henry link
Well-known member
I recently had the opportunity to evaluate two specimens of the new Zen-Ray ED3. I had hoped to write a full review of the 8x43, but that was not possible for reasons that will soon become clear. So, what follow are some measurements and the results of some tests I conducted on two specimens of the 10x43.
The binocular I will call Sample A turned out to be incorrectly labeled, both on the binocular and the box, as an 8x43. It was actually a 10x43. I don’t think I’ve ever seen that happen before, but, of course, without some reference the exact magnification could be hard to estimate. If you buy one of these I would be sure to check it against a binocular of known magnification. Sample B was correctly labeled as a 10x43.
Here’s the good part first. I found the light transmission and color accuracy of the new Zens to be fully state-of-the-art. No improvements need to be made in the areas of AR coatings or dielectric prism coating to compete with the alpha brands. Beyond that, however, I didn’t find things quite so rosy.
The focuser on Sample B was adequate, with just a little slop and requiring slightly more than ideal effort, a situation that might loosen up in time. However, the focuser on Sample A was quite poor, with much more slop followed by stiff jerky movements once the focuser engaged, bad enough to make accurate focus nearly impossible. I considered that focuser to be essentially unworkable under field conditions.
I measured the effective aperture by placing a transparent ruler across the objective and reading how many millimeters spanned the image of the objective at the exit pupil, by sighting through the eyepiece with a magnifier. I found the effective aperture to be slightly under spec, about 41.5mm at infinity focus and about 40mm at close focus when the positive focusing lens moves forward toward the objective and acts as an aperture stop.
Eye relief from the eye lens glass was as specified, about 15mm, but the effective eye relief from the rims of the eyecups is about 13mm from the left eyecup and, curiously, only about 11mm from the right eyecup. That’s because the right eyecup doesn’t screw down as close to the eye lens as the left cup. The right cup is also about 2mm longer than the left when they are fully extended. (See the photos of the eyecups below). I was not quite able to see the entire field in either side when wearing reading glasses.
Resolution measurements at 60x, using the USAF 1951 chart, were not very impressive. The best of the four barrels measured about 5.2 arc seconds. One barrel of Sample A was seriously defective and measured somewhat worse than the others (more about its defects below). For reference, I measured at the same time in the same set-up about 4 arc seconds for a Nikon 10x35 EII and about 3 arc seconds for a Zeiss 8x42 FL. These instrument resolution measurements don’t necessarily mean that less detail will be seen at normal magnification, but they are an indication of the true quality of the optics. In this test 5 arc seconds from a 42mm binocular is mediocre at best.
The star-test photos below show the two barrels of Sample A. The bottom two photos are the right barrel (extra-focus on the left, intra-focus on the right). It has a pretty normal amount of spherical aberration for a binocular and a little astigmatism, but the patterns also indicate a rather poorly made roof prism edge, which causes the dark division of the extra-focal diffraction disk and the splitting of the central spot in the intra-focal disk. Both barrels of Sample B looked similar, which suggests that the roof prisms are just not speced to a very high standard. The top two photos of the left barrel show a very odd abnormal pattern, which may be explained by the anomalies in the moon photo and the phase correction photos to the right of the star-test photos.
I photographed the moon through the left barrel of the Sample A. Notice that it shows a focused mini-moon nestled within the main (unfocused) image of the moon. When the main image is focused the mini-image becomes an out of focus spot of light in the center of the field, which causes a loss of sharpness and contrast in that area of the field center. This is not like a normal ghost image and only occurred in this one barrel. I’ve never seen anything like it before.
This anomaly might be related to another anomaly visible in the phase correction photos at the far right below. These photos are screen shots of my computer’s LCD display. They were made through the objective ends of the Zen Sample A (left barrel at top left, right barrel at top right), a non phase-corrected Brunton monocular (lower left) and a P* coated Zeiss 8x42 FL (bottom right). The camera was fitted with a polarizing filter rotated to a position that nearly canceled the computer screen light. A Porro prism binocular or roof prism binocular with good phase correction should show an almost completely dark image across the light cone just like the darkened computer screen. The Zeiss and a Nikon 8x32 SE I tried did that. The Brunton shows the half lit and half darkened light cone of a non-phase corrected roof prism. The upper right Zen photo seems to show something like partial, rather than complete, phase correction. There is something clearly very wrong in upper left Zen photo. I can only guess that maybe the phase coating was incorrectly applied or perhaps there are internal stresses in the prism glass. Anybody else have any ides? Whatever the cause, that barrel of the Zen Sample A certainly has some fascinating defects I’ve not seen in any other binocular.
I did spend some time actually looking at birds with Sample B and comparing it to the closest thing in my collection, a Nikon 10x35 EII. Besides having lower optical aberrations and a smoother focuser, Sample B was also better collimated than Sample A. I confess I don’t really like 10x binoculars or binoculars with small exit pupils, so be aware that my opinion is negatively biased from the start. The Zen light transmission was excellent, visibly higher than the Nikon, even in bright sunlight, but nothing else about the experience of using the Zen was very tempting. I found that precisely setting the diopter adjustment and exactly aligning the pupils of both eyes with the optical axis were very critical for achieving a decently sharp image at the center, but I really couldn’t maintain that sort of precise alignment very well while handholding at 10x. In addition, what I would call the “semi-sweet” spot was on the small side, not much over 20 degrees, which is a bit worse than the Zeiss FL, my minimum standard for a comfortable view. Overall I found the viewing experience quite a chore compared to the Zeiss 8x56 I usually use, though, in fairness I know part of the discomfort is simply the 10x and the small exit pupil. I imagine I would prefer the 8x43 and I will be interested to see the 8x42 Prime HD model with, presumably, the same excellent coatings, a better performing eyepiece and, I hope, a higher quality roof prism and better quality control.
