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I've been using a housed SLR system for a long time and I'm having more and more trouble seeing well enough through the viewfinder to focus properly. I've been considering switching to an autofocus camera. I'd appreciate your advice.



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Questions and Answers (Q & A's)

From Alan Broder (from Ocean Realm Magazine - September 1994)


There’s absolutely no doubt that autofocus is a useful tool underwater—in some circumstances more that others. For fish photography, it’s generally quicker and more accurate than even the sharpest-eyed underwater photographer attempting to focus manually. Autofocus, however, is a poor substitute for being able to see. Most wide-angle and macro shots are generally better handled by manually focusing. It’s also important to consider that fact this if your vision is letting you down in the focusing department, you’re probably working under some kind of handicap when it comes to composing, too. It seems that by the time we reach a point in our lives when we can afford to buy the kind of camera we always wanted, we can’t see through it anymore—sort of a corollary of the old axiom that "youth is wasted on the young." At about the same time, it gets harder to read those gauges and find subjects on the reef. I’ve been there and done that!

Let’s take a look at the more general problem that focusing is just a part of. We’ll assume that your visual challenge is one of accommodating (ability to focus the eye) and not in the clarity of the lens of your eye. If you’re wearing prescription glasses out of the water, you have a correction for astigmatism, accommodation, or for both. You can solve your underwater vision problems, including focusing your camera’s lens, if you wear corrections underwater. You could wear glasses inside your mask, wear contacts, or have corrective lenses installed in your mask. If bifocals solve your problem on land, then may be the way to solve them underwater.

If you have lenses ground for installation in your mask, the normal procedure is to grind in the correction for any astigmatism and to accommodate the mask for infinity. If you’re satisfied with your ability to meet any visual requirements in your diving with your mask corrected this way and have just found a problem focusing your camera, you can place a lens between your camera finder and the viewing port of your housing. An easy way to do this is to take your mask and camera to your local major drug store and go to the rack of ready-made reading glasses. Put your mask on (be certain that everyone knows that you don’t have a gun) and start placing different reading glasses between your mask and camera finder. You’ll almost certainly find one pair that affords just about perfect vision for focusing. Buy this pair and simply pop the lens out and affix it to the back of your viewfinder before you close the housing. You’ll be good as reborn! If, however, you’d like to have better close vision, you feel lucky, and you decide you want it all, you may want to take a different approach in correcting your mask.

I want a completely unimpaired view through my camera viewfinder, and since most people look directly through the top third of the mask, positioning a bifocal line in the mask is problematic. This may not be a problem for you, as many people claim to do quite well with bifocal masks. However, when looking through a camera viewfinder, the eye must be able to accommodate at about three feet, since this is the equivalent distance at which the focusing screen appears sharp. So I figure that if I’m focused at three feet by my mask, then I can see perfectly through my camera, I can see my gauges fine, and I can find enough of the little kelpie-looking critters in the kelp and sea-fanny-looking creatures in the sea fans to keep me cheerfully occupied.

I explained this new insight to my optometrist and requested that he give me a prescription for my vision a three feet for installation in my mask. Reluctant at first, he asked me how I planned to find the boat. Somewhat annoyed that he would think I hadn’t thought the thing through, I explained that I planned to go to the surface and swim in ever-increasing circles until I bumped into it. He was obviously impressed with my thoroughness and gave me the prescription. I think the system works great. Actually I’m only very slightly impaired at distance as anyone would be if they still had the slightest ability to accommodate. If you’re not comfortable with this solution, you might stay with the lens in your housing, an infinity prescription in your mask, and a close-up lens glued to the outside of your mask low on the lens so you can squint through it to see your gauges.



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