Tests of Atlas Intrepid 8x42 and 10x42

[henry link]

This post was delayed because I’ve been camping in the Great Smoky Mountains National Park this past week. I spent a few hours with these binoculars before I left, concentrating on the 8x42 because I have a Zeiss FL 8x42 for comparison and because I’m just more interested in that configuration. So, what follows are some measurements and tests I was able to do over that time, not a complete review.

True Aperture: Curiously the 8x42 had a little less than the 10x42. The 8x42 varies with focusing distance from about 39mm at close focus to 41mm at infinity focus. The 10x42 varies with focus from 40mm to 42mm.

Eye Relief: 8x42 – 20mm from the eyelens, 15mm from the rim of the fully collapsed eyecup. 10x42 - 18mm from the eyelens, 13mm from the eyecup.

FOV: I didn’t measure this directly, but I carefully compared the FOV of the 8x42 to the Zeiss 8x56 FL and Nikon 8x32 SE, which were the closest in FOV among my binoculars. The 8x42 Intrepid fell neatly between the two, which would put it around 390’-393’ (close enough to Steve’s 396’ measurement). I didn’t measure the 10x42.

Resolution measured at 64x (8x42), 80x (10x42): The four barrels varied from about 3.5 arc sec in the right barrel of the 8x42 to about 4 arc sec in the right barrel of the 10x42. Not good enough for alpha class bragging rights, but perfectly fine. There is much more detail in the image than the eye can see at normal magnification.

Star Test at 64x, (8x42), 80x (10x42): The right barrel of the 8x42 was quite good by binocular standards. The only obvious problem was the expected spherical aberration. All the other barrels had about the same amount SA. I’ve seen less in the best binoculars, but also more in some very expensive ones. The left barrels of both binoculars showed coma, from misaligned optics, possibly a byproduct of collimation. The right barrel of the 10x42 showed some astigmatism, which probably explains its relatively worse resolution measurement. One really good barrel out of four ain’t bad when it comes to binoculars of any price and none of the defects were severe enough for me to notice any effect at normal magnification in daylight. The astigmatism in the 10x42 could soften the image in low light when the full aperture is used. I also star tested the good barrel of the 8x42 stopped down to 30mm to simulate daylight use. As expected, the 30mm the star test was substantially improved as a result of reduced SA.

Chromatic Aberration: Longitudinal CA is very well corrected for a binocular, indicating that the ED glass really does do what it’s supposed to do. The attached photo below on the left shows the cross-shaped center of my CA target as imaged through three binoculars: a conventional achromatic doublet (Nikon 8x32 SE) on the left, the Intrepid 8x42 in the middle and the Zeiss 8x42 FL on the right. The purple fringe in the SE image is typical longitudinal CA found in fast binocular optics, which you can see is almost absent in the other two. I should add that this is worst case CA from the entire objective. In daylight at 8X, even the obvious purple fringe seen in the SE image is not visible at all.

Control of lateral color (Transverse CA) in the 8x42 Intrepid is about average for binoculars. Lateral color is the type of color fringing you can actually see in binoculars in bright light. It becomes stronger away from the field center, but can sometimes be seen in the very middle if the eye is slightly decentered. Some expensive roof prism binoculars with complex objectives have quite a lot of this form of CA. The 8x42 Intrepid shows slightly less lateral color than the 8x42 FL. It has about the same amount as the 8x56 FL, which is a good result for a binocular of this type, but the 8x32 SE or most any other simple Porro has less than any of these.

Off Axis Sharpness: The 8x42 is similar to the Zeiss 8x42 FL (perhaps a little worse), which is to say it’s not particularly good. The off-axis deterioration is dominated by astigmatism just as it is in the FL. The center 20 degrees or so of apparent field is OK, but outside of that area astigmatism gradually increases until there is about 3-4 diopters difference between the sagittal and tangential foci at the edge of the field. Field curvature is low in the sense that the best focus at the edge (midpoint between the sagittal and tangential foci) is less than 1 diopter different from the center field focus. The 10x42 is similar, but perhaps slightly better.

Distortion: As in most binoculars there is pincushion distortion, a bit more in this case than is strictly needed to eliminate the “rolling globe” effect. The amount is about the same as the Zeiss 8x42 FL.

Light Transmission and Color Bias: I used the photo method I described a few months ago to compare the 8x42 Intrepid to the 8x42 FL and 8x32 SE, two binoculars with state of the art light transmission, but different color bias. The right image below shows sunlight reflecting from a piece of white paper. The three small squares in the center show the light after it passes through the optics of the three binoculars. The surrounding area is direct reflection from the paper to the camera. The Intrepid is the square at the upper left, the SE at the upper right.

