Zen Ray ED....initial impressions (1 Viewer)

[FrankD]

I don't wear glasses but I can see where the Zen EDs might have slightly shorter eye relief than the Promaster EDs....via the larger field of view. I cannot really say. Kevin will have to comment.

However, I can say that I prefer the shape of both the Hawke and the Zen Rays' eyecups to the Promasters. The eyecup "edges" are more contoured and feel much more comfortable up against my face.

 

[Kevin Purcell]

I don't wear glasses but I can see where the Zen EDs might have slightly shorter eye relief than the Promaster EDs....via the larger field of view. I cannot really say. Kevin will have to comment.

I don't notice a difference. I can see the full field in both bins (though the PM field is a bit smaller than the ZR field).

Plenty of ER for eyeglass wearers.

 

[mayoayo]

I am really paying attention to contrast and stray light issues these last days....Resolution and DOF are very ,very good in the Zen...Eye relief and FOV are also very good..But the overall contrast ..i dont know...Now i am not sure if is the weather ,or what..I dont have any other bino to compare,but it seems like the overall contrast is not great..I found myself wanting a bit more transparency..This has nothing to do with detail,detail is always there,and lots!!(I would give up other qualities of the image for that detail,i guess)..
Is not really a matter of glare or reflections,more like a constant ,subtle veiling ...but then again..maybe the atmospheric conditions ?...Is just that i remember the LXL and the Pentax ED giving such punchy images..(not as sharp though...)
What is your general impression of the way the ED's renders contrast?..Is it good,average ,decent or is it the weak point in their performance?..

 

[FrankD]

I have seen bins with more contrast (Leica Trinovid for example) but I do not think it is necessarily a "weak" area for the Zen ED. I was just looking out back at the feeders behind my home and find that they "jump out" quite well when I focus on them.

 

[Steve C]

I am really paying attention to contrast and stray light issues these last days....Resolution and DOF are very ,very good in the Zen...What is your general impression of the way the ED's renders contrast? Is it good,average ,decent or is it the weak point in their performance?..

At some point you need to get to the place where you accept the image you get. You can get into separating the image into all of its facets and start to worry if something is lacking. Well of course for somebody, any binocular there is lacks something, if you look hard enough, by golly, you'll find it.

By my thinking, the absolute strong point of both the Promaster and the ZEN is the way that all facets of the image balance. This gives a good sharp, easy view and I quite frankly do not see the point in trying to spoil the impression. I might find a bit better contrast with say a Leica, or a bit better brightness with a Zeiss. But to my way of thinking, so what? It is not worth it to nit pick images too much.

Take a bit of a lesser binocular like the Nikon Monarch, and the contrast does seem lower, and the overall image lacks the balance of the ZEN. So I think that for a binocular to show that balance to me the big thing are the resolution ability, color sharpness and contrast. So in answer to your query, I certainly have no problem with the contrast in either one.

 

[mayoayo]

I am not trying to spoil the overall impression of image quality,and maybe i am nit picking image too much(..for some reason i dont feel alone,though!)..
I do need to accept the image at some point,i agree,I am just trying to determine if i would do it before the 30 days return policy expires...
I have noticed that the ZEN focuses by moving the rear Front element(or group) back and forth....Is this the most common way to focus Roof prism binoculars?...I think the Pentax ED moves the prism..
I dont know if one has advantages over the other,BUT in the case of the ZEN a broad ring of SHINY grease gets exposed when the binocular focuses to infinity(back)..This creates a real RING of reflection,and i am wondering if is the cause of the Donut effect ,and overall decreasing contrast..
I know that flocking the interior of optics ,and blackening the edge of lenses,can GREATLY improve contrast,so i imagine the opposite can be assumed..
I am only wondering if this is a design flaw,and having the grease reflecting light IN BETWEEN the objective lenses is affecting performance .Maybe correcting this problem,and improving overall performance without changing an,otherwise excellent ,design, is as simple as finding a new ,non-reflective ,lubricant..(graphite,teflon..?)

 

[lulubelle]

I dont know if one has advantages over the other,BUT in the case of the ZEN a broad ring of SHINY grease gets exposed when the binocular focuses to infinity(back)..This creates a real RING of reflection,and i am wandering if is the cause of the Donut effect ,and overall decreasing contrast..
I know that flocking the interior of optics ,and blackening the edge of lenses,can GREATLY improve contrast,so i imagine the opposite can be assumed..
I am only wandering if this is a design flaw,and having SO MUCH grease reflecting light IN BETWEEN the objective lenses is affecting performance .Maybe correcting this problem,and improving overall performance without changing an,otherwise excellent ,design, is as simple as finding a new ,non-reflective ,lubricant..(graphite,teflon..?)

My pair does not seem to exhibit this particular issue - at least not that have noticed yet. My left eye cup likes to move up a bit and that caused my view to be askew at times. It happens with some frequency for me, so mine may have to go back for adjusting or a new pair.

