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Under Dark Skies? Put on your "Night Glasses"

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#1 mloffland

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Posted 06 January 2010 - 11:34 AM

Under Dark Skies? Put on your "Night Glasses"

#2 do dawdle

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Posted 20 July 2012 - 01:11 PM

I am a very rookie astronomer, with one SCT, a Barlow and two eyepieces, so my experience and capabilities for celestial observation are minimal. However, I've been an avid hunter for half a century, and optics have always been a make-or-break part of that sport for me. My experiences as a hunter lead me to strongly agree with several of your points about "Night Glasses."

I have binoculars made by Zeiss, Lieca, Leupold and Steiner. The only true low-light binocs in my stable are a 70's vintage set of big, bulky Steiner 7x50 armored Military-Marines. The Steiners weigh as much as any two of the others, but they are always the ones I have ready to use in my home, boat or vehicle. If I am planning to do some dawn or dusk viewing I always take the Steiners which often dictates my use of a mid-sized backpack or field bag. When I'm actually hunting and carrying a firearm, the Steiner's bulk and weight finally negate their portability and then I carry the very excellent late 70's vintage Leupold 9x25 armored hunting binocs, which give a lot of good seeing in a small, tough package. Of course both the Steiners and Leupolds are nitrogen sealed, this being a necessity for hunting glass. My friends love the Steiners and I could sell them for a tidy sum any time if I was that foolish. They simply can't be beat for exit pupil, eye relief, field of view and light-gathering power. Now that I've been bitten by the astronomy bug, I'm finding the Steiner 7x50s to be quite useful as a very wide field, easily-handled adjunct to my telescope.

I also appreciate your praise of the 6x42 binocs, as that is far and away my preferred rifle scope. I've owned probably two dozen scopes of various power, objective and manufacturer. Over the years, long experience under very nasty weather conditions has lead me to Leupold 6x42 scopes, three of which I have mounted on the rifles I use most. Certainly the modern zoom scopes are fine instruments, but I believe the durability and crisp views of the fixed power tubes are a significant advantage to a hunter. Moreover, from a user's perspective, I feel the best qualities of the 6x42 scope are its combination of very friendly eye relief and exit pupil as well as a generous field of view and great light-gathering power. I can vouch for its worthiness in dim light, rain and under timbered forest canopy, and, after using mine, I can understand why the 6x42 is considered a true classic scope in the hunting optics world. I'm sure the old original 6x42s were loved by their users as much as mine are today, but in my opinion our wonderful modern optics have truly made this rifle scope the one to beat.

#3 amicus sidera

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Posted 30 July 2012 - 11:08 AM

Well-written article, but the author fails to point out that, upon reaching middle age, the pupils of most individuals open to 6mm or less, even in total darkness. This negates any benefit that large, low-power binoculars such as 7x50's have to offer, as any light from the large exit pupil that does not reach the eye is wasted - effectively reducing the aperture of the objectives. For most people over 50, a pair of 7x42 (6mm exit pupil) or 7x35 (5mm exit pupil) glasses are just as effective, and of course weigh considerably less.

#4 Peter D.

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Posted 30 July 2012 - 12:09 PM

While it's true that in theory an exit pupil larger than your eye's maximum pupil size is "wasted" in terms of light grasp, in my experience (with my 5-6mm eye pupil) a pair of 7x50 binoculars give a sharper, higher contrast, more "comfortable" view as compared to a pair of 7x35's. This could be due to the performance of the optics themselves, where your eye pupil is essentially "stopping down" the maximum aperture of the optics to an f/ratio that yields higher performance, in the same way that a camera lens performs better when stopped down to a higher f/ratio than the full-aperture value for that lens.

In my case I'm comparing an old pair of 7x50 "Wide Field" Celestrons to more modern 5x35 and 15x70 Celestrons. The optical quality of these examples may not be identical (made in Japan vs made in China), but the difference in contrast is certainly remarkable. Even though the sharpness close to the periphery of the 7x50's (which have a 10 degree actual field of view) is mediocre and the brightness is about the same as for the 7x35's, the sharpness across the central 7 degree FOV of the 7x50's is superior to the sharpness across the same FOV in the 7x35's.

I bought the 7x35's because I knew they would be easier to hold for extended periods, but in fact I don't use them much because the older 7x50's show me so much more.

Incidentally, my recently-acquired Celestron 15x70's are inferior in every regard except magnification to the 7x50's, and are about par with the 7x35's.

Pete






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