The Intrepid result is actually quite good for a binocular using a Schmidt-Pechan prism with silver mirror coating. This image can’t be compared directly to the ones I made of other binoculars under different conditions and should be considered only as an approximation of light transmission, but from what I see I think the Intrepid is certainly dimmer than the alpha Schmidt-Pechan roofs that use dielectric mirror coating (as it should be with silver coating), but brighter than the silver coated Nikon LX-L, with which it shares a red bias. The warm bias probably indicates a relatively steep roll off in transmission from green through violet rather than a really sharp peak in the red. As I recall Ron’s (Surveyor) measurement of the light transmission of the sibling (identical?) Promaster binocular shows that kind of transmission curve. Reduced blue can give optics a snappy high contrast look because the cool shadow areas are slightly darkened compared to the warm sunlit areas and the daylight adapted eye may see an image with reduced blue as sharper because blue can’t quite be brought to common focus with the yellow/green to which the eye is most sensitive in daylight.

BTW, you can also see the warm color bias in the CA test images. Notice the slightly pink target cross and the warm black background in the Intrepid image compared to the nearly neutral Zeiss. The Nikon SE also has a slight red bias, but less than the Intrepid.

Flare Control: I wouldn’t expect any special problems with veiling glare, as I didn’t see any unusually bad internal reflections near the exit pupil. I did find the Intrepid to have superb resistance to ghosting, as good as any binocular I’ve seen.

That’s all the information I could gather in the time I had. The tests indicate very impressive optics for a $350 binocular. In fact, I would say the Intrepids are fully state of the art in two categories: freedom from longitudinal CA and ghosting. I thought the weakest ares of performance were off-axis astigmatism, light transmission and color bias, though none of those were really bad, just well below the state of the art. I didn’t use the binoculars under field conditions, so I don’t have any overall conclusions, but I did notice the very slow focus, which I know I don’t like from my years of using an early Swarovski EL.

[mooreorless]

Hi Henry, Very impressive "tests". I am interested in your resolution results of the Zeiss,SE when you have time to post. I think you might of posted about the Zeiss 8x56FL before. It might be my monitor but I can see the purple fringe in all the CA crosses as well as the red bias in the SE and Intrepid. Maybe it is just me. Thanks for going through the trouble of all this.:-) After rereading I see you already said about the warm bias.:eek!:
Regards,Steve

[henry link]

Hi Steve,

I didn't retest the Zeiss and Nikon for resolution. They've been measured many times. The best side of the Zeiss is about 2.9 arc sec and the Nikon about 3.9.

In the photo below I brightened the CA target photos of the SE and the Intrepid to better bring out the color fringing. The wide purple fringe radiating in all directions in the SE photo on the left is longitudinal CA. The Intrepid photo unfortunately has a little transverse CA visible mostly as the red fringe on the top and right sides of the cross. I found it very difficult to tune that out by centering the target. I think if you compare the fringing visible on the bottom and left edges of the cross in the Intrepid image to the SE you'll notice the reduction in longitudinal CA. Remember these are not APO optics, just better than achromatic. And the image is highly magnified to the appearance of about 60x.

Henry

[mooreorless]

Hi Henry, Thanks so much for this update. Sounds like these are well worth $350. I must say a big thanks for your testing of these binoculars.:t:
Regards,Steve

[marcus]

I see that purple fringe in the SE and the Zeiss.

[FrankD]

Thank you for taking the time to not only do the tests but to post your results as well Henry. Much appreciated.

[ronh]

Henry,
I really enjoyed reading your report, and the photo methods are impressive. I hope you won't mind a couple of questions.

1) Over on CN, EdZ reports that magnification is higher at closer distances, with internally-focussing binoculars. I don't think he actually measures magnification per se, but bases this on the varying size of the exit pupil, and the assumption that the true aperture doesn't change. Are you measuring the exit pupil but turning his assumptions around? Do you know in some other way that it is the aperture, not magnification, that varies?

2) Why is the dim light from a shadow bluer than if the region was well lit?

Once again, the fine shadows cast by the thickness of a piece of white tape in the longitudinal CA tests make nice demonstrations of resolution. The shadow line looks broadest and fuzziest in the SE, and the Zeiss edges the Atlas just a wee bit, or that's how it looks to me.

Thanks for the great report,
Ron

[Kevin Purcell]

1) Over on CN, EdZ reports that magnification is higher at closer distances, with internally-focussing binoculars. I don't think he actually measures magnification per se, but bases this on the varying size of the exit pupil, and the assumption that the true aperture doesn't change. Are you measuring the exit pupil but turning his assumptions around? Do you know in some other way that it is the aperture, not magnification, that varies?

