New Zen Ray ZEN ED 2 Spotter in hand (1 Viewer)

Maybe I shouldn't have mentioned star testing. It's a useful tool, but easily misinterpreted. Here are some of the things to look for.

The star test images below show the second Zen-Ray scope I was sent. As an experiment I star tested it with the aperture stopped down to 35mm to eliminate the contribution to aberrations and defects from the outside 60% of the objective. The series of photos moves from 3 rings outside of focus on the left through focus in the center to about 3 rings inside of focus on the right. Except for the smeary spectrum of color it shows a very respectable looking test. There is good (but not perfect) symmetry in the appearance of the rings inside and outside of focus indicating good spherical correction. The flat spot at 4:00 and the astigmatism in the full aperture test are essentially gone. It's very unlikely that any specimen of this scope would look this good at full aperture, but from these images you can get a sense of what you would like to see (except for the color). Departures from this pattern indicate that something is wrong. Astigmatism causes the circles to become ovals, pinching may deform the circles in unpredictable ways, coma will cause an offset of the center of the rings, spherical aberration cases the rings to appear weaker on one side of focus than the other and there are other less common faults.

I should mention that the star test is very sensitive. Almost every scope shows some faults, so don't panic if the test is not perfect. It won't be.

Interesting. Thanks for the shots.

Do you have a speculation for the cause of the color (blue at 8 and red at 2 both sides of focus?)

Looks like lateral color, but it's right in the field center. The spot in the field where it nulls is about half way to the edge toward 2:00, yet there doesn't seem to be that much coma. It's aligned with the astigmatism so there must be a connection. Maybe something is tilted, perhaps the back element of the objective or a prism.

ZEN-RAY said:

It's official: we will introduce an adapter to allow 1.25" telescope eyepiece to work with our ZEN ED2 spotting scope body. It will be a FREE upgrade for ZEN ED2 spotting scope orders received before 3/31, including all previous orders. We expect to ship the adapter to all of our ED2 spotter customers on 3/31.

Thanks

Charles

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any pictue to show how it works? Can someone recommend an inexpensive, high quality astronomy eyepiece? If I need something for 25-30x fixed zoom, how do I know what focal length requirement for the eyepiece?

this was discussed on the last page -- the focal length of the ZEN ED2 scope is 464mm, so divide that by the focal length of the eyepiece to determine effective magnification.

For example, the Baader Hyperion 17mm (a very popular "budget" widefield astronomy eyepiece) would yield 464/17 = 27x magnification.

I tried to push the Zen magnification a little bit further. So I boost the scope with my 7x36 ED2, and took some shots with my compact camera handheld against the binos, with 105mm equivalent focal length, of an electric power pole +/- 190 yards away.
I didnt sharpen or fix the photos....what you see its what you get!!!!

I wasnt expecting such resolution on hudge magnifications, even when I tried the zoom at 60x, and then aligned the 7x binos with scope.... the view is pretty much uselless, even inside home where you dont have to be worried with the wind...but the wire mesh of the powerline cable was still visible.
I capture the image on small video http://www.youtube.com/watch?v=n2PCtqqUNEc

The eyepiece adapter would be very usefull, for birders like me who need that extra power for color ring readings in some situations.....92x with a 5 mm eyepiece should on some favorable ocasions give us some more detail.

I think is really good...I have used my 8x or 7x binoculars with ED scopes many times,if not for enjoyment,for the ocassional really distant bird that You can not ID otherwise,..Or as you pointed,that color band ..I was pretty impressed with my nikon ED50 at 13X boosted to 91X using the Zen ED2 7x a couple of times.
These samples are very good,I would say...

Does Anyone Knows if Kevin´s review of the scope ever saw the light?..maybe in other thread?

Nope. I never did write it up.

Kevin, why not?

jgraider said:

Kevin, why not?

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No particular reason. Just never got around to putting my notes together.

I've also taken to sitting on a product before reviewing it (I've not written up my Swarovision thoughts either but I really like that bin).

ZR sent me a demo scope to check out. I kept it for perhaps 4 weeks but used it for two and bit weeks.

