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Review of AT Paradigm 8mm and Pentax XF 8.5 mm

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#1 Charlie Hein

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Posted 22 September 2012 - 08:16 AM

Review of AT Paradigm 8mm and Pentax XF 8.5 mm

By George Golitzin

#2 Mark9473

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Posted 22 September 2012 - 04:56 PM

Like you, I sold my pair of XF 8.5; I found a Siebert SSS 8.4 to be better in almost every respect. The main thing that bugged me about the XF is the stray light just outside the exit pupil. I don't understand how that could even be acceptable for daytime use.

#3 russell23

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Posted 23 September 2012 - 09:19 AM

Like you, I sold my pair of XF 8.5; I found a Siebert SSS 8.4 to be better in almost every respect. The main thing that bugged me about the XF is the stray light just outside the exit pupil. I don't understand how that could even be acceptable for daytime use.


Well, one thing to keep in mind is that the obervers exit pupil is smaller in daytime and the objects being observered are fully illuminated in daylight. I've found edge of field brightening to be annoying for certain eyepieces at night, but completely undetectable during the day. Perhaps in daylight the problem is not seen with the XF's.

Dave

#4 russell23

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Posted 23 September 2012 - 09:21 AM

This was a very enjoyable review to read! Nice job George!

I do have my doubts that the AT Paradigm is a clone of the XF's. I always thought it was more likely that they are updated Orion Epic ED's - especially based upon the blackout issues you mention which were severe with the Epics.

Dave

#5 EXT64

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Posted 23 September 2012 - 03:26 PM

I just bought the 8mm AT Paradigm, and I am glad to hear that the difficultly during the day is normal. When I first tried it out during the day I was frustrated by how hard it was to use. However sure enough at night it was no problem. My first night was mostly a scope collimation check so I didn't do much observing. I can't wait to try this eyepiece out in some real observing.

#6 Mark9473

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Posted 23 September 2012 - 03:42 PM

Interesting point David. Of course it depends on focal length. In my 80mm apo, the most likely to be used in the daytime, the XF 8.5 would give 65x and 1.2 mm exit pupil. I think you'd need an f/3-f/4 scope or so before the eye pupil is normally smaller than the exit pupil.

#7 george golitzin

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Posted 23 September 2012 - 04:01 PM

Hi guys--thanks for the good word. It was enjoyable writing my first real review, I hope it went over ok.

Perhaps "clone" was too strong a word--what is clear is that the same overall lens design is used: a two-element barlow, followed by a 1-2-1 arrangement. But clearly some tweaking is going on, because the two eyepieces have very different characteristics--likewise, the HD-60/Celestron X-cel LX are somewhat different, having apparently greater ER, but I'd be willing to bet they're based on the same lens design as well.

So far, my 8mm is holding up under continued use--I had a good time again on Jupiter and also Uranus, spotting Oberon and Titania in it. What gets me is how nicely it controls scatter on something like Jupiter--I'll go from my 7XW to the 8 Paradigm and seriously, I don't feel like I'm taking a big step down at all, except for the narrower field.

I recently acquired the 18 and 5 mm versions. Unfortunately, the 18 has pretty severe field curvature at f/5, and pretty bad at f/6. I was able to return it to Astronomics because it had some manufacturing flaws, but I would have sold it otherwise. The 5mm is very nice, although I think its field is a little restricted, down around 56 degrees. Unlike the 8 and 12, however, it has a glare issue from out-of-field sources: Jupiter, from outside the field, throws a huge wash of light across the eyepiece. The 8 and 12 do not show this problem. However, the 5 has the same nice control of scatter on the planet once it's in the field, and rich color saturation. These are nice eyepieces, not simply "for the money." Just plain nice. I especially like the 12mm.

Thanks for your comments!

George

#8 bdcmd

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Posted 23 September 2012 - 04:50 PM

I'll echo the comments of others above: really nice review! I have been hoping someone would review these eyepieces a little more in depth than previously done, because they seem like they would be a really good upgrade over basic plossls. Really enjoyed your review, and hope to see some followup on how they perform in the future.