I think this is exactly the effect were seeing.

The exit pupil change from 41/39 would be caused by a 5% change in magnification which doesn't seem unreasonable.

The only other explanation would be the aperture is actually changing (by being stopped by the focusing lens ... that's the only part that moves and so he only part that would change the aperture if it was too small). But in these Chinese ED bins the (positive) focusing lens is the same size as the objective lens (and quite close to it) so I don't see that as a reasonable explanation for this.

[henry link]

Henry,
I really enjoyed reading your report, and the photo methods are impressive. I hope you won't mind a couple of questions.

1) Over on CN, EdZ reports that magnification is higher at closer distances, with internally-focussing binoculars. I don't think he actually measures magnification per se, but bases this on the varying size of the exit pupil, and the assumption that the true aperture doesn't change. Are you measuring the exit pupil but turning his assumptions around? Do you know in some other way that it is the aperture, not magnification, that varies?

2) Why is the dim light from a shadow bluer than if the region was well lit?

Once again, the fine shadows cast by the thickness of a piece of white tape in the longitudinal CA tests make nice demonstrations of resolution. The shadow line looks broadest and fuzziest in the SE, and the Zeiss edges the Atlas just a wee bit, or that's how it looks to me.

Thanks for the great report,
Ron

Thanks Ron,

The answer to question 1 is that I measure the aperture directly by placing a transparent ruler across the objective and sighting through the binocular eyepiece with a magnifier (30mm FL eyepiece). So, changes in magnification and exit pupil size have no effect. Most good binoculars I've measured have been within 1mm of the specified aperture, but I've found some extreme examples of internal stop downs of as much as 20% of the specified aperture in some inexpensive binoculars. EdZ has found the same thing.
The Intrepid results are puzzling. I assumed at first that the focusing element was undersized so that it impinged on the light cone in its forward position at close focus. Further examination with the magnifier seemed to suggest that wasn't true. If I still had the binoculars I would investigate some more.

As for question 2 I'm not so sure about the physics. Perhaps the shadow areas in sunlight are mainly illuminated by scattered blue light from the sky? I cooked up a demonstration of the effect below. I photographed the same white piece of paper used in the color bias tests in sunlight, but cast a shadow on the left side. I think it is obvious that it appears dark blue, but to emphasize the color difference in the small inserts I lightened a crop of shadow and darkened a crop of the sunlit side to bring them to approximately the same light value. This difference in color temperature is why cameras need a different white balance setting for shade vs sunlight. I suspect Ron (Surveyor) and Ed (Elkcub) could give you a better answer.

Henry

[ronh]

Henry,
Thanks for the answers. Excellent on 1), and I'll just be John Brown on 2).
Ron

[Surveyor]

“True Aperture: Curiously the 8x42 had a little less than the 10x42. The 8x42 varies with focusing distance from about 39mm at close focus to 41mm at infinity focus. The 10x42 varies with focus from 40mm to 42mm.”

Henry;

I have just checked the Promaster apertures at infinity and 2-meter focus. I took 2 reading of each tube, one with the glass as close as possible to on axis and the other by moving the glass to get a maximum reading (but hard to focus). It confirms your measurements very well. I just never thought to measure at different foci and had just checked at infinity focus.

The results were:

Set 1 @ 10x:

On Axis;

-------Left Side----------------------- Right Side
Inf= 20 to 60.5 mm=40.5 mm----- 83.5 to 124 mm= 40.5 mm----- IPD=63.5
2 m= 21 to 60 mm= 40 mm -------84.5 to 123 mm= 38.5 mm----- IPD=63.25

Allowed off axis

--------Left Side----------------------- Right Side
Inf=20 to 61 mm= 41 mm---------83.5 to 123.5 mm= 40 mm------IPD=63
2m=21 to 60 mm= 39 mm---------84.5 to 123 mm= 38.5 mm----- IPD=63.25

Set 2 @ 5x:

On Axis;

-------Left Side---------------------- Right Side
Inf=15 to 56= 41 mm--------------78 to 119 mm= 41 mm---------IPD=63
2 m= 16 to 55= 39 mm------------79 to 118 mm= 39 mm----------IPD=63

Allowed off axis

-------Left Side--------------------------Right Side
Inf= 14 to 56 mm= 42mm-----------77.5 to 120 mm= 42.5 mm----IPD=63.75
2 m=15 to 55.5 mm= 40.5 mm-------78 to 119 mm= 41 mm-------IPD=63.25

The on-axis infinity aperture was about 40.75 mm and the 2 m aperture was about 39.125 mm for a difference of 1.625 mm, I think the confidence level of these would be about 0.5 mm.

