So, an important part of learning to use Night Vision, which you often learn from being a professional end-user before being a salesman, is ironically, learning when
not to use Night Vision.
When pulling technology out of the kit bag, the question you need to ask yourself, not just about VAS technologies, but anything, is "why am I using this, and what is it accomplishing, and what am I giving up?"
At least in terms of a ground application, the big point when it comes to image intensifying Night Vision is
movement. Traditional I
2 is typically preferred when you are moving from one place to another discretely.
This could be movement to an ORP, or movement on an objective, through a structure or a built up area, etc., the prime benefit of I
2 is that it gives you relatively naturalistic vision minus the fact that it enhances it and allows you to see outside of your normal visual spectrum.
For observation, detection, fixed defense, etc., often thermal devices are preferred, because they provide superior capabilities for those applications, and so long as you're not moving around a lot, they're better tools for the job. This is also one of the reasons that we teach and preach a combination of technologies for full spectrum operations.
Because of this, I
2 tends to be preferred for more... well, "offensive" applications, the classic maxim of "close with and destroy," fast moving actions on contact, actions on objective, etc., as well as movement to the objective, and if you're trying to sneak away unnoticed, movement from the objective.
In terms of how this applies to I
2 Night Vision and manual versus automatic gain, something to consider is the principles of movement and maneuver and patrolling--I won't go into them all, but here's the thing:
If you're under a full moon or fairly high illumination--that is to say, a situation where your NVGs might be "too bright," maybe it's worth considering whether you should be using Night Vision at all? Night Vision has a lot of limitations in terms of situational awareness compared to your natural vision, being able to see further into the dark may or may not be the be all end all of the tactical situation if your environment is so bright that you can see just fine with your natural vision, at least well enough to conduct your movement.
For those that have any experience patrolling and/or maneuvering, the term "SLLS Halt" is likely familiar, an acronym standing for:
Silence,
Look,
Listen,
Smell.
When conducting a deliberate movement, you should be conducting frequent SLLS Halts, and if it's bright out--you should probably be moving primarily without your Night Vision while on the move, mounted to your head, dropping them down when you conduct your SLLS Halt, and preferably pulling out a thermal monocular and scanning with that as well, before resuming movement.
If you're in a team, it can be worthwhile to perhaps have some guys on NVDs, or even better yet, Fusion, during your movement, and FWIW, this is a situation where the use of a monocular or even articulated goggles can potentially shine if you're into that kind of thing, but during the SLLS Halt, everyone should a) know the drill, and b) be taking part.
So, manual gain.
The big advantage to having manual gain on a monocular is that the overly bright image in one tube can cause your brain to essentially "shut off" your other eye. Adjusting the manual gain to a lower level when using a monocular can be extremely important in very dark conditions, because you still want to get as much unaided eye information as possible, better depth perception, better situational awareness, etc., and if the image in one eye is so unevenly superior in one eye versus the other, you may end up at a disadvantage.
Now, if conditions are so dark that you can't see or move without NVDs, and you have dual tube goggles, a) you'll likely want the gain cranked up as high as possible, and b) you'll want to have both eyes in the tubes so that you can take the fullest advantage of the binocular parallax and other advantages of dual goggles.
On the other hand, if conditions are so bright that your unaided eye can see pretty well without the NV tube, then the brightness level of your aided eye is honestly just not that big of a deal--a monocular at high gain will allow you to see deeply into the dark darks, but your brain will "prefer" to use your more natural eye, and if it's that bright, your aided eye won't really be "overpowering" your unaided eye.
So that's rural movement.
Say you're conducting operations and movement in more urban/suburban terrain. Again, mono or duals, mixed lighting or pitch black, a lot of the same things apply, except for this:
If you're in an urban area with mixed artificial lighting, you'll find that there are a lot more inconsistent dark darks, crevices and corners and alleys to hide in, and if you're looking into these areas for potential ambush threats, you'd better believe you want to see everything you can, lest you miss the dirtbag with the AK behind that car in that alley because you cranked your goggles lower than they could be--worse if you're part of a unit movement and crossing a linear danger area, and your ass is the one that got everyone lit up because you were futzing with the gain.
So in urban/mixed light? You want all the gains, and plus, your tubes still have Automatic Brightness Control (ABC) that will regulate the brightness of your tubes as you move between lit and unlit areas. P.S. a lot of these are also good reasons is why it's good to have a good IR, directional IR illuminator to pump mWs into dark spaces when your goggles may be adjusting down and where scumbags can hide that doesn't have a downrange visible signature.
Okay, so wherever you are, you've moved from your Release Point (RP) and you've hit your ORP (Objective Rally Point).
Now it's game the motherfuck on. Whether we're talking an urban/suburban objective, or a more rural one. If you're going to conduct the assault under NODs, and you have the option of dual tubes, you'll want to be under dual tubes, and you'll want the gain up high, because once you initiate the assault, you're moving moving moving until you've completed your actions on the objective, and you're not going to have time to mess around with the gain on your goggles, and again, you don't want to get caught in a situation where you miss something because you've got your gain down too low.
Again, this is why it's critical to have your equipment ready, know what it does and does not do, have everything switched to the right setting, etc., all the stuff I talked about in the other thread in terms of Load and Make Ready procedures--because once the heat is on, you're not going to want to be messing with that stuff.
So, here's the thing. Under none of those circumstances does manual gain make a lick all of difference positively, so instead, you have a control you rarely touch or use, the only thing it adds is the potential to get messed up and accidentally dicked with.
Manual gain dual goggles "brief well," but honestly, IMHO, it's not that important.
I don't hate manual gain dual tubes, I spend a lot of time under PVS-31As which have the manual gain control, and needless to say, a lot of Shooty McShooterson guys use 31As, so it's not like you're going to get "kill't in da streetz" if you have a manual gain knob--the real answer is that the gain control knob simply rarely gets touched (to adjust gain, that is--on the 31As the gain control knob is also the ON/OFF switch, so it gets touched a lot for that
). Just like offset irons + MRD mounting footprint + 1-4x variable magnification range on the SU-230/PVS-C Elcan SpecterDR, sometimes with USSOCOM systems, you have a bunch of Officers (I am one, don't taze me--) that end up sitting around saying "and I want that, and I want that, and I want that..." and you end up with systems that have... just a little redundancy in them and a sprinkle of "good idea fairy" dust for good measure.
At the same time, something to consider is that both the DTNVG and DTNVS were designed and built with a lot of feedback and development from both European SOF and LE
and U.S. professional end-users, and the DTNVG has become one of the most popular goggles among a lot of a prominent trainers in the U.S., many of whom a) buy their own goggles with their own money, whether from us or from others, rather than being sponsored by anyone to push their goggles, and b) are former high-level SOF, and neither the AN/PVS-23 (F5050), nor the AN/PVS-15, or GPNVG-18 have manual gain capabilities, either, with no one that I'm aware of complaining about that fact or feeling that it was a limiting factor, with most of the rest using either PVS-31As or Sentinels, with the arguments for PVS-31As being "it's what my customers use" or "lightweight," never "because it has manual gain."
~Augee