#9 zuben122

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Posted 24 September 2012 - 07:37 AM

I just sprung for the 15mm, 12mm and 8mm Paradigms and enjoyed first light with them last night examining the moon. I compared the 15mm to the Meade Series 5000, 14mm UWA, the 12mm to a Nagler 11mm and the 8mm to the Meade Series 5000, 8.8mm UWA. In all three cases, detail was found to be a bit crisper in the Paradigms but the biggest difference was that the focus for the Paradigms just popped to an optimal image. The Meade's were a bit mushy in focus with the Nagler less so. I am very pleased with the Paradigm performance so far and can't wait to try it out on some DSO's and Jupiter and Saturn later this year.

#10 banatop

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Posted 25 September 2012 - 12:32 PM

Hi George, very interesting review. I recently bought a pair of the 8mm paradigms ( An identical version sold in the UK )based on good reports by Carlos in the planetary forum. I have found them to be very impressive on M13 : very sharp and bright, but most of all on Jupiter. During excellent seeing, using a Meade 178ed f/9 coupled with a Baader 60 degree bino viewer (200x), they gave a very sharp and highly detailed view (one of the best ever). The most impressive thing however was the colour balance. For some reason the Paradigms seem to be very good at bringing out the colours on Jupiter, I have no idea why this should be but I'm very happy with the results. I also use University optics Volcano top orthos and Zeiss Jena .96 Orthos and the Paradigms fit right in, with no drop in quality. Thanks again for an excellent review. Clear skies, John

#11 george golitzin

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Posted 25 September 2012 - 04:22 PM

John--very interesting comments, particularly the comparison to the quality orthos and considering that your scope is a 7-inch ED refractor. Jupiter is a demanding target; I really liked the color (and detail) the 8mm brought out on the planet. So I'm just a little surprised at how good this eyepiece seems to be!

Zuben--hope you enjoy the eyepieces. They do vary over focal lengths. I'll be interested in hearing from you and others what lengths are preferred.

Bruce--thank you. I'll probably post some follow ups in the eyepiece forum, particularly if, down the road, anyone inquires about this line. I'm also interested in seeing how these eyepieces hold up in my estimation--I've not had them very long yet. But so far, I like the 8 and 12 quite a bit.

#12 Doug Culbertson

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Posted 25 September 2012 - 04:33 PM

George,

Excellent review! I can't believe that I missed it for so lomg.

I used to have bino pairs of 12mm and 18mm Paradigms and my experience was quite similar to yours with both focal lengths. I sold them when I got rid of my bino, but now that I have picked up another bino, I do believe that I need another 12mm pair.

#13 CollinofAlabama

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Posted 25 September 2012 - 10:52 PM

George, don't know if you have access to one, but I'd like to see how the 8mm Paradigm and 8.5XF compare to a good 2x barlowed 17mm Sterling Plossl? The Sterlings have at least a 55* AFOV (Paolini has measured it at closer to 58*). They're dirt cheap and available from our sponsor as the AstroTech High Grade Plossl line. Would be interesting to know.

#14 george golitzin

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Posted 26 September 2012 - 12:53 AM

Thanks Doug!--But, are you unhappy with your 12.5 Ultimas?
I assume the Leicas are too wide for binoviewing (or did you send Tammy's back already?) Now that would be interesting...

Collin--I'm afraid I can't help with the Sterling plossl question. Perhaps someone else can oblige.

-g

#15 Doug Culbertson

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Posted 26 September 2012 - 08:03 AM

George,

Nothing wrong with the 12.5mm Ultimas at all but, with my monoviewing eyepiece kit whittled down to three eyepieces, I am out of things to compare. ;)

I keep thinking about a pair of 8mm Paradigms, but I always go back to what Roland Christen said about anything under 10mm magnifying the flaws in the binoviewer's prisms. I really wish that there was a 10mm Paradigm.

#16 Sarkikos

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Posted 26 September 2012 - 09:23 AM

George,

Great review. I've known that the Paradigm are very nice eyepieces for quite awhile now. I really don't understand why they haven't caught on, especially for binoviewing, at which they excel. Some great eyepieces seem to fly under the radar, while others that I consider not-so-good are overly praised. (Need I name names?) :shrug: Maybe the low prices have kept away some of the high-flying amateurs? Low prices have never kept me away. :grin:

So far, my 8mm is holding up under continued use--I had a good time again on Jupiter and also Uranus, spotting Oberon and Titania in it. What gets me is how nicely it controls scatter on something like Jupiter--I'll go from my 7XW to the 8 Paradigm and seriously, I don't feel like I'm taking a big step down at all, except for the narrower field.


