CHAPTER FIVE: CPR FOR YOUR BIG LENSES
Text by Bob Warkentin
Two Styles of Nikonos "Masks"
"So, a $1,200 15mm fits 12 times better than a $100 35mm lens, right?"
"Human error? Not me! I've never had a flood!"
"I always have the lens mounted to the camera when rinsing, that's dumb!"
The Saga Continues: True Confessions of the Lens O-Ring Killer!
The Death of a Lens
CPR Technique (Compression Prevention to Rubber)
CPR Technique #1: Banding the Storage O-Rings
CPR Technique #2: O-Ring Storage Bag
CPR Technique #3: Putting This to Use
Putting It All Together
"If I practice CPR, how long will the dive-only O-rings last?"
"Well, what if I do flood a lens?"
The best way to understand Nikonos lenses and what to do about potential floods is to understand through analogies just what an underwater lens really is. It is nothing more than an "eyeball" on the "face" of the camera covered over by a "diving mask."
Since your own mask is made of rubber-like material, it makes an O-ring like seal to your face, thus preventing water from entering the mask. But, when your mask gets bumped, this seal is broken, and water gets into your mask and eyes. Just like any diving mask, the bigger the lens (for wider viewing ability) or the farther the lens extends beyond your camera, the easier it is to be bumped by your hand, regulator hose or the diver's fins in front of you.
Remember, masks don't leak unless they are bumped, or unless the edges of the rubber are worn out, cracked or full of hair. Well, neither do Nikonos lenses!
The over-all size of a lens is governed by the amount of goodies Nikon puts inside this "diving mask" to give you the right eyeball for the right job. Accordingly, there are two styles of how these "diving masks" are attached to the front of a Nikonos camera:
Style #1: For the 28mm and the 35mm lenses.
Style #2: For the 80mm, the new 20mm lens and the "new-style" 15mm lens. (photo 1)
No, I don't mean that the lenses are not all interchangeable from one camera to another. Even the original Calypso lens, made by Cousteau in the late 1950s will fit - water tight - the Nikonos V, and vice versa. What I am saying is that the spring-loaded bayonet mount holding the lens onto the front of the camera is either mounted entirely above the back surface of the lens' waterproof outer housing (Style #1) or it is recessed inside the outer housing (Style #2). (photo 2)
This is done in order to provide you those specialty wide-angle or telephoto lenses whose optics are of course larger in diameter than those of the standard 28mm or 35mm lenses; the hole through which these optics must go must be larger than for standard lenses.
Wrong! You actually have a bigger target for error, because of the size and weight of the lens. In fact, put your 15mm lens onto the camera, hold the lens pointed straight up, and shake the camera front to back. What you hear is $1,200 worth of your money rattling on the front of your camera.
Well then, let me ask you a few questions:
Q. 1 Have you ever had your diving mask bumped and water leaked in? Of course. That's why you are taught how to clear your mask.
Q. 2 Do you keep the rear lens cap on the lens when not in use? Of course you do. How silly of me to ask.
Q. 3 Do you routinely replace the rear lens mount O-ring with a brand new O-ring before each week of diving? Obviously, another dumb question on my part!
Q. 4 And of course you don't rinse the lens in fresh water separately, dismounted from the camera, by placing the plastic lens cap on the lens before rinsing, now do you?
Well, Q. 4 isn't the situation that causes the majority of water damage or floods to lenses. Nearly all of the water leakage or full floods that do occur to the bigger lenses are because of the combination of a "nearly-new" rear lens mount O-ring and human misunderstanding.
A rubber O-ring changes shapes to conform to the compression between a metal lens O-ring channel and the camera mount. We all know that if we leave the lens mounted to the camera during storage that the lens O-ring will be flattened out and no longer good for diving. So, we do the next best thing, right! We take the lens off the camera and put the lens cap onto the lens to keep out dust.
Well, guess what? That plastic lens cap also flattens and kills the elasticity of the fear lens mount O-ring during periods of storage. (This also applies to that new lens you just bought. It has been stored in the box with the lens cap covering the O-ring.) When you next go to use the lens, the O-ring may have lost enough elasticity that if the lens were to get bumped, water would leak inside.
Ah! Does that mean that the plastic cap is intended to be a watertight seal as good as the camera? No! Prove this to yourself by putting on the lens cap but don't turn it as usual. Notice that it does not fall off. Then, remove the O-ring and repeat the process. Notice that the lens cap falls off this time!
Remember, O-rings are designed for specific functions - i.e., sealing a perfectly round lens into a perfectly round mount on the camera. Unfortunately, no O-ring is designed to seal where side-to-side or up-and-down (bumping/wobbling) movement occurs.
With the standard 28mm or 35mm lenses, you very rarely hear of water leakage from the flattening out of the O-ring by the lens cap. These lenses are smaller and lighter than the Style #2 lenses, and water pressure helps force them against corrosion has spread to the optics and the camera; they are therefore harder to metal gears of the lens. (photo 4) wobble when bumped. Warning! Don't apply old habits learned through the use of 35mms to the "biggies." They require their own special precautions.
