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ZEN ED2 8x43 compared to ZenRay Summit

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#1 EdZ

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Posted 11 August 2009 - 06:30 AM

I received yesterday a ZEN ED2 8x43 roof, through arrangement with one of our members. Over the next few weeks, I'll compare it to my Zen Ray Summit 10x42 roof and several other binoculars.

first few things.

the ED2 8x43 is much longer than the ZRS 10x42.
with eyecups retracted
ZRS 10x42 = 148mm (5.8")
ZEN ED2 8x43 = 168mm (6.6")

The ZEN ED2 8x43 is heavier than the ZRS 10x42, 27oz. vs 26oz.

IPD range
ZEN ED2 8x43 = 55.5mm to 74mm
ZRS 10x42 = 58mm to 74mm

Depth to the eye lens. An issue I've noted with the ZRS is the too shallow depth that might cause potential contact between eye lens and eye glasses.
ZRS 10x42 = 2.3mm
ZEN ED2 = 4.8mm
the ZEN ED2 is considerably deeper. There appears no possibly way eyeglasses could come in contact with the binocular eye lens, or with the metla eyelens ring for that matter.

The ZEN ED2 eyecups twist out and have two positive click stops at about 4.5mm and 9mm extension. Didn't measure eye relief yet, but with the eyecups extended out 1 click, which addes 4.5mm overall length, it just cuts into my view of the edge of the fov. For my eyeglasses, usually I can see the entire fov with 12-13mm relief. I prefer the view with the eyecups fully retracted.
The ZRS have 3 click stop positions covering 8mm of extension, and I prefer the view with the eyecups extended out 1 click.

Eye relief is longer than the Nikon Monarch 10x42 rp, about the same or a bit less than the Celestron Regal 10x42 rp, but is not nearly as long as the Celestron Regal 8x42 or the Bushnell Legend 8x42 rp.

Aperture
Using a loupe, previuosly I measured the ZRS 10x42 aperture as 42mm.
I measured the ZRS 10x42 again at both infinity and close focus and got 41mm.

I measured the clear aperture of the ZEN ED2 8x43
at infinity it measures 40mm
at close focus it measures 38-39mm
I checked this twice, just to be sure. I would say the readings are accurate to within a mm.

Since comparisons will be made, for reference Review of Zen Ray Summit 10x42

edz

#2 Wes James

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Posted 11 August 2009 - 07:17 AM

EdZ-
Glad to see you taking on the Zen's... I'm quite fond of my ED's, anxious to read your impressions of them.

#3 EdZ

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Posted 11 August 2009 - 05:29 PM

More accurate measures of the APERTURE in the ZEN ED2 8x43

measured with a target crosshairs laser, the aperture is 41mm at infinity and 40mm at closest focus of about 6 feet.

Magnification
I checked magnification at close focus by observing a ruler. This method of checking magnification is usable, but not very precise. I recorded 8.25x-8.5x at close focus of 9 feet. I also measured an exit pupil of 4.9mm when still focused at 9 feet. This range checks fairly close to a 41mm aperture.

I measured an exit pupil of 5.25 when focused at about 200yds. This gives a magnification of about 7.8x at long distance. Obviously, somewhere in between 6 feet and 600 feet it really does produce 8 power.


I observed with the laser that it appears the obstruction stopping the aperture may be a metal spacer in the objective lens. It seems no other internal edge is hit by the laser light before that edge. The prism aperture is the next closest stop that the laser may be hitting, and it's really a close call between which of these is the culprit that is reducing overall aperture.

I also observed that the internal moving lens for focusing, at closest focus, comes all the way forward and touches the back side of the objective. The movable lens assembly has a slightly smaller retaining ring than the prime objective metal spacer and when it is moved all the way forward towards the objective for closest focus accounts for the loss of another mm of aperture at closest focus. At longer focuses, that movable lens ring is deep enough back inside the barrel that it does not get hit first.

Based on these more accurately measured results, the ED2 8x43 is operating at 41mm when focused at infinity and 40mm when at closest focus.

So, I measured,
~7.8x41 at infinity, exit pupil approx 5.25mm
~8.25x40 at closest focus, exit pupil approx 4.9mm

a much closer inspection seems to show that when the internal lens element is all the way forward (close focus), the baffle, which is also movable is the limiting factor to aperture. When the movable lens element is all the way towards the rear, the baffle opening is oversized and it is the prism shelf opening that is limiting aperture.