Yes, scatter control is very good for the 8mm, as well as for the 12. I have pairs of both for binoviewing the planets and Moon. I'm happy to hear that the Paradigm 8 compared well against the XW 7. Another reason for me to put off buying more XW's.

The 5mm is very nice, although I think its field is a little restricted, down around 56 degrees. Unlike the 8 and 12, however, it has a glare issue from out-of-field sources: Jupiter, from outside the field, throws a huge wash of light across the eyepiece. The 8 and 12 do not show this problem. However, the 5 has the same nice control of scatter on the planet once it's in the field, and rich color saturation. These are nice eyepieces, not simply "for the money." Just plain nice. I especially like the 12mm.


I don't have the 5, but I'm tempted to get a pair for binoviewing. Since I need an OCA to come to focus in my Newts, though, the effective focal length would be around 2.6mm, maybe a little too much.

The Paradigms do yield a richly-colored image of Jupiter. This surprises me, because I didn't get the idea that they have a "coffee" tone like the TV Plossls. If anything, they are relatively neutral. I'll have to pay more attention to this next time I view Jupiter.

Mike

#17 Sarkikos

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Posted 26 September 2012 - 09:46 AM

Doug,

I keep thinking about a pair of 8mm Paradigms, but I always go back to what Roland Christen said about anything under 10mm magnifying the flaws in the binoviewer's prisms.


Yes, I've read that pronouncement from Rolandus Magnus, also. I don't want to contradict the Great Man, but my own experience has cast doubts on this one opinion of his.

My first suspicion that there may be exceptions to the 10mm Rule was roused when I used a pair of humble LER 6mm to binoview Mars through my 10" f/4.8 Dob. Since I needed a 1.9x OCA to come to focus, the effective focal length was about 3.2x, and the magnification around 375x.

The image was still surprisingly crisp and detailed. And this was with my old-style Burgess Binoviewer. I notice, though, that with lower-focal length eyepieces, it's necessary to seat both eyepieces just right in the focusers. A little fiddling is often required to merge the images and align everything correctly.

Now I have pairs of Paradigm 8, TV Plossl Smoothie 7.4, and Meade 5k UWA 6.7 for binoviewing. I will try them all soon for binoviewing Jupiter. You don't know what will work until you try it. Received knowledge is not always correct.

Mike

#18 Sarkikos

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Posted 26 September 2012 - 09:48 AM

Doug,

I really wish that there was a 10mm Paradigm.


So do I. There does seem to be a dearth of good eyepieces - that I can afford - at 10mm. I have a pair of BCO 10mm on backorder that may fit the bill, whenever they arrive. I'm putting off buying an XW 10mm for now.

Mike

#19 Doug Culbertson

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Posted 26 September 2012 - 09:51 AM

Mike,

Due to Roland's advice, I always stuck to 10mm or longer eyepieces and, also due to his advice, relied on barlows/OCAs/Powerswitches to put the magnification ahead of the binoviewer. It does seem that there are a lot of folks happily binoviewing with higher power eyepieces though, if one reads through the Binoviewer Forum, in spite of Rolando's pronouncement!

I really hope that you will post your results with the various 8mm and shorter eyepiece pairs that you are trying! My bino is with Harry Siebert for the supercharge, so I have time to read other people's opinions for awhile. :cool:

George, sorry to hijack your thread, but I am really interested in how the 8mm Paradigm will perform in a bino. Shoot, I should just go order a pair.

#20 Sarkikos

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Posted 26 September 2012 - 10:08 AM

Doug,

I really hope that you will post your results with the various 8mm and shorter eyepiece pairs that you are trying! My bino is with Harry Siebert for the supercharge, so I have time to read other people's opinions for awhile. :cool:


Yes, I'm interested in finding out the results, too. Mars and Saturn would probably be better objects for a test rather than Jupiter. They seem to take higher power better than Jupiter does. The Moon is out of the question, because at those higher powers my eye floaters would be sheer torture for me.

In any case, the two TV Plossl 7.4 Smoothies should show a good image of Jupiter, you know, what with the "coffee" tone and all. :grin: But I do intend to test all these pairs on Jupiter soon, weather permitting.

I also intend to compare my Paradigm 12mm pair with my Brandon 12mm pair. I don't really want to sell either of these pairs, but if one gives me a better image ... who knows? :shrug:

Whatever comparisons I make, though, will be in terms of planet surface detail and perceived contrast, not necessarily optical aberrations per se, unless they disturb my observations, such as field curvature.