Allowing off-axis measurements, the infinity reading was 41.375 mm and 39.75 at 2 m, a difference of 1.625 mm.

I have no explanation for this. I wonder if the field stop may be just a shade closer to the real image than the effective principle point of the first lens and interacting with either a small magnification change or, perhaps, a small change in the objective effective focal length with the focusing lens movement.

I spent some time yesterday with your color procedure with some promising results. I have never had a FL or SE to get transmission data on so I am limited to comparing with the curves I have for the Promaster. I do have a couple of questions before I go further:

Did you use direct reflection from the card or use a diffuser?
Did you use the camera white balance or turn it off?
Did you use the program mode or fully manual mode?

BTW, thanks for posting your findings. I have a pretty fair idea of the man-hours spent here, probably more than you anticipated when you started.

Have a good day.
Ron

[henry link]

Thanks Ron. Always good to have measurements confirmed even if we don't know what's going on.

In answer to your questions, I'm afraid I didn't have time to be very careful. Sunlight was direct reflection. I couldn't even find the white paper I used last time, so I substituted paper that's a warmer white. White balance was set to sunlight (I don't know how to turn it off) and I used manual mode since I didn't want the exposure to vary.

With the very impressive optics lab you've assembled I think you could do all of this much better than I can with my crude backyard stuff.

Henry

[mooreorless]

Hi Henry, When you said this:

"the left barrels of both binoculars showed coma, from misaligned optics, possibly a byproduct of collimation."

You were not saying that this binocular was out of collimation right? I had someone misunderstand this. I took it as the binocular had misaligned optics and they collimated the binocular and this cause the coma.
Regards,Steve

[henry link]

Yep, that's right. I guessed that the coma in the left sides might have been required to achieve good collimation between the left and right barrels. I forgot to mention that, while I didn't have time to measure it, the collimation of both pairs appeared to be excellent.

Henry

[mooreorless]

Thank you Henry for this information. If I remember right Ron's [Surveyor]Promaster's were out a little, nothing to worry about.[collimation] It didn't bother me.
Regards,Steve

[FrankD]

I guessed that the coma in the left sides might have been required to achieve good collimation between the left and right barrels.

Henry,

Could you explain this in more detail please?

The way I interpreted that comment was that the designer/manufacturer intentionally provided a less than optimal level of optical performance in the left barrel in order to achieve proper collimation. Is this correct? Why would this be the case?

[denco@comcast.n]

This post was delayed because I’ve been camping in the Great Smoky Mountains National Park this past week. I spent a few hours with these binoculars before I left, concentrating on the 8x42 because I have a Zeiss FL 8x42 for comparison and because I’m just more interested in that configuration. So, what follows are some measurements and tests I was able to do over that time, not a complete review.

True Aperture: Curiously the 8x42 had a little less than the 10x42. The 8x42 varies with focusing distance from about 39mm at close focus to 41mm at infinity focus. The 10x42 varies with focus from 40mm to 42mm.

Eye Relief: 8x42 – 20mm from the eyelens, 15mm from the rim of the fully collapsed eyecup. 10x42 - 18mm from the eyelens, 13mm from the eyecup.

FOV: I didn’t measure this directly, but I carefully compared the FOV of the 8x42 to the Zeiss 8x56 FL and Nikon 8x32 SE, which were the closest in FOV among my binoculars. The 8x42 Intrepid fell neatly between the two, which would put it around 390’-393’ (close enough to Steve’s 396’ measurement). I didn’t measure the 10x42.

Resolution measured at 64x (8x42), 80x (10x42): The four barrels varied from about 3.5 arc sec in the right barrel of the 8x42 to about 4 arc sec in the right barrel of the 10x42. Not good enough for alpha class bragging rights, but perfectly fine. There is much more detail in the image than the eye can see at normal magnification.

Star Test at 64x, (8x42), 80x (10x42): The right barrel of the 8x42 was quite good by binocular standards. The only obvious problem was the expected spherical aberration. All the other barrels had about the same amount SA. I’ve seen less in the best binoculars, but also more in some very expensive ones. The left barrels of both binoculars showed coma, from misaligned optics, possibly a byproduct of collimation. The right barrel of the 10x42 showed some astigmatism, which probably explains its relatively worse resolution measurement. One really good barrel out of four ain’t bad when it comes to binoculars of any price and none of the defects were severe enough for me to notice any effect at normal magnification in daylight. The astigmatism in the 10x42 could soften the image in low light when the full aperture is used. I also star tested the good barrel of the 8x42 stopped down to 30mm to simulate daylight use. As expected, the 30mm the star test was substantially improved as a result of reduced SA.