FOV
Close focus field of view, which is always smaller than maximum fov, is
7.6° at 20 feet
7.1° at 9 feet
binocular vision overlap is 90% at 20 feet and 82% at 9 feet.

So maximum binocular vision field of view
at 20 feet is 7.6° x 90% = 6.9°
and at 9 feet is 7.1° x 82% = 5.8°

Actually, these fov values are pretrty good. Of all roofs tested, all were between 88% and 92% at 20 feet and several were as small as 70% at closest focus.

Maximum Tfov when focused at infinity is 7.7°, actually more like 7.65°, but I'm rounding up. Manufacurer Specified fov (max) is 8.1°, so 5.5% of the field of view is lost to angular magnification distortion, fairly normal.

The binocular exhibits moderate pincushion, as would be expected given the angular mag distortion noted above.

edz

#4 Pinewood

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Posted 12 August 2009 - 05:29 AM

Hello EdZ,

Thank you very much for examining this binocular and posting your informative observations.

Clear skies,
Arthur Pinewood

#5 EdZ

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Posted 12 August 2009 - 05:37 AM

Field aberrations
between 50-60% out you can notice the view deteriorate. At 50-60% it is still mostly curvature, as most of it can be focused out. But by 70% out astigmatism begins to take over. Trying to focus out the curvature results in a straight line flipping from vertical to horizontal as you focus inside to outside of focus point. By 90% out astigmatism is so strong the image is not usable.

Comparing the Zen ED2 to the Zen Ray Summit 10x42, the ZRS held on to a good view out to 75% and was still usable out to 90. Both the 10x42 and 8x42 Celstron Regals held on much better, especially the 8x42, which was good to 95% of the fov.

This ED2 8x43 is not a flat field binocular. The curvature present, even in the absence of the astigmatism, would cause stars in the outer fov to look out-of-focus. The Celstron Regal LX 8x42 is a flat field binocular. The Zen ED2 8x43 has more curvature already by 60% out than the Celestron 8x42 has at 90% out. Preliminary indications are the ZRS 10x42 has less curvature than the Zen ED2 8x43, and therefore the ZRS 10x42, although not flat, would be considered to have a flatter field than the ED2. This requires more precise measures to quantify. FWIW, terrestrial users seem to tolerate far more curvature than astronomers, so while the curvature that is present is detrimental to the astronomy view, it may not bother terra users as much.

More on Field Aberrations

the right eyepiece is significantly worse than the left eyepiece.

When tested at 20 feet,
the left barrel was able to read 2+ arcmin (4mm) lettereing all the way out to between 90-95% of the field.
the right barrel could not clearly see 2 arcmin lettering beyond 60% out from center and could not see 3 arcmin lettering beyond 80% out from center.

There is imbalance in the aberration across the field. Both views deteriorated more towards the outside edge of the field, perhaps 5-10% of the field quicker.

When testing the overall view thru both eyes in binocular vision, a 1 arcmin target was lost from view at about 70-75% out to the right side of the view and was lost at about 60-65% out to the left side of the view.

For comparison 2 arcmin lettering would be approx. the same as 2 inches at 100yds.

BEST binoculars can resolve 1 arcmin out to 85% of the field and can see 2 arcmin resolved all the way to 95-100%. AVERAGE performance shows a sharp 1 armin image at 70% out and shows a sharp 2 arcmin image at 85-90% out. POOR image due to aberration is seen in binoculars that lose 1 arcmin resolution after 60% out and cannot see 2 arcmin after 75% out.

The left barrel of the Zen ED2 would measure up above average and perhaps be included in the best. But the right barrel would measure as poor. The binocular vision view would not place these among the better binoculars as far as field sharpness. A binocular needs to be able to see 1 arcmin clearly at 80% out from center to be among the better for sharpness.

I would rate the sharpness across the field as average overall and in the right eyepiece poor.

