Binoculars for butterflies (and other bugs)

[DQE]

Thanks chaps you've reminded me I never got round to getting a pair of these, more for the wishlist! Now I just have to decide whether to get the 6.5x or the 8x...

My partner and I are both enjoying the 8.5 model - I had worried that she'd react negatively to their perceptible (but to me not too stressful) need for alignment with your pupils, etc. The extra mag seems helpful for viewing from a good distance - this morning we enjoyed some small (3-4mm) bees and hoverflies from a standing position while viewing flowers located on the ground. We were standing about 2 feet from the flower pots.

I can however see how if one wants to track rapidly moving creatures such as butterflies, a lower magnification might well be preferable. One's field of view is larger at lower magnifications.

Hmmm...my incomplete understanding of optics is again confusing me: shouldn't one compare bug binoculars in particular at a fixed field size rather than from a fixed viewing distance? If I want a larger field of view, I simply have to move back a foot or two, whereas with a lower mag binocular pair, I would need to move in closer to get a specified field of view.

I want to think this way since my view of how one would use these binoculars is that one would pick a target field size (say 4 inches, as an example, providing nice magnification but allowing one to be about 40 inches away). With lower mag binoculars, one would have to move closer to the subject to have the same field of view and perceived bug size. Since one is directly viewing, there is no opportunity to digitally enlarge the final image, of course, unlike photography.

As with microscopy and camera optics, **it depends** on what you decide is fixed and what is to be varied when comparing optics!

Choosing binocular magnification surely has a substantial component of personal preference, and whether or not one can easily and comfortably hold the things steady under real world conditions. Fortunately, neither my partner nor I noticed any problems with 8.5x magnification. I personally start noticing handheld instability at about 10x magnification. By 12x, forget it unless I can support them against something rigid.

[rjlittlefield]

I see that I managed to overlook DQE's reply since it went on page 2, but to post anyway...

I figured that because both powers are described as having the same minimum viewing distance (1.6 feet), the 8.5X has a smaller minimum field. If I want a bigger field, all I have to do is back off by 25% or so. That will increase troubles with shake due to the greater distance, but it seemed like a good tradeoff.

I may have missed something, of course. Final resolution may need to wait for a review from somebody who has both!

--Rik

[gmazza]

I have the 6.5x version and I'm very happy with it, like the widefield vision (compared with the 8.5x) and the good results on low light scenarios (esp shadowned bushes)

[Cyclops]

8.5X at 19" is a seriously impressive specification!

Is anybody aware of other binoculars that compete with these??

--Rik

Rik, 8.5x19 inch would be a HUGE pair of binoculars!

[rjlittlefield]

Rik, 8.5x19 inch would be a HUGE pair of binoculars!

Indeed. And with an exit pupil over 50 mm diameter, I think they would also be designed for use underwater by a whale or a squid!

--Rik

[Cyclops]

Rik, 8.5x19 inch would be a HUGE pair of binoculars!

Indeed. And with an exit pupil over 50 mm diameter, I think they would also be designed for use underwater by a whale or a squid!

--Rik

But,the resolution!!

[Chris S.]

My set of the 8.5x ones just arrived. . .and will be returned immediately. Should I try another pair, or are they just not going to work for me?

As we know, with binoculars, one adjusts the interpupillary distance until one sees the world as if through a single circle. With the unit I just received, I can do this only for objects at over 20 feet or so. As I focus on closer subjects, the images separate, and I can not bring the two eyepieces close enough together to make the images merge. At near focus, the separation is extremely disturbing--I need to close one eye. Yuck.

My eyes are fairly close together--to use these binoculars at all, I need to set them pretty close to their minimum interpupillary distance--57 mm or so. The minimum interpupillary distance for these units is 55mm.

Has anyone with close-set eyes used these satisfactorily? I'm wondering if my copy has problems, or if the design simply doesn't work when the binoculars are set near the narrow end of their interpupillary range.

Thanks,

--Chris

[DQE]

My set of the 8.5x ones just arrived. . .and will be returned immediately. Should I try another pair, or are they just not going to work for me?

