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Pentax Telescopes & Mounts

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#126 Defenderslideguitar

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Posted 01 May 2021 - 11:43 AM

I can try that Chip   thanks

 

barry



#127 Defenderslideguitar

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Posted 01 May 2021 - 02:18 PM

Thanks folks

 so I should have thought of this myself Chip

 

But the   1.25 adapter from a TV 2 inch diagonal   when I went straight through  there was not enough back focus   so I knew there was hope.

 

Then I used the Tak 1.25 prism diagonal  and presto

The Paradigm ED eyepieces   25mm  15mm  12mm seem to work just fine.. in the daylight on near and far   houses fences trees     I'll try others later on This is just what I needed    something I have on hand and it works....and I have two Tak 1.25  prism diagonals  and I like them a lot

 

more good news is that the clam shell from the TV Oracle is a match to the Pentax    so there is also that...

 

So first we get to use and learn this cool Pentax.....

 Later on we can see about finding other things for it  

  But I am happy with today's progress 

   You folks are the best

 

thanks everyone      

enjoy Derby Day 

and law day

 

 

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Edited by Defenderslideguitar, 01 May 2021 - 02:22 PM.

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#128 Steve_M_M

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Posted 01 May 2021 - 02:29 PM

There you go!  These scopes just need creative ideas to shorten the path.  Looks like the Tak and Lumicon 1.25" diagonals fit the role.

 

I did try the Astro-Tech Diagonal today and it would not come to focus.  So, since it's a rainy day, I decided to design a new adapter which will give me that last 5-7mm of in focus to work with any diagonal. I am printing the first draft now.   Once I print one that works, Ill print 3-4 so everyone who needs one can have one.

 

Look how much spare in focus I have with the Lumicon diagonal focused about 1 mile away.  Even with a big 13mm Stratus on there.  Compare that to the Astro tech diagonal which uses all that extra in focus and is still a couple mm’s away. 

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Edited by Steve_M_M, 01 May 2021 - 02:34 PM.

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#129 Defenderslideguitar

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Posted 01 May 2021 - 04:47 PM

Good job Steve

 Yes I would love to have one of the 3-4 of     the adapter you make if you are making   several available 

 

Love these Tak Prism diagonals btw     they work here in the short Pentax   and they are great in the Longfellow classic refractors  like the 1958 Tasco 10te and the 1959 Unitron 140

 

Of course   they excel in the Taks as well

 

thanks    will use it tonight   if the blue sky holds

Steve    love the pic   and hey we like that finder  same for Volvonium and Coinboy

I can see my want ad now     wanted Pentax Finder   in white with Pentax green stem

 

that color is growing on me btw      we have all seen the Tak  green   and I really always loved the Vixen green/gray color scheme   but Pentax green is sweet


Edited by Defenderslideguitar, 02 May 2021 - 08:03 AM.

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#130 Defenderslideguitar

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Posted 02 May 2021 - 07:56 AM

Epilogue:

The Pentax performed well with every 1.25 eyepiece I tried with it last night

At first Arcturus seemed to pop out first at dusk. I spent a lot of time working down from

an old TV 32 wide field, the TV 18.2 Delite, the Nag 6 -11mm,Nag 6- 9mm, I also tried the Delite 9,the Nag 6 -7mm and Nag 6- 5mm,.   I moved on to Ursa  Major and spent time with Mizar and Alcor et al. All performed very well with no in focus out focus or hocus pocus focus  issues....

 

As I used to do with the Vixen 80fl   towards the end of the session I would pop in a  wide field eyepiece   usually the RKE 28 or the Silvertop 26 and just easy wider sweep around at nothing in particular......Using the Silvertop 26 last night I swept around and felt it was similar to those end of session sweeps with the Vixen 80fl. Bring on the summer Milky Way

 

These Pentax scopes have a great lens  as stated before. It is as  sharp as a  Tak...pun intended but true.  I like the heft of the 5 pound weight and the way it shrinks down quite short with the sliding dew shield. It is several inches shorter compared to the TV Oracle which also slides a dew shield....

