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Unitron 40mm Alt-az Refractors

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#1 Steve Allison

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Posted 09 January 2020 - 10:59 PM

I own two Unitron 40mm, F/17.5 refractors, including a very early example I recently acquired from Dave Trott. Both produce beautiful images for their size and I have had a lot of fun using them.

 

I find that the challenge of finding and observing my favorite celestial wonders with these tiny instruments has made my nights under the stars fresh and new again. Most objects look much different than through my larger telescopes, and it is almost like seeing them again for the first time.

 

I recall several earlier threads where some owners of these little guys found the optics to be less than stellar, so I set up my DPAC rig to see for myself.

 

On my two examples, at least, the lines are ruler-straight and thus indicative of excellent spherical correction. And at F/17.5 for a 1.6" aperture, color is obviously not a problem.

 

Under dark skies, brighter double stars look wonderful due to the large Airy disks, and I even saw a little detail on Mars during last year's opposition. Saturn's rings and a couple of Jupiter's belts are duck soup in these tiny marvels. And most of us are aware of the striking, seeming 3-D images of the moon such small telescopes can deliver.

 

Anyone who has not observed through a diminutive refractor may find, as I did, another dimension to this hobby of ours!


Edited by Steve Allison, 09 January 2020 - 11:01 PM.

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#2 Esso2112

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Posted 09 January 2020 - 11:13 PM

I am amazed every time I look through mine (Model 127) at what a great little scope it is. The moon through a 40mm refractor just has a unique wow factor to it. 


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#3 J A VOLK

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Posted 10 January 2020 - 12:06 AM

I believe the Model 127 turned into the Model 740 around 1962.  Unitron came out with the 700 Series: 40mm, 50mm and 60mm AZ scopes, all with a focal length of 700mm!  It appears to be a marketing strategy to repackage the Model 127, Model 105 and 60mm guidescope optics in a more affordable package then the 127, 105 and 114, and the 760 being a bit more compact then the 114.


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#4 CharlieB

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Posted 11 January 2020 - 11:35 PM

40 and 50mm scopes are my favorites.  They are great grab & go scopes and provide views that surprise most people.  The optics are first-rate.  The Ronchigram is of the Unitron 105.  The only 50mm scope I have that equals the 105 is the Nippon Kogaku.

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#5 Steve Allison

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Posted 12 January 2020 - 01:03 AM

Charlie-

 

Your Ronchigram image shows how my own two 40mm Unitrons look under testing.

 

I used to own a Unitron model 105 myself, and it was this telescope that rekindled my interest in observing back in the 1980's. Mine could resolve the double-double!



#6 CharlieB

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Posted 12 January 2020 - 08:55 AM

A

 

Charlie-

 

Your Ronchigram image shows how my own two 40mm Unitrons look under testing.

 

I used to own a Unitron model 105 myself, and it was this telescope that rekindled my interest in observing back in the 1980's. Mine could resolve the double-double!

As does my 105.  They are exceptional scopes and the mounts are equally fine.


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#7 KerryR

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Posted 12 January 2020 - 12:10 PM

While I don't have a 40mm long focus achro, yet, I've found I've really enjoyed my UO 50mm f10, and Ed.Sci. 60mm f8. Really makes me covet one of those classic long-focus 40-50mm scopes. I'm keeping my eyes open...


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#8 grif 678

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Posted 21 January 2020 - 05:34 PM

Do not have a 40mm long focus, but my 40mm Halleyscope is terrific on the moon, and last night, before the sky got dark, I could see a hint of nebulosity around Orion, without a dark sky. I think that is pretty impressive for a 40mm scope. I have two of these, and these are well built, and optically great scopes for their size.


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