Night vision scopes / Comparison
Sightmark Photon RT 4.5x42 vs Sightmark Photon XT 4.6x42S
Both put about the same number of pixels on a coyote, 52 tall at 100 yards, so neither sees farther.
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Calculated from sensor and lens
What a coyote looks like on each
The sensors are 768 and 656 pixels wide. How many pixels land on the animal comes from pixel size and lens length, not from the sensor's size. Here is a coyote at each distance, drawn with the pixels each unit would give it. Every square is one sensor pixel, at the same size throughout.
Sightmark Photon RT 4.5x42
Sightmark Photon XT 4.6x42S
100 yards
Photon RT 4.5x42
52 px tall
Photon XT 4.6x42S
52 px tall
200 yards
Photon RT 4.5x42
26 px tall
Photon XT 4.6x42S
26 px tall
300 yards
Photon RT 4.5x42
17 px tall
Photon XT 4.6x42S
17 px tall
Telling a coyote from a fox at night
Digital night vision
A camera-style sensor that sees in very low light and in infrared, usually helped by a built-in infrared light. Cheaper than tubes, and it shows color by day.
On digital night vision the infrared illuminator, not the sensor, decides how far out you can name an animal at night, and makers rarely publish how far it reaches. In good light the pixel math above runs to hundreds of yards, which is why we do not quote a yardage here. Hunters report roughly 120 to 300 yards at night, depending on the illuminator.
Ground across the screen at 100 yd
Field width
How many feet of ground fill the screen at 100 yards. Wider makes scanning faster; narrower usually means more detail on the animal.
At base magnification. Wider finds animals faster; narrower shows each one bigger. You cannot have both from one lens.
Key differences
- Both put about the same number of pixels on a coyote, 52 tall at 100 yards, so neither sees farther.
- The Photon XT 4.6x42S runs 5 hours on a charge, the Photon RT 4.5x42 3.5.
Full specs
| Photon RT 4.5x42Sightmark Photon RT 4.5x42 | Photon XT 4.6x42SSightmark Photon XT 4.6x42S | |
|---|---|---|
| Sensor | ||
| Resolution Sensor resolution How many heat-reading pixels the sensor has, such as 384 × 288 or 640 × 512. More pixels show more detail, but the lens matters just as much. | 768 × 576Better | 656 × 492 |
| Refresh rate Refresh rate How many times per second the picture updates. 50 or 60 times a second looks smooth; lower rates stutter when you pan or a coyote runs. | Not published | Not published |
| Infrared | ||
| IR illuminator IR illuminator A flashlight of infrared light that people can barely see or not see at all. Digital night vision depends on it in the dark, and it often limits how far you can see. | 940 nm, built in | 810 nm, built in |
| IR power 850 nm vs 940 nm IR The two common infrared light colors. 850 reaches farther with a cleaner picture but shows a faint red glow; 940 is close to invisible but reaches less far. | 100 mW | 100 mW |
| Color in daylight Digital night vision A camera-style sensor that sees in very low light and in infrared, usually helped by a built-in infrared light. Cheaper than tubes, and it shows color by day. | — | — |
| Optics | ||
| Lens Focal length The lens number in millimeters, like 35 mm or 50 mm. A longer lens puts more pixels on a distant animal but shows a narrower slice of ground. | 50 mm | 50 mm f/1.2 |
| Base magnification Base magnification How much bigger things look before any digital zoom, like 2× or 4×. Higher is not automatically better: it narrows your view. | 4.5× | 4.6× |
| Max digital zoom Digital zoom Electronic enlarging of the picture. It makes the animal look bigger but adds no detail; past about 2× to 4× the image gets blocky. | 9× | 4.6× |
| Field of view Field of view How wide a view you get, in degrees. A wide view makes scanning for animals faster; a narrow one usually means more magnification. | 4.3° wide | 4.3° wide |
| Identification, zoomed to full sensor (calculated) Identification distance Our estimate of how far away you can tell a coyote from a fox or a dog. It is calculated from the lens and sensor, assuming good conditions. | ~520 yd in good light | ~445 yd in good light |
| Detection range (maker’s claim) Detection range The maker's figure for how far away a warm object shows up as a dot or two. It is far longer than the distance you can tell what the animal is. | 153 yd | 131 yd |
| Display | ||
| Display Display resolution How many pixels the small screen inside the eyepiece has. A sharp screen looks cleaner but cannot add detail the sensor did not capture. | LCD 640 × 480 | LCD 640 × 480 |
| Power | ||
| Battery | 4 × AA, removable | 2 × AA, removable |
