D-300 2+ SHP review (long!)

Customer Reviews of Night Vision Equipment

Moderator: Michael

D-300 2+ SHP review (long!)

Postby keck314 » Mon Sep 18, 2006 10:05 pm

I'll start off by mentioning that I've been fascinated by night vision devices since I first saw them depicted in a movie when I was in the 4th grade. Ever since then, I've known I wanted one of my own. One year later, I even went so far as to design one myself using the CAD program on my first computer. Surprisingly, it might indeed have worked (poorly), if I'd had the patience and finances available to build the thing.

During College, I briefly owned a pair of Gen I goggles that I got off eBay - rebranded NZT-22s - but they were stolen before I could get much use out of them. I have to say, they weren't all that bad with the IR on, but without it there was little difference between what you could see through them and a pair of good, dark-adapted eyes. I knew I still wanted an NVD, but next time, I vowed to do better.

Flash forward to today.

I'd been reading about NVDs off and on for the past year, and toying with the notion of getting a new one. This forum in particular was extremely helpful in providing "through the tube" shots; something that no other sites that I could find were willing to furnish. The constant help provided by the sites moderators also impressed me, so I decided that when I did make the decision to buy, I would do it from them. Excellent business practice, guys.

I hadn't liked the night-blindness and lack of peripheral vision that accompanied my previous experience with NVDs, so this time I opted for a monocular. The choice between Gen2 and Gen3 was a far more difficult one, but after much deliberation I settled on the D-300 Gen2+ SHP, with a brand-new DEP tube. It was stretching the limits of the budget that I'd set for myself, but I was determined to do it right this time, so after a careful evaluation of my financial situation, I decided that I could afford it. If the DEP tubes lasted as long as it was reported, I was sure that I'd get more than its worth back in future enjoyment.

I had to work most of the afternoon the day it was supposed to arrive, so it was the next day that I waited with great impatience for the FedEx truck to arrive. When I first held it in my hand, I was reminded of some dialogue from the first "Jurassic Park" movie:

"Ooh, look at this!"
-"Is it heavy?"
"Yeah..."
-"Then it's expensive. Put it down"
"Cool! Night Vision!"

While not particularly HEAVY, the D-300 has a solid feel to it that lets you know it's well-built. The casing is a matte black metal, with rubberized grips around the primary focus and diopter adjustment rings. Both rotate smoothly, with just enough resistance to stay in place without moving accidentally. The battery compartment unscrews from the same bulge that contains the IR illuminator and the single switch that controls all aspects of the device. Next stop: the closet!

My room has a walk-in closet, about twelve feet deep by six feet wide, most of which is full of shelf space, camping gear, and my girlfriend's unnecessarily large collection of shoes, (which is one of the reasons she can't blame me for making "extravagant" gadget purchases :)). During the daytime, with the door shut, the only illumination comes from a dim rectangle of light outlining the door. Initially, one cannot see one's hand in front of one's face in there, but after ten minutes in the dark my eyes were adapted enough to make out the dim outlines of shelves, though what they were filled with was hard to say. On the floor, I spied a mass of rectangular obstacles which I knew were suitcases, but again, the only thing that was visible to me was their general outline. I carefully inserted the battery, screwed the cap back on, and held the NVD to my eye. The familiar brownian motion of dancing phosphor beads slowly appeared in my field of view, but little else. I waited patiently, however, and after the tube had had a minute or two to warm up, objects started coming into focus. The image was grainy, but distinct. I could clearly identify the suitcases, and read the larger markings on some of the boxes. The darker recesses of the closet were still difficult to see into, but significant objects there could still be discerned, if not immediately recognized. Overall, it was significantly better than even what my dark-adapted eyes could do, but the noise limited the resolving power that I knew the DEP tube possessed. For that, I switched on the IR. To no great surprise, the view with the IR on was like noontime, and it was then that the resolution of the tube really set it apart from my previous NVD. I could even read the fine print on the boxes from about the same distance that I would be able to with the light on! There was a slight curved shadow in one side of the FOV where the objective lens protrudes, but I quickly got used to that. Satisfied with the device's performance in the closet, I went back to day-to-day chores, eagerly anticipating nightfall.

