SWS Security
White Papers
"In God We Trust. All Others We Monitor."

Contents

 NIGHT VISION EQUIPMENT

The Truth, the Whole Truth, and Nothing but the Truth ...

Part Three

Well, hello again, and welcome to the show. It's definitely summer, as we trade heating for air conditioning. Vacations for those of us who can spare  the time or money, luscious and colorful things to eat growing in the garden, cute baby animals being born or hatched, no end of work to do around the  place. Dog committing felonies in the neighbor's henhouse. Hard to get excited  about putting in next winter's firewood when temperature and humidity are in  the nineties... But fresh garden vegetables, bluegrass festivals and the smell  of honeysuckle are some of our many blessings.

 After a break for one issue, we're back with this third, and last, part of our series on night vision. Please call the editors of this magazine at 215 538  1240 for reprints of parts one and two if you don't have them and you are interested in technical and operational information on night vision systems.

 If you retained one thing from parts one and two, it should be the thought  that you must do your homework before purchasing night vision.  Many features, accessories, and configurations are available, and no one laundry list is right for everybody. The requirements of a tactical  team who need a night sight for a sniper rifle are completely different from those of a drug unit. Do your homework, get demos, read these articles so you know what questions to ask, pick a vendor you can  trust, get references, and make sure the tech guys make the decision, not the beancounters. By doing all this, you stand a better chance of  getting the proper shaped peg to fit your hole.

 By the way, I probably should apologize for consistently seeming so down on beancounters. As long as bureaucracies exist there will remain beans which need to be counted. I acknowledge the contribution of  beancounters. My acerbic comments are offered, though, after several  years of watching beancounters buy the cheapest price, not the best  value. This is why it's so important for the tech guys to be in the procurement loop. They'll spend years using whatever is purchased, whether it's what they wanted or not. Some night vision specs are so broadly written that I think a watermelon would qualify, and some are so restrictive that they specify technology that doesn't yet exist.  There are right ways and wrong ways to write specs.

 The wrong way is to take a manufacturer's spec and copy them word for word into your IFB (Invitation for Bid). If the bid is going to be wired, why waste your time and ours? Also not appropriate is to specify a Particular Brand "or equal, as long as the alternate brand bid will accept Particular Brand part number ABCDorwhatever accessory we already own." The proper way is to learn enough to know precisely what it is you want to do and buy, and write realistic specs based on this knowledge.

 I'm not allowed to name names, but I'd sure like to compliment some of  the jurisdictions who really have their act together on procurement. I  think a good procurement system depends more on the capabilities of the  person at the helm (or on the phone) than it does on state law or agency regulations. In looking at some bids that came in the mail yesterday, I find a five page bid for a huge surveillance equipment  acquisition (from a department with whom it is a pleasure to work).  There's also a 55 page bid from a county in the south who's buying one  mobile radio (can't hit the trash quick enough). There's an agency in  the west who's letterhead would do an artist proud, and who's logo  colors are so pretty that we hang them on the wall for decoration.

 Wow, I really got off on a tangent there, didn't I?

 I realize that in one of the earlier parts of this article I referred to "multi coated" eyepieces without elaborating beyond that. Pardon. Quality optics will be coated (or multicoated). Coating helps by reducing the amount of light that is lost through internal reflections by about 50%. This means that more of the precious light which reaches  the night vision device can be put to use. Good quality lenses are hard coated with, I believe, magnesium fluoride. This coating reduces reflection and glare resulting in a brighter image, even under unfavorable light conditions. The bottom line is that coating will help  produce a brilliant, clear, sharp image. One way certain manufacturers  cut quality and costs in order to be a low bidder are by using  substandard optics. Don't get so bogged down in intensifier tube specs  that you overlook other, equally important, factors. It doesn't matter what tube you have if you can't get clear, sharp images in and out.