| Runtime Battery life (runtime) How many hours the device runs on a charge, by the maker's test. Real runtime is shorter in the cold and with Wi-Fi, recording or the rangefinder on. | 3.5 h | 5 hBetter |
| Features | ||
| Rangefinder Laser rangefinder A built-in laser that measures how far away the animal is. The rated range is for big, reflective targets; expect much less on a coyote. | No | No |
| Video Onboard recording (storage) Built-in memory that records photos and video of what you see. Useful for reviewing shots and sharing hunts; listed in gigabytes. | — | — |
| Storage Onboard recording (storage) Built-in memory that records photos and video of what you see. Useful for reviewing shots and sharing hunts; listed in gigabytes. | — | — |
| Wi-Fi / app Wi-Fi and app A wireless link to a phone app for live viewing, downloading videos, changing settings and updating the device's software. | Yes | — |
| Riflescope | ||
| Eye relief Eye relief How far your eye sits behind the eyepiece and still sees the full picture. On a rifle scope, more distance keeps the scope off your face under recoil. | 70 mmBetter | 60 mm |
| Recoil rating Recoil rating How much rifle recoil the maker says the scope can take and still work and hold zero. Makers state it in different units, so compare carefully. | — | 1,000 G maximum recoil (spec sheet) |
| Mount Mount How the scope attaches to the rifle: standard rings or a rail clamp, fixed or quick-detach. A good mount does more to hold zero than anything else. | 30 mm tube; standard 30 mm scope rings | 30 mm tube; standard 30 mm scope rings |
| Ballistic calculator Ballistic calculator Software in the scope that moves the aiming point for distance, using your bullet's data and the range to the animal. | — | — |
| Zero profiles Zero profiles Saved sight settings for different rifles or loads. Switch profiles instead of re-zeroing when you move the scope or change ammunition. | — | — |
| Build | ||
| Weight Weight How heavy the device is. Check whether the maker weighed it with or without the battery, because brands do it differently. | 30.7 oz | 23.6 ozBetter |
| Water rating IP rating (water rating) A two-part code for how well the device keeps out dust and water. IP67 means dust-tight and survives a short dunk; an X means not tested. | Not rated | IPX4 |
| Operating temp Operating temperature The temperature range the maker says the device will work in. Batteries lose much of their runtime well before the low end of that range. | Not published | 5°F to 122°F |
| Buying | ||
| Warranty Warranty How long the maker promises to repair or replace a faulty unit. Check whether it needs registration and whether it passes to a second owner. | 3 years | 3 years |
| US price US price The price we found for the unit in the US, with where it came from and when. Prices change often, so treat it as a snapshot. | Discontinued | Discontinued |
| MSRP MSRP The maker's suggested retail price in the US: the list price, before any sale. Useful for seeing how good a deal really is. | $720 | $600 |
Check prices
Affiliate links. Prices change; the retailer's page is the current one.
How the numbers are worked out. Each pixel covers an angle equal to pixel pitch divided by focal length. A coyote is drawn to scale, 36 inches nose to tail base and about 22 inches at the shoulder. Identification uses Johnson’s criteria: about 12 pixels across the animal’s smallest dimension, here shoulder height. That lands where hunters report it, around 150 to 200 yards on common units. Digital zoom makes the picture bigger but adds no pixels, so it changes none of these figures.
Sources. Sightmark Photon RT user manual (SM18015 to SM18018, spec table; Sightmark's PDF hosted by OpticsPlanet), Sightmark press release, October 20, 2017 (Photon RT lineup and SKUs), Sightmark support: Photon warranty and replacement (3-year digital night vision warranty; Photons discontinued), Wayback Machine capture of the sightmark.com product page, October 29, 2018 (archived maker page; spec table: lens focus 50 mm, field of view 4.3°), Wayback Machine capture of the sightmark.com product page, August 3, 2020 (archived maker page; same figures) (read 10/11/2026) · Sightmark Photon XT user manual (SM18007/SM18008/SM18009, spec table; Sightmark's PDF hosted by OpticsPlanet), Sightmark spec sheet SM18008 (Sightmark's PDF hosted by OpticsPlanet), Sightmark press release, August 4, 2016 (Photon XT lineup), Sightmark support: Photon warranty and replacement (3-year digital night vision warranty; Photons discontinued) (read 10/11/2026)