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#1 starman876

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Posted 10 May 2013 - 02:03 PM

Thought you would all like to see this patent application in 1983 from Al Nagler describing how he makes his telescopes.

http://www.google.co...tents/US4400065

#2 starman876

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Posted 10 May 2013 - 02:06 PM

It also references many other telescope patents that some of you might find useful. got some achromats you want to play with. My Vixen NA120 uses this design.

#3 terraclarke

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Posted 10 May 2013 - 02:42 PM

Hey Johann,

You are the only other person that I know with an Vixen NA120. (I do know someone with the NA140.) At any rate. I purchased a Vixen NA120 new in the spring 2001. It had absolutely horrible CA, especially on the lunar limb. Far, far worse than my Celestron 150mm F5 refractor. It looked like the moon had a purple sea of waves. I liked the scope in other ways but I hated the CA so much that I sold it within a year or so. I just assumed it was inherent in the design, given the 120mm or aperture at F6.67. Does your NA120 have similar CA? If so, do you just not use it on bright objects? At that time it was my primary scope so I couldn't tolerate it. My Vixen 4 inch F9 Fluorite on the other hand, was one of the best scope I ever had. (Sold it too unfortunately.) The NA120 is kind of a rare bird. Vixen replaced it with the NA140 just a few years later and they still have it. (I have heard very good things about the NA140 btw.)

#4 jrcrilly

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Posted 10 May 2013 - 02:54 PM

The NA120 is kind of a rare bird. Vixen replaced it with the NA140 just a few years later and they still have it. (I have heard very good things about the NA140 btw.)


There was an NA130 in between those two. I've owned all three at one time or another. The 120 and 130 were Vixen-produced, while the 140 is outsourced. All are decent quality. I think my 120 had the least CA of any of them; about like a 120mm F/13 achromat.

#5 starman876

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Posted 10 May 2013 - 02:56 PM

Terra
I have had the NA140 and still have the NA120. The NA120 does not show any color even on Jupiter. The optics are very sharp. Maybe Vixen changed the spacing between the two achromats over the years. I have been very surprised with the sharp images this scope provides with it's short focal length. However, that is what this design is supposed to do. Provide a very wide flat field for photography. If you ever want to see just how good your optics are image a bright star. The CCD imagers are very sensitive in the blue light region and will show you a very nice blue halo if the system is not well corrected for all colors. Most achromats will fail this test.

#6 terraclarke

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Posted 10 May 2013 - 03:36 PM

Maybe I just had a bad one? At any rate, its long gone.

Thanks guys,

Terra

#7 peter scherff

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Posted 10 May 2013 - 04:48 PM

Here are some photos of the scope described in the patent:

Attached Files



#8 peter scherff

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Posted 10 May 2013 - 04:49 PM

another:

Attached Files



#9 peter scherff

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Posted 10 May 2013 - 04:50 PM

one more:

Attached Files



#10 starman876

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Posted 10 May 2013 - 05:40 PM

and???

#11 ngc2289

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Posted 10 May 2013 - 05:47 PM

According to Orion Telescopes the native focal ratio of the NA120 front element was f/12. The rear element was a focal reducer. The CA of this scope was made worse if the front, and rear elements got out of alignment.

#12 starman876

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Posted 10 May 2013 - 06:35 PM

Wonder how this lens would do if I took out the focal reducer which is really another achromat. It is hard to get them out of alignment they are in very nicely machined cells.

#13 terraclarke

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Posted 10 May 2013 - 08:19 PM

Mine must have been out of alignment then because the CA was really bad, it was sure not behaving like any F13. And I bought it brand new. Everything looked perfect, cosmetically and mechanically, just not optically. It must have been out of collimating but I don't recollect the front cell being collimatable. Is it a push pull (six screw) cell?

#14 clintwhitman

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Posted 11 May 2013 - 07:11 AM

Peter.
Great looking scope and some very Classic Photos! Nice. Question, why is the focuser changing colors?
Clint :bow:

#15 peter scherff

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Posted 11 May 2013 - 07:32 AM

Good eye Clint. I purchased the scope as military surplus. The Marines had used it for some kind of infra-red camera. They removed the focuser and it was not with the scope when I purchased it. After talking to Al about it I realized that it was going to be easy to replace. He had taken a stock Edmunds focuser and machined it for the scope. A friend had an MPT, he kindly let me borrow his focuser to use as a model to machine the Edmonds one I had found. NEAF was comming up in a few days and I didn't have time to match the paint so I put some white on it and took it to the show. Since then I have painted the focuser the original color. Hence the color change.

Thanks,

Peter

#16 starman876

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Posted 11 May 2013 - 07:50 AM

what a deal as surplus. How are the optics and what size is the lens. Love the iris in the back. However, to change aperture that would be more useful on the front of the scope.

#17 peter scherff

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Posted 11 May 2013 - 08:33 AM

Perhaps, however having the iris near the eyepiece lets me "tune" out the chromatic aberration when viewing bright objects. I don't know if I would use it as much if I could not reach it while looking through the scope.

Peter

#18 starman876

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Posted 11 May 2013 - 08:48 AM

Good point. What size is the lens and what is the focal ratio? I find it amazing you have the scope in the patent description. I was searching for information on the design of these type scopes so I could put some achromats to use. I love playing around with optics. Well, most of us do.

#19 peter scherff

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Posted 11 May 2013 - 08:57 AM

It is a 5 inch f4 or a 1 inch f20 or anything in between!

Peter

#20 starman876

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Posted 11 May 2013 - 09:09 AM

Is the only one ? Did Nagler tell you how many others this style are out there?

#21 terraclarke

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Posted 11 May 2013 - 09:18 AM

Very interesting Telescope. I know of at least one other that I believe is identical to it. Same aperture, F/ratio, and Petzval design, also with the rear iris diaphragm. I am not sure that it had the Tele-vue label but its owner told me that it too was a Nagler prototype. This was in SoCal about 15 years ago. I had an evening's opportunity to use it with him. It was pretty cool.

#22 peter scherff

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Posted 11 May 2013 - 01:34 PM

Hi,

The scope I have is #6, Al thought that he made less than 30. The highest serial number that I have seen is #26.

Peter






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