 

[Kevin Purcell]

I have noticed that the ZEN focuses by moving the rear Front element(or group) back and forth....Is this the most common way to focus Roof prism binoculars?...I think the Pentax ED moves the prism..

Moving a focusing element behind the objective is the most common way to focus internal focus bins (roof or porro). This element can be a stand alone element (closer to the prism than the objective) in some designs or it can larger and closer to the objective in others. I've seen both used.

Moving a roof prism will not focus a bin ... you need to move a lens or change the path length to focus a bin. Moving the SP prism doesn't change the path length of the optics (it just moves the prism up/down the optical axis).

The other question is does the lube actually bounce light down the tube? Does scattered light actually get by the large lens support (3mm thick?) that projects about 3mm in front of the focusing lens.

I suspect not as that geometry would be stopping rays that scatter at less than 45 degrees from the side wall from entering the focusing lens.

Note there is also a sharp edge stop just after the objective lens that defines the input pupil and I suspect keeps some of the light off that section of the tube (to get by it it has to be pretty far off axis).

So I don't think this is an issue with this bin (it's off axis baffling is not perfect but it's certainly not terrible either).

 

[falcondude]

From what I learnt before, the prism is used only to erect the image and reduce the overall physical length of the binocular. It does not do any focusing. But if Pentax SP uses prism to focus, it will be quite an achievement for not messing up collimation while moving the prism back and forth.

I was obsessively nit picking binoculars when I first got my EL a few years ago, despite of the fact that I still knew very little about optics even now. I was reading every review I could get hold of, and looking for every possible real or imaginary flaw. In parallel, I was also setting up my first decent home theatre. For the first two months, I didn't watch any movie. Instead, I spent most of the time, trying to adjust the contrast, white balance, and use sound meter to adjust the the output of each speaker. I always found something wrong (at least to my eyes and ears) every couple of days, and went back to redo the setup.... Until one day, a poster on a sound/video forum advised me that if I quit spending all my time behind the TV, instead, grab a bucket of popcorn and sit in front of it, all my misery will go away. I followed that advice and reset everything back to factory setting. I have been happy for about 3-4 years now. I did the same thing with my EL and stopped paying attention to the binoculars itself.

 

[mayoayo]

Kevin...When observing the focusing action in the Pentax ED,I wasnt sure if the moving part was a lens or part of the prism assembly ,but it was definitely moving in the back part of the binocular,versus the objective (like in the Zen)..
My scope focuses by moving part of the porro prism assembly back and forth ,thus changing the length of the path and focusing the scope.(There are two prisms in the assembly ,one to Erect and one to Reverse,Changing the distance between both determines the focal point.) I assumed the same system could have been used to focus roof prisms..
I see the large support that you mention,holding the focusing lens,and also the sharp edge just behind the objective...
I know that a really black,non reflective surface,would be better to control glare than the super shiny grease that gets exposed in between the objective and the focusing lens.I couldnt help to see this as a source for extra inner reflections and loss of contrast.I wish binoculars were like TV's and contrast/brightness could be Adjusted!!!(there is an idea!)
When the focusing lens is back,towards infinity,the exposed band of grease is about an inch wide,I didnt realize that both ,the 3mm support and the sharp edge would block the stray reflections created in there...If i think about it ,i still wonder ,What happens with the reflected light when it hits the edge of the support..?

 

[henry link]

Mayoayo,

A prism can't be moved for focusing in a roof prism system like a Porro because no movement is possible that doesn't cause the prism to move off the optical axis.

I've seen many cases of glare arising from the edge of the focusing element cell and/or the edge of the objective cell. Often the edges are not well baffled. A baffle behind the objective is no guarantee. It may be incorrectly sized or positioned, Sometimes a shiny focusing element edge is masked by the first prism aperture at close focus, but comes into view at longer distances as it moves forward. Sometimes the focusing element masks glare at the edge of the objective cell at distant focus but allows it to be seen at close focus as the focusing element moves back (I've never seen a focusing element that moves back toward infinity. Are you sure about that?).

It's much easier to see what's going on if you use a loupe (I use telescope eyepieces) to examine the interior of the binocular when glare is present. The source will usually be obvious when it's magnified and focused. The damaging stuff is typically right at the edge of the exit pupil, almost always a reflection from the objective cell, the focusing lens cell or the first prism aperture.

Henry

 

[Tero]

It might help if someone can locate a cross section picture of a roof prism binocular.

The simplest focus mechanism is in the 50 dollars and under pocket binos. My Nikon Sporstars do this. There the objective lens moves back and forth. There may be additional glass in front in bigger models.

The reverse porros I have on hand also move the objective lenses.

