magnifying glass

[jjach]

We are going to Bonaire in a few weeks, so I was wondering about all the little stuff there is to see. But as I am getting older the eyes are not what they used to be. I remembered a trip we took to Roatan, that a guy on the boat had a magnifying glass he used to see the real small stuff. Looking online I am finding out that just any old magnifier will not do, they should be glass with air between the 2 lenses. I found a website "Reefnet" that has lenses. But I don't want to spend $200.00. Does anyone know where I can get a good lens fairly cheaply, and quick, since I leave in 2 weeks.

Thanks
Jeff

 

[redacted]

It has to be a glass lens and strong - 8x or 10x to work well UW. I found this: Amazon.com: 10X 2" Chrome/Brass Body Magnifier Powerful Glass Lens: Office Products but metal is not good. I could not find it in a plastic handle but you probably could fashion something on your own. Another option is to mount 2 or 3 lenses together but that get a bit complex.

 

[3D diver]

FWIW: I went the glue-in bifocal route (also from amazon):



The refractive index of the water will lower the magnification of a magnifying glass compared to what you're used to in air.

 

[driftwood]

While not the optimal solution, these have worked for me, Konus 4x Quicklens Magnifier 3239 FREE S&H 3239. Konus Magnifiers.

I use one all the time.

 

[KeithG]

There is cheap and then there is technically correct. I now have and use both.

For years I have carried a set of no name magnifying glasses in my pocket. I got them at a dollar type store. Each one was under $5. There were different sizes so I bought 2. I accidentally broke the cheap plastic handle off of one. So the frame is held to the lens wit duck tape. Lens still works as good as it ever did.

I also bought the reef net diopters for my camera.

I use both products. The subsea goes on my camera, the el cheapo magnifying glass is in my pocket. I pull it out every now and then to look at something that I do not want to stare at through the camera.

For the price I suggest you try a few dollar store magnifying glasses. If they are a waste of time them donate them to some local kids.

 

[chillyinCanada]

Are you sure it was a guy you met that was using the magnifying glass? LOL, OK, it's not as if I believe I'm the only one to ever carry one. In any event, I also gifted one to Mark when he was a DM. Perhaps it was Mark you saw using it. In any event, my magnifying glasses come from the dollar store. They have plastic rim and glass, work just fine. I've also found some for a bit more money and better quality at a medical supplies store. Also sold at crafts stores such as Michael's. No need for a $200 to be spent. What I am having trouble with is figuring out how to attach it to me, now that I no longer have a proper pocket to stuff it into. Thinking of drilling a hole in end of handle to attach with retractable bungie on a d-ring. Any ideas out there?

 

[miketsp]

You really need an airspace to get any decent magnification; water and glass are just too similar.
There are many DIY designs on SB and elsewhere:
example:
The Sea Slug Forum - Underwater Magnifying Lens

 

[chillyinCanada]

For clarification, my magnifying glasses do have glass lenses and they work just fine. I suppose if I wanted to try and identify the sex of a small nudi, they might not be adequate.

 

[miketsp]

For clarification, my magnifying glasses do have glass lenses and they work just fine. I suppose if I wanted to try and identify the sex of a small nudi, they might not be adequate.

The problem is that they are significantly less efficient than when used in air. This is because the refractive index of air is 1, water is 1.33 and common crown glass is 1.52.
Of course if you don't want to be bothered with an air-space then the solution is to use a heavy flint glass lens (1.6 - 1.8) or even a diamond lens (2.4).
Building an air-space effectively restores the original magnification.

http://scubageek.com/articles/glasses.pdf

really nice simulator here:
Refraction - Snell's Law

 

[blue steal]

This is what I use. Cost about $10 from Amazon. Has worked well for me. I clip it off on my harness and use a coiled lanyard so I don't lose it. I bought several and gave them out to the DM's in COZ.