At the moment I rarely do resolution tests. Not because I don't think they are useful, but because by doing them I discovered how unreliable my eyes are. If I had the hardware to standardise the light conditions, boost the image, regulate the exit pupil, and employ MTF then I would as it reveals a lot, not only about the binoculars but also how they would behave under different conditions.
Some of the things I learned about how my eyes deceive me.
One test I did was to see if I got the same resolution result with the target at different distances as I should. To simplify the results, they switched between 12 " and 15" repeatedly. That is more than enough to rank the resolution differently if they had been different pairs. It turned out that it was caused by clouds dimming the view and therefore increasing my exit pupil. I got the poorer result when the sun went in. It could have been that the smaller exit pupil meant I was using the better part of the lens as Ron and Henry suggest (and I've certainly seen), but I now have reason to believe it was my acuity changing. It gets progressively worse in poorer light, way before I realised it did.
I had a cheap 10x that I was convinced had poor resolution. Turned out stray light was the issue, reducing the contrast, the resolution was OK.
I can't measure the transmission spectrum, but I've noticed pairs with more blue in the appear brighter to me but seem to have lower resolution than those with a warmer balance. Nonsense!
In poor light I've confused the acuity drop with the scotopic switch for poor resolution.
I could go on. The point is that now I've figured out some of the false information my eyes and brain are telling me, in normal hand held use it is very rare above a fairly low price point for me to find a pair of 8x where optical resolution is limiting in any way. However there is a bunch of other stuff which I can begin to sort between quality and preference in choosing pairs to buy. In the mean time I'll treat any ranking on resolution that is not done under lab conditions with a degree of scepticism.
Ron, I'll try to get back to some of your points when I've had more caffeine and thinking time.
David
Some of the things I learned about how my eyes deceive me.
One test I did was to see if I got the same resolution result with the target at different distances as I should. To simplify the results, they switched between 12 " and 15" repeatedly. That is more than enough to rank the resolution differently if they had been different pairs. It turned out that it was caused by clouds dimming the view and therefore increasing my exit pupil. I got the poorer result when the sun went in. It could have been that the smaller exit pupil meant I was using the better part of the lens as Ron and Henry suggest (and I've certainly seen), but I now have reason to believe it was my acuity changing. It gets progressively worse in poorer light, way before I realised it did.
I had a cheap 10x that I was convinced had poor resolution. Turned out stray light was the issue, reducing the contrast, the resolution was OK.
I can't measure the transmission spectrum, but I've noticed pairs with more blue in the appear brighter to me but seem to have lower resolution than those with a warmer balance. Nonsense!
In poor light I've confused the acuity drop with the scotopic switch for poor resolution.
I could go on. The point is that now I've figured out some of the false information my eyes and brain are telling me, in normal hand held use it is very rare above a fairly low price point for me to find a pair of 8x where optical resolution is limiting in any way. However there is a bunch of other stuff which I can begin to sort between quality and preference in choosing pairs to buy. In the mean time I'll treat any ranking on resolution that is not done under lab conditions with a degree of scepticism.
Ron, I'll try to get back to some of your points when I've had more caffeine and thinking time.
David