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16x50's for Astronomy

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#1 Guest_**DONOTDELETE**_*

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Posted 25 April 2004 - 11:43 AM

Hello Again All,
I'm seriously considering purchasing some 16x50 Nikon Action VII's. Does anyone have any opinions of the views that I can expect to see. I am already familiar with views through 15x70's and 20x60's.
Would the 50mm Objectives really limit my views of deeper sky objects such as Nebulas and other Messier objects?
Nikons are supposed to be about the best 16x50's out there!
What do you think?
Ray A. :question:

#2 lighttrap

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Posted 25 April 2004 - 03:46 PM

Just out of curiousity, is there any reason why you would prefer the 16x50s to something like the Oberwerk 15x70s?

I'm not familiar with the Nikon Action series 16x50s, but just generally, regarding the Nikon Action series line, I'd suggest to really hand pick a set. I've seen more QC variations between supposedly identical models in that line than in many other lines. Some are good, and some really aren't.

Mike Swaim

#3 I hate spam

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Posted 25 April 2004 - 07:24 PM

Well, if your just going to turn around and sell them after a week buy'em and find out. :grin: ;)

#4 Guest_**DONOTDELETE**_*

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Posted 26 April 2004 - 07:24 AM

The 16x50 binos in comparison to the 15x70, will have an overall reduced limiting magnitude. The magnification is slightly greater, but the aperture is much less. The net effect is a reduction in limiting magnitude. You can still see some Messier objects, but with less light reaching your eyes.

#5 EdZ

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Posted 26 April 2004 - 07:43 AM

The limiting magnitude will vary by only 0.1 to 0.2 magnitudes, at most. Where the 15x70s may reach to mag10.8, the 16x50s will reach only to mag10.7 or mag10.6.

The biggest differences will be in brightness of image. With a much smaller exit pupil in the 16x50s, Faint extended objects will not show up nearly as well in the 50mm binoculars. Observations of faint nebula and extended galaxies would be much more difficult with the 16x50s.

In your favor, the larger exit pupil in light polluted skies admits more bright sky background into the total image. In this case a smaller exit pupil might be a benefit. Under darker (NELM mag 5+) skies, the larger exit pupil should perform much better on extended objects.

edz

#6 BarrySimon615

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Posted 26 April 2004 - 07:49 AM

Generally speaking, I would think twice about purchasing any binocular for astronomical use if the eyepiece/objective combination dropped the exit pupil below about 3.5 mm. For 50 mm binoculars that happens with any magnification above 14x. So for most applications a 12x50 pair of binoculars would be my personal limit. At 16x, binoculars really should be mounted so the smaller size of the 50 mm binoculars in respect to weight is of inconsequential value.

If views thru other binoculars at about 15x/16x have you interested in that magnification, you may want to consider either the Pentax 16x60 or the Oberwerk 15x70. The Zeiss 15x60 is one we would all like to have but the price keeps it out of range.

Nikon improved the view and the build quality of their Action line with the recent release of the Action Extreme, a waterproof model available in many sizes including the size you are interested in. Early Action models, such as the one you mention are all reduced at most dealers as they are no longer being made. If you ultimately get the earlier Nikon Action 16x50, be prepared to spend some additional money on a decent tripod. While some claim they can reasonably handhold binoculars with this magnification for reasonably long astronomy observing sessions, conventional wisdom and time under the stars proves otherwise.

Barry Simon

#7 lighttrap

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Posted 26 April 2004 - 11:18 AM

Generally speaking, I would think twice about purchasing any binocular for astronomical use if the eyepiece/objective combination dropped the exit pupil below about 3.5 mm.


I used to think the same thing. Then I got to play around with some Miyauchi 40x71s with 1.775mm exit pupils. That pretty much opened me up to the idea that there's really little reason why binoculars can't be made to perform with exit pupils as small as 1mm. Unlike telescopes, I wouldn't want to go below 1mm, with binoculars because precise eye alignment would be too difficult. Granted, that's a completely different animal than what most folks think of when they think of binoculars. But, when you get into the category of binocular telescopes, there's really little reason why they can't be thought of in terms similar to telescopes as far as usable exit pupils, etc. These days, I'm perfectly open to the idea that such obscure combinations as 22x60, 22x71, 40x71, 37x100, 40x100 are all viable. Of course a very steady mount is mandatory. And of course at that level of expenditure, thinking twice, thrice and then some more is prudent.

However, all this has nothing to do with the orig. question, and I would tend to 2nd Barry's generalized advice, particularly the point about the weight savings of a 50mm lens being irrelevant to a mounted 16x binocular.

Mike Swaim

#8 Guest_**DONOTDELETE**_*

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Posted 26 April 2004 - 02:29 PM

Thanks for the help all,
informative to say the least!
Ray A.


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