Chromatic Aberration: Longitudinal CA is very well corrected for a binocular, indicating that the ED glass really does do what it’s supposed to do. The attached photo below on the left shows the cross-shaped center of my CA target as imaged through three binoculars: a conventional achromatic doublet (Nikon 8x32 SE) on the left, the Intrepid 8x42 in the middle and the Zeiss 8x42 FL on the right. The purple fringe in the SE image is typical longitudinal CA found in fast binocular optics, which you can see is almost absent in the other two. I should add that this is worst case CA from the entire objective. In daylight at 8X, even the obvious purple fringe seen in the SE image is not visible at all.

Control of lateral color (Transverse CA) in the 8x42 Intrepid is about average for binoculars. Lateral color is the type of color fringing you can actually see in binoculars in bright light. It becomes stronger away from the field center, but can sometimes be seen in the very middle if the eye is slightly decentered. Some expensive roof prism binoculars with complex objectives have quite a lot of this form of CA. The 8x42 Intrepid shows slightly less lateral color than the 8x42 FL. It has about the same amount as the 8x56 FL, which is a good result for a binocular of this type, but the 8x32 SE or most any other simple Porro has less than any of these.

Off Axis Sharpness: The 8x42 is similar to the Zeiss 8x42 FL (perhaps a little worse), which is to say it’s not particularly good. The off-axis deterioration is dominated by astigmatism just as it is in the FL. The center 20 degrees or so of apparent field is OK, but outside of that area astigmatism gradually increases until there is about 3-4 diopters difference between the sagittal and tangential foci at the edge of the field. Field curvature is low in the sense that the best focus at the edge (midpoint between the sagittal and tangential foci) is less than 1 diopter different from the center field focus. The 10x42 is similar, but perhaps slightly better.

Distortion: As in most binoculars there is pincushion distortion, a bit more in this case than is strictly needed to eliminate the “rolling globe” effect. The amount is about the same as the Zeiss 8x42 FL.

Light Transmission and Color Bias: I used the photo method I described a few months ago to compare the 8x42 Intrepid to the 8x42 FL and 8x32 SE, two binoculars with state of the art light transmission, but different color bias. The right image below shows sunlight reflecting from a piece of white paper. The three small squares in the center show the light after it passes through the optics of the three binoculars. The surrounding area is direct reflection from the paper to the camera. The Intrepid is the square at the upper left, the SE at the upper right.

The Intrepid result is actually quite good for a binocular using a Schmidt-Pechan prism with silver mirror coating. This image can’t be compared directly to the ones I made of other binoculars under different conditions and should be considered only as an approximation of light transmission, but from what I see I think the Intrepid is certainly dimmer than the alpha Schmidt-Pechan roofs that use dielectric mirror coating (as it should be with silver coating), but brighter than the silver coated Nikon LX-L, with which it shares a red bias. The warm bias probably indicates a relatively steep roll off in transmission from green through violet rather than a really sharp peak in the red. As I recall Ron’s (Surveyor) measurement of the light transmission of the sibling (identical?) Promaster binocular shows that kind of transmission curve. Reduced blue can give optics a snappy high contrast look because the cool shadow areas are slightly darkened compared to the warm sunlit areas and the daylight adapted eye may see an image with reduced blue as sharper because blue can’t quite be brought to common focus with the yellow/green to which the eye is most sensitive in daylight.

BTW, you can also see the warm color bias in the CA test images. Notice the slightly pink target cross and the warm black background in the Intrepid image compared to the nearly neutral Zeiss. The Nikon SE also has a slight red bias, but less than the Intrepid.

Flare Control: I wouldn’t expect any special problems with veiling glare, as I didn’t see any unusually bad internal reflections near the exit pupil. I did find the Intrepid to have superb resistance to ghosting, as good as any binocular I’ve seen.

That’s all the information I could gather in the time I had. The tests indicate very impressive optics for a $350 binocular. In fact, I would say the Intrepids are fully state of the art in two categories: freedom from longitudinal CA and ghosting. I thought the weakest ares of performance were off-axis astigmatism, light transmission and color bias, though none of those were really bad, just well below the state of the art. I didn’t use the binoculars under field conditions, so I don’t have any overall conclusions, but I did notice the very slow focus, which I know I don’t like from my years of using an early Swarovski EL.

Nice review Henry! It's interesting to see that your tests confirm what I am seeing through these binoculars. A superb image. Can't wait to get the Zen Ray 7x36 ED2's. With the improvements they made including dielectric prisms they should be a quite nice pair of binoculars for $370.00.

Dennis

[henry link]

Frank,

I'm not sure how these binoculars are collimated, but collimation is typically done by moving only one element in the optical train, which causes it to move out of alignment with the other elements.

