I would have to agree with everything
@Magsz18 has posted about them.
As far as the diopters, there’s a trick that pretty much works with any goggle. I’ll attach a photo below, but essentially you just need to find a really wide ranger band (twice as wide as the one in my photo preferably), and slip it over the diopter and allow it to hang over onto the ocular lens housing. The grippy rubber will hold the diopter knurling in place and prevent you from accidentally bumping them out of adjustment. I’ll usually devote an evening to carefully adjusting my diopters, marking with a paint pen (easily removed with alcohol), and finally applying the ranger band, and then never touch or worry about them ever again. This also works exceptionally well with pvs14 lenses.
As far as my input on the 31Ds: I’ve owned most of the common night vision housings to include anvis, pvs15, rnvg, rpnvg, 1431, pvs31A, 1531, photonis PD Pro, DTNVS, multiple bridged pvs14 setups, and probably some other binos I’m forgetting, and of course my current set, the pvs31D.
It’s hands down my favorite housing due to its tasteful balance of features, weight, and my perception of its durability (it’s got the tightest articulation of any goggle I’ve ever used). The M24 tubes perform very well against Filmless, with Filmless having about 5% better low light performance, and better halo performance spec for spec. The outdoor photos above were taken on a overcast night under tree canopy (please pay attention to the photo labels to help differentiate between devices). To the eye, it was really splitting hairs trying to compare the M24 Elbit tubes Vs the Filmless tubes in the 1531. And I can say that was definitely dark enough for a good comparison, the brighter photos were enhanced, the dark photos are how each device looked to the eyes (gain was maxed on both devices). Any darker out and we probably would have started using IR to help navigate that particular trail, as some parts were slightly sketchy.
The last two photos show how thin filmed vs Filmless tubes react to halo. You can always test this yourself by creating whats called a “artificial star”, by placing aluminum foil over a flashlight head and using a pin to poke a tiny hole in the middle of the foil. This will mimic a really bright star or normal laser pointer splash, and allow you a consistent way to reference halo specs between different devices.
Both devices had a halo of .7 on paper, yet you can easily tell that Filmless responds to light far better than the thin filmed Elbit tubes, at least in this example (although it holds true across the board imo). This comes into play when using laser pointers, navigating urban environments, or for law enforcement if you can imagine for a moment… needing to see past things such as vehicle headlights and through a vehicle windshield. Or trying to ID someone who is surrounded by a well lit area or who may be shining a light your direction. This is why I will always recommend Filmless to professionals that are put in life/death situations, as these small performance characteristics can make a huge difference. However, for the people who don’t shoot others for a living, you’ll find that thin filmed tubes have a better performance to cost ratio (at least at this point in time). This halo difference is a much bigger factor than what little low light performance differences I’ve witnessed. In lesser/older thin filmed tubes I’ve been able to see more performance loss in low light, but these high end Elbit tubes really do well.
In my opinion, it’s always ended up seeming like I was paying ~30% more money for about a 5-10% difference in performance going with Filmless. I like them all honestly, but I don’t feel disadvantaged having a set of pvs31D over a set of pvs31A, as the 31D housing has impressed me more, and the tubes are so close to what you get with Filmless apart from the halo aspect.
One last comment: the lenses of the 31D are absolutely superb, and are one of the few proprietary lens systems which can come very close to the gold standard Carson PVS14 lenses. I’ve used other high end binos with their own proprietary glass, and have been let down by the eyebox, eye relief, and flatness of the image. The 31D lenses do not disappoint however, and I essentially forget about them and feel like I’m wearing a regular set of binos with pvs14 lenses
Also, big shout out to Ryan @ Apolo Gear, as thats where my 31Ds came from also.
Sorry I haven’t posted in a while, I’ll try to jump back in here more often.
Bonus 31D photos. Higher light environment