Mike

#21 cheapersleeper

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Posted 27 September 2012 - 12:03 AM

My 5mm Paradigm remains in my EP case despite my having bought three different eyepieces that I thought might supplant it. Of those three, two were "less glass," and they are all now gone while the Paradigm remains.

#22 george golitzin

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Posted 27 September 2012 - 01:25 AM

... I'm happy to hear that the Paradigm 8 compared well against the XW 7. Another reason for me to put off buying more XW's...

...I also intend to compare my Paradigm 12mm pair with my Brandon 12mm pair. I don't really want to sell either of these pairs, but if one gives me a better image ... who knows?...

Mike


Well hold on now, Mike, let's not get carried away! Far be it from me to keep you from buying the 7XW. And I'm afraid some will see the Brandon comment as possibly sacrilegious...

Enjoying the comments about binoviewing...if I had two good eyes, I would definitely use these guys for inexpensive pairs. I used to use a 2x TV barlow as an OCA with my (no longer owned) WO binoviewer; with that rig, even the 18s would be just fine: I found at f/10 that they no longer showed much curvature.

My 5mm Paradigm remains in my EP case despite my having bought three different eyepieces that I thought might supplant it. Of those three, two were "less glass," and they are all now gone while the Paradigm remains.


Cheapersleeper--so what, may I ask, were the ones you sold?

---------------------

These eyepieces still await a really critical test, as far as I'm concerned, on planets and Moon, versus the XWs and possibly my Tak LE (unless I sell it). But I'm already convinced I'm not going to see any serious difference on axis except possibly at high power in really good seeing. (And I'm quite happy with them off-axis, as I've indicated already.)

I was out this evening looking at the floor of Gassendi in my 10-inch with paracorr, switching between 5 XW, 5 LE, 5 Paradigm, and 12 Paradigm + 2x TV barlow + extension (for an effective 5mm), so up around 300X. Seeing, unfortunately, kept coming and going, but occasionally, for a few seconds at a time, was pretty good. Looking at a very fine rille south of the central peaks that flicked in and out of view, I had the impression that just possibly it had better definition in the XW. But I can't say for sure. Again, it will take a night of really steady air. So, in the meantime, I have to reiterate that I don't feel I'm missing much of anything when I'm out with these little guys.

--geo

#23 cheapersleeper

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Posted 27 September 2012 - 05:45 AM

geo,

I had, all at the same time the 5mm Paradigm, a 5mm LER, a 5mm UO Volcano top ortho and a 6mm Sterling plossl. During moments of best seeing, mostly on Jupiter, the planet would go from belts to "textured" using both the Paradigm and the Volcano Top Ortho. The others did not give that effect. It was as if there was a load of tiny fine and subtle detail. As time went on, I kept on using the Paradigm and the Ortho and then finally decided that they were about equal but the Paradigm was comfortable. So all the others were sold.

B

#24 Sarkikos

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Posted 27 September 2012 - 07:29 AM

B,

I like the UO VTs for their ability to show fine surface detail with high perceived contrast and good color rendition. I like the BGO's for the same reasons, but even more so.

I have 6mm and 18mm pairs of the LERs for binoviewing. The 6mm's binoviewed gave me a surprisingly good view of Mars last Spring. The 18mm pair are decent for binoviewing the Moon; they seem to have a cool-to-neutral tone. I think they are better eyepieces than the TMB Planetaries, but probably not as good as the UO VTs. The 18mm's did surprise me, though, for lunar.

I have a 6mm Sterling - the Owl version - that I bought after reading many posts praising it. After viewing through it, I had a hard time understanding why it deserved such praise. I ought to sell it. [Correction: My eyepiece was actually an Owl Enhanced Super Wide 6mm, not a Sterling 6mm. IMO, they should both be avoided, but for different reasons. - Mike]

It is interesting, though, that you ranked the Paradigm 5 and UO VT 5 about the same, except for the Paradigm being more comfortable. That is saying something. :ubetcha:

Mike

#25 cheapersleeper

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Posted 27 September 2012 - 07:49 AM

Mike,

I don't actually claim to be right. Just reporting my impressions. :lol: It is entirely possible that neither myself or my scopes are up to the task of discerning very fine differences in detail.

B






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