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Review of Canon 10x32 IS (1 Viewer)

Part Five: Star-Test and Summary

Sorry, I haven’t been able to add anything for the last few days. I’ll try to wrap things up now.

The full aperture star-test photo below is the best I could do. Outside of focus is on the left. As usual, the patterns were clearer to the eye and a bit less colorful. Monochromatic spherical aberration, (viewed through a narrow band green filter) was good for a binocular at full aperture, but spherochromatism (as seen in the very colorful out of focus images) was probably higher than usual and continued to look about the same with the binocular stopped down to 26mm to simulate the effect of the eye’s pupil in bright light. A 15mm stop down cleared things up nicely, but of course that is far below a 10x32’s effective working aperture range of 32mm to about 25mm in the brightest light.

The odd anomaly of multiple center spots seen in the photo appears between 2-3 rings outside focus and dissipates between 5-6 rings. There’s an extra pink spot and an extra violet spot, which revolve around the center, sometimes merging at the center. I’m going to guess that this has something to do with the complex objective design, but I have no idea how it might affect performance. Other defects where minimal in this sample, the worst being slight astigmatism in the right side.

Overall, the star-test didn’t reveal anything too surprising about the axial aberrations (except those odd spots). By far the most visible aberration at or near the field center is the normally non-axial aberration of lateral color. I think that it along with a healthy amount of longitudinal CA are the main things that prevent the binocular from achieving a completely cleanly focused star at the field center. There is always at least a little lateral color, magenta and green flaring from different directions of a focused star point no matter how carefully it is centered and focused.

In the end, I found the Canon 10x32 IS to be a binocular with some excellent, even state of the art qualities, but with one quite severe flaw (excessive lateral color), which unfortunately often mars the view for me in bright high contrast light. More personally, after using a 7mm exit pupil 8x binocular for many years, I‘m not really keen on any binocular with such a small fiddly exit pupil and 10x has some disadvantages compared to 8x (like narrower depth of field) that are not addressed by image stabilization. For pure visual pleasure I was always happy to return to the world of a very low aberration 8x view whenever I switched back to my 8x56 FL.

I know I haven’t said much about the 600 lb. gorilla here, image stabilization. I think I still don’t have enough experience with it to have a very informed opinion. There are many situations I haven’t tried like a rocking boat or moving car. I had expected some advantage in long range scanning over our local lakes, but I’ve found that to be somewhat disappointing. Even a stabilized 10x doesn’t have enough advantage over 8x at the distances I usually encounter waterfowl, so the scope is still needed for IDs about as often as before. Maybe I’ll find a more effective use for IS when spring migrants start showing up. I’m hoping to get easier IDs from glimpses of warblers in trees too distant for a conventional 8x. My experience so far with small winter birds at such distances looks promising.

I will say that I find the “Stabilizer” mode more useful than “Powered IS”. “Stabilizer” is very forgiving of both inadvertent binocular movements and those needed to follow a moving target, while still offering an effective level of stabilization. “Powered IS” seems to be capable of tripod like stability, but only if the binocular is quite still. Even small binocular movements will disturb the stability and lead to swimmy over and under corrections that cause queasy sensations, at least for me.

Finally, I’ll say a little about my experience using a 3x booster with the 10x32. The stabilization mechanism can keep up well enough at 30x, but the image quality problems from CA are naturally worse. If the lighting conditions allow it the image can be reasonably clean if somewhat dim, but high contrast situations will show very vivid longitudinal and some lateral CA. Still, with only the addition of a pocketable booster it’s a pretty nifty way to see smaller details hand held than can be seen at 10x.

Henry Link

Oops, almost forgot to mention a partial solution to the problem of the terrible eyecups. I and I think most people will find it necessary to fold down the eyecups even without glasses. This leaves my brows as the only contact area between my face and the binocular and my eyes fully exposed to side glare from a wide angle. I happen to have a "Bino Bandit" glare blocker that I bought a few years ago and quickly relegated to a drawer full of rejected eyecups. Finally a binocular has come along that works with it (see photo below). New ones appear to come with buckles that allow the thing to be folded into a sort of rain guard.

https://alpineproducts.com/product/bino-bandit-glare-blocker/
 

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Thank you for all the hard work, Henry, and for the good write-up!!!
Your five part review has been a revealing and very interesting read for me.

