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02-07-2009, 09:39 PM   #1
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Got A New Pentax Lens Today ...

EDIT: Celebrate the International Year of Astronomy by buying Pentax astronomy products! Convince them to continue this line! And help to fight light pollution by eliminating unnecessary exterior lighting, and buying lighting fixtures that direct the light down instead of creating glare for your neighbors.

Images of this Pentax lens are below.


I picked up a new Pentax lens today, but something a little different. 8 elements in 6 groups. SMC. Not a "K" mount, but something Pentax calls an "American" mount. Focal length: 7mm. Has a built-in shade. Beautifully built with a metal (aluminum) exterior. Great performance, with just a bit of pincushion distortion, which is not bad for this focal length. Made in Japan.

Anyone want to venture a guess as to the intended use of this lens?


Last edited by GaryML; 02-10-2009 at 10:34 AM.
02-07-2009, 09:51 PM   #2
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QuoteOriginally posted by GaryML Quote
I picked up a new Pentax lens today, but something a little different. 8 elements in 6 groups. SMC. Not a "K" mount, but something Pentax calls an "American" mount. Focal length: 7mm. Has a built-in shade. Beautifully built with a metal (aluminum) exterior. Great performance, with just a bit of pincushion distortion, which is not bad for this focal length. Made in Japan.

Anyone want to venture a guess as to the intended use of this lens?
Are you a proctologist or GI specialist?
02-07-2009, 10:09 PM   #3
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QuoteOriginally posted by GaryML Quote
I picked up a new Pentax lens today, but something a little different. 8 elements in 6 groups. SMC. Not a "K" mount, but something Pentax calls an "American" mount. Focal length: 7mm. Has a built-in shade. Beautifully built with a metal (aluminum) exterior. Great performance, with just a bit of pincushion distortion, which is not bad for this focal length. Made in Japan.

Anyone want to venture a guess as to the intended use of this lens?
Intended use? Ever see the movie Innerspace?
02-07-2009, 10:13 PM   #4
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QuoteOriginally posted by tranq78 Quote
Are you a proctologist or GI specialist?
Nope. Not one of those. If it was, I certainly wouldn't pick it up. Yuck.

02-07-2009, 10:14 PM   #5
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QuoteOriginally posted by jsherman999 Quote
Intended use? Ever see the movie Innerspace?
Definitely not "innerspace."
02-07-2009, 10:16 PM   #6
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QuoteOriginally posted by GaryML Quote
Definitely not "innerspace."
Ah - "Outer Space"?

What kind of telescope are you mounting it on?
02-07-2009, 10:21 PM   #7
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QuoteOriginally posted by GaryML Quote
I picked up a new Pentax lens today, but something a little different. 8 elements in 6 groups. SMC. Not a "K" mount, but something Pentax calls an "American" mount. Focal length: 7mm. Has a built-in shade. Beautifully built with a metal (aluminum) exterior. Great performance, with just a bit of pincushion distortion, which is not bad for this focal length. Made in Japan.

Anyone want to venture a guess as to the intended use of this lens?
7mm xw astro eyepiece
02-07-2009, 10:40 PM   #8
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QuoteOriginally posted by jsherman999 Quote
Ah - "Outer Space"?

What kind of telescope are you mounting it on?
Yes, a Pentax XW 7mm eyepiece for a telescope:

Pentax 7mm XW Eyepiece - 1.25" - OPT Telescopes

I'm using it on a Vixen (Japanese) 4" APO refractor. With this f/9 scope, it gives me about 130X which is perfect for planets and the Moon. I tested it in the store today and it definitely out-performs the highly rated Televue Nagler 7mm. Better contrast, better eye relief, and less pincushion distortion. I'd be looking at Saturn with it right about now, except tonight it is cloudy and raining.

The sad part is that the salesman told me that Pentax had stopped production of their telescopes and eyepieces, and once the current stock is gone then they will no longer be available. Pentax makes a range of refractors, from little ones to huge ones (with matching huge price tags). They have several of them on display in the showroom of the store and they are beautiful. I was looking at this one today - too bad it is out of my price range:

Pentax 125 SDP APO Refractor with Case - OPT Telescopes

Their eyepieces are also very nicely made, and I may pick up one or two more before they are gone.

