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Pentax ep series?

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#1 dyslexic nam

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Posted 30 December 2013 - 10:32 PM

I am wondering how many Pentax ep series are out there. I have recently picked up an xp 3.8mm, and a 5mm XO to go with some other Pentax odds and ends, so it got me thinking about other series that Pentax has made. Ultimately, I may try to collect some of them, so it would be good to know what is out there.

In addition to the two aforementioned lone reps from the XP and XO series, I have owned examples from the XLs and XW series (both great, shorter fl eps). I also own the .965 eps that came with my vintage J80 refractor (6mm ortho, and 12.5mm and 25mm Kellners), and an oddball 20mm Kellner that came with the Pentax 500 spotting scope.

While I haven't owned any of them, I am also aware of:
- two zooms (7-21 and 8-24)
- the XFs (8.5 and 12mm)
- the SMC orthos (in .965) and SMC Kellners

I am wondering if there are any others out there that I haven't covered? I will probably try to get some SMC orthos in the future (may even sacrifice a 5mm XO to do it), but I am curious if there are any other Pentax series out there that should be considered.

And if anyone feels like posting a pic of their Pentax ep collection, it sure would be nice :)

Happy New Years all!

#2 Jim Curry

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Posted 30 December 2013 - 10:51 PM

Boy, I wouldn't get rid of that 5XO if you do high X observing. That is one good piece of eyepiece. I have the SMC ortho collection complete except the 60mm. Really, really quality views, whether planetary or deep sky. Low to no scatter and excellent transmission. Pretty close to perfectly parfocal as well.

Jim

#3 dyslexic nam

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Posted 31 December 2013 - 09:59 AM

Thanks Jim - I actually have a second XO5, so I would still have one for critical viewing. It was the factors you mentioned that attracted me to the XO - and, by reputation, to the SMC orthos.

#4 BillP

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Posted 31 December 2013 - 11:25 AM

The commonly known ones are what you have mentioned...

XW
XL (succeeded by the XWs)
XO
XP
XF
SMC Ortho/Kellner (discontinued; .965)

There are also older .965 Orthos, before the SMC variety that come up on the used market now and then. link.

#5 dyslexic nam

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Posted 31 December 2013 - 12:02 PM

Thanks Bill - they look interesting. Doing a bit of hunting around, I also found this one, which looks to be a different series as well (different style from the pre-SMC orthos you mentioned). I am curious how many older runs/series there are.

#6 stevetaylor199

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Posted 31 December 2013 - 12:28 PM

What is the story on the XF series? Purpose? Strengths? Competitiveness? Any discontinued focal lengths?

#7 backwoody

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Posted 31 December 2013 - 02:22 PM

I was told by a dealer that the XF series was designed specifically for Pentax spotting scopes. But astronomers quickly discovered that XFs work equally well in most telescopes. Strengths - lightweight, sharp images edge to edge, bright contrast - many say that XFs perform as well as XLs or XWs, with reduced FOV of 60 degrees. Weaknesses - only 60 degrees.

I use both 12 and 8.5mm XFs frequently, they are among my most-used EPs.

#8 george golitzin

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Posted 31 December 2013 - 02:27 PM

The 12 xf also shows notable field curvature in newts; the 8.5 not so. Their build quality also is a bit below the level of the XWs, I believe, and their coatings were not the same either, IIRC.

-geo

#9 JustaBoy

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Posted 31 December 2013 - 02:27 PM

Since designed for spotting scopes (short refractors), do you think that field curvature might match up best here in that kind of scope?

I see that you are using a scope that is very flat @ 1524mm.

Thanks,

#10 jrbarnett

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Posted 31 December 2013 - 03:12 PM

Recently: SMC Orthos and SMC Kellners, XPs, XLs, XFs, XWs, and XOs.

Regards,

Jim

#11 stevep

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Posted 31 December 2013 - 03:59 PM

That one is from the late 70's series,
here is a pic of a few more, brochure states
there were also HM 12.5, 20 & 25mm, a K20 all in .965 as well
as K40, K50 & K60 with the 38mm barrel like the K30, I have seen pics of the K40 but not the 50 or 60mm so not sure on those 2,

Regards
Steve

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#12 dyslexic nam

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Posted 31 December 2013 - 04:03 PM

^ very nice. That is a series I am not familiar with at all. I assume these are pretty hard to come by.

#13 Scanning4Comets

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Posted 31 December 2013 - 05:23 PM

This is a great thread! :bow:

#14 backwoody

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Posted 31 December 2013 - 05:26 PM

Since designed for spotting scopes (short refractors), do you think that field curvature might match up best here in that kind of scope?

