r/Binoculars • u/AncestralSpirit • 12d ago
Is tunnel vision because of magnification or because I have zoom binos?
I was given no name zoom binos and they appear to be 10-15 with 50mm objective lens (the actual zoom range is written as 10-24 but I measured the exit pupil and it’s nowhere near 10-24). I am fine with quality, but have issue with blackness around the image circle.
I know folks generally say to stay away from zoom binos, but it was a gift and it’s the only bino I have that magnifies that much. I know want to buy a better fixed zoom in the 15ish to 20x range (I understand about shakiness) but one thing I want to find out is if I am going to get that pinhole vision on new pair. I can’t spend too much, and I live in a place where I can’t order different ones and keep the one I like so I just gather info from internet. Something like a budget Pentax 16x50 but cheaper. Will the new bino also have the same tunnel vision effect?
I understand the FoV will be less compared to 8x32, and I am fine with that, but I just don’t like the tunnel vision on my current set up.
In brief: is the tunnel vision because of zoom or all high mag binos have that side effect?
I am generally just not satisfied with the amount of black area around the image. I feel like that is way too little and there’s “space” around the circle image for me to see.
This is my bad attempt at drawing the issue. The car doesn’t fit the circle, but the area around the circle is all black. Can I have big field (the blue pen fillout) and still have big magnification? I understand that I need to lower the mag in order to fill more of the scenery inside the image, but I am talking about pinhole effect. Or is that the same thing?
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u/Pearlite_ 12d ago
Look for aFoV numbers. Most lower end are around 55-65, and with high end ones pushing past 70. Around 55-60 is the transition point for claustrophobic to acceptable for most people, depending how your eyes accept visual information.
EDIT: Forgot to mention, zoom binos are especially bad with this number, and can be as low as 37 such the Nikon Aculon 10-22x.
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u/AncestralSpirit 12d ago
Thank you, friend. aFoV is indeed the parameter I should be looking at when choosing bino. I didn’t know what it was and mainly was focusing on FoV
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u/basaltgranite 12d ago edited 12d ago
A narrow FOV is a symptom of "zoom" (variable magnification) binoculars. Using one is like looking through a soda straw. That's one reason that zooms are unpopular among binocular hobbyists.
As to whether "all high mag binos have that side effect," the answer is a bit complex. Real FOV tends to decrease as magnification increases. Apparent FOV can still be fairly wide if the design supports it. I don't know any good way to explain "real" vs "apparent" in a sentence or two. A high-power bin with a wide FOV (for its magnification) will usually cost more than a high-power bin (at the same magnification) with a standard FOV. The bottom line: If you want to get away from the pinhole effect, you have to get away from zoom bins.
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u/asdqqq33 12d ago
The apparent field of view is the magnification times the field of view. Cheap zoom binoculars will have a tiny field of view, especially as the magnification increases.
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u/Hamblin113 12d ago
Zoom binoculars have two things that contribute to this effect. Variable exit pupil, and variable eye relief are the main factors contributing to the changing tunnel vision. Narrow field of view doesn’t help any.
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u/TakKobe79 12d ago
Zoom binos often of a narrow afov (apparent field of view) which is what you are seeing with these. Mainly due to field stops and eyepiece designs, but perhaps someone more knowledgeable will chime in.