Underwater, it is so easy to bump a large "Pinocchio" lens. When that lethal up-and-down or side-to-side bump occurs, water can leak past a somewhat "dead" O-ring and enter into the lens from behind. For Style #1 lenses, there is about a 3/8th inch of dead space before the water can actually get into the lens. But for Style #2 lenses, the water almost immediately enters into the main optical and mechanical guts of the lens. (see photo 2)
The amount of salt water that can leak in may be so slight that it will go unnoticed. Within two days, however, the lens may become hard to mount onto the camera, or the bayonet mount may be frozen by corrosion - thus making it impossible to even get the lens off the camera. The distance and f-stop knobs may be difficult to turn, and you may see white specks of "powder" loose in the front dome glass. (photo 3)
You then get the lens to the "doctor," and as he begins to remove the bayonet screws, one by one, they break. Removing the parts, you soon see that the saltwater corrosion has spread to the optics and metal gears of the lens. (photo 4)
Hopefully, these CPR techniques will become second nature to you. These techniques can be applied to all other user-serviceable O-rings just as well as the big lenses.
Before each dive trip, we all scramble about buying new O-rings for our photo equipment. Soon, the top of our camera case is littered with opened bags partially filled with assorted O-rings. We have taken off the old ones, and not wanting to throw them away for some reason, we have put them back inside one of the already-opened bags. Now as time passes and our memory fails, we can no longer remember what is what. As we look over our collection of O-rings, we can't tell a used round black O-ring from a new round black O-ring unless it is as flat as a pancake.
Obtain a vinyl dye from an automotive supply store (or a waterproof marking stick at an office supply store) - in a color you like but one that can be seen when applied to the black rubber. Vinyl dyes work in much the same way that a wood stain does; waterproof markers may or may not. Take an obviously used O-ring, degrease it completely, and apply the vinyl dye in 1/2-inch marks every inch or so along the lens O-ring. After allowing it to properly dry, re-grease the O-ring as you would any other Nikonos O-ring. Now, you have just made yourself a "storage O-ring." (Please, do not use the rubberized paint that is available in dive shops. This paint really builds up on the surfaces of the rubber, and can be easily worn off - in pieces - preventing a new O-ring from sealing properly.)
Now the tough part of all this: Getting you to write onto only one of the plastic O-ring bags in your collection, "camera or lens or strobe," - and then throwing away all the other bags and O-rings. If you are the type who needs a string on your finger to remind you, then also write "black for diving; striped for storage."
You again have a collection of O-rings, but this time only one set for each piece of equipment. The set will be either all black O-rings in the respective plastic bag (meaning that the storage O-rings are installed in the equipment and not ready for diving), or the set will be all banded O-rings (meaning that each and every one of the necessary O-rings has been changed, properly cleaned and greased, and that the equipment should be ready for diving).
As a precaution, we recommend that you inspect the O-ring channel of your equipment for possible traces of pieces of debris or vinyl dye, just in case you applied the dye too heavily and some has worn off. As recommended in our previous articles, use the Nikonos 35mm lens as a magnifier. (If you are trying to inspect your 35mm lens, borrow a buddy's lens.)
Let's face it, diving can be a clumsy sport with all that equipment on, or with currents pushing us into other divers or coral. So, those big expensive lenses that stick out so far from the front of our cameras are easy targets for getting bumped. It absolutely will happen, sooner or later! So, when it happens, you will have installed on the back of those Pinocchio lenses as fat and plump a lens mount O-ring as possible. You must have "as much rubber meeting the road" (to paraphrase a tire commercial) as possible if you expect a $1,200 lens to survive the inevitable.
The CPR techniques prevent confusion of which O-rings are which, and will get you out of the pre-dive ritual of buying more for your collection. They will also prevent the premature loss of elasticity to O-rings during storage. Have only one set for diving and one set for storage for each piece of equipment, know which is which, and change them.
Excluding the common mistakes of using dental picks or knife blades to remove O-rings, or damage caused by excessive heat and improper cleaning and re-greasing before use - or yes, even using the wrong size O-ring, the CPR technique should extend the life of your O-ring (and the safety of your lens) from just a few dive trips to maybe two to three years. Please remember that I am talking about those big lenses that stick out a good distance from the camera.
For professional photographers whose equipment is in the water constantly, with "dive only" O-rings installed on the equipment continuously, I strongly recommend that you change the lens mount O-rings on your speciality lenses at least every three to four months.
Unfortunately, Nikonos lenses are not pieces of equipment that readily lend themselves to do-it-yourself repairs. Spanners, special rubberized tools, realignment and refocusing tools are also needed.
The main problem will arise from water trapped inside the optical groups. The water can not be rinsed out without element-by-element disassembly. Otherwise, in your efforts to rinse out the lens casing, you will force water into the optical groups. Force-drying causes salt crystals to permanently adhere to the coating, causing strange photos. Alcohol can damage the coatings, and for the 15mm lens, it will also discolor the f-stop/distance plastic window, which will then break by itself.
First remove the four spring-loaded screws on the bayonet mount (six on the Style #2 lenses), so that these screws don't freeze up and break off during later disassembly. Next, drain out all the water you can.
Then, get the lens immediately to someone who can service it properly. If you must wait until you return home, put on the rear lens cap - but don't turn it to lock it on. Just rubber-band it on to protect the rear optics from getting scratched.
Reprinted with permission from Bob Warkentin's Southern Nikonos Service Center, Inc.
9459 Kempwood, Houston, TX 77080 713/462-5436