Is there an optimun exit pupil diameter for daylight conditions?

[Marley]

Hello to everyone.

As some of you may have noticed on a previous post, I am in a bit of a quandry regarding a pair of 8x50 Ultravids.


They are certainly great bins (as are my other 2 Leica bins), but I seem to have a great deal of difficulty with blackout in daylight settings, even if the eye cups are extended all the way.

I do not think that I have experienced such problems with bins of small objective sizes, but it could just be my faulty recollection. I will go back to the optics store today for some comparison shopping.

My question is: Is there an optimum EP diameter range for daylight viewing? Will I see just as much blackout with an 8x45 Ultravid as with the 8x50? I have read in other posts that bins with large diameter objectives are prone to blackouts. I have also read that you can learn to properly use the bins and eliminate most of the problem.

Any thoughts would be most appreciated as I have 30 days to return the 8x50s and I will do so if the problem can be eliminated by choosing a bin with a smaller objective.

Rgds,

Steffan

[Rich N]

Hi Steffan,

My Leica 8x42BN has very good eye relief and I've never had a blackout problem with them. The same for my Swarovski 8.5x42EL.

I've used a friends Zeiss 7x42 Classic. It has a large exit pupil, very good eye relief and no blackout problem.

I like a 5+ exit pupil for daytime viewing. They are fast getting on a target.

My two biggest concerns with the Leica 8x50:

1. It's heavy, 35+ oz. (the Ultravid)

2. It has a relatively small true field of view for an 8x binocular.
8x50 Ultravid = 345 ft at 1000 yards
8x42 Ultravid = 390 ft at 1000 yards

Rich

[mcdowella]

I don't think blackout is simply related to pupil diameter, or to much else. I have a Nikon 8x30 E II which, as other people have reported of its 8x32 SE big brother, is somewhat blackout-prone. Neither my 8.5x44 Swift Audubons, 7x42 B&L Discoverys, nor 8x25 Nikon Sportstar IIIs are backout-prone. Until I saw your post I thought it might be related to large apparent fields of view making what should be an automatic process of lining your binoculars up with your eyes less reliable.

I wouldn't like to predict whether or not any particular design would be blackout-prone, but some people don't have problems so you might be able to train yourself or adjust yourself out of it. If I would you I would try raising the eyecups to reduce the eye relief, and get into the habit of moving the binoculars fractionally away from my eyes to recenter them when blackout occurs. I think with practice I have become a little less liable to backout with the E IIs (but to be honest, I use the Swift Audubons as my main binocular because - amongst other reasons - I have never had a blackout problem with them).

[Marley]

Thank you both for your replies.

After reading several posts and doing some research, I have come to the conclusion that the larger objective must have something to do with the blackout problem. Many have told me that there Leica (and others) _x42 bins don't have a blackout problem, and after yesterday, I have to believe them.

I hate to say it, but for me, a solution has been found.

I went back to the optics shop and spent some time with the runner-up in my bin search. The Swaro 8.5x42 ELs are not only the sharpest bin that I tested, but with an eye relief equal to the 8x50 Ultravids (18 mm), I experienced no blackout problems. I do wish that I had a chance to test the 8x42 Ultravids, but the shop was out of stock. Needless to say, the Leicas went back and I bought the ELs.

That was a tough choice. The build quality of the 8x50 Ultravids was absolutely outstanding. They were SPOTLESS, inside and out and the focus was smooth as silk. They were also a pleasure to use in low light. For the record, anyone that owns a pair of Ultravids owns a pair of bins that at least equals the best in the business.

But one of my goals in buying a new pair of bins was ease of use, as my wife (and perhaps others) will be using these as well. I just could not see coaching people on how to hold my bins. For top of the line money, you should receive top of the line performance. I was also able to try the Zeiss FL and the Leica Trinovid. While they also provided excellent performance, the minute I held the ELs up to my eyes, I knew that they were a match for me.

Folks on the forum have said several times that you have to go with what works for you and not for others, and I am happy to say, that is what I did. That is really great advice. Buy what works for you. Your money, your eyes, your satisfaction.

Thanks again for everyone's help in this search. You have all been a terrific help.

Rgds,

Steffan

[Robert Ellis]

Well, even if we didn't figure out why they didn't work for you, you managed to get a pair that did work instead. I'd call that a success.

Merely having a big objective wouldn't cause that, there is probably something about the overall design of the optics that did not work with your eyes.

[Rich N]

Congratulations, Steffan!

The 8.5 EL is outstanding.

Rich