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Old unidentified 8" newt

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#26 figurate

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Posted 13 June 2014 - 06:36 AM

Classics forum seems to be going through a blue telescope phase. Whatever it is, I like it! I haven't looked at "sky gazing" in years and this prompted me to crack it open. Dr Paul, according to the jacket notes, contributed to the ATM books (I believe a schmidt camera IIRC), but judging from the bio wouldn't have necessarily had a lot of time for optical work. Definitely something of a telescope collector. The book should be required reading around here; does anyone know what happened to the Porter fork-mounted newt-cass on page 113?

Fred

#27 Chuck Hards

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Posted 13 June 2014 - 06:51 AM

I have a home built 8 inch Schmidt Cass from 1965 - 1966 that has a darker blue tube. If i can pull it out of storage we can approximately help date the Paul telescope.

Al Paslow
Bethel Park, PA


Please post pics of anything you have from that time, Al, it's a wonderful trip down the classic memory lane. Good stuff. You could start a new thread if you have many items to post.

Thanks!

#28 DAVIDG

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Posted 13 June 2014 - 09:18 AM

Good point Dave...Ill check it out if possible. BTW so the optical window is just to prevent spider vane diffraction? Its not an optical figured glass. Do you think he made this mirror? Cant really find much info about him on the net . Bob


Bob,
I get the sense that Paul was a builder of scopes but might not have been a maker of optics. He was an optical engineer I believe. He wrote two books, one on astrophptography and on telescopes. In his telescope book he does stated that he made a few mirrors thou. He did have a custom 12" Newt, made by Cave for him and the back of your mirror has the fine ground back that was signature feature of Cave optics so Cave might have made the mirror for him. I would look it over very closely and see if there are any other markings on it. Not trying to be a "Debbie Downer" when it comes to the signature on the back of your mirror but all the mirrors I have made and sent to be coated or recoated have returned with my name on the back.
The optical window is used to remove the diffraction spikes causes by a typical spider and the seal the tube to help reduce tube currents. It has no optical power so it is not correcting the image. It needs to be optically flat on both sides and the faces need to be parallel to each other so it is not a simple element to make. Paul was big into photography so removing the diffraction spikes makes for nicer astro-images. He shows a 6" in his book with a window and states it is used to remove the diffraction spikes. My guess is that the window was a war surplus element that he reused. It could have be a protective filter for a large format camera. He worked for Kodak and did large amount of optical design work during the war. He was also pretty active at Stellafane and there are a couple of pictures of him and some of his scope on the Stellafane website.
By the way a memebr of my club had a 10" Cave with blue Parks tube and the club owns a 12" Starliner with a gray Parks tube.

- Dave

#29 bob midiri

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Posted 13 June 2014 - 03:46 PM

Thanks Dave, quite interesting. I contacted Paul valleli, he stays at the same INN every year with me at Stellafane, he new Dr Paul, and Im sure it will be part of our conversation at Stellafane this year. bob

#30 bob midiri

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Posted 16 June 2014 - 09:27 PM

This scope is getting more intriguing see the pictures but I did a little more cleaning on the OTA and want to share some interesting things, as u see in the pictures I removed the corrector/optical window. I was amazed at how small the secondary mirror is? I also am wondering (picture 3) what that lens element is that is inside the focuser, I took it out to show you. Any idea what that might be?. As I looked through the now cleaned corrector/optical window...it appears that ist just an optical window as if you look through it at the lawn in the picture...there is no difference in the view from the glass or the are not looking through the glass. What your thoughts? Thanks bob

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#31 bob midiri

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Posted 16 June 2014 - 09:28 PM

side view

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#32 bob midiri

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Posted 16 June 2014 - 09:29 PM

with corrector/optical window removed you can see an inserted lens element in the bottom of focuser? Wonder what this is? Looking through it it makes objects appear smaller

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#33 bob midiri

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Posted 16 June 2014 - 09:30 PM

and after removal of the element. You can see the size in comparison to a Cheshire eyepiece

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#34 bob midiri

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Posted 16 June 2014 - 09:31 PM

side view of element

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#35 bob midiri

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Posted 16 June 2014 - 09:32 PM

and just for fun the elbow finder he has on the scope

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#36 davidmcgo

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Posted 16 June 2014 - 10:10 PM

My take is the small lens is a relay lens assembly that allows a smaller secondary obstruction. The front window is quite likely just that, flat on both sides but gets rid of spider diffraction.

Nice find, can't wait to hear how well it works when you have it back together. Could be a really nice lunar and planetary scope!

Dave

#37 DAVIDG

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Posted 17 June 2014 - 08:59 AM

It's most likely a barlow. You have a "barlowed Newtonian" used for planetary viewing and imaging. Because of the barlow lens, the secondary can be placed farther away from the primary and hence it can be smaller in size so less diffraction effects. The since the barlow is increasing the focal length of the scope you can use longer focal length eyepieces which have better eye relief to get the same mag. that would require those "pin hole" eyepiece ( ie 4mm types).

