Monday, March 11, 2013

Leupold BX-4 McKinley HD 10x42 Binocular

From Frank D. in Eastern PA:

5/5 Rating

Amazing performance and handling

I finally have had the opportunity to sit down to put together some thoughts on this Leupold BX-4 McKinley HD 10x42 Binocular after a few days of use.

Let me start off by saying that I like this binocular. I really do. Really impressive in such a variety of different ways. As I always do though I want to start off with optical performance. Why not? When it comes to whether or not a binocular is a "keeper" it really does just boil down to how it performs optically overall and also in comparison to other binoculars that the individual has on hand. I do not have any "alpha" binoculars in my current selection to compare it to but I think Steve did a very nice job of comparing it to its primary competition either in terms of performance or price.

So, here is what stands out to me when I look through these binoculars:

Sweet Spot:

Huuuuuggggeee! Really Big. Practically edge to edge when all things are considered. For the average binocular user it will appear as if the apparent sharpness does stretch from one edge of the field of view to the other. Really impressive. There are only a handful of binoculars on the current market that you can say this about (Swarovision, Nikon SE and EDG to name a few). What makes it more impressive is that this model (and one other competitor) are able to stretch that flat, wide sweet spot over an 8 degree (420 foot) field of view. (8x42 model)

Closer inspection reveals some slightly different results. As I have often found with many binoculars with a field flattener element though the apparent sharpness is not necessarily consistent from one edge to the next. The central "sweet spot" is a good 70-75% of the field of view. Then there is a small "band" around the next 10-15% of the field of view where apparent sharpness falls off ever so slightly. I would have a hard time putting a specific percentage on the amount of degradation but it truly is minimal. You have to look for it to see it. The remaining 15-20% of the field of view is just as sharp as the central "sweet spot".

Chromatic Aberration (color fringing)

Because of the extra low dispersion glass element located in the objective design this binocular excels at reducing chromatic aberration throughout a huge portion of the field of view. My "litmus test" for this is to stare at the top edge of a mountain ridge and then move the binocular up and down so that the ridge "edge" moves through the entire field of view. With most "well-corrected" binoculars CA is well controlled within the sweet spot but does show up at varying degress outside of the sweet spot.

That is the case here with the Leupold McKinley 10x42.

The "kicker" though is that the sweet spot is so wide on the model. CA is practically absent throughout the entire sweet spot. In the small "ring" where sharpness falls off slightly CA is still well controlled and no worse than in the central sweet spot. In that last 10-15% of the field of view where apparent sharpness returns to the same level as the center then I can see CA along the ridge but it is very well controlled. I would rate it at close to the same level as the Zeiss FL of similar configuration.

Apparent Brightness

I would rate this model as excellent in this area....particularly in low light situations. When we refer to "apparent" brightness it is not just referring to measured light transmission levels but rather when a variety of factors such as contrast influence how we perceive the brightness levels of the image presented. The brightest roof prism model I have owned/tried was the Zeiss FL. I don't have one on hand to compare it to but I would be surprised if the FL produced a brighter image in anything but extreme low light conditions.

Apparent sharpness

As most individuals that frequent this forum are aware, even 8x binoculars are able to deliver more detail than our eyes are capable of seeing. Still, I think even an untrained eye can pick up on when a given binocular model is "less than sharp". Taking that a step further there are a few binocular models on the market that deliver an image which makes us feel as if we are seeing as much detail as we want...and then even a bit more. I hold no reservation in saying that this is one such model.

Case in point, as I type this I am occasionally looking out at an oak tree about 50 yards away. With the McKinleys focused on the bark of the tree I can see every minute detail...the contour and text of the bark, the small bits of moss growing at various spots, the subtle graduations of where one section of the trunk melds into the next. Really quite impressive.

To take it a step further I am also looking at a Turkey Vulture as it soars along the mountain ridge that I referenced earlier. The ridge itself is well over a mile away and yet the shape and detail of the bird is easily apparent as I focus the binocular.