 

I see it as a fine flat field  easy G and G scope with quality optics in a compact travel package...

Finally,  when I sold the Vixen 80fl to raise funds for the old Tak FC-76  I knew I would miss the Vixen and I do. The FC 76 is outstanding an I am glad I made that move....but now the Pentax seems to do some of what the Vixen used to do....While it may not view planets the way the Vixen 80fl did, it does other things very well.....Someday I will figure out how to put my

Cannon t2i on it...


Edited by Defenderslideguitar, 02 May 2021 - 08:05 AM.

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#131 coinboy1

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Posted 02 May 2021 - 08:28 AM

Very good to hear! I too was also impressed with my Pentax 75SDHF. My star test was very good with a hint of undercorrection but a very nice “snap” focus and airy disc. Only a hint of CA on the brightest stars. Very similar to an FC76 i once owned but not quite as good as a Vixen 90mm Fluorite I once owned which had the best star test I have ever seen.

You should be able to use your 2” adapter and a Canon to 2” adapter to make your camera work. I am about to experiment with mine and a FujiFilm XT3 camera.
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#132 photoracer18

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Posted 03 May 2021 - 05:12 PM

Steve   nice solution. This is a fortuitous thread for me to run into because I just got one of these Pentax EDHF III 75mm fl 500  today and I cannot do anything with it..      It did not come with any diagonal ..... I will need to fix the in focus issue apparently as others already knew. Not sure what to do or what to buy. I put a two inch diagonal on it with a 1.25 adapter   and it will not focus on a house 200 feet away.

 

I am okay addressing this issue but I do not want to buy stuff and do trial an error if other folks know what to do already A couple  of questions for everyone if I may.  What is the little green diagonal in Steve's pic? Is that the original? It sure looks original in lovely Pentax green It seems it is 1.25 but went into a a two inch focuser? Anyone have any idea why they might make a scope with obvious in focus issues and not provide a solution? How did these scope come for sale when new  and was this an issue then?Or is it that the original design of these scopes did this on purpose for a reason that eludes me? 

 

I would like to buy a correct diagonal and what ever else I will need if I am going to keep this Pentax.

That is their stock diagonal. The eyepiece end is 24.5mm (.965") ad the other end is some standard Japanese focuser barrel, 36mm and some change. That is how I got the tube from the Meade projection adapter to work as its inside was 31.7mm (1.25") and the outsdie was the same 36+mm.


Edited by photoracer18, 03 May 2021 - 05:14 PM.

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#133 Defenderslideguitar

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Posted 11 May 2021 - 05:56 PM

Tried out the adapter   made by Steve M  M  in the Pentax  EDHF   It is perfect   light yet solid with more focus room. better than the TV 1.25 adapter I was using

Thanks    so much    Steve

 

Barry   

 

P.S.  It looks good in black.   


Edited by Defenderslideguitar, 11 May 2021 - 05:57 PM.

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#134 JIMZ7

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Posted 13 May 2021 - 10:38 PM

Also had a Pentax J60 that was very nice, the mount is one of the best alt az mounts I've used. Worm and gear on both axis.

That's the one I purchased used for $40 but I spent more on gas to buy it. Eventually sold it for health issues.

Jim


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#135 Faber

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Posted 14 May 2021 - 01:19 AM

I owned the Pentax 75SDHF with the reducer and the 85 f12 achromat with original mount and I really miss both of them for differenti reasons. Never used Pentax reflector but I remember they produced some. It’s ssd the Pentax stopped the production of telescopes.

#136 ccwemyss

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Posted 14 May 2021 - 08:17 AM

I had the Pentax 85 out last night, and happened to do a star test on it as I was interested in comparing another refractor to it. The Pentax was textbook perfect. Round rings, exactly symmetrical and well defined on both sides of focus with a 9mm eyepiece. 

 

Chip W. 