- Dave

#38 terraclarke

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Posted 17 June 2014 - 09:30 PM

That is truly a fascinating telescope and a rare find as well Bob. A real collector's item that saw real duty in the trenches back in the day! Wow! I have a book by George Keene called "Stat Gazing with Telescope and Camera" that I have had since the 1960s and it mentions Dr. Paul on several occasions and also has several pictures of his gear at the time. The "optical window" is extremely interesting. Also, to me it looks long enough to be an F8. Have you measured it? Congrats on a truly "stellar" find! :bow:

#39 bob midiri

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Posted 18 June 2014 - 08:56 AM

That is truly a fascinating telescope and a rare find as well Bob. A real collector's item that saw real duty in the trenches back in the day! Wow! I have a book by George Keene called "Stat Gazing with Telescope and Camera" that I have had since the 1960s and it mentions Dr. Paul on several occasions and also has several pictures of his gear at the time. The "optical window" is extremely interesting. Also, to me it looks long enough to be an F8. Have you measured it? Congrats on a truly "stellar" find! :bow:

Terr, I think its an F7, judging by the distance from Mirror to focuser, taking into account the intercept distance, about 58 inches give or take!! I have more interesting things coming.. esp this old mount by the "Alpha Group" from 1956...Only if I can lift in into my van tomorrow....bob

#40 bob midiri

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Posted 06 August 2014 - 10:31 PM

Some new information. I picked up a book by Dr Henry Paul called Telescopes for Skygazing . in this book he mentions things about this very scope . I will scan the info and post at a later time, but in essence this scopeaccording to him is an excellent planetary scope. the mirror is f8 (you were right Terra!!) with a 1.1" diganola, mounted on a flate glass optical window, with a built in negative lens at the base of the focuser making this instrument an f15 according to Dr Paul



#41 terraclarke

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Posted 07 August 2014 - 07:26 AM

And the saga continues. That is a really neat scope and unusual scope! I just re-read the entire thread. Being in my dotage years, I needed to refresh my memory. :p  I will be happy when the rest of our pictures migrate over. Hat built in negative lens/Barlow and the optical window are really different! I can't wait to hear how it does on Jupiter in a few months! Well, I was wrong about one thing Bob, I said earlier that it was a "stellar find" and it turns out to be a planetary one!  :lol:



#42 bob midiri

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Posted 07 August 2014 - 07:46 AM

And the saga continues. That is a really neat scope and unusual scope! I just re-read the entire thread. Being in my dotage years, I needed to refresh my memory. :p  I will be happy when the rest of our pictures migrate over. Hat built in negative lens/Barlow and the optical window are really different! I can't wait to hear how it does on Jupiter in a few months! Well, I was wrong about one thing Bob, I said earlier that it was a "stellar find" and it turns out to be a planetary one!  :lol:

Yes Terra a planetary Find!! You can read these few paragraphs in Dr Pauls book!!Attached File  drpaulbookbluescope.jpg   159.07KB   2 downloads


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#43 bob midiri

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Posted 07 August 2014 - 07:50 AM

 

And the saga continues. That is a really neat scope and unusual scope! I just re-read the entire thread. Being in my dotage years, I needed to refresh my memory. :p  I will be happy when the rest of our pictures migrate over. Hat built in negative lens/Barlow and the optical window are really different! I can't wait to hear how it does on Jupiter in a few months! Well, I was wrong about one thing Bob, I said earlier that it was a "stellar find" and it turns out to be a planetary one!  :lol:

Yes Terra a planetary Find!! You can read these few paragraphs in Dr Pauls book!!attachicon.gifdrpaulbookbluescope.jpg

 

probably should read the page prior included here that explains the optical window

 

Attached File  drpaulbookbluescope3.jpg   197.47KB   0 downloads


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#44 EverlastingSky

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Posted 07 August 2014 - 03:13 PM

Thank you for the page scans from Dr Pauls book. So it uses an optical flat plate made by "Ferson" (I wonder who that was?).

This reminds me of the Mak Newt design, as well as old Cloudynights discussion topics regarding the superiority of using an optical window in small Newtonians of this aperture, to approach an APO contrast advantage. I believe in this way of thinking.

 

I'd like to hear more about this old 8" Newt. Especially observing reports when it gets used eventually.

Err... it will get used as a dedicated planetary instrument won't it?



#45 bob midiri

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Posted 07 August 2014 - 03:35 PM

Thank you for the page scans from Dr Pauls book. So it uses an optical flat plate made by "Ferson" (I wonder who that was?).

This reminds me of the Mak Newt design, as well as old Cloudynights discussion topics regarding the superiority of using an optical window in small Newtonians of this aperture, to approach an APO contrast advantage. I believe in this way of thinking.

 

I'd like to hear more about this old 8" Newt. Especially observing reports when it gets used eventually.

Err... it will get used as a dedicated planetary instrument won't it?

I see another Dr Paul scope in CN classifieds....This is interesting. I am now quite excited about mounting this scope and thoroughly checking out the optcs


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