Quote: 1. During daylight viewing, the min. light loss of the binoviewer is not an issue. But the wider scope apt. will allow you to acheive higher magnifcations with less aperture diffraction vs. the smaller (but equivalent) binocular apt. Chalk this up to a huge PRO for the Bino viewer vs. the binocs.
Quote: 2. The BV/Scope with bigger apt., will produce wider exit pupils (per equivalent binocular), but considering the brightness levels, the wider exit pupils are a welcomed benefit as they will only be slightly greater than eye pupil, making it more comfortable to hold the view in each eye. Of course, this is a general statement and varies based on what magnifications you are dealing with.... I am using 40 - 60x, as anything less than this, well, you wouldn't be handling gear this big to begin with. Since the exit pupil is now slightly bigger than the eye pupil, there is a slight increase in diffraction and light loss, but this is minor compared to the ease of viewing, IMO. This is quite the opposite of astro viewing where the eye pupils are huge and the exit pupils are tiny (from very high magnfication) Another PRO for the BV/Scope.
Quote: 3. Bino viewer has interchangeable EP's, and you can vary the AFOV and TFOV based on your needs. At best you might have two choices with a binocular, if any. (always referring to the big binocs, 40x100 range) Another PRO for the BV/scope.
Quote: 4. Since you're only buying ONE objective and ONE tube, you can end up with higher quality glass and a more compact package with the BV/scope for the same dollars spent. Of course this varies with what you're comparing, you can't select a 200mm refractor for comparison :-) It must be within reason here. Another PRO for the BV/Scope.
Quote: 5. With a BV, you only have one objective, this reduces the risk of mismatched magnifications causing retinal rivalry, or stressful fussing the two images. Also, with two objectives spaced very far apart, (much greater than IPD), many suffer from ill effects such as cardboarding, (3d subjects appearing 2d) and spatial relationship issues, and also improper perceived size of objects for some how are hyper IOC sensitive. Many suffer these ills from improper stereo vision but are never able to quantify why they get a headache or stress in their eyes. Again, a PRO for the BV. BTW, its remarkable how powerfrul the 3d effect is with a BV.... considering there is no stereo to begin with. The brain is obviously fooled.
Quote: I can list some other advantages of BV for terrestial use, but I would consider them less significant, such as easier to mount BV, easier to point upward, some scopes like Borgs break down for easy travel, scope can provide super high magnification views, can be used for photography, etc. etc.
Now, can someone give me some binoc. PROS, or BV CONS, for terrestial use? Of course, in the magnfication ranges we are talking about here. Seems to me, the BV is one heck of a daytime terrestial viewer! TYIA
Quote: I refer to the long eyerelief of eyepieces such as 30mm and 40mm plossls. It's not bad enough to try and get your eye centered to eliminate the kidney bean of these long eyepieces. It's even harder to eliminate it when you are trying to do the same in two eyes. Therefore very long eye relief eyepieces that are prone to kidney bean issues are not always good choices for binocular viewing. edz
BTW, the eye relief distance, or exit pupil distance is the point at which you would see the entire filed of view and see all the light from all the rays. You do not see all at any other point.
One of your points in your first post was about how the BV can achieve large enough exit pupils to rival the brightness in a binocular. My whole point is there are very few if any eyepieces that will permit you to do that. The ones that will are not suited or are not easy to use for binocular vision. edz
Quote: Anumber of the Oberwerk BT models are non-proprietary, and some of the APM and other similar BTs from other distributors are the same. The Miyachis have limited proprietary choice, but include several selections. I believe the Vixen BTs are non-proprietary. edz
Quote: The binoviewer presents a binocular image to the eyes and hence to the brain. Stereopsis is a function of binocular vision. Do you think it would be that much different in a BV vs a binocular? edz
Quote: This is an issue shared equally by both instruments. Most of my eyepiece pairs were NOT bought at the same time and I don't have any issues with magnification. edz
Quote: I'm not sure where your going with these numbers here, but to see 200 line pairs per mm in a binocular that would probably not focus closer than 100', would take you a MINIMUM of near 300x in a 16" aperture. For the apertures and magnifications being discussed here it might be better to think in terms of 60x to 50x to see 40 lp/mm to 50 lp/mm.