Canip
 
Henry,

Thanks again for your in depth look at the Canon. Much appreciated.

The IS did not work well enough to tempt me on their old IS models, or the couple I've seen using Kamakura technology, but it sounds like it may have improved in this model. I'll take a fresh look when I get a chance.

The star tests do seem a little curious, though not as bad as many I've done. As I said I'm not convinced of the value at binocular resolutions, but I've never been sure if I had the set-up quite right. I found a copy of Harold Suiter's book this week. He seems to stipulate some some very precise test conditions. I think I was mostly in the right ball park, but perhaps not close enough? Something I'll look at again.

Cheers,

David
 
Thanks Canip and David,

It's too bad the Suiter book is all black and white. A chapter with color simulations of the effects of longitudinal CA and spherochromatism on out of focus patterns would be very helpful for understanding short achromats like binoculars. In my experience spherical aberration affects the image quality long before it actually degrades measured resolution. At high magnification the unfocused rays look like a fog partly but not completely obscuring a focused core image.

Looking back on the last part I think I gave the advantages of IS too little credit. I spent some time with the USAF 1951 trying to determine at how much greater distance I could resolve the same line pairs hand held with the Canon vs my 8x56 and a conventional 10x. I found the distance increased about 1.6 times with the Canon 10x32 vs the 8x56 and the view of the resolved line pairs was much steadier through the Canon. I could only get occasional unsteady glimpses of the same line pairs at 1.2 times the 8x distance with a conventional 10x. Overall, the experience with the Canon IS convinced me that a 10x hand held binocular would only work for me if it included image stabilization. The 10x32 may be the second or even third best Canon 10x binocular, but I think I would still prefer it to any conventional 10x binocular for daylight birding.

Henry
 
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Henry,

Would it be right to assume that by "fog" you mean contrast at lower spatial frequencies?

There is much of Suiter's book I still need to digest, but it was interesting to see that modest levels of spherical aberration affects lower frequency contrast has virtually no effect on resolution, yet It's pretty obvious that loss in resolution frequently results in loss in contrast. That would make spherical aberration a poor predictor of resolution.

I'm a bit short of time at the moment, and so far I've only located your assessment of the Zeiss HT 8x54. I know we both had a very low opinion of that model but I still can't square your star test assessment with either my visual assessment or the brief look I had of the Zeiss stopped down MTF result. That was a few years ago would. Would you still draw the same conclusions? I know we both had a low opinion of the Swarovsli CL 8x30 as well, but I haven't been able to find what you posted on that occasion. Can you point me in the right direction for that as well?

On a number of occasions when I have attempted a star test the resultd have been disrupted by a significant diagonal distortion which it's tempting to think is due to some issue with the roof prism edge. Unfortunately Suiter seems to be silent on prisms. Have you seen anything similar?

Cheers,

David
 
Henry,

I was about to ask you about the IS benefits as I had thought that you glossed over that part of the performance rather briefly before, but now you have re-visited the topic. Thank you for that.

A 1.6 times difference, or even 1.33 times difference (normal 10x vs stabilised 10x) is in my view a pretty big factor when considered against the minute differences we usually tend to obsess about when comparing an alpha W against an alpha Z. Also, its in line with what I have observed time and again when testing the 10x42 IS L, and does a nice confirmation bias number on me.

With the 10x42 IS L, you would get rid of the excessive CA while retaining the IS benefits, so I feel you really ought to try it out eventually.

David,

Diagonal distortion artefacts are common in star-test patterns of roof prism binoculars, and a thin diagonal line can usually be seen even in the best models and samples although it doesn't necessarily compromise the image quality if it is small enough. Lower-quality roof prism binoculars can have any levels of prism-induced flaws, worst being severe spiking and astigmatism. The angle of the diagonal artefact is different in left and right barrels, and comparing the two also helps you guess something about quality variations in prisms for that make and model.