 The most important thing we're going to cover this month on night vision is recording the evidence you're gathering on either 35mm film  or videotape. Most of what we observe is a lot more useful if we can  capture it for future prosecution. This capability should be high on  your list when evaluating night vision. Most, but not all, night vision  systems are able to be coupled to a camera of some sort. The trick  comes in how easy, inexpensive or versatile it is. Does the system you  are evaluating require you to purchase their own special lens? Is the hookup easy and repeatable, or do you have to monkey with it every time? Is there some provision for supporting the weight of the night vision or does it just hang off the front of the camera by the soft  aluminum threads? Can the average high school educated officer figure the thing out, or do you have to call the dealer to talk you through it whenever you want to use the thing?

 A few important accessories are needed to hang your night vision in front of a camera. These accessories almost always are not standard  accessories, so confirm this before you place an order. Let's start  with the 35mm film camera situation. You need a relay lens and a T  ring. A relay lens threads in where the eyepiece normally lives. Its job is to focus the image from the intensifier onto the appropriate  place (optics or film) in the camera. And, actually, the image produced by the intensifier is upside down and backwards. You can see this if you look through the thing without the eyepiece attached. Another function of the relay lens is to turn the image right side up and  forward again so everything comes out properly in the end.

 We mentioned that the relay lens replaces the eyepiece on the NVD (this means Night Vision Device, for those of you who weren't yet born when  we defined all these terms in part one of this series). It should be obvious to the most casual observer which end of the relay lens fits the NVD. Wait, the other end doesn't fit my camera! That's right, it  doesn't. The reason is that there are numerous schemes used to attach lenses to 35mm camera bodies. Some are bayonet (meaning insert and twist a quarter of a turn or so), some are thread in, and so forth.  Because of these differences, it is necessary for the relay lens to be  sort of universal. This is where the T ring comes in. When you order  your equipment, your salesman should have asked you to specify what camera body you would be using with the NVD. T rings are made for a  particular camera. The T ring goes between the end of the relay lens  opposite the eyepiece and the front of the camera body where the lens normally would attach.

 Once you've got the whole monstrosity (objective lens, NVD, relay lens, T ring, camera body) coupled together, you must focus the relay lens for the clearest image. Each different brand has its own particular  method of focusing everything to each other so I can't give you generic instructions. Crack the manual on the thing or call the manufacturer for another copy. Experiment ahead of time. Go back and forth between  everything that will focus, peaking everything repeatedly for the best overall picture. Relay lenses can be expensive - two to five hundred dollars. T rings  usually run about twenty bucks. Save the box it comes in so you can get another one if you lose or break yours. T rings can be purchased at most decent camera stores. If you need another one, take your camera body and relay lens to the store so they can sell you the right one.

 One popular brand of night vision uses a simple and inexpensive adapter that lets your existing 50mm camera lens serve as a relay lens. A 50mm lens is considered standard, and is what usually comes with a camera when you buy it. So if you have a 50mm lens, you can save hundreds of dollars by using it as a relay lens instead of buying another one. This  same manufacturer also has a "one touch" arrangement on his relay lenses where, once you set the focus, you can lock it in to that particular camera permanently. If nobody monkeys with it, you might  never have to set the focus again. Compare this to the relay lenses from most other manufacturers, where every time you remove the camera  you have to refocus the whole mess all over again. I'm not allowed to  mention this particular manufacturer in print, as other manufacturers throw a temper tantrum when I do. But feel free to call my office (orifice?) at 301 879 4035 for their name if you would like it.

 Feel free to experiment to find the best combination of film type,  exposure settings, processing, etc. for your particular combination of  camera, NVD and application. Keep in mind that you do not necessarily  need color film, as the night vision is all green. Neither do you need  a fast film, as you are photographing the output of the night vision, not the dark night. It is OK, though, to use a fast film to let you run  quick shutter speeds if you need to capture fast action. I've found, though, that at night things don't happen very fast. Maybe this is because it is dark and people would bump into things if they moved too  quickly?

 The following information has been developed for the Dark Invader line  of night vision, but should be applicable to other brands, at least as  a starting point. Try Kodak TMAX P-3200 black and white film. This film  can be pushed in processing from ASA 1600 to ASA 25,000, allowing for  high speed action to be photographed.

