Long ER question (1 Viewer)

Do MFGs assume that a lower-power binocular user will be wearing glasses? I'm just curious why the Viper HD 6x32 has such a long ER? For me, even with the eyecups fully extended, I still have to place my eyes back from the eyecups. I can just barely brow-hold the binocular but it's not very comfortable.

I've noticed that in my collection most of my binoculars have relatively similar ER distances. It seems like my ideal range is between 15-17mm but once I start going over that, it's not as "relaxing" of a view.

It's not uncommon that the eye cups of binoculars are not really suited to the eye relief. I guess the 6x32 has identical eyecup length as the 8x32 which has shorter eye relief.

I've noticed, generally speaking, that lower power binoculars like 7x42 and 6 x32 usually have longer eye relief than higher power binoculars. I think it might be because the oculars used in them have longer focal lengths than higher power binoculars do. For instance, in a 42mm binocular with a focal length of 168mm @ f4 a 7x binocular would use an ocular with a focal length of 24mm while an 8x ocular would be 21mm.

Of course use of a wide field ocular with a different design would change the eye relief so there are other factors at play.

Also, in your case with the Viper 6x32, Vortex may not be using an eye cup that is long enough for the eye relief. I remember purchasing an inexpensive 10x28 Hurricane at a close out sale from Vortex years ago that had eye cups far too short for the eye relief I needed to use it without glasses. I gave it to my son who wears glasses and he had no trouble with it.

Bob

cnick6 said:

Do MFGs assume that a lower-power binocular user will be wearing glasses? I'm just curious why the Viper HD 6x32 has such a long ER? For me, even with the eyecups fully extended, I still have to place my eyes back from the eyecups. I can just barely brow-hold the binocular but it's not very comfortable.

I've noticed that in my collection most of my binoculars have relatively similar ER distances. It seems like my ideal range is between 15-17mm but once I start going over that, it's not as "relaxing" of a view.

Click to expand...

You are talking about what I call "forced eye relief". It can be very irritating.
Many priceybinoculars have that issue, whatever the eye relief. Some binoculars
with 20mm or more don't have the 'blackout' problem. For newly bought,
you have to see to be sure, but there are makers who help the situation.
Most Meoptas, for example, have 3 or 4 positions for the eyecup so you
can fit to the 'finicky horse' premium optics. I can go with and without
glasses on the Meoptas. That's what I insist on.

Spending doesn't always correlate with the maker not forcing your eye position.
On the cheap end, the LL.Bean/Bushnell Discoveries work flawlessly with and
without glasses, even at 8x25.



The issue is more prevalent the higher the power and smaller the objective,
generally. Most 7x50s,for example, have naturally high eye relief but you can place
your eyes almost anywhere.

OPTIC_NUT said:

You are talking about what I call "forced eye relief". It can be very irritating. Many priceybinoculars have that issue, whatever the eye relief. Some binoculars with 20mm or more don't have the 'blackout' problem. For newly bought, you have to see to be sure, but there are makers who help the situation. Most Meoptas, for example, have 3 or 4 positions for the eyecup so you can fit to the 'finicky horse' premium optics. I can go with and without glasses on the Meoptas.

Click to expand...

Yes, I think this is what Bob pointed out regarding the focal length. This longer focal length. Unlike Meopta, it looks like Vortex didn't care enough about this issue to offer extended eyecup positions.

OPTIC_NUT said:

The issue is more prevalent the higher the power and smaller the objective, generally. Most 7x50s,for example, have naturally high eye relief but you can place your eyes almost anywhere.

Click to expand...

But isn't that due to the porro design?

Not due to the Porro design,
but due to a combination of a wider exit pupil and more optical depth of field, which
transforms into more error-tolerance with EP and eye placement.
This makes a vastly bigger "egg" of space your eye can be happy in.

All this happens in roof designs as well. Apparent 3D depth has nothing to do with
optical tolerances involved in depth of field.

Porros are sometimes better because the path length is longer,
but that is due to market pressure on roof binocular length.
Buying the shortest is begging for trouble, but that's what people do.

I'd agree.....that is a boo-boo in Vortex engineering.