Since I got my first pair of really good binocs - Nikon Monarchs 8x42, I'm becoming more aware of the important things like eye relief, field of view, and such.
As I try to find a good pair of higher power binos in the 9x to 10x range, at a low price, I'm always looking at eye relief. Since my Monarchs have 19.6 (I think) eye relief and I always wear glasses, I always look for binos with at least 19 eye relief.
But, do I really need 19mm eye relief? I wear glasses. The glasses sit on my nose normally, not close to my eyes and not on the tip of my nose, but normally. I'm happy with my Monarchs.
So, would I get good eye relief with 18mm or 17mm or even 16mm? I've read if you wear glasses don’t' go below 16mm. But I've also read from bino users not to drop below 19mm and maybe go for 20+mm.
So, how low can I go with eye relief?
I'm talking about binos for birding. 9x to 10x.
Much Thanks!
What you want is the "correct" ER for you: the one that puts the exit pupil coincident with the entrance pupil of the eye (the iris).
It depends on your prescription (myope/near or hyperope/far? how strong?). Myope glasses with a negative prescriptions lengthen the effective ER. Positive prescriptions shorten it.
It depends up how closely your glasses fit i.e. how far the eyeglasses are from your eyeball. This isusually taken as 12mm but it varies by plus or minus 5mm depending on your glasses.
It depends on what the maker means by his ER number? The technically correct: ER from the backside of the last ocular lens? That gives the biggest numbers. Or perhaps more useful: the usable ER. From the closest point you can place your eye (well eyeglasses) which depends upon how the ocular lens mount and eyecup are designed.
Throw in a couple of mm for lens thickness to (that goes up with your prescription) depending on the thickness of your eyeglass lens. Again hyperopes get screwed with their lens being thickest in the center.
Answer: Only you can know by checking out the bins.
For me I tend to have more problems with modern bins with blackouts and too much ER rather than too little!
If you have more than one pair of glasses you can "tune" them to the ER.
Search for "eye relief" amongst my posts ... I've talked about this quite a few times. In great detail.
Hi HoosierGuy!
I think I am in the same occasion as you are. I need long eye relief and mostly close to 20mm. I think Monarch 8x42 is quite comparable to Swarovski SLC 7x42 in this case. I have the Swarovski SLC7x42 and have also tried Monarch 8x42. Maybe you will make it with 2-3mm less eye relief than these have. But remember that the stated numbers of eye relief isn't always comparable. You have to try before yoy by. Nikon SE porro glasses are stated to 16mm eye relief and works well for me.
Regards, Patric