 Try also, Kodak Tri-X, which is ASA 400 black and white. Develop the  negatives with D76 1:1 at 80 degrees. Push 50% for 9 minutes total. Use  a two stage stop bath with Photo-Flo. Air dry 15 minutes. Process the prints with Kodak Rapid Process Film. Use an Afga actifier/stabilizer  unit if you have one. Try exposure as F16 from 2 seconds to 5 seconds. Thanks to Tommie Prevette of the Harford County (Maryland) Sheriff's Department for compiling this information.

 Film is cheap. Experiment. Tri-X is the film usually used in bank cameras, which means you can get it in 150 foot rolls and rewind it  into your own 35mm canisters for maximum economy. TMAX seems hard to find. We get ours from the place that does our new product photos, so  maybe it's special purpose stuff that you might have to ask around for.

 Video is similar to 35mm. You still need a relay lens, but a different  one from the film camera lens. If you want to do both photography and videotaping, be sure you get both relay lenses. A video relay lens usually comes out as industry standard C mount, which will fit any CCTV  camera. This is fine for fixed applications, like intensifying a CCTV  camera at a prison or whatever. But if you're using a portable camera,  particularly the excellent Panasonic WVD5000 or its predecessors the WV-32XX series, you will need a bayonet to C adapter. The Panasonic  AD16 is such an adapter, but it needs some slight modification to work with a relay lens. Call us for details of the modification.

 If you're interested in using the NVD for videotaping in the field, you're probably going to end up with a camcorder. If you want the best,  go with a separate camera and recorder (Panasonic WVD5000 camera and AG2400 recorder). But the convenience of a camcorder is hard to beat.  The best camcorder we've found for use with night vision currently is  the Panasonic AG170. Get this one or whatever is the most recent model  in the Panasonic industrial series when you go to buy. The AG170 has  power zoom, autofocus, a high speed shutter, integral time date generator, and is standard VHS.

 There are significant cost and performance advantages in going with a camcorder for your night vision. If you pick the proper manufacturer,  you will be able to do the whole thing without a relay lens. You merely  purchase a camcorder bracket, which is custom machined for your particular brand of camcorder and the NVD. This bracket will attach to both units and provide mechanical as well as optical coupling. The entire thing makes a compact, high performance night vision/video recording system. Either the NVD or the camcorder can be removed in  seconds for use independently. You really have to see one of these packages in action to appreciate how versatile it is.

 Well, that's about all I can think of to share on the topic of night  vision. This column is here for your benefit, so please make your requests known either to me or to the staff of the magazine. We do  requests, and every article that we've printed here has been in response to a reader inquiry. We need your ideas for future topics. If  you ask for nothing, then that's exactly what you'll get. Where else  can you go to get technical and operational information, custom written  for the law enforcement officer, for free? Cheap at twice the price.

 Did you do anything for April Fool's Day? We left urgent messages for one of the LT's from a Mr. Lyon and a Mr. Baer, with a return telephone  number of the city zoo. Some promotions were announced at one of the agencies on April 1st, which was a joke in itself.

 The word processor and computer I use to write these articles (WordPerfect 4.2 and homemade AT) has a utility that analyzes documents  and reports a number of factors about the document. One thing it reports is the average grade level of reading it takes to understand the article. I thought you would be interested to know that this series of articles consistently average out at 12.5 to 13.5 grade level.

 Bought one of those DAK breadmaking machines a few weeks ago. Works great. Bit expensive at over $200 once you include shipping, but nothing beats homemade bread. After using the thing for a while, you'll  turn into a snob and thumb your nose at the cardboard those grocery stores sell you as bread. Even being in the electronics business I continually admire the things man can create. Good wedding or  retirement gift.

 All for now. Maybe we'll see each other again, or maybe we won't. You never know.

 Copyright (C) June 1989 by Steve Uhrig, SWS Security. All rights reserved.

"Please note: At the time these articles were written, SWS distributed the Dark Invader line of night vision equipment, manufactured by B. E. Meyers Company. We no longer recommend this brand of equipment or this company. Please see our links page for a link to another night vision supplier who we recommend."

Contents