On Suiter, my sense is that his instructions for a star-test setup are more precise than is necessary for practical binocular or even spotting scope testing. Most of the essential information for a fast focal length objective with more than moderate levels of aberrations (which most binocular lens systems are) can be obtained with a glitter point or such that is bigger, smaller, brighter or less bright than what Suiter proposes as necessary. With boosted images, best focus Airy disks (if the quality of the objective allows for one) don't work so well if the artificial star is too large, and obviously it cannot be so dim that you stop seeing diffraction rings outside of focus, but other than that one can get quite a bit of information with less than professional setups.

That said, I'm considering getting a "proper" artificial star instead of the .08 mm hole in a metal sheet I'm currently using indoors.

Kimmo
 
Henry:
A very nice review, and it seems the small exit pupil of a 10x32 is important in this model as well as it
is in any binocular. Ergo's are important also, so it is hard to move beyond that.

I am wondering if you are keeping this binocular or will return it.

Jerry
 
Regarding CA, I have noticed before that when using binos with some CA, after a while I can hardly see it. I think my brain somehow adapts and process the view. I have some Vortex binos where that happened. Really did not like them because of CA to start with, but now I cannot see any. Takes a lot of use for that to happen maybe. I hope for that with my Canon 14x32s and will give them a chance in 2019. I do think the CA in these are a bit too much for my brain though ;-) But who knows!
 
Regarding CA, I have noticed before that when using binos with some CA, after a while I can hardly see it. I think my brain somehow adapts and process the view. I have some Vortex binos where that happened. Really did not like them because of CA to start with, but now I cannot see any. Takes a lot of use for that to happen maybe. I hope for that with my Canon 14x32s and will give them a chance in 2019. I do think the CA in these are a bit too much for my brain though ;-) But who knows!


That's an interesting comment.

I've been an amateur astronomer as long as I've been a birder. One of the realities of using telescopes is learning to see - teaching your eye/brain to ferret out all the detail the telescope can reveal and detecting the faint objects that are at the border of perception.

I've recently been wondering if learning to see goes beyond that. Some time ago I had a Celestron SPC102 here, a 4-inch f/9.8 achromat. Out of curiosity, since it had been years since there was an achromat available, I spent some time observing Jupiter with it. At first I found the secondary color - the magenta halo of the unfocused red and blue ends of the spectrum surrounding Jupiter - obvious and annoying. With time behind the eyepiece its presence slowly receded and became less intrusive. It seemed my eye/brain was learning to partially ignore it. (At their lower powers color errors in binoculars are less obvious.)

In the astronomy community there are claims that some people are simply more sensitive to chromatic aberrations. That may be true, but perhaps the eye/brain can learn to tune them out, or become better trained to spot them.

I spend the vast majority of my binocular time looking at, enjoying, and identifying birds. I rarely notice any color fringing, even along high contrast borders. When I do it's usually near the edge of a field.

My wife once complained about color fringes in my 12x36 IIs when we were out hiking on a bright, sunny day. I suggested she had the IPD set wrong. She adjusted it and said the fringing vanished.

I've long been a strong advocate of 'Trying before buying,' but I ignored my advice and bought a pair of the new Canon 12x32 IS. I hoped they would be a good replacement for my 12x36 IS IIs, which has been my main birding binocular for more than 16 years (their only curse being horrid close focus). Based on some of the reviews I was apprehensive, but I find them quite satisfactory and am very happy I took the chance.

I do agree that the rubber eyecups are horrid if you leave them up, but I wear glasses. Folded down I like them better than the eyecups on my 12x36s.

Clear skies, Alan
 
David, I'll just add one more source to roof prism lines showing up in star-tests of binoculars at boosted magnifications. If the booster has a roof prism it may appear as a shadow line running through the outside of focus pattern (see the example on the left below). For some reason it appears to be more of a problem when photographing star tests than visually. Other distortions of the diffraction patterns can come from dust and oil droplets on the eyelens of the binocular and floaters in the eye.

