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Very Hot Topic (More than 25 Replies) Happy Birthday to Me - Unertl Scope (Read 17250 times)
westerner
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Re: Happy Birthday to Me - Unertl Scope
Reply #15 - Dec 7th, 2013 at 6:05pm
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Okay, got all that. So the extra eye piece is just an extra? Or you don't know your own self and that's why you can't answer.  One little ole eyepiece, phew!   

    Joe.
  
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John Boy
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Re: Happy Birthday to Me - Unertl Scope
Reply #16 - Dec 7th, 2013 at 6:20pm
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Hmmm - check this out ... (You need to Login or Register to view media files and links)
Says the 1 1/2" Target came in a 24X!
  
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Re: Happy Birthday to Me - Unertl Scope
Reply #17 - Dec 7th, 2013 at 10:42pm
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In the process of designing a scope. Numbers say about 15X maximum for an 1.5" objective. Higher magnification and you start to loose brightness on cloudy days or targets in the shade. Any comments?
Chuck
  
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Re: Happy Birthday to Me - Unertl Scope
Reply #18 - Dec 7th, 2013 at 11:55pm
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Lyman made a 30 power 1 1/2" scope. Excellent when the day is bright.  Had to replace one with a 20 power late in the evening at Etna Green. Power is over rated.

     Joe. 

  
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Re: Happy Birthday to Me - Unertl Scope
Reply #19 - Dec 8th, 2013 at 3:22am
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Chuck,

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Re: Happy Birthday to Me - Unertl Scope
Reply #20 - Dec 8th, 2013 at 12:09pm
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Thanks for the comments. Excellent website. Interesting statement: "Human eye has maximum resolution with an exit pupil of between 2 and 3 mm."

Sorry, John. Did not mean to hijack. That is a beautiful and excellent scope and the two different eyepieces make it better. Don't have to change scopes, just eyepiece.
Chuck
  
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John Boy
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Re: Happy Birthday to Me - Unertl Scope
Reply #21 - Dec 8th, 2013 at 12:44pm
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Gents - Hijack at will!  The more we learn about these scopes the more educated we become, especially me.

OK, something I have never seen in the reference books that I have about scopes.  So, go back to the link above ... 
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Look at the information that Dewy Greiner has on his site for all the Unertl scope models ... Power - Field (ft) & Lumens

Because both the oculars on the Unertl are not stamped and not a whiz bang with math - I'm going to take the oculars to my friendly optometrist and have him measure the power of each 

  
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Re: Happy Birthday to Me - Unertl Scope
Reply #22 - Dec 8th, 2013 at 2:02pm
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Don't know what to do with Lumens, but looks like it has to do with the square of the exit pupil. Double the magnification and get 1/4th the Lumens or measure of brightness.

Have your friendly optometrist measure the focal length of the oculars or use Frank's method. If you know one makes the scope 20X, then the magnification with the other one can probably be calculated. 
Chuck
  
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John Boy
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Re: Happy Birthday to Me - Unertl Scope
Reply #23 - Dec 8th, 2013 at 4:02pm
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Quote:
Don't know what to do with Lumens, but looks like it has to do with the square of the exit pupil.

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Quote:
The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (radiant flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye's ability to perceive it. A lux is one lumen per square meter.
  
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Re: Happy Birthday to Me - Unertl Scope
Reply #24 - Dec 8th, 2013 at 5:55pm
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On the 2nd page of the pdf, in the 2nd paragraph under the topic Brightness, the author D.R. Wulfinghoff states:

"The light could be reflected or transmitted. For example, the bright surface could be the surface of a fluorescent tube, a page of a book, a window with a view of the sky, or a store window with reflections." 

Sounds good to me... the target we want to see is much like a paper page of a book, the light provided by the sun is reflected off the target and transmitted to our eye through the lenses in our scope.

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John Boy
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Re: Happy Birthday to Me - Unertl Scope
Reply #25 - Dec 8th, 2013 at 7:56pm
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Quote:
Footcandles and Lux
“Footcandles” and “lux” are units that indicate the
density of light that falls on a surface. This is what light
meters measure. For example, average indoor lighting
ranges from 100 to 1,000 lux, and average outdoor
sunlight is about 50,000 lux

"I was at the range and the light wasn't too good, it was only 30,000 lux.  Every range box needs a lux meter and posting 'it was cloudy' is now passe  Wink 

I presume also, one can put the meter in front of the scope and measure how well it gathers outside light
  
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Re: Happy Birthday to Me - Unertl Scope
Reply #26 - Dec 8th, 2013 at 9:24pm
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John Boy,

Is that 3.6 lumens shown on the unertl36.htm page for the 1 1/2" 20x Targetscope obtained with outdoor sunlight at 50,000 lux, or at 30,000 lux?
        Grin

  
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John Boy
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Re: Happy Birthday to Me - Unertl Scope
Reply #27 - Dec 12th, 2013 at 4:20pm
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westerner wrote on Dec 7th, 2013 at 6:05pm:
Okay, got all that. So the extra eye piece is just an extra? Or you don't know your own self and that's why you can't answer.  One little ole eyepiece, phew!  
    Joe.

Update to respond to Joe's post:
*  Found in my references - Cornell Publication's - 1956 Unertl Catalog reprint, 37 pages with all one wants to know about Unertl's
*  They list Interchangeable High & Low Power Eye-Pieces for their scopes to increase or decrease power:
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Turn the page-pg 30, Unertl 1 1/2" Target Scope.  I applied the two eyepiece's power increase & decrease to my 20x scope:
20x < 35% = 13x ... the lower power eye piece
20x > 35% = 27x ... the higher power eye piece
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Turn the page - pg 36, Physical and Optical Propertied. and Dimensions of Unertl Scopes ... including 1956 prices

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In 1956, one could buy the 1 1/2, 20x - 25" tube & extra eye piece for $97.50.  Inflation adjusted from 1956 to 2013, the scope & eye piece is $836.16 (758.6%).  Guess I found a deal - I paid $395 plus $15 shipping ... a real Happy Birthday To Me! 
Turn myself in at the nearest police station?
Nope Red, going be a fugitive for this purchase Lips Sealed
« Last Edit: Dec 12th, 2013 at 4:26pm by »  
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Re: Happy Birthday to Me - Unertl Scope
Reply #28 - Dec 12th, 2013 at 5:28pm
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Thanks for that reference John.  I'll have to get that reprint.

Chris.
  
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Re: Happy Birthday to Me - Unertl Scope
Reply #29 - Dec 12th, 2013 at 7:24pm
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Thanks John,this is great info on these Unertl scopes Regards--Fritz
  
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