As we know, with binoculars, one adjusts the interpupillary distance until one sees the world as if through a single circle. With the unit I just received, I can do this only for objects at over 20 feet or so. As I focus on closer subjects, the images separate, and I can not bring the two eyepieces close enough together to make the images merge. At near focus, the separation is extremely disturbing--I need to close one eye. Yuck.

My eyes are fairly close together--to use these binoculars at all, I need to set them pretty close to their minimum interpupillary distance--57 mm or so. The minimum interpupillary distance for these units is 55mm.

Has anyone with close-set eyes used these satisfactorily? I'm wondering if my copy has problems, or if the design simply doesn't work when the binoculars are set near the narrow end of their interpupillary range.

Thanks,

--Chris

Chris,

I'm hardly a binocular or optics expert, but it seems to me that something must be wrong with your set.

Neither my binocs nor the identical pair my partner just bought (also for bug-watching) behave anything like what your describe. We both can easily keep the proper binocular image formed close-up and at large distances. She is small in stature and her interpupillary distance is definitely at the numerically low end of the range.

I wonder if the "CLOSE" (an acronym) mechanism is broken in your pair? If one looks in the front (light entrance side) of the binocs, and rotates the center focusing knob, one can see front optics elements move back and forth. Perhaps you could watch yours and see if anything is moving as you focus? Yet I would think that you wouldn't keep a sharp focus if the "CLOSE" mechanism is broken or stuck...again, my limited knowledge is not helping clarify this situation.

Hopefully Rik and/or others will once again provide the benefit of their expertise.

Now that several of us have these binocs, I'm sure we'll at collectively be able to help you figure out if yours are not working properly.

Would some close-up photos peering inside the entrance side of the binocs as the focus is moved very close be helpful in determining if yours is working properly??? Just a thought.

[Chris S.]

Thanks, Phil. Your first-hand experience (and your partner’s) is a help.

Prior to purchasing, I’d read this review, which is accompanied by a photo showing a frontal view of the binoculars. By moving the mouse over the photo, one can see how the optics move for close focus. My pair does look like this--it was one of the first things I checked. So thanks for offering to take some photographs of yours—but unless there is something to see not show at the link above, I probably don't need to take you up on the offer.

If two pairs work for your partner, then probably I should return this set and try again.

Thanks again, and cheers,

--Chris

[rjlittlefield]

My set of the 8.5x ones just arrived. . .and will be returned immediately. Should I try another pair, or are they just not going to work for me?

My guess is that your binoculars are working as designed and either the design is not going to work for you or you will have to consciously retrain yourself to tolerate what you're seeing.

As we know, with binoculars, one adjusts the interpupillary distance until one sees the world as if through a single circle.

True, but there's actually more going on "under the covers". To understand the Papilio binoculars, we have to look a level down.

With binocular eyepieces on any instrument, one adjusts the interpupillary distance until the exit pupils of the eyepieces fall within the entrance pupils of the eyes. When this happens, neither eye vignettes, so that both eyes see a full circular field.

If both eyes also see the same full circular field, then indeed "one sees the world through a single circle".

This is the natural condition for far-focus binoculars, assuming that they're well made with parallel sides.

For close-focusing binoculars, the problem is harder because the fields naturally tend to separate. At closest focus, my 8.5X Papilios have a field width of only 40 mm. They also have an inter-objective distance of about 29 mm. So, if the two sides remained parallel, at close focus the two 40 mm fields would have only 11 mm of overlap -- not quite useless but pretty awful.

To compensate for this problem, the Papilios simultaneously converge as they focus closer. If this were done perfectly, then again both sides would see the same circular field.

But the convergence is not perfect. With my unit, at close focus the two fields are offset by about 9 mm (versus the 29 mm of offset they would have without convergence).

As a result, at close focus my eyes see the subject covered by two circular fields that are 40 mm wide and overlap by 31 mm.

Anything within that overlap field can be easily fused in stereo, but when this is done, the black circular boundaries of the fields do not align.

Of course I can wiggle my eyes around so as to align the black circular boundaries instead, but then the subject is no longer fused. Bad idea.

This problem has very little to do with interpupillary distance. Rotating the prisms so as to change the IPD of the eyepieces has almost no effect on the field position. Ideally it would have no effect whatsoever. On my unit there is a small effect, but it's only about 1/2 mm change in field position over the entire range of interpupillary distance. So no matter what IPD I set, at closest focus the fields stubbornly remain offset by 9 mm.