 

[mayoayo]

Henry..Thanks for the information..I still dont really understand why the whole roof prism assembly can not be moved back and forth along the optical path ,while staying on axis..I must be missing something..
In regard to the ZEN focusing action,the focusing lens moves back (close to the prism and apart from the objective)when focusing to infinity..(Maybe is the objective moving back and forth ,like the models mentioned by Tero,and the front element is only a sealing glass??).
Most of the focus range, from infinity to 20 feet ,happens in that distance,(back from the objective),so the exposed shinning grease is exposed pretty much all the time...
Is kind of a tricky concept,because the grease is there to help the mechanics operate,but i am not sure if a highly reflective surface ,JUST in front of the focusing lens,was taken into account when designing the optics..
The ZEN is a great binocular,..resolution is just amazing,and as a birding tool,it has proved to me to be great..It brings "scope-like" views,is the sense that it really shows detail,even in distant targets,where is really needed...
I will send an email to ZEN-RAY and comment about this real or imaginary flaw,in an honest attempt to share my first impressions about the binocular,..Maybe the manufacturer can find a way to lubricate the Moving parts,in a less shiny manner,and maybe this can translate in a minute improvement in performance that will bring the ZEN another marginal percentage closer to the already proverbial "ALPHA" performance..
(Did i miss any commas?)

 

[Tero]

Here is a cross section of a Zeiss roof prism bino. You can see two pieces of glass up front. One of them could move. The prisms are in the middle and do not move.
http://www.zeiss.com/C12568CF00206298/GraphikTitelIntern/MI_Obj_Lens/$File/MI_Obj_Lens.gif

you have to cut an paste that in the address bar of your browser.

 

[henry link]

Simply moving the entire prism cluster (Porro or roof) back and forth has no effect on the optical distance between the objective and the eyepiece. In a Porro focusing system only one of the two prisms is moved. That movement increases or decreases the space between the two prisms and that change in spacing lengthens or shortens the focal length between the objective and the eyepiece without changing the actual distance between them. That's the way your spotting scope works.

That can't be done in roof prism systems because the light path between the two prisms, unlike a Porro, is not parallel to the main optical axis. If one of the two prisms is moved to increase the space between the prisms it simultaneously moves off axis for either the objective (front prism) or the eyepiece (back prism).

I'm mystified by the backwards moving focusing lens on the Zen Ray. I don't see how that can work.

Henry

 

[Kevin Purcell]

I'm mystified by the backwards moving focusing lens on the Zen Ray. I don't see how that can work.

Same mechanism is used in the Promaster (8x42 and 7x32) and Hawkes 8x43, Pentax 8x36. I stopped checking at that point).

The focusing lens moves away from the objective to focus to infinity i.e. the objective + focuser becomes less positive to focus on more distant objects.

For two thin lenses of focal lengths f1 and f2 separated by distance d (just as an example ... real life is a little more complicated)

1/f = 1/f1 + 1/f2 - d/(f1 * f2)

1/f is just the power of the lens so that negative sign means that increasing the distance d between the two positive lenses decreases the overall power of the pair of lenses (makes it less positive) which is exactly what you need to focus the bin.

 

[Steve C]

My impression of the non standard focus direction is that the elements used in the focus operation still work in the same direction. This doesn't change. What changes is simply the direction of the cut of the gears (LH thread vs RH thread), so some need to move CW and others CCW. I have always assumed that a simple change in gears would then change focus wheel direction, but not the focus lens direction.

But I have to admit to being somewhat confused by mayoayo. It sounds like the suggestion (implication) is that there is grease inside the lens mechanism. Now I thought that the focusing was accomplished by a rod which is outside the lens assembly and that thus any lubricating grease (which would be on the rod and the gears associated with moving the rod) is therefore also outside the lens assembly and should not be able to be viewed at all. I can't imagine a decent binocular design that would let grease into the lens and prism housing.

Or have I just succeeded in missing the whole point? That would not be the first time and probably won't be the last either. :h?:

 

[henry link]

Same mechanism is used in the Promaster (8x42 and 7x32) and Hawkes 8x43, Pentax 8x36. I stopped checking at that point).

The focusing lens moves away from the objective to focus to infinity i.e. the objective + focuser becomes less positive to focus on more distant objects.

Oddly enough it apparently can work either way. Of the four instruments I have on hand that use focusing lenses three move the focusing lens toward the objective to reach infinity focus (Zeiss 8x42, 8x56 FL, Nikon 60mm Fieldscope ED) and as it turns out one (Kern 7x50 Focalpin) does the opposite. I hadn't noticed the direction of the Kern before. It also requires counter-clockwise focuser rotation toward infinity.

 

[Kevin Purcell]

If they use a negative lens for the focuser it would work the other way. Optics designers choice

But that is an interesting point about focusing rotation and direction of motion of the focuser. So perhaps they all use the same sense threaded rod and cams and the focusing optics differ. I should look at my collection for a correlation in rotation direction and movement of the focuser.

 

[Tero]

I did not look at all the details of it, but all my roof prisms have a moving lens in the area between prisms and the front. Bushnell Legend was very close to the front, Pentax DCF was a little deeper inside.

So do I still call the last piece of glass that I can touch the objective lens?