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/