OK. Thanks for trying to help.I have no clue ...... carry on.
OK. Thanks for trying to help.I have no clue ...... carry on.
My premise in this thread is comparing two bins of nearly identical quality, Victory SF 8x42 and 8x32, differing in objective size.The focal length of the 42mm is longer than the 32mm, so this goes the other way and increases resolution if the eyes are say 2.5mm pupil size.
It is far too simplistic to just compare a low powered 32mm and 42mm binocular.
Regards,
B.
dries1.... in the comparison, I'm trying to hold as much constant as I possibly can, aside from objective size. So, in my example above: Zeiss Victory SF 8x32 vs. Zeiss Victory SF 8x42.ZD hart, are you looking through (directly comparing) an 8X32 SF and 8X42 SF, or are you comparing the view through a 8X32 SF and 10X42 SF?.
My SFs are 8x32 and 10x42, so quite different experiences between the two (8x vs. 10x powers). The 42s seem perhaps a little sharper, but they are 10x compared to 8x, so not a very good comparison.Which view do you prefer if you are stationary and viewing out to your back yard, the 8X32 SF or the 8X42 SF?
No, probably not. If the 42 is longer, it probably has longer focal length objectives.My premise in this thread is comparing two bins of nearly identical quality, Victory SF 8x42 and 8x32, differing in objective size.
So, I'm confused when you state that the focal length of the 42mm is longer than the 32mm - aren't the focal lengths (8x in both cases) the same?
I am not very knowledgeable, at all, on internal lens design. So, you're saying that the magnification of an SF 8x32 lens is different than the magnification of an SF 8x42 lens?No, probably not. If the 42 is longer, it probably has longer focal length objectives.
Again, one of the fundamentals of optics is that Magnification = Focal length of objective / Focal length of ocular.
Perhaps you could re-state/elaborate on your your statement? To impart a little more understanding to the reader. Now, I understand you better - you're not interested in doing so.I'm sorry, but you really do need to do some reading.
No, that's not what I said at all.
My premise in this thread is comparing two bins of nearly identical quality, Victory SF 8x42 and 8x32, differing in objective size.
So, I'm confused when you state that the focal length of the 42mm is longer than the 32mm - aren't the focal lengths (8x in both cases) the same?
I thought better of that post and edited it, before I even saw your response.Perhaps you could re-state/elaborate on your your statement? To impart a little more understanding to the reader. Now, I understand you better - you're not interested in doing so.
Generally speaking, camera lenses tend to be sharpest when stopped down two to four stops or so. As you stop down more, diffraction begins to creep in - but there is a fair bit of variation between individual lenses, different brands, different imaging formats, and different qualities/price points of camera lenses.Dear ZDHart,
An 8x32 binocular with f/4 objectives has objectives of 128mm focal length.
Eyepieces 16mm focal length.
An 8x42 binocular with f/4 objectives has objectives of 168mm focal length.
Eyepieces 21mm focal length.
The fact that the eyepieces differ so much has implications regarding complexity, eye relief etc.
A person with exceptional eyesight, 20/8 or better, might notice the difference in long focus astro scopes of 32mm and 42mm aperture at say 12x, 10x or possibly 8x.
But binoculars are so poor optically. I doubt that anybody would notice a difference between 8x32mm and 8x42mm binoculars unless boosted magnification was used.
Regards,
B.
Hi dries1. Thank you. I absolutely agree that one needs to judge for oneself. If I had an 8x42SF to compare with my 10x42SF, I would certainly be doing that - perhaps to an extreme degree, with a tripod, just to see for myself.ZDhart,
As I see it you seem to appreciate the larger aperture, however it would help that you looked a 8X42 with the 8X32 SF together, and your eyes will tell you which one you prefer. As long as I am able, I will always reach for a 8X42 over an 8X32, however others will prefer an 8X32, and folks prefer these formats for different reasons larger EP on the 8X42, light weight of an 8X32, etc. The best way is to determine your self with your own eyes.
What you perceive as a "sharper image/more resolution" in a binocular is a combination of many different factors. It doesn't just depend on diffraction:And still, much to my surprise, no one aside from myself has put forward any explanation as to why the x42 in this particular comparison might offer a sharper image/more resolution, than the x32.
Good post Hermann! Thank you for that. All salient points in the discussion.What you perceive as a "sharper image/more resolution" in a binocular is a combination of many different factors. It doesn't just depend on diffraction:
This list doesn't cover all the factors.
- It's also factors like the presence or absence of stray light or glare, especially veiling glare. These affect contrast in a big way. Stray light isn't necessarily related to the size of the objective lenses, there are e.g. 8x32s that suppress stray light very well, others don't.
- Then there's the question of ease of view - and ease of view is to some considerable extent related partly to the size of the exit pupil. The larger the exit pupil the "sharper" a binocular may seem, even in bright light. Ease of view is also related to the construction and the focal length of the eyepiece.
- Then there are ergonomics and weight. They also affect your ability to actually "see" a sharp image. Ergonomics and weight are or course highly subjective, they depend on the shape of your hands, your strength and so on. As an aside: Note lighter isn't always better, I personally find for a steady and "really sharp" image (of an unstabilized binocular) a weight between 700 and 800 gr. ideal. And of course the steadier the image is the sharper it looks. YMMV.
My own take of the situation is that size matters if you want the very best ("sharpest") image. This holds true as long as the optical quality of the binoculars is exactly the same. (This isn't necessarily the case, not even in binoculars from the same series. The old Leica 8x32BA for instance was IMO "better", i.e. "sharper" than the 8x42BA.) So if you compare, say, an 8x20, 8x32, 8x42 and 8x50/8x56 the 8x50/8x56 wins even in bright light and/or if your eye pupils don't open to 7mm anymore. In fact, if the exit pupil is below ~4mm the binocular isn't even in the running, at least not in handheld views. On a tripod it may be alright, handheld it isn't.
However, using binoculars with large objectives comes at a price. So even though it may have the "best/sharpest image" with the highest resolution it may not be want you want in a given situation. I did a pretty thorough comparison years ago between an 8x32, 8x42 and an 8x56. The 8x56 had the "best", sharpest image in any light even when I had the binoculars on a heavy tripod. BUT in some circumstances even a puny 8x20 may be a better choice than an 8x32.
I sure wouldn't want to carry an 8x50/8x56 monster around for hours on end.
Hermann
As I mentioned previously, I think diffraction is the primary explanatory factor.