I think the easiest to understand example is eccentric objective rings. The objective lens is mounted within two eccentric rings. If the rings are aligned so that the thickest part of one ring lines up with the thinnest part of the other then the objective is perfectly centered within its cell and for the sake of this example we'll say it's also perfectly aligned with the eyepiece. If the left and right images don't merge when two such telescopes are put together with a hinge between them then one or both of the objectives will need to be moved laterally by rotating the eccentric rings until both telescopes optically align with the hinge and each other. Unfortunately that moves the objective off center with the eyepiece and introduces coma. Fortunately it takes a lot of coma to really mess up the low magnification image of a binocular.

Of course this isn't the only possible source of coma, but it's the one that's inherent in binocular design.

Henry

[FrankD]

Thank you Henry. I do believe I understand the concept now.

I think this must fall back to an assumption I made on the tolerances of current manufacturing processes. I had always just assumed that it was possible to creat tight enough tolerances to eliminate this type of collimation issue. Apparently I was wrong.

[Surveyor]

Thank you Henry. I do believe I understand the concept now.


Good morning, FrankD;

I will add a comment, actually a supposition, to Henry’s comments. Since a majority of people are right handed and may have a right master eye I think makers and repairmen favor, and hold, the right side adjustments. I do not know this to be fact but a large majority of the binoculars I have tested have had the best results on the right side.

Have a good day.
Ron

[Kevin Purcell]

Good morning, FrankD;

I will add a comment, actually a supposition, to Henry’s comments. Since a majority of people are right handed and may have a right master eye I think makers and repairmen favor, and hold, the right side adjustments. I do not know this to be fact but a large majority of the binoculars I have tested have had the best results on the right side.

Have a good day.
Ron

Well that's testable.

I don't actually beleive handedness and eye dominance are related. Eye dominance seems to come from the brain picking the best eye. So the selection I think is more to do with how the eye forms and changes with growth.

So for me

right handed
left dominant eye (right eye has more astigmatism than the left so my brain made the right choice ;) )
left footed (which is less usual)

So I'm rather happy with diopter adjustment on the right eye. ;)

[Surveyor]

Hi Kevin P;
Interesting, I am strongly right sided, right handed, right footed and strong right master eye, but my left eye is the stronger of the two. My prescription is OD -0.5 -1.5 90* and OC +0.25 -.75 75*. All my family is the same except one half brother, left handed but a right master eye.

Best

[Surveyor]

http://en.wikipedia.org/wiki/Ocular_dominance (http://en.wikipedia.org/wiki/Ocular_dominance)

Hi Kevin P.

A quick look found the wiki page above and supports you that there is not much of a correlation between hand/eye dominance, but does say about 2/3’s of the population is right eye dominant. I do not know the percentage of right handed people but seems that I have heard it is something like 75+%. I did not go into the bibliography listed.

Best

[APSmith]

If the left and right images don't merge when two such telescopes are put together with a hinge between them then one or both of the objectives will need to be moved laterally by rotating the eccentric rings until both telescopes optically align with the hinge and each other. Unfortunately that moves the objective off center with the eyepiece and introduces coma. Fortunately it takes a lot of coma to really mess up the low magnification image of a binocular.

Henry

I'm enjoying the discussion - interesting information. Thanks Henry for posting all this good stuff, especially this simplified collimation explanation.

I kinda had the same notion as Frank concerning mfg tolerances though. I wonder how much variance we're talking about. For instance, how much adjustment is typically possible with eccentric objective rings?

"Sample variation" is making more sense now. One has to expect the "alphas" to have sufficient QC for the design to be the primary limiting factor in product performance. But, is that necessarily so, and is it so as we drop down to lesser products? I guess that's one of the things we naturally question about these Chinese EDs. Can they do all those necessary things right, and keep costs low? Henry's fine review, along with all the other related posting, suggests that they're at least coming very close.

May have to jump on the wagon soon ...


Thanks, Adam

[FrankD]

For instance, how much adjustment is typically possible with eccentric objective rings

Do they still typically employ this method in current roof prism models? I know this was used with some older porro style binoculars from what I read.

Adam,

You then bring up an interesting point. Assuming that manufacturing tolerances are tight enough on the SwaroZeissLeica models then maybe one of the shortcuts that these open-bridge ED binoculars utilized for collimation is the method Henry described. Though I personally have a hard time seeing the optical difference between certain Alphas and certain open-bridge EDs I have to agree with others who have said that the price difference has to come from somewhere besides the exchange rate. Maybe this is one of those areas.

[Kevin Purcell]

Do they still typically employ this method in current roof prism models? I know this was used with some older porro style binoculars from what I read.