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#137 Steve_M_M

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Posted 16 May 2021 - 01:19 PM

I am ready to do a comparison with my 75EDHF, the Pentax 85, and an Orion Eon 115mm.  They are all mounted and aligned on my G11 and ready to go.  Unfortunately, the weather forecast has us all locked down with clouds for at least the next 10 days.

 

By the way, I see a 75SDHF just sold with finder and clamshell for $1100.  Is there a huge difference between the EDHF and SDHF?  I know the differences in the build, but is the SDHF noticeably better at the eyepiece?


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#138 gwfbmd

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Posted 12 June 2021 - 07:31 PM

After years of using .965 eyepieces (with little complaint, in fact!) I recently converted my Pentax 75EDHF to a 2" diagonal.  There is an adapter bushing from Baader which will let you remove the odd and long 1.5" adapter from the telescope and put the diagonal right into the 2.4" hole.  The ring has countersunk Allen-head screws to hold it in place, so there is no lip on it to increase back focus.  Focus is still close to the limit, but most or all of my 2" eyepieces will work, including my wonderful ES 18/82 and Vixen 18/83SSW, as well as the Pentax 30 and 40 70 degree XWs.  It is close, though, and if your eyes are way out there it may not focus, or may require you to leave your glasses on.

 

I would recommend this conversion for anybody with one of these instruments.  You just about have to dedicate a diagonal to it, however, because the adapter bushing is cumbersome to remove and reinstall on the diagonal.  Also, no dealer in the USA would order the bushing for me, and Baader wouldn't sell it direct, so I had to order it from a dealer in Western Europe!  Shipping cost more than the adapter.

 

Most people who have looked through my Pentax have stated it is either one of the best, or simply the best, small refractor they have ever looked through.  It makes the Moon look like the Little Prince's planet, so incredible is the exaggerated 3D effect produced by such contrast!

 

This is the adapter:

 

https://www.baader-p...60mm-to-2".html


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#139 gwfbmd

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Posted 12 June 2021 - 07:37 PM

As an additional note to the post I just made, I would also note that any adapter which had a lip on it would not have worked.  The eyepieces focus within 2mm or so of the stop!



#140 Steve_M_M

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Posted 12 June 2021 - 08:24 PM

After years of using .965 eyepieces (with little complaint, in fact!) I recently converted my Pentax 75EDHF to a 2" diagonal.  There is an adapter bushing from Baader which will let you remove the odd and long 1.5" adapter from the telescope and put the diagonal right into the 2.4" hole.  The ring has countersunk Allen-head screws to hold it in place, so there is no lip on it to increase back focus.  Focus is still close to the limit, but most or all of my 2" eyepieces will work, including my wonderful ES 18/82 and Vixen 18/83SSW, as well as the Pentax 30 and 40 70 degree XWs.  It is close, though, and if your eyes are way out there it may not focus, or may require you to leave your glasses on.

 

I would recommend this conversion for anybody with one of these instruments.  You just about have to dedicate a diagonal to it, however, because the adapter bushing is cumbersome to remove and reinstall on the diagonal.  Also, no dealer in the USA would order the bushing for me, and Baader wouldn't sell it direct, so I had to order it from a dealer in Western Europe!  Shipping cost more than the adapter.

 

Most people who have looked through my Pentax have stated it is either one of the best, or simply the best, small refractor they have ever looked through.  It makes the Moon look like the Little Prince's planet, so incredible is the exaggerated 3D effect produced by such contrast!

 

This is the adapter:

 

https://www.baader-p...60mm-to-2".html

Exactly what is needed.  Thanks for providing the link.
 


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#141 gwfbmd

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Posted 12 June 2021 - 08:30 PM

Exactly what is needed.  Thanks for providing the link.
 

No problem.  I had a hard time getting anybody here in the USA to order it for me.  I called several mainline dealers which sell Baader but they wouldn't be bothered.  I won't say who finally sent it since I am unsure how dealerships work, and whether they were supposed to sell it to me, but it was outside the USA.  Scout around and you can get one.