Color bias and representation

For a variety of reasons many binoculars display what I refer to as a "color bias". Those reasons could include such things as the type of reflectivity coating utilized on the roof prism, the light transmission levels and the choice of antireflectivity coatings utilized throughout the entire binocular. To my eyes the McKinley is entirely neutral in color representation. I detect neither a warm (reddish-yellow) or cold (blue or green) color bias. Even when looking down the objective end with a white piece of paper in front of the ocular lenses I can detect no additional color.

The colors themselves are rich and well saturated. Reds are very red. Blues are very Blue.

Apparent Contrast

Again, I can find nothing to fault in this area. Contrast seems particularly good. Blacks and whites are in stark contrast to one another. Even the other night when looking up at the moon it seemed to almost be "alive" because of the level of contrast represented between it and the surrounding space.


No complaints with regard to the ergonomics. This is a traditional hinge model with thumb indents placed under the barrels. As you will see in one of the pics I attached I have no concerns with the placement or depth of the thumb indents. My index finger fits neatly on the focus knob with the middle and ring fingers across the central hinge and the pinky wrapped around the front end of the barrel.

Furthermore, the texture of the rubber armoring is very comfortable to hold. It has a small amount of texture added to it which, though comfortable, still allows you to obtain a very secure grib. I would have a difficult time believing that this binoculars would slip out of your hand even under wet conditions.

The focus knob itself is large but not obtrusive.

I do not have an issue with the length or weight. The McKinleys seem to be of average length for most 42 mm models. The weight is definitely there but I would not call it excessive. It is well balanced and certainly lighter than some of the 42 mm models I remember owning in the past (thinking Leica Trinovid, Meopta Meostar, Swarovski SLC, etc...)

Mechanical Qualities/Fit and Finish

When evaluating this area I look for a variety of small issues. Does the focusing knob have any play in the feel? Do the eyecups twist up and stay locked in placed? Is the central hinge tension tight enough not to move inadvertently and yet loose enough to adjust when exchanging the binocular from one person to the next? I can happily relate after examining all of these issues and more that this binocular "passes" with flying colors.

There is no play in the focusing knob on this particular unit. Central hinge tension is perfect. The eyecups are metal under the rubber armoring and they slide precisely in their tracks. The binocular reeks of quality in my opinion. Interestingly enough I think this is one of those binoculars where the whole is notably greater than its parts. When you pick one of these up in your hands you will understand what I am referring to. The solid weight, balance and overall fit and finish make this one of the most attractive binoculars I have had the opportunity to evaluate.

I also feel the need to comment about the over styling/look of the binocular. I have never used the term "sexy" when it came to a binocular for a variety of reasons. But, if there was ever a model that I did find attractive, at least in terms of styling, then this is it. The Golden "L" indented into the armor coupled with the Leupold name in gold along the barrel, plus the contours in the rubber armoring just make this one visually appealing binocular in my opinion.

If this binocular does not prove what Chinese manufacturers are capable of then I have not found one that does.


Just one at the present time. What initially "turned me off" with this model had to do with the oculars and the eyecup design. I have been using a variety of binoculars lately but primarily still utilize the Sightron 8x32s as my primary choice. The eyecup diameter on that model is relatively narrow. Subsequently I am accustomed to having the eyecups sit somewhat passed the bridge of my nose and below my eyebrows. That is not the case with the McKinleys. Because of the large ocular and eyecup diameter the binocualrs actually sit on top of the bridge of my nose and in front of my brow. Thankfully there is still sufficient eye relief to allow me to see the full field of view.

This issue took some getting accustomed to as it felt vastly different from any other model in recent memory.


  1. I thought the McKinley is a JAPANESE product??

    1. good catch. I thought Leupold were made in USA but I guess another one of those Assembled in USA with foreign parts deal.
      by the way, how do you find out where a particular Leupold is made?