Let’s talk about Sentinels and auto vs. manual gain

Let’s sit down and have a little chat about Sentinels. Specifically some perceptions that seem to be popular.

Ball-detent adapters and rear battery packs are cool.
They’re not, and I’ll explain why but it will require a timeline of sorts. Sentinels were born out of operators, realizing the limitations of monocular PVS14s, requiring binocular night vision in the field. The first place they looked were their pilot friends and their AN/AVS-6s and -9s. Because that’s all that existed then (not every unit had access to the prohibitively-expensive PVS15s) and the AVS units were ONLY able to use the ball-detent mount, units were purchased along with supporting parts such as ball-detent adapters (Wilcox DPAM, Wilcox L4 G01, L4 GSGM) and the legacy battery pack.

Operators ran them this way for a while but found that this setup was far too flimsy for ground operations, not to mention that the rear battery pack lacked sufficient ballast for the front-heavy goggle. Thus was born the Sentinel – the rugged AVS6/9 for ground operations. The BIGGEST changes that the Sentinels introduced were:

  • Provisions for an on-board CR123a battery, with a lifespan of 30 hours (thus eliminating the need for an external, rear battery pack and the cumbersome cable)
  • A dovetail interface, which made the entire unit lighter. The dovetail interface could be swapped back out to a ball-detent, if desired.

These innovations effectively rendered all air-to-ground adapters and rear battery packs obsolete. Therefore, if you bought Sentinels and prefer running the rear battery pack and the ball-detent, CONGRATULATIONS. You have effectively regressed the system to a more primitive state.

Sentinels are waterproof
They are, despite the myriad of exposed wires running under the bridge. And as long as you don’t turn them on when you’re in water that’s mineral-heavy. Both pods are sealed as is the battery compartment, just don’t expect to do any night diving with it.

I have 2 manual-gain PVS14s and I want to make them into Sentinel binoculars
Let’s talk about some history again. Because of the fact that pilots often didn’t have the extra hands to dial the gain up and down as the situation required, AN/AVS-6/9 (ANVIS) goggles had MX-10160 auto-gain tubes. Auto-gain works extremely well in the cockpit where light sources are often much farther away and is part of a much larger panoramic scene, but dynamic range becomes a much more serious concern for ground operations due to the loss in brightness in important parts of an image.

As most anybody who has had field experience fighting with night vision will tell you, the dynamic range of lighting conditions and the much-closer proximity of light sources on the ground, makes running auto-gain night vision systems extremely annoying. For example, if you want to actively engage a target that’s standing beside a vehicle with headlights, the chances of you being able to see him well, is hampered by the auto-gain tube dropping the gain in order to compensate for the bright lights. You get something that looks awfully similar to the image below:

The biggest mistake I see people make when they want to make the jump to binocular night vision is assume that auto-gain Sentinels work well for ground operations, then drop perfectly-good MX-11769 manual-gain tubes in, leaving the gain pigtails un-attached. In actual fact, you actually want a manual-gain housing to house MX-11769 tubes. This method allows you to dial the tubes up and down as the situation dictates, and will allow you to view targets at a dynamic range that YOU choose.

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