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12 x or 15x

Started by darylc, 10/24/2002 12:11PM
Posted 10/24/2002 12:11PM Opening Post
I have decided to buy a pair of Orion Little Giants 70mm, to compliment my 5" Mak. I want it not only for "pre-scouting" areas intend to put the scope on, but I want ot use it as well when on the road. I want the ability to be able to see and show others such things as M81, M33, M31, M13, M22, etc you get the picture. I am interesed in the opinion of this group whether they would prefer the 12x70 or the 15x70. For use at home I intend to create a simple bino rest for extended view. Thanks for the input.

Daryl Crowley
Ludington, MI
Posted 10/24/2002 12:46PM #1
Hi Daryl,

From your post it sounds like you would not be taking a mount on the road. I have used 12x binoculars for travelling, but found that 12x is borderline for hand holding. Some may say that they can do it, but I was always looking for something to steady them on (signpost, roof of my truck, etc.) and ultimately went to higher power with image stabilization.

Also, while showing others the M's you mentioned through hand held binoculars is certainly possible, it might be frustratingly difficult. I have found that if someone is unfamiliar with the night sky, you can't just hand them the binoculars and expect them to find anything.

For the above reasons plus the slight increase in light grasp discussed before on this forum, I would say go with the 15x and carry a lightweight tripod and mount with you.

Clear skies, Milt
Posted 10/25/2002 03:43AM #2
The above statement is accurate. In order to show anyone else an object in binoculars for all but the brightest objects, they must be mounted.

The Little Giant binoculars are said to have image sharpness fall off dramatically beyond 50% out from the center. My experience with two other Orion Binoculars, the Ultraview 10x50 and the Giant 16x80 is the same. Image degrades by the time you are 60% out from the center to the point that you cannot see Alberio split as a double star. That is poor performance. As for the center 50% of the fov, the Orion 16x80 were one of the sharpest binoculars I've ever owned. But that is not a good indication of how usable they are.

My point is this: If you have a binocular with a 4 degree field of view and only the center 50% is sharp, you have reduced the usable area of view from the maximum possible of 12.5 square degrees down to only 3 to 4 square degrees. That is poor performance. I own six different pair of binoculars. This kind of performance drop off is readily noticable when you go from one pair to the other.

Oberwerk 15x70s hava a max fov of 4.4 degree with a sharp field ver 80%+. Pentax PCF 12x50 have a 4.2 degree field ov view with a sharp field over 90%.

You would not notice the drop of in sharp field performance when viewing double stars or small globulars, but you would have a hard time with M81 and M82 in the same fov, or you might have a hard time with an extended object like M33.