Henry Link
The binocular I will call Sample A turned out to be incorrectly labeled, both on the binocular and the box, as an 8x43. It was actually a 10x43. I don’t think I’ve ever seen that happen before, but, of course, without some reference the exact magnification could be hard to estimate. If you buy one of these I would be sure to check it against a binocular of known magnification. Sample B was correctly labeled as a 10x43.
Here’s the good part first. I found the light transmission and color accuracy of the new Zens to be fully state-of-the-art. No improvements need to be made in the areas of AR coatings or dielectric prism coating to compete with the alpha brands. Beyond that, however, I didn’t find things quite so rosy.
The focuser on Sample B was adequate, with just a little slop and requiring slightly more than ideal effort, a situation that might loosen up in time. However, the focuser on Sample A was quite poor, with much more slop followed by stiff jerky movements once the focuser engaged, bad enough to make accurate focus nearly impossible. I considered that focuser to be essentially unworkable under field conditions.
I measured the effective aperture by placing a transparent ruler across the objective and reading how many millimeters spanned the image of the objective at the exit pupil, by sighting through the eyepiece with a magnifier. I found the effective aperture to be slightly under spec, about 41.5mm at infinity focus and about 40mm at close focus when the positive focusing lens moves forward toward the objective and acts as an aperture stop.
Eye relief from the eye lens glass was as specified, about 15mm, but the effective eye relief from the rims of the eyecups is about 13mm from the left eyecup and, curiously, only about 11mm from the right eyecup. That’s because the right eyecup doesn’t screw down as close to the eye lens as the left cup. The right cup is also about 2mm longer than the left when they are fully extended. (See the photos of the eyecups below). I was not quite able to see the entire field in either side when wearing reading glasses.
Resolution measurements at 60x, using the USAF 1951 chart, were not very impressive. The best of the four barrels measured about 5.2 arc seconds. One barrel of Sample A was seriously defective and measured somewhat worse than the others (more about its defects below). For reference, I measured at the same time in the same set-up about 4 arc seconds for a Nikon 10x35 EII and about 3 arc seconds for a Zeiss 8x42 FL. These instrument resolution measurements don’t necessarily mean that less detail will be seen at normal magnification, but they are an indication of the true quality of the optics. In this test 5 arc seconds from a 42mm binocular is mediocre at best.
The star-test photos below show the two barrels of Sample A. The bottom two photos are the right barrel (extra-focus on the left, intra-focus on the right). It has a pretty normal amount of spherical aberration for a binocular and a little astigmatism, but the patterns also indicate a rather poorly made roof prism edge, which causes the dark division of the extra-focal diffraction disk and the splitting of the central spot in the intra-focal disk. Both barrels of Sample B looked similar, which suggests that the roof prisms are just not speced to a very high standard. The top two photos of the left barrel show a very odd abnormal pattern, which may be explained by the anomalies in the moon photo and the phase correction photos to the right of the star-test photos.
I photographed the moon through the left barrel of the Sample A. Notice that it shows a focused mini-moon nestled within the main (unfocused) image of the moon. When the main image is focused the mini-image becomes an out of focus spot of light in the center of the field, which causes a loss of sharpness and contrast in that area of the field center. This is not like a normal ghost image and only occurred in this one barrel. I’ve never seen anything like it before.
This anomaly might be related to another anomaly visible in the phase correction photos at the far right below. These photos are screen shots of my computer’s LCD display. They were made through the objective ends of the Zen Sample A (left barrel at top left, right barrel at top right), a non phase-corrected Brunton monocular (lower left) and a P* coated Zeiss 8x42 FL (bottom right). The camera was fitted with a polarizing filter rotated to a position that nearly canceled the computer screen light. A Porro prism binocular or roof prism binocular with good phase correction should show an almost completely dark image across the light cone just like the darkened computer screen. The Zeiss and a Nikon 8x32 SE I tried did that. The Brunton shows the half lit and half darkened light cone of a non-phase corrected roof prism. The upper right Zen photo seems to show something like partial, rather than complete, phase correction. There is something clearly very wrong in upper left Zen photo. I can only guess that maybe the phase coating was incorrectly applied or perhaps there are internal stresses in the prism glass. Anybody else have any ides? Whatever the cause, that barrel of the Zen Sample A certainly has some fascinating defects I’ve not seen in any other binocular.
I did spend some time actually looking at birds with Sample B and comparing it to the closest thing in my collection, a Nikon 10x35 EII. Besides having lower optical aberrations and a smoother focuser, Sample B was also better collimated than Sample A. I confess I don’t really like 10x binoculars or binoculars with small exit pupils, so be aware that my opinion is negatively biased from the start. The Zen light transmission was excellent, visibly higher than the Nikon, even in bright sunlight, but nothing else about the experience of using the Zen was very tempting. I found that precisely setting the diopter adjustment and exactly aligning the pupils of both eyes with the optical axis were very critical for achieving a decently sharp image at the center, but I really couldn’t maintain that sort of precise alignment very well while handholding at 10x. In addition, what I would call the “semi-sweet” spot was on the small side, not much over 20 degrees, which is a bit worse than the Zeiss FL, my minimum standard for a comfortable view. Overall I found the viewing experience quite a chore compared to the Zeiss 8x56 I usually use, though, in fairness I know part of the discomfort is simply the 10x and the small exit pupil. I imagine I would prefer the 8x43 and I will be interested to see the 8x42 Prime HD model with, presumably, the same excellent coatings, a better performing eyepiece and, I hope, a higher quality roof prism and better quality control.
Henry Link