However, I should note, this is fairly typical performance for an 8° 8x binocular. If we compare just to other 8° binoculars, only the Nikon SE 8x32 field sharpness exceeds this one. But once you step down into the well populated range of 6.5° 8x binoculars, quite a few outperform the Zen ED2, and some by a wide margin. For instance, the Celestron Regal 8x42 is only 6.3°, yet it has a 25% wider sharp useable field of view than this 7.7° Zen ED2. Both the Pentax 8x40 WP and WPII have only a 6.3° fov, and yet the Zen ED2 8x43 has no more wide sharp usable fov than either of them.

edz

#6 EdZ

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Posted 12 August 2009 - 06:11 AM

When observing at the edge of dark treetops against a bright sky, there appears a significantly wide arc of ghosting across the bottom of the view. The arc was approx 1/4 to 1/3 around the view. This appears as a very large ghost image (perhaps of a stop somewhere in the light path), separated from the field stop by the normally darker unaffected space all around the edge. It appears it may be a ghost image caused by the prisms. I did notice the size and extent of the ghost image could be affected by eye placement and eye angle. BUT, to eliminate the ghost my eye angle had me looking into the binocular image directing my eyes towrds the top of the fov, to a point abou 80% out from center, a very uncomfortable position angle to assume.

For comparison, I pulled out my ZenRay Summit 10x42 rp and noted the exact same ghost arc in the image, also at the bottom of the view. The only difference being that the ghost in the ZRS was much fainter. Likewise, I noted a similar faint ghost arc of light in my Celestron Regal LX 8x42 rp, but in the Regal, there was no definitive dark space outlining the edge. And although seen, I noted an even fainter ghost arc in the image of my Pentax 8x40 WPII. However, no such ghost could be seen in my Nikon SE 10x42.

The Zen ED2 had by far the brightest and most prominent ghost arc, washing out the contrast of quite a large portion of the image. The others are listed here in decending order of how much it seemed to interfere with the overall image.

edz

#7 daniel_h

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Posted 12 August 2009 - 06:21 AM

Edz, maybe it was bad QC that got the right ep thru - maybe they tried to goto wide - what is the fov of the ep's

#8 Wes James

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Posted 12 August 2009 - 06:30 AM

The differences you're describing between the left and the right eyepieces sure do sound like a Q/C issue...
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#9 EdZ

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Posted 12 August 2009 - 06:44 AM

The differences you're describing between the left and the right eyepieces sure do sound like a Q/C issue...
Wes


I think I would be fair in stating, I see similar differences in about 1/3 of all binoculars.

edz

#10 EdZ

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Posted 12 August 2009 - 06:54 AM

Slow focus / Fast focus

simialar in some respects to the Zen Ray Summit 10x42, this Zen ED2 varies considerable from extreme slow focus at close distance to fairly fast focus at mid distance.

From closest focus which measures 5 feet, it took a bit more than 1 1/4 turns of the focus dial to focus out to 100 feet (2m to 30m). That is 470° of dial turn, by far (at close distance) the slowest focusing binocular I've ever seen, out of over 70 binoculars. The next slowest at close distance was in fact the ZRS 10x42.

From 100 feet to 100 yds (30m to 100m) I needed only turn the focus dial 45-50° to change focus, quite fast focus in this range.

For comparison
the Nikon SE 10x42 takes 300°/60° to cover these same distances, much faster at close distance and a bit slower at mid distance.
the Celestron Regal 8x42 rp 300°/30° to cover these ranges
Nikon Monarch ATB10x42 rp uses 180°/ 30°, a truly fast focus binocular
Bushnell Legend 8x42 rp uses 180°/ 30°, a truly fast focus binocular.

The ZEN ED2 add claims "SpeedDialTM focus wheel offers 30% faster focus rate". Faster than what? Certianly not the Regal the Monarh or the Legend. Other fast focus binoculars are the Fujinon BFL 8x42, Oberwerk Mariner 8x40, William Optic 7x50 ED and Nikon ProStar 7x50. The Zen ED2 doesn't even come close to these.




edz

#11 EdZ

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Posted 12 August 2009 - 07:19 AM

what is the fov of the ep's


As stated by the manufacturer the Tfov is 8.1°. that would mean the eyepieces are 8.1 x 8 = 65° Afov.

However, as is always the case, that specified value always includes the angular magnification distortion, and the real fov, which is based on the eyepiece field stop, is generally less. I have found the real Tfov is 7.7° and the real magnification at infinity is 7.8x, so that would give an effective Afov of 60°.