So, if I change the IPD in hopes of fixing the offset between fields, I'm going to get very frustrated.

Instead, the solution is adjust my expectations. At close focus I no longer expect the outlines of the fields to remain fused into a single circle. I pay attention only to the subject and just let the outlines of the fields do whatever they want to. That naturally results in a sort of horizontally extended field in which there's a central roundish section seen by both eyes in stereo, flanked by two crescent-shaped sections that are each seen by only one eye.

Yep, it looks a little odd and I wish the convergence tracked better. But for my eyes the behavior is acceptable as is, particularly since I now understand what's going on.

BTW, the Papilios include a tripod mount, so all this behavior I've described is easy to investigate. Just mount the Papilio on a tripod, stick a fixed target in front of it, and look alternately through each eyepiece to see exactly what's where in each field. That approach worked well for me, anyway.

I would be interested to hear from other Papilio owners if their units have the same behavior I've described above. It would be particularly interesting to know if the 6.5X units act the same.

--Rik

[Chris S.]

Rik, thanks for your very interesting and informative answer. I'll be re-reading several times.

In the meantime, as Papilio users report in, I'd find it interesting if they also note how well stereo images, such as are often posted in the galleries, work for them, as I suspect that there may be parallel mechanisms (eye function, brain function, or behavioral) phenomena in operation with both things.

For me, at this moment, the closeup view through my Papilios is so disturbing that it would be hard to imagine being able to train myself to work with it. Similarly, I'm one of those people for whom stereo images don't work well. Nearly every time an interesting stereo pair is posted in the galleries, I try to view it. Sometimes, I succeed for part of a second, before it all falls apart. That brief glimpse is often wonderful, but the amount of muscle and eye strain it takes to obtain it is pretty bad. I envy folks who have it easy. Maybe this is a learnable skill; if so, I haven't learned it--but not for lack of trying.

Thanks again for your insight. It takes a long time to write and edit a post like yours. Much appreciated!

--Chris

[rjlittlefield]

In the meantime, as Papilio users report in, I'd find it interesting if they also note how well stereo images, such as are often posted in the galleries, work for them, as I suspect that there may be parallel mechanisms (eye function, brain function, or behavioral) phenomena in operation with both things.

I would be very interested in that as well. I suspect you're right that some of the same mechanisms are involved.

Sometimes, I succeed for part of a second, before it all falls apart. That brief glimpse is often wonderful, but the amount of muscle and eye strain it takes to obtain it is pretty bad

If you haven't done this already, get yourself a set of Wheatstone Mini-Scope viewers, download a copy of StereoPhoto Maker, and spend a few minutes playing with the SPM window size and the convergence dial on the viewer. You may even prefer to remove the lenses from the viewers, so they're just an adjustable set of mirrors. Once you have everything tweaked to play well together, stereo pairs will lock up with no more effort than looking at a physical model. This is the approach that I use to show stereo to my family and visitors, none of whom can fuse without aids.

It takes a long time to write and edit a post like yours. Much appreciated!

Thank you for the kind words. It does take some time, but I think a majority is actually spent on investigation rather than wordsmithing. I had noticed a sense that something was not perfect with the binoculars, but had not gotten around to investigating. Your question prompted me to figure out what was going on, with the happy result that now I'm more comfortable with them too. I chalk it up to "personal education".

--Rik

[DQE]

Rik, thanks for your very interesting and informative answer. I'll be re-reading several times.

In the meantime, as Papilio users report in, I'd find it interesting if they also note how well stereo images, such as are often posted in the galleries, work for them, as I suspect that there may be parallel mechanisms (eye function, brain function, or behavioral) phenomena in operation with both things.

For me, at this moment, the closeup view through my Papilios is so disturbing that it would be hard to imagine being able to train myself to work with it. Similarly, I'm one of those people for whom stereo images don't work well. Nearly every time an interesting stereo pair is posted in the galleries, I try to view it. Sometimes, I succeed for part of a second, before it all falls apart. That brief glimpse is often wonderful, but the amount of muscle and eye strain it takes to obtain it is pretty bad. I envy folks who have it easy. Maybe this is a learnable skill; if so, I haven't learned it--but not for lack of trying.

