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Question about binocular aperture

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#1 stevereecy

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Posted 27 October 2021 - 04:05 PM

I just bought a mint Sears discoverer 60 mm pair of binoculars. It’s mint with all the caps and the original case. Not sure if I’m a Binocular person so I might sell this later if I don’t love it.

My question is how much light gathering does this have compared to a telescope? On the one hand it has the light gathering ability of two 60 mm Telescopes. However that light gathering is divided into two separate eyes, but then goes into one brain. So is it about the same as a single 85 mm telescope, or is the image comparable to a 60 mm telescope?


Edited by stevereecy, 27 October 2021 - 09:26 PM.


#2 markb

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Posted 27 October 2021 - 04:53 PM

The generally accepted rule of thumb is 1.4 x the single aperture of a binocular telescope (it gets most often applied on big BTs like the APM 100s etc).

 

It seems pretty accurate on the bigger BTs, I never did an A-B on 'little' binos.

 

What model is the Sears? I don't think I read about one before, or hit one on eBay. 

 

So 60mm per barrel looks like a single 84mm to the brain.



#3 markb

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Posted 27 October 2021 - 04:59 PM

Single mag, that is, on the Sears model.

 

I know Tasco did 60 and 70mm zooms in the 90s IIRC, I have those. Handy little (well, medium sized) devils. I assume Sears rebranded those like many earlier products.


Edited by markb, 27 October 2021 - 05:00 PM.


#4 stevereecy

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Posted 27 October 2021 - 05:03 PM

The generally accepted rule of thumb is 1.4 x the single aperture of a binocular telescope (it gets most often applied on big BTs like the APM 100s etc).

 

It seems pretty accurate on the bigger BTs, I never did an A-B on 'little' binos.

 

What model is the Sears? I don't think I read about one before, or hit one on eBay. 

 

So 60mm per barrel looks like a single 84mm to the brain.

Model 473.25870   Definitely seers and definitely 60 mm. I found one by googling. Very rare apparently.


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#5 sevenofnine

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Posted 27 October 2021 - 09:22 PM

Sears imported some pretty decent astronomy gear in the old days. Test your binoculars for collimation by observing a long horizontal line like a fence or tiles on roof. If the lines merge to form one line from one ocular to the other then it's good. Out of collimation binoculars will cause eye strain and fatigue. If you got a good one, they should be great for viewing the night sky waytogo.gif


Edited by sevenofnine, 28 October 2021 - 07:16 PM.


#6 markb

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Posted 28 October 2021 - 12:37 AM

I guess they are the 10-40 zooms?

 

Zoom 60s and 70s are my zoom exceptions. The aperture keeps the high power usably bright. I always thought the higher zoom power forced the designer to take more care in objective design and execution to get a solid image without breakdown at the high power. It might be just in my head but I thought mine were better objectives than run of the mill Sears/Tasco/etc 50mm binos.

 

I'd test collimation both vertically and horizontally.

 

The building line test is good, but I use a test with the instrument held far enough from my face that I can isolate a single shared distant object like a 1/2 mile distant street lamp or, better something farther like a star.

 

If there is a problem, and there.likely is not...

 

Since oldies often have eccentric objective cell collimators, collimation is possible, with practice.

 

Your Sears might be too late for eccentrics.


Edited by markb, 28 October 2021 - 12:38 AM.



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