Underwater magnifier

[Uncle Pug]

Water and glass have a close enough refractive index that just taking a regular magnifier underwater will not yield appreciable magnification.

An airspace is needed on each side of the glass lense.

I used a plastic handled magnifier and cut two lexan pieces for each side and siliconed them on the frame using a spring clamp to hold things together while the silicone cured.

I took it out diving the next day and it work! But unfortunately it also leaked and soon the airspaces were filled with water.

I cleaned off the silicone and tried it again being more careful in applying the silicone so as not to entrain air pockets in the seal. I then decided that careful and neat should be thrown out the window and proceeded to goober silicone all over the area between the edges of the two lexan plates.

It works. So far I've had it down to 120'+ and though the lexan bows in and contacts the lense in the middle no leaks or cracks.

The magnifier is fun for looking at stuff on the bottom but I have found that I enjoy using it most on deco stops. I really like looking at the little micro critters in the water column!

 

[diver-greg]

Great idea! Perfect for my tired eyes and looking at the great small stuff we have here. Mmmm, now where to find a magnifier in East Timor... Not to mention the lexan, oh and the silicone. Sounds like a project for my next trip to the US.

Greg

 

[crab]

That is a cool device! I like the idea of taking a closer look at organisms in the water column during a stop. Now, let's see... I could make one for myself, or pay $50 for one if they show up some day at my LDS. Decisions, decisions...

By the way, is that a metal to metal retainer on the handle?

 

[Charlie99]

DIY underwater magnifying glass

 

[Charlie99]

A Cozumel DM had a nice magnifying glass that worked underwater. Just a simple double convex lens. He said it was taken out of an old camera. My guess is that it was a high index of refraction crown glass. Crown glass commonly runs 1.5-16, and flint glass goes up as high as 1.75.

Cheap glass is 1.4, water is 1.33, so normal cheap glass magnifiers don't work, but good quality optical glass ones will work, at reduced power.

 

[Uncle Pug]

By the way, is that a metal to metal retainer on the handle?

That is a metal ring to plastic handle connection.

Charlie99... have you made one of those? I wonder what the depth limit would be? I haven't test mine past rec limits but suspect that with the low air volume and thick lexan it will go as deep as I will. Also I would think that with a higher air volume that one might need some weighting to be slightly negative.

 

[Gary D.]

That is a metal ring to plastic handle connection.

Charlie99... have you made one of those? I wonder what the depth limit would be? I haven't test mine past rec limits but suspect that with the low air volume and thick lexan it will go as deep as I will. Also I would think that with a higher air volume that one might need some weighting to be slightly negative.

Just going off memory but 1/4" Plexiglas is around 2200 psi per sq inch. That's deeper than rec limits by just a bit. The seams are what will fail first.

Gary D.

 

[miketsp]

I just bought a pair of cheap reading glasses in a pharmacy - a bit stronger than my tired vision (due to age) needs and siliconed them onto my mask. After 100+ dives, quite a few in the 30-40m range, a few stress cracks are starting to form but they work fine and are easy and cheap. Just like using bifocals. Since there is air on both sides of the lenses they work fine.

 

[WVMike]

great idea, I will have to try it. I got the small glue in magnifying glasss in my mask to be able to read my gauges, tired old eyes as well.

So I read the post this morning and then while diving today and doing a saftey stop I thought of it. So I put my mask right on the bottom (lake diving) and started looking at the little critters with the magnifyers. Pretty cool. I am going to try your idea.

Mike

 

[el-ninio]

you can probably use a concave air cell as a magnifing glass. the air has a much smaller index, and efectivly has "negative" index in water. for shallow dives, you could pobably do with a thick mettal ring with good plastic wrap - the air will condence, and the plastic will form a hiparabula like shape- wich shold give resnable optics.