Never did get a star test to work (that's me not the scope) but I did take it out to bird with once. I learned that it's much more difficult to do AB testing on a pair of 80ish mm scopes than it is on a 40ish mm bin. Especially if you are a walker and a cyclist like me.

Overall it's a Kowa-ovski "clone". Externally it looks like the Kowa down to the enclosure and stay-on case design but the eyepiece physical (and perhaps optical?) design is more like the Swaro. It even goes beyond the Zeiss in that the EP is a sealed unit (with a glass plate at the end so both the EP and tube are separately immersible. The Zeiss FL EP is only immersion proof when on the scope (the "bottom" isn't seal unless it seal is up against the scope body). It looked nicely made (CNCed out of chunks of aluminum)

It's also very, very similar to the Vortex Razor scope. I checked some pictures and it looks very similar. So perhaps the inheritance is Kowa/Swaro -> Vortex Razor -> ZR ED2 scope. I've not played with that scope but I suspect these two are in competition.

Construction was OK but I though I saw a hair or a mark on an internal lens. The scope came with fingerprints on the objective but I think those were from Charles using it as a demo in Portland.

Optically its very good. It's amazing how far the Chinese have come. I get the feeling it's better compared to the alpha scopes than the ED2 bins are to alpha bins.

Charles should pack the scope in a larger external box. There was perhaps 1cm between boxes and vey few pellets. I wonder if that's what caused issues with getting to Henry in NC?

I had problems getting the eyepiece to latch in place. I think the seal wasn't seated. After about 1 week mounted on the scope and some effort it clicked into place. This meant that I couldn't take it out because I was worried with it falling off. The EP doesn't have knurling on it so was a bit of a pain to twist on. Not sure if the issue was in the tube or the EP: I suspect the silicone seal at the bottom was a bit proud either too large or out of spec slightly or not seated (though I tried to reseat it).

FOV is about average amongst modern scopes these days (seem my 80mm FOV thread) which is to say less wide than the wide Zeiss but wider than scopes used to be in the recent past (which still seems to be my default viewpoint). So plenty good enough AFOV.

ER was similar but a little worse than the Zeiss with Zeiss or Baader EPs. I felt like I was push onto the EP a bit more at the "dip" in the ER around 30x. So if you get a EP adaptor a fixed 30x 68° astro EP would be good addition for general use. If the bayonet adaptor stays on the EP it would even nicer to use.

Weight was good. In fact I was expecting it to be heavier than my 85FL but it didn't appear to be. I don't have a scale but they seemed to be very similar in weight. So it's no Celestron Regal heavyweight.

Pushing the scope the longitudinal CA a bit worse than the Zeiss 85FL at 60x on a difficult (white letters on a black background) target. You can just see the fringes in the ZR scope but the Zeiss just gives a hint of color (more a change in color bias). But most of the time you'd never notice the CA at 30x but it's not a Kowa in terms of no CA but it is good.

It does miss on couple of things.

The Manfrotto shaped foot is a great idea but the execution is hopeless. The cutout orientation is backwards (as I've pointed out before) but one should still be able to use the foot "the right way around. It does fit into a 128RC head and latch but it's "90 degrees" off. When I tried it in my 701RC2 (that should be the right orientation) the foot wouldn't fit in that head. It seemed to be too wide. I didn't try removing the rubber insert to see if that was causing a problem. It would seem that if you make the effort to do this that you'd pick up the orientation (and sizing) error in testing and fix it. Apparently not or I missed something.

I had problems getting the case on. The fit wasn't great (and you need to fit it without the EP being in place ... I never did figure that out as it's not a requirement of my other scopes. I suspect if I had one I'd get a more padded case for transport and leave off the case SOC that comes with it.

But they're minor things but show the attention to detail.

I didn't like the slightly rough external paint finish (or the pink metallic ring) but apparently people do like the finish so that's just me.

The view was good. I didn't do a lot of glare testing or any testing against resolution targets. For waterbirds it looked fine. It's was sharp and controlled colors well. Lateral CA in the EP is well controlled too: you pretty much have to move out the side of the ocular to see lateral CA.

