Vortex Razor UHD 10×50 head-to-head with the Swarovski SLC 10×42

What is worse? Not getting what you ask for or… getting what you asked only to wish you hadn’t? This has been a tough review! I keep thinking of phrases like, “finer than frog hair” or “a photo finish” and “by the skin of your teeth”. Think of any phrase that would represent extremely narrow margins and you’ll understand my torment. Honestly, I was often tempted to simply flip a coin and pick a winner, but the truth is too precious. This review is my best attempt at splitting hairs. As my title says, this is my head-to-head between Vortexes latest release—the Vortex Razor UHD 10×50—and the alpha-class Swarovski SLC 10×42. More info here.

Just The Facts
  • The Vortex Razor UHD 10×50 are 7 9/16” tall and weigh 37.7 oz.
  • The Swarovski SLC 10×42 are 5 5/8” tall and weigh 27.3 oz.
  • That’s a difference of 1.93” and 10.4 oz. Significant for sure.
The Vortex UHD 10×42 are made in Japan and the quality is evident
Personal Preference

The diopter adjustment rings are different.

To adjust the SLC, you pull the center focus knob toward you. The focus knob will now “click” as you adjust the right ocular. The upside is that once you find your setting and push the center focus knob back into place, it locks the diopter adjustment. The downside is “limited” adjustment. You must accept the position of each click, but I challenge you to distinguish the difference between single clicks.

Vortex Razor UHD 10×50

The Razor UHD has a smooth rolling diopter adjustment on the right barrel. The upside is infinite adjustment. The downside is the possibility of inadvertently rolling the diopter adjustment. In which case, you would simply reset the diopter.

How They Feel In Hand

Ergonomics are nearly impossible to quantify. No two people have the same hands, and no two people have the same feel. Both binoculars have thumbs grooves. Neither felt bulky or awkward or annoying (to me). Personally, I preferred the Razor UHD because my palms extended past the end of the SLC lenses. A good trade-off for the increased weight of the Vortex UHD 10×42


I have beehives in my backyard. If I focus on a honeybee sitting on an archery target at 50 yards, the Vortex UHD will hold a sharp focus out to about 200 yards. The focus on the Swarovski SLC starts to go soft closer to 150 yards.

However, if I set the initial focus on the wildflowers across the road at 70 yards, both binoculars easily hold their focus for great distances. I can still see the trees at the tops of mountains approximately two miles from my house.


The UHD 50’s have a larger field of view than the SLC 42’s, (they should with a bigger objective) but the difference is not what I had assumed. At 346’ at 1000 yards vs. the SLCs 330’, I wanted to set wooden stakes in a field to demonstrate the difference between the 50’s at 500, 1000, or 2000 yards, but it doesn’t work that way. There is a difference. It is perceptible, but it isn’t realistically measurable.

When I glass a mountainside at about 1.5 miles, I’m guessing that the UHD 50’s has an extra 100 yards of visibility left to right? Maybe less?

Edge-to-Edge Clarity

They’re the same to my eyes. Sitting on tripods, side-by-side, I literally could not tell the difference. I let my eyes wander within the FOV as far as the eye relief would allow. They both held their clarity and their image. Their sight picture doesn’t drop off or round down at the edges.

Eye Relief

They are physically the same. If there is a difference in distance from my eye to the lens, it was imperceptible but there was a functional difference. The UHD will tolerate noticeably more head movement than the SLC before blackout begins to invade the edges of your FOV.

1951 USAF Resolving Power Chart

This was the most infuriating element of the entire review. Mid-Day performance is phenomenal. The elements are crystal clear.

Twilight performance had me pulling out my hair. I genuinely and sincerely could not distinguish a difference. This was when I wanted to flip a coin. I wanted something, anything to tip the scale but there was no rescue.

Chromatic Aberration

I’ve experienced chromatic aberration before. For me, it has happened while using cheap binoculars with snow on the ground. I set the resolving power chart against the side of a white wall tent trying to simulate snow, but I was never able to induce chromatic aberration.

Buy Wisely

When we dive deep into the small details, it’s because they matter. Sometimes ten ounces is a deal-breaker and sometimes the extra FOV at a mile is necessary. If you don’t have a strong opinion one way or another, I’d make my decision purely based on price and availability. The newest edition to Vortex’s popular UHD line retails at $2150. Rumor has it the 10×42 SLC is discontinued but as a leader in category, I wanted to compare the new Vortex. Learn more and find retailers here.

A word of warning, once you start using glass of this quality you’ll never go back!

Vortex UHD 10×42 is factory-fitted with a 1/4-20 adapter. These UHDs really shine when tripod-mounted.

Several guys have been using the Vortex Razor UHD 10×50. If you want to visit and ask questions you can find us here.

Check out the rest of our optics reviews here.