The eccentric rings are still there for the final tweak in the Chinese EDs.

The difference between older porros and these is the prism isn't moveable. It's glued in place with a UV set adhesive. The assembly procedure should either guarantee a good enough alignment (with the bits mating firmly to each other) or they can tweak it during assembly then set the adhesive when it's correct. I believe at least Swaro (and I suspect other Top Bin mkers) use this sort of technique.

[FrankD]

So the Chinese EDs still use the eccentric rings but the top end Euro models do not? Do your Zeiss FLs?

[Alexis Powell]

So the Chinese EDs still use the eccentric rings but the top end Euro models do not? Do your Zeiss FLs?

At least some, if not all, top-end binos still use eccentric rings or their equivalent. They are really obvious in the pocket roofs on the oculars, at least in the Leica Ultravid and Swarovski models (remember the goggle-eye complaints of the fellow who was concerned about holes in the Swarovski EL--Paul was it?). My Swarovski 8x32 EL went out of alignment shortly after I purchased it, reportedly due to a slightly loose ocular lens element.

--AP

[henry link]

I think Alexis is correct about eccentric eyepieces often being used in high end roof prism binoculars for collimation. Eccentric objective rings are also still used in the best Porros, like the Nikon Prostar, Astrolux, SE and EII and the Fujinon FMT-SX series. Inexpensive Porros these days tend use the inferior prism tilting method which is notorious for easily losing collimation. The very cheapest may not bother with collimation at all.

[FrankD]

Thank you for the clarification gentleman. So utilization of eccentric rings for collimation is not an outdated design...just the opposite actually. Interesting.

[APSmith]

Anyone know how much adjustment these eccentric rings give?

[henry link]

Enough to cause some pretty severe coma in the unlucky situation where the maximum eccentricity has to be employed to reach collimation. I just checked an old Nikon 8x30 E by simply unscrewing one barrel. A centered object traced a circle about 2 degrees of apparent field in diameter and that objective is not set for maximum eccentricity. I would guess the maximum adjustment for this binocular including both barrels would maybe fall somewhere between 5 and 10 degrees of apparent field.

[HoosierGuy]

Question - do these new Atlas binos have a plastic cap on the focus knob similar to the Zen Ed's? Can you post pictures of these binos? I can't find many picks of the Atlas binos anywhere.

[Fireform]

Thanks for posting the review, Henry. It confirms what I see through them very closely.

[Kevin Purcell]

Question - do these new Atlas binos have a plastic cap on the focus knob similar to the Zen Ed's? Can you post pictures of these binos? I can't find many picks of the Atlas binos anywhere.

It's the same enclosure and knob ... see the photo at EO

http://www.eagleoptics.com/binoculars/atlas-optics/atlas-optics-intrepid-ed-8x42-binocular

[Steve C]

Hoosier

The Atlas focus knob and cap is just like the ZEN ED. The difference is on the cap it says Atlas-8x42-Intrepid in dull white letters. And that is the only lettering on the binocular.

[henry link]

The Intrepid certainly has a plain generic look. Apparently no effort at all was put into designing a logo or graphics for them, which suggests a rush to market. I would be willing to bet that the Intrepid is an off the self product identical to the Promaster ED. Anyone who has both available can easily determine if the optics are identical by carefully scrutinizing the reflection patterns that return from lens elements. Identical patterns means identical optics.

I'm dubious about the reports here that these Chinese EDs with identical housings come in subtly different optical flavors. An importer can apparently order them with different coatings on the external surfaces and maybe with different size eyepiece fieldstops (I'm not so convinced about that one), but until I see it myself I'm very doubtful about the reports of different off-axis sharpness. That's a hard thing to compare accurately even using tripod mounted binoculars and a target specifically designed for it.

[FrankD]

I'm very doubtful about the reports of different off-axis sharpness. That's a hard thing to compare accurately even using tripod mounted binoculars and a target specifically designed for it.

Two thoughts on this Henry since I was probably the one that made comments of that nature. One, with quality control being as it is at any given price point and the inconsistancies we have seen with even high end binoculars don't you think it is possible that some variation in something like the size of the "sweet spot" is possible in any given binocular? I would argue this could probably even be the case from unit to unit not to mention model to model.

Two, as I think many of our discussions have come down to there is an actual physical, verifiable difference in a specific optical characteristic and then there is the perception of that characteristic. Would it not be possible, through the use of specific coatings, or some other process to create the perception of a larger sweet spot possibly even by decreasing sharpness in the center of the field?

Lastly, though I have no information to support it, could it not be possible that all of these ED binoculars are operating from some basic design with input on the "details" being left up to whoever the company is that is requesting them?