For a 100mm binocular telescope at best you could see 40 lp/mm if using about 60x to 70x. For an 8" scope with binoviewer, you'd be able to see 80 lp/mm, but you would need about 140x to see it. These are about 1.5mm exit puils. raise the exit puil to 3mm with these same instruments and you would only be able to see 20 lp/mm or 40 lp/mm. Raise the exit pupil to 6mm and the line pairs you would be able to see would be down to 10 for the 100mm binocular and 20 for the 8" scope. edz
Mardi 4" achromat, ETX-70, 8"cat. Whitepeak Lunar Observatory Website
Quote: As for seeing 200 lp/mm ..... sorry I was not more clear. I referring to the diffraction limited resolution caused by the aperture diam, i.e. comparing binocs vs. BV. For example.... the most the eye can theoretically resolve is 200 lp/mm. (of course this varies on many factors, as we are human, we age, etc.) The 200 lp/mm is based on cone density of the retina.... so whenever a projected image is above this range, the eye /brain can not appreciate any more resolution. So based on your previous thread, you mentioned the effects when the exit pupil is greater than the eye pupil. This creates a new diffraction limited apt to be considered. So I ran some scenarios to see if this newly introduced, eye pupil diffraction, ever degrades the projected image below 200 lp/mm. If it did, this would be strike against BV/scope combo as the false exit pupils could diffract the views, while the binoc view would not do the same, as the exit pupils are true. (formula compliments of Jared)Scenario 1 - (worst case) Very bright light terrestrial viewing, using BV, I will assume the smallest possible pupil diam. is 3.0mm, as the BV robs half the light to each eye... so to calculate the projected lp/mm to the retina...Variables…3 diam, mm eye pupil550 fl scope100 aperture scope100.0 EP fl, mm6 x - magnification17.0 eye fl94 mm, effective fl of entire optical train0.9 f stop of entire system1,500 diffraction constant1,604 lp/mm projected on retina18.2 mm, Exit Pupil diam.0.17 eye pupil/exit pupil, diffraction factor265 lp/mm projected on retinaafter pupil diffraction if any.In this case, the larger false exit pupil is causing the eye pupil diameter to become the diffraction limited factor (.17), or reducing resolution 83%. But even at this very low 6x magnification, the resolution is still greater than the eye can resolve (200 lp/mm). Now, without going through an exhaustive check on this post, if you work these numbers, you will see that you can never drive the lp/mm projected to the retina lower than 265 lp/mm, with a 3mm or larger pupil diam. Until of course, the eye pupil/exit pupil factor (.17 above) becomes greater than 1. At which case, all diffraction comes from aperture diameter and this exercise is mute. I assume with half of the light lost in the BV, you can NOT get an eye pupil smaller than 3mm. However, even at 2.5mm, the same applies. So this was the basis of what I was describing. It seems in theory, the false aperture produced by BV could degrade the view by the added pupil diffraction it induces (vs. binocs), but it seems that is NOT the case. Or maybe I just missed the scenario where false pupils do degrade the view? So my point is, false pupils cause the eye pupil to become the limiting diffraction factor (as opposed to scope apt.), but not to the point of degrading the view, as it does not fall below the yes max. resolution limit. Does this make sense? Is the math flawed? If not, then I would suggest, the larger false exit pupils is actually beneficial outcome of a BV/scope, as larger exit pupils create a more comfortable viewing experience....i.e. not allowing the view to black out when pupil alignment is not perfectly coaxial with the EP. Albeit if the exit pupil is too large vs. the eye pupil, noticeable light loss will occur, as in the example above. But the example above is not realistic at 6x magnification. As these huge contraptions are not made for 6x magnifications, often we would just use our small binoculars at these magnifications. At about 30x + magnification the eye pupil diffraction factor becomes a mute point. At 20x magnification, the eye pupil diffraction factor is .61, or a 40% loss of light, in bright light viewing, I would consider this an acceptable trade off, i.e. viewing comfort in lieu of slight light loss.
Quote: the most the eye can theoretically resolve is 200 lp/mm. (of course this varies on many factors, as we are human, we age, etc.) The 200 lp/mm is based on cone density of the retina.... so whenever a projected image is above this range, the eye /brain can not appreciate any more resolution. So based on your previous thread, you mentioned the effects when the exit pupil is greater than the eye pupil. This creates a new diffraction limited apt to be considered. So I ran some scenarios to see if this newly introduced, eye pupil diffraction, ever degrades the projected image below 200 lp/mm.
Quote: > BTW, the eye relief distance, or exit pupil distance is the point at which you would see the entire filed of view and see all the light from all the rays. You do not see all at any other point.
For some reason, I never experience this. When I view through an EP with 20mm ER, but locate my pupil at 5mm position, I see the entire image circle? What am I missing here?
Quote: > One of your points in your first post was about how the BV can achieve large enough exit pupils to rival the brightness in a binocular. My whole point is there are very few if any eyepieces that will permit you to do that. The ones that will are not suited or are not easy to use for binocular vision.
Can you please give me some examples here.... I am not understanding what you are saying....but I think there is something important in this message. I was referring to getting larger exit pupils through the BV, since it has a larger apt, was that your understanding?
Quote: Often the outcome of these problems are never quantified by the users, as they do not have the knowledge to ascertain what is occurring.... instead, what you hear is... I don't like the BV, it gives me a headache, I get slightly lightheaded, my eyes hurt, etc. etc... all symptoms, based on how bad the stereo issues are and how sensitive the user is to the stereo issues, these symptoms can surface in minutes, or maybe not for several hours, so its a mixed bag. Just something for people to be aware of....
