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Meade Adventure Scope 80

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#451 Redbetter

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Posted 22 December 2020 - 02:12 AM

The conversation regarding exit pupils and light loss reminds me of those 2.3x40 wide-field binos. While they have a 40mm objective, their effective aperture is determined by the eyes' pupil dilation, so the effective aperture ends up being less than half of the objective diameter, and gets smaller with less dilation. The binos still "work", though, because the image is still far brighter than naked eye, and the binos present that significantly brightened image in a FOV that's tough to get any other way.

 

While I tend to prefer 'pupil matching' for lowest magnifications most of the time, I don't worry too much about light-loss when I violate the exit pupil 'rule'; the scope is still pumping far, far more light into my eye than my eye alone, and therein lies the utility. Kind of like those 2.3x40's.

I like the 2.3x binoculars because of the enormous field of view for a "semi-naked eye" observing experience, and because I can use filters with them to see large nebula better.  They operate at the max brightness that a person's pupil will allow, essentially the same surface brightness as naked eye observing.  The improvement in scale is enough to show what lurks just beyond our visual range.

 

One clarification is necessary:  the 2.3x isn't really brighter than naked eye in terms of surface brightness.  However, a given object is brighter as measured by total light reaching the eye from the object.   The total luminosity from the object reaching eye will be the square of the 2.3x factor, because of the increased scale projecting that same surface brightness to 2.3x2.3= 5.29 as much retinal area. 



#452 hcf

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Posted 22 February 2021 - 09:21 PM

Just noticed that the Meade Adventure 80 is available on Amazon again for $100 (vs the previous $90).

 

https://www.amazon.c...1/dp/B06XR5L9TK

 

It had been out of stock for a while.




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