Binoculars review

Leupold BX-4 Pro Guide HD 8x42

Leupold BX-4 Pro Guide HD 8x42
4 July 2021
The BX-4 Pro Guide HD series produced by American Leupold consists of six roof-prism pairs of binoculars with the following parameters: 8x32, 10x32, 8x42, 10x42, 10x50, and 12x50.

The optical system, described shortly as HD, features fluorite elements that are supposed to ensure a perfect correction of chromatic aberration.

The producers claim that all optical elements of binoculars from this series are anti-reflection multi-coated. Apart from that, the surfaces of outer elements are covered by hydrophobic coatings and Schmidt-Pechan prisms are phase-correction coated.

The chassis of the binoculars is nitrogen-purged and waterproof. Buyers get in the box with the instrument: objective caps, a rainguard, a strap, a case, and a cleaning cloth for optics. The series comes with a lifetime warranty of the producer.

  • Lornetka Leupold BX-4 Pro Guide HD 8x42
  • Lornetka Leupold BX-4 Pro Guide HD 8x42
  • Lornetka Leupold BX-4 Pro Guide HD 8x42
  • Lornetka Leupold BX-4 Pro Guide HD 8x42
Manufacturer data


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Magnification Lens diameter Angular field of view Prisms Eye relief Weight Price
8 42 123/1000(7o) BaK-4/roof 19 mm 663 g 2469 PLN
Results of the review
Real front lens diameter Left:   41.6+/- 0.05 mm
Right:  41.5+/- 0.05 mm
6 / 8.0 pkt
Real magnification 7.84+/- 0.05x 3/3.0
Transmission 85.4+/- 1% 13/25.0
Chromatic aberration Excellent correction. Negligible both on the edge and in the centre. 8.9/10.0
Astigmatism Slight. 7.5/10.0
Distortion Distance between the first curved line and the field centre compared to the field of view radius: 87% ± 3% 10/10.0
Coma Coma appears already in a distance of 75% of the field of view radius and on the very edge is between medium and high. 6.7/10.0
Blurring at the edge of the FOV Blurry areas appear in a distance of 69% ± 5% from the centre. 3/10.0
Darkening at the edge the FOV Moderate. 3.6/5.0
Whiteness of the image Very slight yellow-green hue. 4.6/5.0
Collimation Perfect. 5/5.0
Internal reflections
Left: Right:
Leupold BX-4 Pro Guide HD 8x42 - Internal reflections - Left Leupold BX-4 Pro Guide HD 8x42 - Internal reflections - Right
A little less than ideal situation.
Housing Classic 'open hinge' design with very moderate dimensions for the 42 mm class – the Zeiss Victory SF 8X32, tested by me at the same time, was actually longer! Good quality rubber armour with very pronounced texture on both sides that ensures you a firmer grip. The armour sticks to the chassis very well , near objective lenses you can pull it away just a bit.Rubberized eyecups with three detention stops. The binoculars is a joy to use, very comfortable to hold and to look through. Produced in Japan. 7.8/8.0
Focusing A big, rubberized central wheel with scallop. It moves smoothly and is properly damped. The focus throw amounts to an angle of 730 degrees. An additional ring on the central wheel that can be pulled out for individual focusing. Nothing moves outside so the binoculars remains completely weather-sealed. 5/5.0
Tripod There is an exit but far from the centre of mass. 2.5/3.0
Interpupilary distance from 56.3 to 74.6mm 5/6.0
Closest focusing distance 2.50 meters. 1.5/2.0
Eyepieces FOV Apparent field of view of 54.4 degrees according to simplified formula or 50.9 degrees according to tangent formula. 6/20.0
Field of view Measured by us amounted to 6.94 ± 0.04 degrees and was slightly narrower than stated in official specifications. The field a tad too narrow for this class of equipment. 5/8.0
Quality of the interior of the barrels Inner tubes are dar, matt, and ribbed. You can spot additional apertures. The focusing element cell and bottom of the prisms are dark and slightly rough. No worrisome features, just single specks of dust on the prisms. 4.3/5.0
Left: Right:
Leupold BX-4 Pro Guide HD 8x42 - Vignetting - Left Leupold BX-4 Pro Guide HD 8x42 - Vignetting - Right
OL: 0.53%, OR: 0.25%
Prisms quality Good quality BaK-4. 8/8.0
Antireflection coatings Greenish-purple on objective lens, green on the prisms, green-yellow-purple on the eyepieces. Medium intensity. 4.5/5.0
Warranty [years] lifetime 6/6.0
Final result
137.7 / 190 pkt
Econo result 0pkt.