02-09-2009, 09:02 PM   #9
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Now I know why you sold all of your lenses to me
Congrats..............and please post some photos
02-09-2009, 10:25 PM   #10
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QuoteOriginally posted by kibipod Quote
Now I know why you sold all of your lenses to me
Congrats..............and please post some photos
They call it "aperture fever" in the astronomy biz: sort of like LBA for astronomy gear. Of course, it has rained non-stop here for the last two days so I haven't even tested the new eyepiece in the nighttime sky.

I can post a few pictures of the setup when I get a chance. I don't have the capability to do any decent astro-photography -- that's a whole other can of worms. That Pentax 125mm 'scope would help with that, but $7000 is a bit out of my budget at present.
02-10-2009, 10:39 AM   #11
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Ok, the weather has cleared. But a full moon tonight.

Last edited by GaryML; 03-10-2009 at 12:33 PM. Reason: Deleted photo
02-10-2009, 01:18 PM   #12
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QuoteOriginally posted by GaryML Quote
Yes, a Pentax XW 7mm eyepiece for a telescope:

I'm using it on a Vixen (Japanese) 4" APO refractor. With this f/9 scope, it gives me about 130X which is perfect for planets and the Moon.
You can send it to me and it will a neat place on my small travel refractor, a Pentax 75 SDHD. (it deserves not to be mounted to a Vixen)... I also have some Pentax eyepieces, but only orthos for max. resolution and use on my bino viewer.

QuoteOriginally posted by GaryML Quote
The sad part is that the salesman told me that Pentax had stopped production of their telescopes and eyepieces, and once the current stock is gone then they will no longer be available. Pentax makes a range of refractors, from little ones to huge ones (with matching huge price tags). They have several of them on display in the showroom of the store and they are beautiful. I was looking at this one today - too bad it is out of my price range:
Pentax was for a long time the manufacturer of the largest refractor on any manufacturers standard price list. The 250mm Apo. I have never seen one, but it was priced at 2.5 Million USD (complete with mount) and you'ld need a 4 to 5 meter dome to house it. They also make (made?) a few Cassegrainians, but these were special order items and are very rare.

The problem with Pentax scopes was always the price tag. For the same price you could have a TeleVue and most other top class Apos are considerably cheaper thasn Pentax, except perhaps the old Zeiss modells.

Ben
02-10-2009, 05:29 PM   #13
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QuoteOriginally posted by Ben_Edict Quote
You can send it to me and it will a neat place on my small travel refractor, a Pentax 75 SDHD. (it deserves not to be mounted to a Vixen)... I also have some Pentax eyepieces, but only orthos for max. resolution and use on my bino viewer.
Now let's not start saying bad things about my Vixen! It was a good deal and it performs very well for a ED doublet (semi-apochromatic?). It certainly lacks the fit and finish of a Pentax or Televue, but the optics are good and it performs very well.

I admit that the Pentax XW eyepiece is a little over the top on this scope, but it will be the last 7mm eyepiece that I will need to buy. I'm sure there is a Televue, Takahashi, or even Pentax premium refractor in my future some time down the road.

I saw the Pentax 75 at the store last weekend. A very nice scope and very well made, but rather expensive compared to the wave of cheap 80 & 100mm ED doublets on the market.

QuoteOriginally posted by Ben_Edict Quote
Pentax was for a long time the manufacturer of the largest refractor on any manufacturers standard price list. The 250mm Apo. I have never seen one, but it was priced at 2.5 Million USD (complete with mount) and you'ld need a 4 to 5 meter dome to house it. They also make (made?) a few Cassegrainians, but these were special order items and are very rare.

The problem with Pentax scopes was always the price tag. For the same price you could have a TeleVue and most other top class Apos are considerably cheaper thasn Pentax, except perhaps the old Zeiss modells.

Ben
The store only stocked the Pentax 75 through the 125mm, but I have seen photos of much larger ones. The big ones are probably more of a custom order thing, for a school or very wealthy amateur.

I agree that price is a problem with Pentax, but other companies who sell premium telescopes seems to be doing ok. Televue charges a lot more for their TV 76 than Pentax charges for the 75. But Pentax does no advertising at all for their astronomy products, so they lack the name recognition. I could not find a single bit of information on a Pentax company Web site about their telescopes and eyepieces, and I had to dig deep to even find a reference to their binoculars. How sad is that?