After dinner, I drove to a large city park popular with hikers and mountain bikers. That night in Phoenix, the sky was covered with clouds, lighting everything up with the sickly pink glow that anyone who lives near a large city knows all too well. Climbing to the top of a butte, the surrounding terrain was easily visible to the naked eye, though not in much detail. Under these conditions, the D-300 lit everything up like daylight, with every night-hiker and cluster of teenagers within hundreds of meters sharply standing out against the motionless backdrop of saguaros and scrub brush. Here too was where I first really tried out the commercial headgear I'd bought with the scope. It took some adjustments and experimentation to get it aligned correctly, but once it was on, I definitely enjoyed having a second eye that was still dark-adapted. I also retained peripheral vision - but only on one side - so I still found it necessary to pan my head back and forth to cover my blind spot. That will be something I'll have to get used to doing if I ever want to play lasertag with this device. The first night, another hiker managed to pass by me within 15 yards undetected because I hadn't been scanning enough. Under such bright illumination conditions the IR illuminator did practically nothing, so I left it off. I prefer the look of natural lighting anyway, and besides, the bright red dot would make me an easy target in a gaming environment.

One important observation that I made while using the D-300 under these conditions was that while at close ranges the device did little but add some detail to terrain I could already see, the further away I looked the more the NVD revealed features that were impossible to see with the naked eye. It appears that nighttime degrades one's view of distant objects far more than it does for objects nearby, and there the DEP tube's resolution really shines, especially under brighter conditions.

The next night the clouds had dissipated, and I went in search of a seriously DARK outdoor environment to test the scope in. Luckily, my neighborhood has some tree-lined alleyways that are almost ideally suited to this purpose. The last quarter moon had yet to rise, so the only source of illumination was starlight and the occasional light from a neighbor's window filtering through the trees. So as not to terrify anyone, I left the headgear at home. I flipped the power switch and WOW! Now THIS is what night vision is supposed to be! What had previously been a pitch-black and forbidding alley was suddenly visible up and down its length, with all the forbidding shadows along the sides instantly vanishing. In their place were simple everyday trash cans, fences, and discarded pieces of broken furniture. The image, though slightly grainy, was FAR superior to even the best dark-adapted eye. The light was not sufficient for the DEP tube's superior resolution to really strut its stuff, however; for that IR was still necessary. As I walked along, I could see neighborhood cats lying lazily atop garbage cans, bats swooping after insects in the air, and once, even a neighbor fifteen yards away taking out the trash, completely oblivious to my presence. I can't express how cool it was to use the D-300 outside under such conditions. Extremely satisfied, I was walking past a garage, about to turn back when *click*!

I walked straight into a motion-activated floodlight.

I immediately brought the monocular down and covered both apertures with my hands. Slowly backing out of the horribly bright pool of light, I patiently waited for the timer to extinguish the flood, while silently cursing my clumsiness and wondering if my stupidity had just turned the D-300 into an extremely expensive paperweight. After the light switched off, I gingerly brought the scope back up to my eye, and was pleasantly surprised to find no obvious damage. The image was just as bright as before, and the IR illuminator against a neutral surface showed nothing out of the ordinary. It appears that the automatic brightness control had saved me, but it's most definitely NOT an experiment I would like to repeat anytime soon.

Overall, I am very pleased with my D-300. The optics are quite good, with only the slightest fish-eye distortion visible when panning across a straight object; you really have to be looking for it to see it. The photosensitivity is also very good, though to really take advantage of the DEP tube's resolution you need moderately bright conditions or the IR illuminator. The commercial headgear, once you get used to it, is perfectly comfortable, though in Phoenix in September one still sweats quite a bit, especially under the chin-strap. If adjusted properly, the FOV overlap between eyes is seamless. This monocular is very close to being the ultimate NVD for me. The only things I would change about it would be a less visible IR LED, and perhaps a photosensitivity two to three times higher, just to eliminate grain in those extremely-low-light regions. If only such devices were available!

(must...resist...urge...to...spend...money!)


So, with that in mind, a few questions:

1) What is the peak wavelength of the D-300's LED? Is it replaceable with a longer one? Also, what is the longest wavelength that is still usable for the SHP tubes? I'm thinking of getting an 850nm flashlight to supplement the built-in.

2) While after several days of subsequent use, no ill effects are obvious, are there any tests I can perform that would definitively reveal whether or not my encounter with the floodlight has damaged the tube?

