what causes "blackouts" when panning? (1 Viewer)

So I'm test-driving the Stokes DLS 10x42.
with eye cups all the way down, I get the blackouts when panning. What causes this?

WIth eye cups fully extended, It's as if I'm looking through a small tube/tunnel to get to the image.

For me, the cups have to be halfway out. But then they do not stay solidly
in place as other designs, but that's another story . . .

It's all about eye relief--blackouts occur when the eye gets too close to the eyepiece, the tunnel effect when it's too far away. That's why good quality adjustable eye cups, permitting exact positioning of the eyes, are important.

You did not say if you have glasses on. If you find the ideal position, you can use rubber bands or o-rings to hold them there. Take caer when storing, as the eye cups can be knocked off if stored the wrong way among other junk.

no glasses.

methinks if I have to rig them with o-rings or rubber bands, then they are not the bins for me. They should just WORK!

Sean,
Often a binocular that gives a nice view if you simply look at the center of the field, will "black out" if you look at the edge. This can be due to two effects, moving the eye pupil out of the binocular's exit pupil, and "spherical aberration of the exit pupil", a fancy phrase meaning different eye relief distances for different viewing angles. The size of the exit pupil doesn't change with distance behind the eyepiece, so you are experiencing the latter.

When panning, it's not natural to keep your eyesight centered in the field. Vision will momentarily fix on a detail, follow it for a bit, then jerk to another detail, etc., otherwise the view would be a meaningless blur. In this process, the eye often looks close to the edge of the field, with the potential for blackouts.

Fine-adjustable eyecups help to locate an eye relief setting that best combines full field and tolerable blackouts. In a wide field binocular, a blackout-proof setting often costs a bit of true field.

I guess any binocular takes some getting used to. In my Leica BA, with eyecups out, the adjustment is conservative yet comfortable--there is no panning blackout, but although the entire field is visible, the edge is a tad dark from vignetting. In a Swaro EL, with cups out, the setting is bold--the impressively wide field is well illuminated, but there are blackouts when panning. Blackouts are disturbing when you've already got your hands full trying to get on and focus a bird flying through the brush, and I prefer the relaxing feel of the Leica. My wife likes the Swaro though, and has learned to back her eyes away a bit when panning. The Leica just clicks in or out, that's it. Like the Stokes, the Swaro twists, but won't hold in-between settings.
Ron

Probably less than half of the bins I've tried felt ok just putting them up to my eyes and using them.
Our faces are of many different shapes and sizes. Some of us hold binoculars differently, too.
I have two similar binoculars, Pentax 8x32 SP and ED. I believe that the ED has slightly more actual eye relief though they have the same eyecups. With the SP, I hold them very tight to my face, while with the ED I can relax a little. I got blackouts at first with the ED. There is also a difference in the curvature of the separate sides of the binocular when they are both set to the same IPD. It's slight, but it's there. I've had the SP longer, used it more, and it fits my hands more naturally. Because of this, I automatically try to adjust the ED down further than it should be every time I use it, which results in some blackout when panning. I actually bought one of those Vortex Binoc-Locs that holds your IPD. I thought it seemed corny, and felt dumb putting it on my bins-and it works great.
I had eye relief issues with the 10x42 Meopta Meostar, and even bought eyecups for a different model, trying to get it just right. Something inside a lens showing up in the view was my reason for returning them, but the eye relief was an issue, too. Proably nothing wrong with them, they just weren't fitting my face.
As you know, I have the 10x42 DLS right now, too. When using the fully extended position it looks fine to me, though I have to hold the cups very firmly against my eye sockets.

Sometimes it takes a little getting used to a new binocular. I got frustrated with my DCF ED several times the first couple of weeks I had it. Now that I automatically hold it "right", and have the IPD fixed, it's perfect.
Right now the underside of my brow is sore from the DLS eyecups, which are harder than what I'm used to, and have been used for several hours the last couple of days. Plus, I think I was really grinding my face into the binoculars, straining to see details with what is apparently a diopter issue. I'm sure they, or their replacement if I go that route, will be fine.
Guess what I'm saying is "they should just work" sounds good, but it doesn't always work out that way. Sometimes we have to adjust.
Looks like those collapsing eyecups are going to be a real problem for you, though. Good luck.

