Vortex Kaibab 15×56 and Swarovski SLCneu 15×56

Vortex Kaibab 15×56 and Swarovski SLC 15×56 Binoculars

Technically speaking, this started a while back when Vortex asked me if I am interested in reviewing their new Kaibab 15×56 binoculars and I politely declined.  The reasoning for that was simple: I like to compare products to their competition, rather than review standalone products.  “Big Eyes” are generally not my cup of tea, so I really had nothing to compare it to.  The bad part was that I really liked this binocular when I looked at it during SHOT show and wanted a chance to play with it. Now, if I were to compare the Kaibab to something, it would have to be the current “king of the hill” in the world of Big Eyes: a similarly configured Swaro SLC, which was the design target for the Kaibab.  Luckily, SWFA has stepped up and allowed me to borrow a Swaro SLC 15×56 from the Samplelist.

Here is the short version:

Both are exceptionally nice binoculars.  Swaro has a slight edge as far as pure image quality.  However, the Vortex is more user friendly owing to its longer eye relief and, arguable, better eyecups.  Once price comes into the conversation (and Swaro is appreciably more expensive), this becomes a difficult choice.  Unless you wear glasses, that is.  Then the choice is easy, go awith the Vortex. When wearing contacts I preferred the Swaro.  When wearing glasses I opted for the Vortex every time.

Now for the long version.

Just about any 15×56 binocular is going to be fairly massive. It has to be.  Here are some basic specs:

Vortex Kaibab 15×56 Swarovski SLC Neu 15×56
Weight, ounces 44 45.5
Height, inches 7.7 8.47
Width, inches 5.7 5.04
Field of View, ft @1000 yards 225 231
Close focus, ft 23 26
Interpupillary Distance, mm 60 – 74 59 – 76
Eye Relief, mm 17.4 13


Both are massive binoculars.  Based on the numbers, there isn’t much to differentiate the two: Swaro has a touch more field of view, while Vortex has more eyerelief.  Visually, Vortex looks a bit slimmer, but overall design is quite different between the two.  Swaro has the diopter adjustment on the center knob, while Vortex has one on the right barrel.  Also, the eyecups on the Vortex looks positively massive next to the Swaro.  Here is what they look like side by side:

side by side

Here is another snapshot with the eyecups extended:
extended eye cups
Ordinarily, I would go into a lengthy discussion here about how I ended up holding the binoculars in a different way due to the design differences.  Not this time around.  Handholding these binoculars is about as productive as investing into the stability of Zimbabwean economy.

If you are in the market for one of these binoculars, get a steady tripod (incidentally, Vortex comes with a pretty nice quick detachable binocular adapter).  

Mechanically, both are excellent binoculars. Focusing knobs have a slightly different feel, but were easy for me to get used to.  I think I slightly preferred the focusing on the Kaibab, but both were good.  Vortex was able to focus a little closer than the Swaro, but I did not dwell on observing objects nearby.  I spent most of my time trying to discern objects very far away.  For example, I spent a fair amount of time in Malibu Hills looking at distant homes.  It is amazing what a binocular like this will let you see.   To really appreciate these binocualrs you need some open spaces:

open spaces

Good atmospheric conditions do not hurt either.  I stacked the binoculars the best I could, but their shapes are not really very conducive to stacking (please note that in the photo below the exit pupils of the two binoculars look different due to the way the picture was taken; when measured they are quite identical):


I ended up buying a quick detachable tripod adapter for the Swaro (same type as the one that came with the Kaibab), so that I could swap between the two binoculars quickly and look at the same scene.

What I found was that the Kaibab is much easier to get behind than the Swaro. That extra eye relief definitely comes in handy.  I also found the Kaibab eyecups a bit more comfortable for me, but that is personal.  I generally wear contacts, and with contacts I could use both binoculars in similar comfort.  With glasses it was a different story.  I simply could not get a full Field of View with the Swaro while wearing glasses (just for the record, lower magnification Swaro SLCs are much more comfortable in this regard).  With the Kaibab I had no such problems.

Here is another look at how the eyepieces stack up:


I asked a few people on several occasions to look at these binoculars side by side and tell me what they think.  In the first five minutes of looking, EVERYONE preferred the Vortex.  After a more extended observation period, eye glass wearers still preferred the Vortex, while about three quarters of people without glasses changed their allegiance to the SLCs.