You probably noticed that I mentioned in the old 8x54 FL review that its image at 8x seemed to be worse than it ought to be from examining its stopped down high magnification star test. I speculated then that excessive lateral color near the field center (which doesn't show up well or at all in a high magnification star-test) was the possible culprit, just like the Canon 10x32 now.

Kimmo, If you're considering the Hubble Optics artificial star, I have one now and have found a few problems with it. Firstly, it comes with a plastic diffusing disk between the LED bulbs and the metal disk with the pinholes, which dims the star points considerably. It's just bright enough for visual use in low light, but photography requires very long exposures at my camera's highest ISO setting of 1600. Removing the diffuser helps, but it's still not very bright.

The other problem is that the LEDs have a strong blue/violet bias, which causes any blue/violet component in CA or spherochromatism to be highly exaggerated, like the blue spot in the defocused photo of the five pinholes made through the 10x32 below.

Wolf Beam, if the lateral color in the Canon eventually disappears for you, I think you'll never have to worry about CA in any binocular again. ;)

Henry
 

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Henry,

Thanks for the warning.

Just from appearances, I put the effective resolution of that first HT 8x54 I tried between 170 and 190/D. From what I saw of the Zeiss stopped down MTF, it appeared their test sample was at the top end of that range. I suspect there might have been a bit more than a little bit of CA and SA going on, but they certainly weren't going to spill the beans. ;)

David
 
Henry,

Thanks for the comments on the Hubble Optics artificial star. You have saved me some trouble and a little bit of money. I may look into a fibre optics solution with a halogen light source instead.

There's one more test I'd like you to conduct with the 10x32 IS: low light detail or resolving power. Not that we use binoculars that much for terrestrial viewing in dusk or twilight or, indeed, night time, but it is another area where I've found IS to be very effective, and it is also an area where a small exit pupil is a decided disadvantage.

Kimmo
 
Henry, Kimmo,

Looks like the target I made for indoor use was was about 0.1mm or 5-6" at 4m which is probably not good enough, even for stopped down testing. The ballbearing I've used as a glitter point should have been OK though. I have one binocular that has always given me quite distorted patterns in one barrel at full aperture and almost absent inner rings stopped down, yet still manages a respectable 126/D and seemingly a better than average contrast profile. The other barrel seems to gives something much closer to the standard pattern, yet only 136/D and just slightly worse contrast. The I'll give it another go when I can.

David
 
David,

How large are the exit pupils in your tests? In my experience with boosted binoculars the airy disc at best focus and defocused between 2 and 5 rings is much easier to evaluate with a 0.5mm exit pupil.

Henry
 
Sorry Henry, what is the value of doing that? The pupil of the eye cannot contract to 0.5mm.

I had a another look at chapter 1 of Suiter's book and now realise I had made a fundamental error in expecting to see the classic pattern of rings to be revealed as the effective resolution approached the diffraction limit. I now realise I should have expected the opposite.

This is how Suiter produced his reference pattern. Fig. 1-5
"The contrast of the pattern has been increased by using one very pure red light from a helium-neon laser reflected in a small reflective sphere. A hole punched in metal and placed over a small refractor created the aperture."

The critical thing there is monochromatic light. This is how he describes the result of using a white light source.
"Each contributing color exhibits a different number of rings in its expanded disk. The minima of one color sit on top of maxima of another color, and the net effect is largely to wash out any variation of the interior of the disk."

That pretty much describes what I saw through the left barrel in #54 and noted testing other binoculars with even higher effective resolutions. I had assumed they were flawed results as they contrasted with many I'd seen here. They may have been excellent results, but I'd need to follow Suiter's check list to be sure. It now leaves me wondering what might have been the nature of the defect was that produced the misleadingly 'normal' pattern in the right barrel #54?

Unfortunately it isn't always obvious if Suiter's illustrations were produced by monochromatic or polychromatic light. As you said, coloured illustrations would have been enormously helpful. I'll need scrutinise things more carefully.

David
 
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