to the point that the EP too slow for his field requirements -- keep in mind that he uses an external optical "gun" sight to quickly aim his scope, before trying aquire the target through the scope.

He also pointed out that the difference between 60 and 70 degress apparent FOV is of little significance in field conditions. To that end, the Pentax 8-24mm zoom EP, that varies from 16.25 to 48.75 power (on the PF65), with 60 degree apparent FOV at 8mm (48.75x) is of very good value with little compromise at maximum power, but, I would love to compare it to a high quality EPs in the 7 to 10mm range.

If I had deep pockets I would have many fixed EPs, all things being equal the fixed EP should provide better resolution than a zoom at the same power and comparable or better FOV. Just yesterday I found a new XL10.5 ($300) -- Xls are no longer made, but then I would love to have a CA-35 and a K10D and . . .

Happy Trails

Jeepnut,

I don't believe the comparison between a w/a eyepiece and lens is valid, as they are at opposite ends of the optical system. Lens is analogous to the scope body.

The size of true FOV of a 60deg 10mm EP (1.538deg) and 82deg 10mm EP (2.10deg) is very small when compared to the TFOV of a wide angle lens (over 100deg), so you aren't going to get the rectilinear distortion displayed in a fisheye lens even using a ultra wide angle EP.

I'm more inclined to think that Sout Fork was experiencing problems getting his pupil aligned with the exit pupil of the EP. This is a issue of eye positioning the eye correctly in space behind the EP and could be a problem given the large physical size of the XW Ep's. According to the specs for the XW10 on the PF80/100 the "sweet spot" is a 1.6mm diameter spot of light 20mm behind the EP glass. If your pupil is not perfectly aligned with the exit pupil you are going to experience fade outs, jelly beaning, or blackouts.

The other EP Sout Fork refers to is physically smaller so there would be less chance of misplacing the eye in relation to the "sweet spot", and less surface area to hunt for the sweet spot if the eye was not correctly placed.

The XW owners manual makes the following comments relating to the adjustable eyepiece ring:

(3) They have been designed so that users who do not wear glasses will gain the best view in the most extended position and users who do wear glasses will gain the best view in the most contracted position.
Differences will, however, occur between individuals, and further adjustment will be needed to ensure the optimum view.

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The adjustment of the eyepiece ring will obviously effect the positioning of the pupil in relation to the "sweet spot".

I'm pretty sure that difficultly finding the "sweet spot" is completely unrelated to distortion.

cheers
Paul

PaulJacobson said:

I'm more inclined to think that Sout Fork was experiencing problems getting his pupil aligned with the exit pupil of the EP. This is a issue of eye positioning the eye correctly in space behind the EP and could be a problem given the large physical size of the XW Ep's. If your pupil is not perfectly aligned with the exit pupil you are going to experience fade outs, jelly beaning, or blackouts.

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Paul,
you are essentially correct about what I was trying to say. Jelly
beaning and blackouts was the main issue I had the 10mm XW. I probably
use my equipment more often and under more extreme conditions than most.
So my final "authority" on equipment is does it work in the field under
the conditions I find myself at the time. It's hard enough to align a
powerful scope on a flying raptor without adding the problem of precise
alignment of the eye to the eyepiece as well.

I think it should be remembered that all of the eps we have been
discussing were designed with the astro user in mind not birders. I'm
sure a Nagler or the 10mm XW is very fine for use with with relatively
stationary targets but will they cut it for fast moving wildlife? In my
opinion, after birding for almost 40 years, I must have equipment that
allows me to take advantage of very fleeting moments and must be very
fast to use. All the perfect color correction, high resolution,
excellent contrast and brightness distortion free field of view does no
good if you can't get the target into your fov within about 10 seconds
or so.

As far as long distance observation is concerned-the most important
optical element when using a scope at, say, two miles is not the size
or quality of the objectives nor the prism nor that $350 designer ep.
It's that 10000 feet of turbulent unstable air between the target and
the scope objectives.

I was recently posted in a blind on a high bluff on the south shore of
lake Superior. For those who don't know Lake Superior is an fresh water
inland sea 3/5 the size of England. A Canadian high had moved in and the
air was crystal clear with a temp of -22F (-30C). From my vantage point
I could see the opposite shore about 40 miles away. Anyway I was with
two others both with 80mm Swaros+zooms. One of them spotted a raptor on
a far distant bluff. It could not be determined if it was a Golden Eagle
or a immature Bald Eagle. So I popped in the 5mm TMB/BO (124x) and we
had a confirmed sighting of a Golden Eagle at a distance of just over 2
miles. This was as far as I have ever reached out with a scope with
really good viewing. Otherwise, in most cases, the 5mm is useless to me
even on the 100mm except on small birds at a close to medium distance.

Take care all,

SF