Field of View

[devonsue]

Help please. I know this might sound stupid but how can I assess the FOV with glasses off and glasses on? In other words I want to see if I lose any FOV when wearing specs. What test can I perform please?

Sue

[PeterB]

I would have thought you would need to fix the bins (I assume you are talking bins) firmly in place and set them on a target you can see the edges of and note. Perhaps the side of a big building where you can count windows or even bricks. Then do the comparison.

Really curious though, what do you think is happening?

[dales birder]

To test f.o.v. I use a brick wall about 100m away and count the bricks in view.Never found the need to fix the bins in place as long as you have a fixed point on the wall in a set place in your view.I tried many pairs this way recently as an ongoing eye problem seems to be easier with bins (and I suppose 'scopes) with a wide field.A birding eye specialist said this may be worth trying and after 4 or 5 outings I can see the advantage.

[devonsue]

Thanks guys I'll give it a whirl. I was on the right lines but just wanted to be sure as I'm currently testing some alpha bins and need to be absolutely sure they are right for me. Sue

[dales birder]

You will be very lucky to get full field of view with glasses and it seems to vary with shape/size of your frames

[devonsue]

I have just tried them out on a wooden slatted garage door (no brick walls here) and I do manage the same FOV with and without glasses. That is obviously altering the eye cups accordingly. The stated FOV is 140m @ 1000m so whether I actually achieve that is anybody's guess and as maths and equations were never my strong point I'll pass on that!!! It makes me wonder whether any of us actually achieve it as if you alter the eye cups too much you actually lose FOV. Anyway I'm happy that my glasses aren't narrowing the FOV.

Thanks again,

Sue

[aquila 1]

I would have thought the field of view would be the same, with or without glasses, as most bino's are made for either. mac

[devonsue]

Hi Mac

Yes and no. It does depend very much on eye relief. It's taken me many months to actually find a pair that suits me when wearing specs. I used to have to take them off to use the bins in previous pairs I had and then of course the bird has flown!!!

Sue

[magpie]

I would have said it would be the same, what I found was it depends on the eycups, I got our local shop to fit mine with ones that fit snug with my specs.

[Dave H]

My older Imagic Poros has those thin rubber fold down eyecups. I've added some velcro, wound round the eyepiece to extend it a little. I don't wear glasses, but it's clear when too much relief is used as the border of the FOV changes from a hard transition (to black) to a soft, fuzzy transition.
Is this the same for glasses wearers?

Dave