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#142 Volvonium

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Posted 23 June 2021 - 03:19 PM

I've recently added a new Pentax to the collection:  

 

Pentax 100 EDUF

 

400mm focal length, 100mm aperture (f4), 4 optical elements in two groups in a Petzval-like configuration, with ED glass.  First manufactured in the 1980's, the EDUF and its more recent siblings are also known as Tsuchinoko, after the mythological Japanese snake known for its short, stout body.  Tsuchinoko...REAL!    

 

Q5zGNn5h.jpg

 

I'm determined to use this both visually and for imaging (4" of aperture with potentially a 6 degree fov, without the need of flatteners or additional reducers cannot be resisted.)  These earlier versions of the Pentax astrograph likely exhibit more chromatism than the newer Pentax 100 SDUF and modern f3.8 $6000USD Vixen VSD100 version, which I haven't tried yet.   I expect some of the differences between EDUF and SDUF to be similar to those of the Pentax 75 EDHF vs SDHF.   

 

For visual use, I ordered a Baader M84 (Zeiss format) to M68 adapter, which will work on both my 75 EDHF and this 100 EDUF and then I will use a low profile M68 format 2" visual back/eyepiece holder to get additional inward travel over the factory adapters.   Previously, I was using a machined 2" to 2.5" adapter to work with the Pentax accessories, but I think the M84 to M68 adapter will be a more elegant, low profile solution for using standard 1.25" and 2" eyepieces.  My adapter should arriving today and cut at least 30mm of light path length.

 

I knew this would fail, but just had to try:

70CMs0eh.jpg


Edited by Volvonium, 23 June 2021 - 03:20 PM.

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#143 coinboy1

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Posted 23 June 2021 - 03:36 PM

Beautiful scope!

#144 davidmcgo

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Posted 23 June 2021 - 09:31 PM

That 100 f4 Pentax is begging for a 30mm Pentax XW and an O-III filter and some time on the Veil and North American Nebulas!

 

Dave


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#145 Haukka

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Posted 29 July 2021 - 02:41 AM

I am using a Pentax 75 SDHF as my main imaging setup, works amazingly well, she's a keeper. I am the second owner, the serial number is 2275, I am curious to know the manufacturing year, if someone does know?

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#146 Amin85

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Posted 10 August 2021 - 10:26 AM

Hi to all Pentax lovers, I bought a Pentax 100 ed and it came with all the invoices and prospectuses for the device.
Since there is unfortunately little information about the pentax, I would like to share it with you

This Pentax sold in Year 1987 in Germany for 12379 D-Mark (6189€ - 7255$).

 

Pentax J 60
Album: Pentax ED
17 images
0 comments

Pentax 100 ED Apochromat
Album: My Pentax 100 ED Apochromat
11 images
0 comments


Edited by Amin85, 10 August 2021 - 10:30 AM.

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#147 Piaget

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Posted 10 August 2021 - 10:55 AM

That is a gem , Thanks for sharing access to your albums , Piaget

Hi to all Pentax lovers, I bought a Pentax 100 ed and it came with all the invoices and prospectuses for the device.
Since there is unfortunately little information about the pentax, I would like to share it with you

This Pentax sold in Year 1987 in Germany for 12379 D-Mark (6189€ - 7255$).

 



#148 ccwemyss

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Posted 10 August 2021 - 11:45 AM

Cool! I sold them in the early 80's, and wasn't even aware of a pedestal option. Maybe the pedestal came later. The drive looks like a more modern DC version, compared to the earlier DC to AC inverter type that came with the P100's at the time I worked in the shop. Otherwise, the mount looks the same. The 100ED was the ultimate development of the Pentax line, but it arrived as APOs were starting to take off.

 

Chip W. 



#149 Amin85

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Posted 10 August 2021 - 12:02 PM

I have done the job to photograph the entire instruction manual (German) for a Pentax 100

I Hope you enjoy it ;)


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#150 BigC

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Posted 24 August 2021 - 09:12 AM

I just received a poor man's Pentax: a J60C.
Just the OTA no finder. Seems very finished and helical focuser works smoothly.Came with OR6 eyepiece and good quality diagonal. Daytime view was sharp.
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