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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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