Main Menu
Join Undercurrent on Facebook

The Private, Exclusive Guide for Serious Divers Since 1975 | |
For Divers since 1975
The Private, Exclusive Guide for Serious Divers Since 1975
Join Undercurrent on Facebook
"Best of the Web: scuba tips no other
source dares to publish" -- Forbes
January 2006 Vol. 21, No. 1   RSS Feed for Undercurrent Issues
What's this?

Delight in the Details

from the January, 2006 issue of Undercurrent   Subscribe Now

On my last trip to Cozumel, besides nurse sharks and turtles, I didnt see big critters. But I saw an eye-popping painted elysia sea slug looking as fine as the one pictured in Paul Humanns Reef Creatures.

When I was a new diver, I was out for the big stuff. But after seeing hundreds of barracuda and lobsters, I appreciated more diverse pleasures in the reef environment.

Thats where my magnifying glass comes in. The tiny shrimp lurking in the lettuce coral, the clinging crab in the anemone, and the pipefish in the sand flats are easier to ID and a lot more spectacular with a good glass. I also get a lot more detail on other denizens, including the corals.

Delight in the DetailsIf you want to go small, you need a glass lens, not plastic. Thats because the index of refraction of water is about 1.33. Plastic lenses have about the same index as water, so they become useless underwater. Optical glass has an index of about 1.52, so it works, though the magnification underwater will be a bit less than above.

Index of refraction? Thats a measure of how much a substance slows the speed of light, and thus bends (refracts) it. Waters index of 1.33 also explains why objects appear 1/3 larger underwater, and why your buddy swears that a 3-foot grouper was a 4-footer.

Magnifying lenses in your mask (bifocals) are not very useful for viewing underwater subjects except gauges. This goes for the plastic stick-on bifocals as well as the Mares ESA mask, which has separate lens frames in which you can put magnifiers.

Instead, you need a good hand-held glass. Ive tried several and my favorite is Edmund Scientific (www.scientificsonline.com). Look for the Round Magnifier With 10X Spot Lens. The 4-inch lens (you dont want a small one that you need to hold too close to the subject) is available there for $11.95, plus $6.40 for shipping. It fits in a BC pocket and has a hole in the handle for a lanyard. Happy hunting.

M.A.

I want to get all the stories! Tell me how I can become an Undercurrent Online Member and get online access to all the articles of Undercurrent as well as thousands of first hand reports on dive operations world-wide



NEW! Find in  

| Home | Online Members Area | My Account |
| Travel Index | Dive Gear Index | Health/Safety Index | Environment & Misc. Index | Seasonal Planner | Forums | Blogs | Free Articles | Book Picks | News |
| Dive Resort & Liveaboard Reviews | Featured Reports | Recent Issues | Back Issues | Login | Join | Special Offers | RSS | FAQ | About Us | Contact Us | Links |


Copyright © 1996-2016 Undercurrent (www.undercurrent.org)
3020 Bridgeway, Ste 102, Sausalito, Ca 94965
All rights reserved.

cd