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Old Saturday 22nd November 2014, 16:47   #1
Jaybrams
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Join Date: Aug 2009
Location: Boca Raton, Florida, USA
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Field of View Question

I recently purchased a pair of Minox BL 8x33 BR binoculars which I like just fine. My question is probably more generic than just applying to these particular glasses. The glasses are rated at a field of view of 421 feet at 1000 yards.

During the setup of these glasses, i needed to move the barrels closer together to adjust the glasses to my particular vision needs, which is a normal adjustment. My question is: when adjusting the glass either closer or farther apart, does this affect the field of vision? Also, how does extending the eyecups affect field of vision?

Thanks.

Jay A.
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Old Sunday 23rd November 2014, 04:23   #2
Highway Dog
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Hi Jay,

The Field of view is stable when your eyes are lined up on the central axis of the eye piece. It is viewable, the whole area, when you put your eyes at what is known as the "eye relief" distance away from the eye piece lens. That is engineered by the manufacturer and their optical designers.

It might be obvious, that as you swing your binocular tubes together, that clear the sides of the binocular that obstruct your view. Then your eyes have clear view through it. Another way to say that the full Field of View is blocked until you eyes get lined up. A neat detail is that all the grid points that could be marked on the objective (the lens that is held away from your face) are getting the image of what you are looking at. If you had a small splatter of paint on that lens, the view would still be clear, not blurry, but just a bit dimmer.

Now for the eyecups. The eye cups help you hold the binoculars at that special distance from your face that is defined as the eye relief. The distance for that Minox BL is a bit more than 2/3rds of an inch, which is 17.5 mm. At that point you should see that entire view of 421 yards at a thousand feet, which comes to an angle of 8 degrees. When you have the eyecups extended so that your eyes are pushed beyond that 2/3rds distance, then the field of view becomes cut off around the edges. Then you would only see a 7 or even a 6 degree angle. Sometimes I hold a pair of binoculars about 15 inches away from my face. Then I see like looking though a tube, like it is 2 degree angle. Most of the Field of View is cut off. I find that my eyes are relaxed and just gently looking without strain. I can now detect if one of the tubes is slightly tuned away from the other tube.

If your eyes are pushed too close to the binoculars eye lens, then you could experience a "black out" where the view fails to get projected into your eye. Or some designs may still let you see, but you are now seeing some unwanted light reflections or artifacts inside the binoculars.

Now did I answered your questions, or if I should put this in other words?--

I hope you enjoy those fine binoculars! What bird did you last see through them?

Rob.
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Old Sunday 23rd November 2014, 18:27   #3
Jaybrams
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Thanks, that helped a lot. As it has been rainy here the past few days, I have been restricted to looking in the back yard. And, then, only briefly since it has been dark when I get home from work. My real passion is bird photography and we have several amazing refuges nearby here in south Florida. I wanted the Minox to take along on my photo expeditions. We will be having visitors for the next couple of days and then its off to New York for the holiday. I hope to get out this afternoon and a bit with our guests' indulgence and will report back.

I know there is a newer version of these binocs out now, but I chose to patronize the only shop in our area where I could try various binocs before making a selection. Although they didn't have the newest version in stock, I wanted to support them and I really liked the Minox and expect to have many years of excellent service from them. They will certainly be easier to hold and use than my 14 year old Swift Audubon 804s.
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Old Monday 5th January 2015, 05:14   #4
WJC
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Quote:
Originally Posted by Jaybrams View Post
Thanks, that helped a lot. As it has been rainy here the past few days, I have been restricted to looking in the back yard. And, then, only briefly since it has been dark when I get home from work. My real passion is bird photography and we have several amazing refuges nearby here in south Florida. I wanted the Minox to take along on my photo expeditions. We will be having visitors for the next couple of days and then its off to New York for the holiday. I hope to get out this afternoon and a bit with our guests' indulgence and will report back.

I know there is a newer version of these binocs out now, but I chose to patronize the only shop in our area where I could try various binocs before making a selection. Although they didn't have the newest version in stock, I wanted to support them and I really liked the Minox and expect to have many years of excellent service from them. They will certainly be easier to hold and use than my 14 year old Swift Audubon 804s.
A 14-year old Audubon is still a real gem.

Bill
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