They have some astro great products, and it looks like those products will disappear due to incompetent management.
02-11-2009, 02:52 AM   #14
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QuoteOriginally posted by GaryML Quote
Now let's not start saying bad things about my Vixen! It was a good deal and it performs very well for a ED doublet (semi-apochromatic?).
No, no, the Vixens are very fine scopes, widely underrated, because they are so much of a commodity. I was just kidding, that a Pentax eyepiece deserves a Pentax scope...

QuoteOriginally posted by GaryML Quote
I agree that price is a problem with Pentax, but other companies who sell premium telescopes seems to be doing ok. Televue charges a lot more for their TV 76 than Pentax charges for the 75. But Pentax does no advertising at all for their astronomy products, so they lack the name recognition. I could not find a single bit of information on a Pentax company Web site about their telescopes and eyepieces, and I had to dig deep to even find a reference to their binoculars. How sad is that?

They have some astro great products, and it looks like those products will disappear due to incompetent management.
Yes, Pentax Astro Products is something of an enigma. No advertising, noe website, hardly a handful of dealers, though they announced (here in Germany) something like a retail offensive one or two years ago. Now we have two or three more dealers, that sell their products with completely outdated information. It is a shame. One strength of the Pentax scopes, which they simply do not advertise, is, that you can use all of them with medium format cameras out of the box, no expensive additional field flatteners and the like needed. Somehow it all is very typical of Pentax in general.

Ben
02-11-2009, 11:29 AM   #15
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QuoteOriginally posted by Ben_Edict Quote
No, no, the Vixens are very fine scopes, widely underrated, because they are so much of a commodity. I was just kidding, that a Pentax eyepiece deserves a Pentax scope...

Yes, Pentax Astro Products is something of an enigma. No advertising, noe website, hardly a handful of dealers, though they announced (here in Germany) something like a retail offensive one or two years ago. Now we have two or three more dealers, that sell their products with completely outdated information. It is a shame. One strength of the Pentax scopes, which they simply do not advertise, is, that you can use all of them with medium format cameras out of the box, no expensive additional field flatteners and the like needed. Somehow it all is very typical of Pentax in general.

Ben
I know you were kidding about the Vixen. I just had to speak up as a matter of honor.

Both the Pentax 105mm and 125mm have an 88mm image circle, sufficient to cover most any medium format camera. The 125 has this giant helical focusing ring-the draw tube size is somewhere between 3 and 4 inches. That thing will hold any camera or imaging device. When I was at OPT last weekend I was checking it out and it is very well made and smooth in operation.

Pentax 105 SDP APO Refractor OTA - OPT Telescopes

Pentax 125 SDP APO Refractor with Case - OPT Telescopes

I finally had a chance to use the Pentax 7 XW eyepiece last night. Conditions were not ideal as the jet stream is still overhead and the upper atmosphere is quite turbulent. Overall, I really like this eyepiece. It brings out the best in my current telescope and it is ready for anything i might get in the future. Eye relief is fantastic for this focal length, and the 70 degree field of view is perfect for me. You can get "black-out" and "kidney-beaning" if your eye is too close. But if I crank out the eye shade to the right length, then I can hit the focus spot with ease.

About an hour after sunset Venus was setting to the west and the full Moon was rising in the east. Venus looked good and was equally sharp across the entire field of view. M 42 looked beautiful and was also sharp edge to edge. The 4 brightest stars of the Trapezium were clear and sharp, but with the turbulent air and the moon glow the fainter stars were not visible. My wife came out at that point and was was quite impressed with the view of M 42 (or maybe just humoring me with my new toy). She had no problem getting the focus spot.

A couple of hours later I went out again to look at Saturn and the Moon. Saturn looked good with the edge-on rings just super-crisp. I could just barely make out a hint of banding on the surface of Saturn, but the air and the Moon glow were affecting visibility. The Vixen has a two-piece lens cap for the objective, and you can remove the center section to "stop down" the scope. I used this to look at the Moon. I have to say that the 7mm was a bit too much for such a bright Moon. Looking through the 7mm, some detail was lost because everything looked "overexposed." I saw more detail with my 12.5mm Celestron Ultima. Maybe a filter would have helped with the Pentax 7mm.
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