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#12 Richard McC

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Posted 12 August 2009 - 08:53 AM

Slow focus / Fast focus

... The ZEN ED2 add claims "SpeedDialTM focus wheel offers 30% faster focus rate". Faster than what? Certianly not the Regal the Monarh or the Legend. Other fast focus binoculars are the Fujinon BFL 8x42, Oberwerk Mariner 8x40, William Optic 7x50 ED and Nikon ProStar 7x50. The Zen ED2 doesn't even come close to these.


I believe the 30% faster focus rate is compared to the earlier Zen-Ray ED binoculars which preceded the newer ED2 series.

#13 EdZ

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Posted 12 August 2009 - 09:02 AM

I believe the 30% faster focus rate is compared to the earlier Zen-Ray ED binoculars which preceded the newer ED2 series.


Perhaps.

Unfortunately, at close distances, (2m to 30m) that still leaves this Zen ED2 8x43 as the slowest focusing of any binocular I've ever tested.

edz

#14 EdZ

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Posted 12 August 2009 - 12:03 PM

Edz, maybe it was bad QC that got the right ep thru


Frankly, based on other tests, I'm fairly certain it is not the eyepieces. However, before I post prelim tests, I'll confirm with positive tests.

To answer another question above, what I'm describing is a)the difference in image between the two barrels and b)the centered balance of the image in the view. I just happen to be looking thru the eyepieces to see it. So the difference is between the optical image delivered thru each optical path.

(I've removed the word eyepiece from my post and replaced it with the word barrel), so it doesn't read as viewed thru the right eyepiece, it now reads as viewed thru the right barrel.

FYI, it's almost always NOT the eyepieces. Image aberration is mostly the eyepieces. But differences in the appearance or placement of image aberration is generally something else.

edz

#15 EdZ

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Posted 12 August 2009 - 06:30 PM

curvature
measured in daylight on line pairs target. All of these values would be 75% worse on stars

measured at 60 and 90% out from center
total values are rounded

Zen ED2 8x43
at 60% out
total aberration is 50 arcseconds (400 arcsec apparent), 40 arcsec of it is curvature
at 90% out
total aberration is 110 arcseconds, 75 of it is curvature

In the Zen ED2, at 60% out in the fov, fully 80% of the total aberration is curvature. Near the lens edge, about 70% of the total error is due to curvature. Overall the amount of curvature is fairly strong. For observing astronomy, this will degrade the view. However, terrestrial viewers may find this adds to the image.

Curvature has the affect of forcing the focus point further out in the fov to focus on closer objects as curvature gets stronger. It almost always increases the apparent depth of the view which appears in focus, since it makes closer objects, which almost always appear in the view towards the outer edges of the fov, appear more in focus.


For comparison the ZenRay Summit 10x42
at 60% out
total aberration is 20 arcseconds (200 arcsec apparent), 18 of it is curvature
at 90% out
total aberration is 80 arcseconds, 45 of it is curvature

The Zen ED2 has about twice as much curvature and residual aberration at 60% out, and still about 1.5x as much of both at 90% out, as compared to the ZRS 10x42.


The ZEN ED2 8x43

has less curvature than
Nikon Action Ex 8x40
Nikon Action VII 8x40

has about the same as
Bushnell Legend 8x42 roof

has more than
Nikon Monarch ATB10x42 roof
Celestron Regal 10x42 roof
Nikon SE 10x42

has much more than these
these progress towards flatest field binoculars
Fujinon FMT-SX 10x50
Vixen Foresta 7x50
Zen Ray Summit 10x42 roof
Fujinon BFL 8x42
Celestron Regal 8x42 roof
Nikon SE 8x32

edz

#16 EdZ

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Posted 13 August 2009 - 10:45 AM

resolution
usaf 1951 res line pairs chart

normal power at 7.8x
saw 10.83 arcsec for apparenet res of 84 arcsec
that's pretty good, puts it in the top 20, but not in the top 15.
most roofs fell between 88 and 81
all 7x and 8x binocs fell between 92 and 75

boosted power at 48x (left barrel)
saw 4.07 arcsec for apparenet res of 195 arcsec
that's very good, puts it in the top 10
that's the best boosted reading from any roof
other better roofs fell between 204 and 227
ten 7x and 8x binocs fell between 183 and 211

boosted power at 48x (right barrel)
saw 4.3 arcsec for apparenet res of 206 arcsec
that's still very good, puts it in the top 15

with the boosted power, I checked both barrels also at about 60-70% out. the right barrel lost a full step, or one size bar pattern = 12%, vs the left barrel. In both barrels the vertical bars became blurred and only the horizontal bars could be seen clearly.