[Kevin Purcell]

Henry: different Chinese EDs do have different field stops in them. They have differing FOV specs too. So at least that part is customizable.

They also different in "extra" hydrophobic or oliophobic coatings, prisms mirror coatings and so on.

Talking to Charles at ZR he says his bins are not made by Bosma, for example. But Bosma does make very similar looking bins using the same enclosure and similar optics (the Atlas may or may not be Bosma made). So there are at least two manufacturing OEMs and I suspect more than one locations.

I think it perhaps makes more sense to say there is an underlying company that developed the optical design + mechanical design of the enclosure (that is made by some company) but that design/enclosure is sold on to anyone who wants to buy and use it. How that OEM decides to customize it (e.g. glass from a different bulk glass producer, glass finisher, AR coatings, etc) I think can vary quite a bit whilst sticking to the basic underlying design. It even give the option for the company to tweak the EP design too if they should so wish.

The manufacturing model should be something more like a tree of suppliers rather than a single factory (like a Ford/Mercury rebadge ... same car with slightly different options and colors for a slightly different audience).

Without pulling apart the bins and measuring them carefully that is going to be difficult to prove.

For the plain EO look it doesn't mean they were in a rush it just means they picked the "ODM version" with standard armor and "your brand" applied on the focus knob. I suspect this is more about minimizing capital outlay (using existing armor molds) than timing. And a set of options from the extra features is interesting too. For example they chose to use oleophobic coating but not hydrophobic coating and are the only Chinese ED to make this choice. But that must have been a choice (the default and the cheapest would be no repellant coating). A slighly odd one but perhaps they didn't like the look of the bin with hydrophobic coating (or it was too delicate and they worried about returns).

[Steve C]

Charles at Zen Ray also says the ZEN ED does not have eccentric collimation rings. He was also pretty emphatic in a conversation with me that he does not use Bosma for the ZEN ED.

Look at my description of lens coloring in the Intrepid reviews. All three, ZEN, Promaster, and Intrepid were just a bit different in lens colorings, and in the differences in the way they reflected.

[henry link]

[QUOTE=Kevin Purcell;1519985


Without pulling apart the bins and measuring them carefully that is going to be difficult to prove.

[/QUOTE]

Sorry guys, I've learned not to place too much trust in the information that comes from manufacturers and importers, and even less in the internet speculation about what they might be doing. Fortunately some things that are easy to confirm or disprove yourself, like aperture, FOV, eye relief, resolution, aberrations, etc And it doesn't require disassembly to determine if two binoculars have the same optics. Just place a bare lightbulb over your shoulder and carefully examine the pattern of lightbulb reflections that return from both the objective and eyepiece ends of the binoculars (be sure that the focus is set the same on each). You have to be careful and look deep into the binocular. Turn the binoculars until you see the reflections in the optics from the same angle and maybe use a magnifying glass. If the patterns are the same the optics are the same.

As for determining the exact size of the "sweet spot". It's difficult to do with lots of things to go wrong. I don't trust casual impressions especially if memory is involved, my own or anyone else's. To do it right requires a controlled test with a calibrated target, tripod mounted binoculars and repeating the test a number of times.

[mooreorless]

Hi Henry, I sort of tried to check the sweet spot in two Nikon 10x42SE last summer. The targets were not close enough together and I didn't have enough of them.;) This was a lens test kit I bought off ebay, seven lens. I gave away a few of them so far. They are way better than the big one I got off Edmunds.
Regards,Steve


edit:actually I was trying to compare edge performance between the two 10s, they were very close.

[marcus]

I just opened my new ATLAS Intrepid ED today and when I first took them out the box I thought how similiar they look to my ZEN-RAY ED. I suppose the smooth sides of the Intrepid opposed to the 'bumpy' sides of the ZEN-RAY seperates they way they look. And the neck-band connecter clamp is certainly different too. I very much prefer the ZEN-RAY's.
It's pretty dark out now so I won't really be able to check out the real optics although looking around my bedroom through them seems very clear. But the focus knob is going to bother me. It's too tight, but I'll hope that it will loosen after I've had them for a while.

[FrankD]

It's too tight, but I'll hope that it will loosen after I've had them for a while.

That was the case with the unit I had in my possession. It loosened up over time.

[Tero]

I don't know if this is the current thread on these, but I am interested in hearing how the focus...stiff or not... is performing out in the field for the Atlas owners.

I use a 8x42 Bushnell Legend porro where I would use these, and though the focus there is a little stiff...maybe cheaply made...it does not need all that much focusing for birds that are the usual distance away. The apparent depth of field is what I like about the porros. But they are heavy for all day use.