Thanks again for your insight. It takes a long time to write and edit a post like yours. Much appreciated!

--Chris

Interesting about the relationship of ease of stereo fusion of posted pairs of images vs the ease of use of the Papilio binocs.

FWIW, I probably have a well-functioning, very quick ability to fuse stereo pairs of images.

This is at least in part due to my career in medical radiography R&D (I'm now retired) as follows: one of my former employer's best customers was the Mayo Clinic, which developed a custom stereo chest radiography system. Basically, they modified their chest x-ray tube (the x-ray source) so that it moved just the right amount between a pair of very closely spaced exposures, creating a pair of medical x-ray films of a patient's chest that formed a stereo pair at normal viewing distance (arm's length from the viewbox).

Some radiologists required or preferred to use a custom viewer in which were placed the pair of 14x17 inch chest radiographs. From distant memory I think that the images were placed side-by-side in the viewer and one placed one's eyes in a binocular eyepiece assembly in order to very easily and comfortably view the stereo pair in "3-D". My memory is that it seemed as if one were looking at a patient's chest in 3-D rather than the usual projection onto a single black-and-white transparency x-ray film. To a non-physician, the effect was quite startling and remarkable. Time and again they could find a lesion that would otherwise have been hidden behind a large blood vessel or something, and could easily see where the lesion was in depth as well as in a projected plane. Since the two radiographs were taken in very rapid succession and at very short exposure times, patient motion wasn't necessarily an issue. Needless to say, as a film manufacturer, we wished that everyone would adopt such a system!

Having spent many full-time-equivalent weeks viewing their stereo radiographs, I became able to quickly fuse stereo images, and this ability has persisted over the years. Macro 3-D photo pairs are usually easily fused, too.

Many radiologists could fuse the stereo chest radiographs without the viewer, and simply placed them side-by-side, stepped back the standard "arm's length" distance, and quickly viewed the pair in 3-D. I don't think anyone failed to be comfortable viewing 3-D in the viewer but not everyone could view the radiographs without the viewer. This was informally attributed to the differences between peoples' vision systems, and may have been researched in detail during the development of the system, in their usual fashion.

Perhaps this is just a long-winded and anecdotal way of saying that people differ in terms of their relationship with stereo imaging. I wasn't aware that people differed so much in this regard that we wouldn't all be reasonably comfortable in using binoculars.

Thanks to Rik for providing another very educational and interesting tutorial about this optics-related topic.

Perhaps this discussion is somewhat related to the variability of visual depth perception from person to person? I seem to recall that good depth perception is a "must pass" test requirement for people who would like to become, for example, a fighter pilot.

-------------
EDIT:

I see now that we discussed this topic previously. My memory just isn't what it used to be...

http://www.photomacrography.net/forum/v ... c459b2cfbd

[Harold Gough]

I bought a pair (8.5x) this week.

The package arrived together with several others containing computer parts and I was expecting the binoculars to come later in the week. I bent down and picked up the largest package and there was a loud "chirp", apparently from the package. Having guests in the next room, I took it to the utility room to 'defuse' it. It contained the binoculars.

I then returned to the little heap of remaining packages and picked one up, to another loud "chirp".

To cut a slightly longer story short, the smoke alarm, mounted on the ceiling above me, had chosen just those moments to start complaining about a low battery!

Anyway, within 24 hours they have shown their versatility. Yesterday I had done a hurried repair to a leak in the bituminised felt cover of flat roof of our ground floor extension. This entailed climbing out of a bedroom window (4 foot drop), trying not to sit on a vertical window latch pin on exit and entry. What I was able to do, having done the repair was to check the drying progress in great detail with the binoculars by leaning, not climbing, out of the window.

This also recalls a problem I had monitoring activity of a honeybee colony which had a nest hole under our eaves this summer. I took out my 10-30 x50 binoculars. I had to back off halfway up our drive, maybe 50 feet from the nest, to get them in focus at the closest focus and the magnification was very low. The Papilios would have been ideal.

Harold

[lauriek]

Man I hate those smoke alarm chirps, that sound seems to be designed such that a human can't detect from what direction the sound comes! Every ruddy time that happens I end up searching the house for the offending item!