Overall, I have to say resolution is very good. It's not the best I've seen, but it's right up there.

edz

#17 EdZ

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Posted 13 August 2009 - 02:14 PM

internal glare
returning to the issue of what I previously called ghosting, or as it was more appropriately referred to by Henry Link, glare.

There have been a number of different suggestions made as to what this might be, among them improper eye position. Frankly, I was pretty certian that wasn't it for me. And it has been described several ways, some even saying they see a dark gray band. Well that wasn't it for me either.

I first saw this when viewing at the tops of trees with a bright sky behind the trees. It was suggested that my head position and extreme angle caused my eyes to be NOT properly positioned behind the exit pupil and that caused the glare. OK, I needed to check this. So I looked a bit further into this.

I set up several binoculars, all tripod mounted, with all the binoculars viewing level. I pointed them at a dark woods scene in the trees about 120 feet across my yard. My trees are fairly tall, about 80 feet high. Very bright overcast skylight was pouring in over the tops of the trees. I would say sky was up at an angle about 30° to 40° above my view.

With the binoculars level and with my eyes positioned perfectly behind them, the glare is quite apparent. The glare shows across the bottom of the field of view. So this proved to me, it wasn't a result of my head angle, since in this test, I'm standing straight behind the mounted binoculars, at ease, and looking level, straight on into the exit pupil which is elevated to my eye level.

In the ED2, the glare presents itself as a bright arc, separated from the field edge with the separated unaffected area just as dark as the normal view, but with the arc of glare a bright diffuse wash of light, perhaps accounting for why some were describing a grey band. It is not a gray band that is seen, it is a bright wash of glare separated from the field edge.

I could make it go away, but to do so I had to move my eyes considerably off-axis into an unusual and uncomfortable position to make this glare go away. So that convinces me it is not related to my eyes being not centered behind the exit pupils, since I needed to move considerably away from centered to make a change.

So, I did this very simple test. I held a sheet of cardboard over the front of and above the binoculars to shade my view. The glare instantly went away.

The fact that a simple lens shade held above the binocular resulted in the disappearance of the glare, and the fact that it instantly returned when the lens shade was removed, proves to me that the glare is being caused by reflection of off-axis sky light entering from above the binocular. It is being seen across the bottom of the view because the bright sky light is shining down at an angle into or onto the bottom front of the binocular and is causing a reflection in the bottom portion of the view. I was able to remove/replace the lens shade and make the glare appear/disappear at will.

This glare is being caused by a reflection.

In each of the following binoculars that showed glare, holding the light shield above the front end of the binocular caused the glare to immediately disappear. I checked these other binoculars and I note the results for each. In order from most glare to least glare, they are:

Zen ED2 8x43, most prominent (brightest) glare, well defined reflection arc separated from field stop by a thin band where the reflection arc did not encroach. This reflection spans about 1/4 to 1/3 the way across the bottom of the view and at its thickest encroaches perhaps 20% into the field of view

Zen Ray Summit 10x42, moderate glare, less defined than ED2, still shows defined arc 1/3 across view

Nikon AE 10x50, slight, light is diffuse, but arc is defined and separated from edge leaving that apparent darker area that creates the arc edge

Nikon AE 8x40, identical to Nikon AE 10x50

Oberwerk 12x50 Sport roof moderate glare, diffuse, no defined edge, across bottom 1/3 to 1/4 of view

Celestron Regal LX 8x42, slight to moderate glare, extends from field stop across bottom 25% of view, more diffuse, fainter

Bushnell Legend 8x42, slight to moderate, diffuse, extends to field stop, no defined arc edge, quite faint

Pentax PCF WPII 8x40, slight, diffuse, not intrusive

Nikon SE 10x42, no glare at all

Nikon Prostar 7x50, no glare at all

Fujinon FMTSX 10x50 no glare at all.