Quote: their is a huge reduction in stereopsis effects when you use one objective vs. two.
Quote: Quote: > BTW, the eye relief distance, or exit pupil distance is the point at which you would see the entire filed of view and see all the light from all the rays. You do not see all at any other point.For some reason, I never experience this. When I view through an EP with 20mm ER, but locate my pupil at 5mm position, I see the entire image circle? What am I missing here? Your missing a portion of the light. Not all rays are visible at other than the exit pupil distaance. that's where all rays come together to form a completely illuminated image.
Quote: > BTW, the eye relief distance, or exit pupil distance is the point at which you would see the entire filed of view and see all the light from all the rays. You do not see all at any other point.For some reason, I never experience this. When I view through an EP with 20mm ER, but locate my pupil at 5mm position, I see the entire image circle? What am I missing here?
MarkLeica 8x20; Nikon Action 7x35; Vixen Apex Pro 8x42; Orion 15x63; Docter Nobilem 15x60WO Megrez II 80 FD / APM 107mm f/6.5 / Mewlon 210 on DM-6 + Berlebach Planet
Quote: I understand the explanation, but I NEVER once experienced this... with my eye almost slammed on the glass, I see every ounce of image that I see at the ER position. Do you not experience this also? I always notice people slamming their eyes into a Bino viewer for this same reason....
Quote: If the scope is 800mm fl, then 800/125mm apt = f 6.4. 1500/6.4 = 234 lp/mm, the max. aerial lp/mm the lens can project.
Quote:Ed, I appreciate you taking the time to work through all this....But, you are mis understanding .... you continue to treat the 200 lp/mm as a target, it's NOT a target. I can not explain it any better than I have. Maybe someone else can ring in. The 200 or so, lp/mm is simply the theoretical limit of resoluton that scope EP can produce. Most high end optics including scopes and camera lens can come very close to these diffraction limited aerial resolutions. 1500/ fstop has NOTHING to do with focus distance. Its the physical limit of resolution which can be passed through a lens with a certain circumfrence vs. it's fl. It's that simple, it applies to all lenses, not just camera lenses, scopes, microscopes, binocs, etc. Camera lenses which are tested btw, which can project 600 lp/mm are often tested at ininity focus, rarely at 5 feet. I agree with you math for testing targets, but testing targets introduces a slew of other variables... what I presented was the theoretical best case scenario an optic can deliver, being limited only by aperture diffraction.
Quote: If you double the distance, you double the size of the symbols to get back to the same resolving capability,
Quote: you will see how the diffraction limit is NOT effected by distance....
Quote:Anyway, this tiny bit of depth in a single eye view I believe is created by the ultra sharpness of the optics. With the optics adding contrast to the image and edge sharpness, with a low enough pupil diameter, say 2mm, (which is the perfect balance between the eyes abberations vs. pupil diffraction),
Quote: What this means in practice is that the highest quality retinal image will be formed using exit pupils of 1mm or less and NOT at 2-3mm as is the case when the eye pupil controls diffraction effects (which latter is the case ONLY when the eye form images unaided by external optics--like a telescope or binocular or microscope.)
Quote: There is a big difference between resolving a small target by adding magnfication vs. seeing diffraction effects.
I think I clearly understand how we are missing each other.
Quote: I went and rechecked my scope today, viewed a close subject.....and...
at 2mm exit pupil the view was 2x sharper than 1x exit pupil (half the EP fl)
The diffraction limited projected resolution is always 88 lp/mm * exit pupil diam. So once again, the 176 lp/mm is delivering what I perceive as 2x sharper view (although its hard to quantify this), which demonstrates with my eye/brain, any gains of using the sweet spot of the eye lens's sweet spot (1mm exit pupil) is trumped by adding more resolution, assuming you have not exceeded the retinas ability to resolve.
From this, I would propose, for terrestrial viewing with no seeing issues, 2 - 2.5 mm exit pupils represent the BEST compromise between the eyes sweet spot of sharpness (as it relates to exit pupil size) and the diffraction limited resolution imposed by using smaller exit pupils. Now, I am curious, if anyone reading this gets their scope out and views something close, please report your findings on this, i.e. 1mm exit pupil vs. 2mm exit pupil, which is sharper?
Ed, I realize you reported the sharpest you seem to experience is at 1mm exit pupils, but your comments were astro based, which IMO is a different animal. Can you run this experiment with viewing something close, the differences I believe will be VERY obvious. I am curious of your findings.
Quote: One idea...the lower the ratio of raw resolution to apparant resolution the more aesthetic the image quality, i.e. the "sharper" appearing-- though not the most resolved
Quote: I notice in the apparant resolution graphic that the apparant resolution ..... really takes off at ~1.5mm ep. I wonder what accounts for these ... changes of slope in the apparant resolution vs. the smoothly rising slope in actual resolution/exitpupil?