Not sure about the pricing. I think the $1000 or less price point is more appropriate for the scope. I suspect we will be seeing more Chinese ED scopes over the next year and perhaps see the price point start to stabilize.

I sent the scope back because I already have Zeiss 65FL and 85FL that cover what I need.

I could see a lot of folks being very happy with this scope and not needing anything more especially given the insane prices of the top five scope makers.

Thanks for the review, Kevin. Like you, I noticed the similarity between the Zen-Ray and Swarovski 20-60x zooms. I spent some time comparing them closely and concluded that the Zen-Ray appears to be a direct copy of the Swarovski. Reflection patterns from all the internal elements are identical and everything I could measure (overall dimensions, diameters of the eye and field lenses, focal length range, FOV, ER) appears to be the same. I'll be posting some comparison photos with my review, hopefully later this month.

I also spent a little time examining a Vortex Razor when I ran into a birder using one. Its eyepiece also appears to be suspiciously similar to the Swarovski. I couldn't make a direct comparison of the optics that day, but the mount end of the Razor eyepiece appeared to be identical to the Swarovski (and Zen-Ray): same bayonet, same three retaining screws and locking pin hole, same cover plate protecting the optics, etc. I'll try to arrange a similar direct photo comparison of the Vortex and Swarovski zooms.

What was the problem with star testing the Zen-Ray?

Henry

What was the problem with star testing the Zen-Ray?

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Me

As an apartment dweller, in the late winter, finding a place to do a star test was a problem.

At that time of year using a "natural star" in Seattle didn't pan out and my feeble attempts to make a battery powered artificial star came to nothing.

FWIW, the Kowa 880/770 series eyepieces also have an optical window sealing on the bayonette side. I also feel using a glitter point during the day more reliable than a real star. Lot's of them in an urban environment or make your own with a small bearing or BB glued on a stick.

Yes Kevin..thanks for the review...I have been using the LED from my bicycle to star test my scopes,I use all king of masking tapes to make the pinhole ,but the tin foil worked quite well..I didnt use regular wrapping foil,but the more sturdy type that came from a cofee can(now just go and buy a scope from Cameraland,and you got it!)..not sure if the LED is the most reliable light source to see color aberration,but since I always use the same light I have a constant reference.

I've been thinking about an LED solution. I didn't think about using a bike light.

I'd really like to find an old style LED where you can actually see the chip. That gives a pretty small emitter directly.

A green or red led would be helpful in cleaning up the diffraction rings (compared to a while LED or other light source).

What distance do you view the bike LED artificial star from?

20 to 30 feet..I had trouble with some of my scopes focussing at minimum distances of 21 feet and not having ,or barely ,enought distance in a straight line in some of my living spaces..now I live in two contiguos old apartments and opening all doors ,I can reach 50 feet indoors ,from one apartment to the other across the landing.
I do have a red LED light..also From my Bike!..maybe ill try it later to see what kind of star it creates..

Good advice here about making artificial stars or finding them on a sunny day. My indoor set up is quite crude, just a pinhole in tin foil, placed in front of a halogen task lamp at about 30'. I've found that even if the pin hole is not quite small enough to function as a true point source many defects like astigmatism, coma, pinching and bad roof prisms will still be visible. Outdoors, I use various shiny round objects. For impromptu testing there's nothing better than cars in sunlight. They're covered with shiny curved spots that make fine artificial stars as long as they are far enough away.

I'll just mention two caveats about using close sources. First, spherical aberration changes at close distances. A scope that is well corrected for infinity focus may look under corrected when tested at 20-30' from an artificial star. Suiter recommends a distance to the star at least 40 times the scope focal length. Also, in some scopes (like the Zen-Ray) the change in position of the focusing prism at close focus stops down the aperture. That may reduce or eliminate aberrations associated with the edge of the objective.

Finally, if you are going to use a colored light source to clean up the diffraction rings, green is the one to use since that's the reference color for best spherical correction in most telescopes. I use a very sharp green filter (Baader Solar Continuum) to remove the spherochromatism.

Henry

I remembered this site.."THE ABERRATOR"...some start test information and samples in there..


http://aberrator.astronomy.net/scopetest/