There is no question left in my mind now that this glare is caused by reflection. Whether it is a reflection off of the metal in front of the objective lens, off of lens edges, or from off-axis light redirected internally, I do not know for sure. But I do know that a light shield does not have an affect on eye placement and I do know that when you move a light shield over/away from the entrance and the glare appears/disappears, that the light shield is blocking light and having an affect on the outcome.

This also may explain that it may not always be seen. I was out viewing this morning from my deck, but standing under my canopy since it was drizzling. No overhead light shining down on my binoculars. I was looking into the woods. Under those conditions, there was no available overhead light to shine down and hit any portion of the binocular to cause reflection. Standing indoors, on a porch or under a shaded area may have the same effect.

Of the binoculars checked by this method, the Zen ED2 has the brightest and most distinct arc of glare caused by reflection. I have a suspicion that the light is being reflected off of the metal retainer in front of the objective lens. In the ED2 that metal retainer is smooth and shiny while on most of the other binoculars that metal retainer is either beveled away, ribbed or very dull grey.

edz

#18 art6

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Posted 13 August 2009 - 04:31 PM

Could you please explain how the "boosted power 48x" is performed? Thanks.

-- Art

#19 EdZ

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Posted 13 August 2009 - 04:36 PM

Could you please explain how the "boosted power 48x" is performed? Thanks.

-- Art


See the Best Of threads - Testing Aspects of Binoculars - Testing Resolution

for a full explaination.

simple explanation, a small 6x monocular is mounted behind the 8x binocular and I read the same chart. The power is multiplied.

edz

#20 EdZ

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Posted 14 August 2009 - 08:01 AM

internal glare
This glare is being caused by a reflection.

Whether it is a reflection off of the metal in front of the objective lens, off of lens edges, or from off-axis light redirected internally, I do not know for sure.

I have a suspicion that the light is being reflected off of the metal retainer in front of the objective lens. In the ED2 that metal retainer is smooth and shiny while on most of the other binoculars that metal retainer is either beveled away, ribbed or very dull grey.

edz



It was my suspicion that it was stray light reflecting off of the retaining ring. I may have proved that suspicion incorrect this morning.

I added black flocked felt (green sticky felt blackened with marker) to the retaining ring, and it didn't change anything. The fact that the flocking seemed to be no help indicates to me it is stray light reflecting from some internal surface, or perhaps even more than one surface.

The bright arc can be seen in the exit pupil if you step back from the binoculars and look AT the exit pupil. In fact, I checked several binoculars this morning and in some you can actually watch the bright reflection change as you refocus and move the position of the movable internal focusing element. In those cases, you can be assured the movable element is involved in the cause of the reflection, either causing it or blocking it. However, I'm still not sure which surface is the cause in the ED2, although I'm now much more convinced it is internal.

I used a loupe to observe the exit pupils of several binoculars in which the glare issue was present. Particularly in the Zen, but also in several others, you can see the glare surface move as you focus the binocular. It seems possible it may be the internal focusing mechanism. It did not get smaller as I moved the focuser all the way forward, so it's not covering up something as it moves. It could it be an unblackened lens edge in the movable focusing lens. It could be the metal housing around the front end of the movable element. Not sure, but using a loupe to look at the exit pupil, you can for certain see the glare move as you turn thru focus.



edz

#21 EdZ

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Posted 16 August 2009 - 03:36 PM

Zen Ray was kind enough to send me another ED2 8x43, so I could compare to see if the imbalance in off-axis resolution would be improved in another sample. Here's the results of the test comparison and both are then compared to the Zen Ray Summit 10x42

I don't have graphics to put in this post, unfortunately, because that would make it so much easier to understand these values. but here goes.