In terms of image quality, Swaro outresolved the Kaibab ever so slightly.  Contrast was fairly similar between the two, but the color fidelity was different.  To my eyes, Swaro had a slightly warmer image.  Kaibab color looked a bit more neutral.  However, another person saw the Swaro as looking very neutral and the Kaibab as a bit cold.  That just re-enforces a simple fact that everyone’s eyes are different.

I spent a lot of time with these binoculars in an attempt to figure out which one gives me greater eye fatigue.  They ran neck in neck there, with a slight edge to the Vortex, likely due to the eyecups being more comfortable for me.  One interesting thing was trying to cut through mirage (a common thing during a hot California afternoon).  I am not sure what the scientific explanation for this is, but the Swaro was a touch better there.  While I was out trying to gauge eye fatigue, I also spent some time running a compact spotting scope next to the binoculars: Pentax 65mm ED spotter with an XF 20-60x eyepice.  There were a couple of reasons for that.  One was to figure out how high of a magnification a one eye instrument has to have in order to match a two-eye instrument.  Another, once again, was to gauge eye fatigue.

In practical terms, I saw about the same amount of detail with the spotter set on about 23x-24x  as I did with the 15x binoculars.  Not surprisingly, if you plan to do any serious time glassing, I would pick the binoculars every time.  Despite the lower magnification, using both eyes really makes up for a slightly smaller image.  If I were to use a higher end spotter instead of my Pentax, I suspect that ~18x-20x spotter magnification would equal 15x with a binocular.  As the light got dimmer, the advantages of using both eyes became more pronounced.  That is partly due to the better glass in Vortex and Swaro and partly due to the remarkable interpretive ability that our brains possess.

As far as low light performance goes, I do not think a 15×56 binocular is the first configuration that comes to people’s minds.  3.73mm exit pupil is a bit small for that.  However, magnification makes up for some of it.  When looked at side by side in low light, Swaro was a bit better than the Kaibab if there were no bright light source in or near the field of view.  Simply looking at a dark scene, the Swaro pulled out more details out of the image than the Vortex did.  In the dark, the differences really came to light (could not resist making a joke, for the life of me; that’s what you get for reading the ramblings of an optics nerd).  However, once some light came into a picture, things got cloudy, so to speak.  Placing a bright light source within the field of view of the Swaro caused some unexpected flair.  The amount of flair was not extreme, but it was noticeable.  This was not veiling flair (flair that looks light a curtain).  Rather, it looked like something weakly reflecting off of prism housings.  Vortex Kaibab did not exhibit these problems.

Traditionally, one of Swaro strengths has been large sweetspot.  That holds true for the 15×56 version.  The edges are a little worse then the center spot, but not by much.  You see a little asymmetrical coma aberration at the edges during a star test, but curvature of field and distortion is minimal.  Also, right near the edge of the field of view, there were what looked like mild difractive effects.  All these things were pretty hard to see unless you were really looking for them.

Vortex Kaibab performed somewhat similarly in this regard except the sweetspot was a touch smaller.  Field curvature and distortion were similarly well controlled.  Coma aberration was weaker and less noticeable, but diffractive effects strayed a touch further from the edges.  There was a little Chromatic Aberration in both binoculars.  I did not see a whole lot of practical difference between them in that regard. 

Truthfully, as far as both of these binoculars go, I am really nitpicking here.  Both are absolutely superb optical instruments.  The choice between the two really comes down to a few considerations:

  • price: Vortex is cheaper by about 30% or so.
  • Eyeglasses: if you wear glasses, go for the Vortex.
  • Resolution: Swaro is slightly better

If you can afford the Swaro, and do not wear glasses, the SLC is still King of the Hill, albeit by a nose.  Does the performance edge justify the price difference? That is between you and your wallet.

For my part, I hope Vortex expands the Kaibab line-up.  A lower magnification Kaibab would definitely attract my interest. Looking over Vortex’ extensive binocular line-up, I noticed that they do not make a high end 7×42 to compete with the alpha makers.  I think a Kaibab in that configuration would easily run neck in neck with Zeiss, Swaro and co.

Copyright ILya Koshkin 2009 All Rights Reserved
 Posted by at 12:53 am

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