BirderSean said:

no glasses.

methinks if I have to rig them with o-rings or rubber bands, then they are not the bins for me. They should just WORK!

Click to expand...

Well that's OK for you to want your binos to fit you out of the box but it is not any kind of indictment of a particular pair of bins. Everyone is different and so what may not fit you perfectly will work for another just right.

BTW modifying a pair of bins to customize them for you is pretty common.
Here's the O-ring trick. In your case you'll want to add multiple rings until the ER is just right:
http://www.birdforum.net/attachment.php?attachmentid=156832&d=1219765299

ronh said:

Sean,
When panning, it's not natural to keep your eyesight centered in the field. Vision will momentarily fix on a detail, follow it for a bit, then jerk to another detail, etc., otherwise the view would be a meaningless blur. In this process, the eye often looks close to the edge of the field, with the potential for blackouts.

Click to expand...

These eye movements are called saccades.

http://en.wikipedia.org/wiki/Saccade

Animals that don't use saccades can do a similar thing by moving their whole head quickly between fixed positions e.g. many birds "bobbing" their heads as they walk. It is also believed that this head bobbing can be used to infer depth information:

http://www.biomotionlab.ca/Abstracts/ICN2001_Troje.htm

Interestingly pied wagtails bob their heads quite dramatically, but hold them in a fixed position relative to their body when they run. I *assume* while they run they do not have a very good picture of what is around them, and rely on remembering what was there before they started running.

Kevin Conville said:

Well that's OK for you to want your binos to fit you out of the box but it is not any kind of indictment of a particular pair of bins. Everyone is different and so what may not fit you perfectly will work for another just right.

BTW modifying a pair of bins to customize them for you is pretty common.
Here's the O-ring trick. In your case you'll want to add multiple rings until the ER is just right:
http://www.birdforum.net/attachment.php?attachmentid=156832&d=1219765299

Click to expand...

this is a good rationale, thanks.

I love the ergonomics of my browning 8x32s, but these are clearly different bins.

I like the optics on these- brightness, contrast, color- they were sharp out in the field; the construction is solid, etc. etc. and the price.
I'm like Jerry's Dad (Marty) from that Seinfeld episode where I get real excited about "getting a deal". In Marty's case, he was excited when Jerry bought him the "tip calculator" and thought it was "hot" (black market).
But I digress . . .

I'm going to go back to a store and feel a couple other bins, but will probably just keep these and modify them if I need to.

I think I'm used to smashing the brownings against my face, and probably don't NEED to do that with these.

BTW, I'm fairly new to this site (lurked for awhile) and appreciate the wealth of information and quality feedback, especially the differences in opinions- helps to consider all viewpoints before making decisions.
Thanks everyone.

I think I'm used to smashing the brownings against my face, and probably don't NEED to do that with these.

Click to expand...

I have the same thing with 8x42 Vipers. They need to be held off a bit, they seem to have almost too much eye relief. I rest them on the top, below my eye brow. I do this with all my bins anyway.

Usually with eyecups that only have two position the design is such that for the some average face the eye when the cup is down is good for an average eyeglass user and the cup when up is good for an average

Can you see the whole field when the cup is up? That's a design requirement.

The Stokes DLS 10x42 FOV isn't very wide at 5.8 degrees and so it's apparent FOV isn't wide either (approximate 58 degrees but it's really less than that at about 54 degrees if you do the accurate calculation) so some "tunnel" feeling is appropriate. These aren't wide angle binoculars.

Field of View 308 ft./1000 yds.
Eye Relief 17 mm

If you are curious about eye relief I wrote up a pretty good explaination on it some time back

http://birdforum.net/showthread.php?t=125903

BirderSean said:

what causes "blackouts" when panning?

Click to expand...

Standing up too suddenly when you think you've finally found gold??? :eek!:

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