I see that you are using a scope that is very flat @ 1524mm.


Hi Chuck, like you, I suspect the field curvature is less visible in short refractors/spotting scopes. In a newt like mine, the curvature ought to be more apparent, but I don't seem to notice it. The XFs are among my favorites for planets, Luna, and doubles-- which are usually centered in the FOV.
c/s,

#15 stevep

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Posted 31 December 2013 - 05:35 PM

^ very nice. That is a series I am not familiar with at all. I assume these are pretty hard to come by.


Yes, but they pop up now and again, still looking for the K20 & 40, might get lucky one day, out of interested they are very good :jump:

#16 jrbarnett

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Posted 31 December 2013 - 07:50 PM

Those are the pre-SMC generation Kellners and Orthos.

XOs:

Posted Image

Regards,

Jim

#17 dyslexic nam

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Posted 31 December 2013 - 07:57 PM

So, the one in Bill's link looks differerent from the pre-SMC's picture above. Does anyone know if these are totally different series or just a bit of cosmetic change amongst essentially the same series?

#18 jrbarnett

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Posted 31 December 2013 - 08:08 PM

I'd guess that the pre-SMCs are pretty similar to one another irrespective of housing design, save that they lack the fancy SMC multi-coatings of later Pentax eyepieces. It's also possible though that with Pentax's consumer grade department store achromats (they did make them) they did what most other purveyors to that segment - rebrand cheap mass-produced generic Japanese optics.

- Jim

#19 stevep

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Posted 31 December 2013 - 09:40 PM

So, the one in Bill's link looks differerent from the pre-SMC's picture above. Does anyone know if these are totally different series or just a bit of cosmetic change amongst essentially the same series?


As far as I know, these were not a series, these were just issued with the J60 & J80 scopes, and are not quite the same in performance to the pre smc or later smc series,
a personal opinion, I have owned the 6mm version and it's not pre smc or smc quality, both which I still have,

Steve

#20 csrlice12

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Posted 31 December 2013 - 09:49 PM

I have the Pentax 12.5 Kellner like Steve has...nice .965 eyepiece...Think it came with the J100, but not 100% certain...

#21 dyslexic nam

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Posted 31 December 2013 - 09:59 PM

The ones that came with my J80 are the middle set in the pic below (other threads have also shown these sold with the J60/J80). These are different both from the 'family pic' you posted, and the 5mm orthos in Bill's link.

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#22 stevep

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Posted 31 December 2013 - 10:09 PM

I'd guess that the pre-SMCs are pretty similar to one another irrespective of housing design, save that they lack the fancy SMC multi-coatings of later Pentax eyepieces. It's also possible though that with Pentax's consumer grade department store achromats (they did make them) they did what most other purveyors to that segment - rebrand cheap mass-produced generic Japanese optics.

- Jim


Jim, not far of the mark !, the pre smc and the smc 6mm are pretty close, just a tad brighter image in the smc, :bow:

#23 etsleds

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Posted 01 January 2014 - 02:26 AM

^ very nice. That is a series I am not familiar with at all. I assume these are pretty hard to come by.


Not that hard to find...

Construction and performance of both series compared well with their SMC brethren. I'd guess there is a slight difference in transmission, but I'm not going to claim that I see it (these are my eyepieces in the ad, the 6mm still available).

I believe the 5mm in the picture is the newer of the two, while the 6mm an older series. The older 6mm has a satisfyingly solid construction and had much flatter black paint inside than the 5mm.

Neither of the sets of optics have the appearance of MgF to me, but never measured them in any way to check. It wouldn't be surprising - Pentax had multi coatings in their Super Takumar lenses many years before going to SMC as a branding and I'd assume there are several generations of multi coatings as they grew more sophisticated in their coating technologies. I think that fits with the vintage of these eyepieces spanning the 70's through 80's.

Optical quality is great. The 5mm possibly gave up a little in scatter to the older 6mm and the SMC orthos, presumably because of the shinier insides, but they were all sharp and well-corrected to a degree that I couldn't tell you which generation was in the eyepiece holder.

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#24 dyslexic nam

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Posted 01 January 2014 - 10:35 AM

They look great. Hopefully I can acquire some at some point. I def think this is the direction I will go for my short fl planetary eps.

#25 stevetaylor199

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Posted 01 January 2014 - 04:01 PM

Thanks Woody and George for the background on the XF series.


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