  • shapely, lightweight casing made of magnesium composites,
  • excellent correction of chromatic aberration,
  • good correction of astigmatism,
  • very good colour rendering,
  • practically zero distortion,
  • good blackening and cleanliness inside the tubes,
  • almost round exit pupils,
  • prisms made of BaK-4 glass,
  • good quality anti-reflection coatings,
  • lifetime warranty.

  • a lot of blurry areas on the edge of the field of view,
  • parameters stated by the producers differ from reality,
  • a bit too low transmission for this price point.

When I test 500-1000 USD binoculars I always have high hopes for them. Why? For such an amount of money you can produce a really well-put-together optical device with an excellent price/performance ratio. If the constructors apply themselves to that task and try to do their best, they can even offer you an instrument that will be able to compete successfully with much more expensive top-of-the-rivals.

That's why I got interested in the Leupold BX-4 Pro Guide HD 8X42, with a price tag of 500 USD, and I decided to test it thoroughly. Its field of view was not especially large but 7 degrees in this class is nothing to be ashamed of; what's more, a smaller field might mean very good aberration correction from edge to edge. You got also a very comfortable eye relief distance, amounting to as much as 19 mm. The binoculars, a very shapely instrument, were supposed to weigh just 663 grams. Finally, it's a product manufactured in Japan, something that happens less and less frequently nowadays when it comes to binoculars sold at this price point.

My attitude was really very optimistic but during the initial check of basic parameters I got the first cold shower. At this price point you should expect a full accordance between the official specification and real life measurements; meanwhile I found out the objective lenses, along with magnification, and the field of view, were a tad smaller than declared. The binoculars were also heavier, weighing 677 grams. The differences weren't very big but, from a future user's point of view, all of them were, unfortunately, less than favourable.

The edge of the field of view is another matter. In the case of an 8x42 class binoculars, with a field of 7 degrees, you would expect a perfect correction; meanwhile the Leupold performs weakly when it comes to keeping good sharpness on the edge and you can have some reservations connected to coma correction as well. Additionally, at this price point you should also get transmission definitely closer to 90%.

Fortunately, the binoculars also have a lot of assets and they managed to get a very sensible final score in our test, exceeding 137 points. Images in the centre are clear, bright, and with proper colour rendering. Chromatic aberration is corrected exceedingly well – you won't notice it in the centre and you won't be able to spot it on the edge either. The BX-4 8x42 HD has no problems whatsoever when it comes to distortion.

The real problem of the Leupold BX-4 Pro Guide HD 8x42 might be a fierce competition in this market segment. The Nikon Monarch 7 8x42 got practically the same result in our test and it is a device a tad cheaper and with a wider field of view. Binoculars such as the Bresser Pirsch ED 8x42 PhC or the Leupold BX-2 Alpine 8x42 got not much weaker results and they are cheaper as well. What's more, on the market you can find models that are cheaper than the Leupold and have fared better in our tests, for example the Bushnell Forge 8x42 or the Olympus 8x42 PRO. Compared to that, what's the selling point of the Leupold ? In fact, only its place of production – you can hope that a pair of binoculars, manufactured in Japan, undergoes a better process of quality control and, as a result, is more solid. Still, will it be indeed the case? Who knows...

To sum up, after the test I might say not all of my great expectations concerning the Leupold were met and it's a pity.