3) When I encountered the flood, I covered both ends of the NVD, just to be safe. In reality, only the front aperture is susceptible to damage, correct?

4) Do the 2x and 3x magnifiers screw onto the existing objective lens, or must one first unscrew that one and replace it with the 2x/3x? Does one loose much light with those lenses, or does the brightness stay more or less the same?


Wow - if you've read this far I can only congratulate you; I had not expected the review to go on this long. Thank you all for reading!

Here are some pictures:
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keck314
 
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Location: Tempe, AZ

DEP AD!

Postby link » Tue Sep 19, 2006 6:56 am

Some one should alert DEP Photonis to this review. I'm very impressed by the effort you have put into this review, excellent work!

I had a few questions for you, which are listed below.

Could you clarify the following; "The familiar brownian motion of dancing phosphor beads slowly appeared in my field of view, but little else. I waited patiently, however, and after the tube had had a minute or two to warm up, objects started coming into focus."

A tube should never have to warm up as the performance level is not related to temp, time on, electron or voltage build up. Would it be that your eyes had to adapt to the image being emitted from the phosphor screen and is not related to the tubes on time.

Farther on in the review you stated, "The photosensitivity is also very good, though to really take advantage of the DEP tube's resolution you need moderately bright conditions or the IR illuminator." and "It appears that nighttime degrades one's view of distant objects far more than it does for objects nearby, and there the DEP tube's resolution really shines, especially under brighter conditions."

This directly relates to the photocathodes ability or inability at generating electrons at low incident light level and is a reflection of a low PC sensitivity. The resolution will be at it's best under relatively low light levels and actually decreases as the levels increase. In urban environments with relativly high ambiant light levels (1-1.5lux) resolution will actually start to decrease and in high light situations (1.5-3.0lux) it will take a dive bomb. It is under these condition that the scintillation (noise) would decrease leading one to believe that the resolution has increased and infact it is a change in the SNR. Resolution is not related to scintillation. Scintillation or Snow effect is a combination of SNR,EBI and MTF. A small amount can be contributed to incident electron emission from the PC but this primarily comes into play at near black out levels where the amount of photons striking the PC are minimal.

You should be able to replace the LED Diode with one of a higher wavelength (850-920nm), but surely that would void any warranty. Keep in mind that a LED rated at 850nm has a high percentage of spillover and the PEAK wavelenth will be 850nm. The LED will probably start to emit around 790nm and go all the way up to 870nm or higher.

You did a stellar job on your post and I'm sure we all look forward to more from you.

Take Care!
Last edited by link on Tue Sep 19, 2006 10:31 pm, edited 1 time in total.
link
 

Postby Michael » Tue Sep 19, 2006 11:30 am

I second Links comments: Excellent work!

To significantly improve low-light performance, you would have to get a Gen 3 :twisted:

1. The built-in IR has a peak wavelength of 805 nm (we found this to be the best compromise in sensitivity of various generations, as well as overall performance of the illuminator). SHP tubes should be sensitive up to 850 nm (I believe), but you will get degrading performance the higher you go.

2. The damage would occur immediately or not at all.

3. Only the objective lens needs to removed/covered from a bright source of light.

4. There is no 2x (that I know). There are 2 versions of the 3x (commercial and mil.spec.) as well as a mil.spec. 5x. The commercial 3x replaces the 1x lens. Both the mil.spec. lenses are a-focal and will attach to the existing 1x lens. There will be some degradation of brightness, but it is quite a bit less with the mil.spec. optics.
Michael
mike@opticshq.com
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Postby Kalua1969 » Tue Sep 19, 2006 2:02 pm

I third Link's and Michael's comments... good job on the review :) Thanks for taking the time to post it, as I'm sure it'll be very helpful to others looking for guidance on the selection of their next night vision unit.

As you yourself had earlier stated, our "Night Vision Images" page has proven to be one of the more popular pages here as it offers *real world* pictures of NVD units in action; as opposed to those silly "photoshop'd" images so often used for marketing purposes by many NVD dealers.

The continuing success of this page is a result of forum members like you who are willing to contribute their time and photos to share with other NVD enthusiasts... so feel free to post more pics there at any time (such as: outdoor comparisons of with / without NVD and IR, distance / depth, or anything creatively fun that you can think of). Thanks again for your review! :D
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