I tested each barrel of binocular separately, and for the positions off-axis, I also tested the inside edge of fov and the outside edge of fov. Lower resolution readings are indicative of better performance.

readings at 60% both sides of center and center on-axis best resolution
out reading is 60% towards outside edge of fov
center reading in best on-axis resolution
in reading is 60% towards inside edge of fov
all values are direct readings arcseconds of line pairs in daylight
since I noticed a difference between my two eyes, my right eye not getting readings as good as my left, I recorded all readings here using my left (better) eye, and focused each barrel separately to best resolution for my left eye.

sample 1 ED2 8x43
left barrel out-17.2--10.8--12.2-in --- in-15.3--10.8--19.3-out right barrel

sample 2 ED2 8x43
left barrel out-15.3--10.8--13.6-in --- in-17.2--12.2--17.2-out right barrel

ZR Summit 10x42
left barrel out-12.2--8.1--12.2-in --- in-12.2--8.1--12.2-out right barrel

Celestron Regal LX 8x42
left barrel out-16.2--10.8--15.3-in --- in-15.3--10.8--15.3-out right barrel


readings of 10.8 in the 8x vs 8.1 in the 10x are virtually equal
readings of 15.3 in the 8x vs 12.2 in the 10x are virtually equal
this just represtns the difference in the powers between the two models.

What you can notice from these readings is this:

the ZRS 10x42 has on-axis and off-axis resolution balanced in each barrel and the two barrels are balanced to each other. You can expect you will see the same resolution at 60% off-axis anywhere at 60% out in the fov.

The Celestron Regal LX 8x42 is nearly as well balanced as the ZRS with one minor blip.

both the ED2s have differences between the right and left barrels, and three out of the four barrel sets are out of balance from the inside edge of view to the outside edge of view within the barrel.

the 2nd sample ED2 was much better than the 1st sample, but that 2nd sample is still not balanced with 3 out of 4 off-axis readings being different. In addition, the 2nd sample had a lower overall on-axis resolution that did not match the on-axis resolution of any of the other three in this test.


When you have a binocular that is unbalanced in off-axis resolution or what is commonly referred to as field sharpness or sharpness across the field, what happens in the fov is that an object that appears clear and sharp in one barrel appears unsharp in the other barrel. It is important for the fov sharpness to be consistent and for the barrels to be matched.

edz

#22 EdZ

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Posted 17 August 2009 - 12:44 PM

Having on hand two samples of the same binocular, the ED2 8x43, provides me with opportunity to check some of the other measures I've recorded in the first sample.

Sample 2:
on-axis resolution - noted in the post above, slightly lower than sample 1
off axis field sharpness - also noted above, slightly better than sample 1
aperture - measures nearly identical, 40mm at infinty, 39mm at close focus
glare - same as sample 1, significant unless purposely shielded

edz

#23 94bamf

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Posted 17 August 2009 - 05:25 PM

ED, do you think there is any new roof bino out there right now that is better than the Zen Ray Summit 10x42 for under $300?

How does the ZRS 10x42 compare to the Nikon Monarch 10x42? Is it vastly better?

I was on a quest to find a really nice roof 8x42 or 10x42 for under/around $300, it looks like the Zen Ray Summit would be a good choice and its under $200..

Ken

#24 EdZ

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Posted 17 August 2009 - 06:45 PM

I don't follow the roof market close enough to know what's out there, so I can't say if "any new roof bino out there right now that is better" but

I do know the Zen Ray Summit measures up very good. The ZRS 10x42 beats out the Nikon Monarch 10x42 in resolution and some mechanical aspects. the Monarch beats ot the ZRS in field of view, and equals field sharpness and wins in some other mech aspects. In fact, my ZRS 10x42 even measures up in some aspects better than the ED2 8x43. Overall the ZRS 10x42 is close to the Nikon Monarch 10x42, but its better value. I would call the ZRS 10x42 a good choice.

edz

#25 jonstarrysky

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Posted 18 August 2009 - 02:56 AM

Very interesting. I have its near idendical twin the Hawke 8x43ED. It has noticable glare, but not enough to be real trouble. I have not much to compare this to, except the Orion Ultraview 8x42 which actually has much worse glare which requires very careful eyeplavement to keep in check.

Edz - how do you explain the discrepancy between manufacturer stated specs and measured ?? This especially applies to aperture as that is presumably a simple parameter. Maybe they measure the actual lens before its inserted into the binocular ?

My Hawke 8x43ED gives nice sharp contrasty images and is very bright. My main gripes are they are the focusser is stiff and they are actually quite heavy. I have an old pair of 10x40 Chinon roofs (Japanese). Optically they are medoicre to poor. But they are so light and thin, they just slip into your palm and you barely notice them. Not so with the Hawkes. Optical quality vs. comfort - sometimes i'd opt for the latter.






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