Help with a collimator lens

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Davide
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Help with a collimator lens

Hi all, This is my first post.
I have this Chinese underwater light for macro photography. The lamp has a two part snoot to concentrate the light in one spot.


Idea is good but the implementation is not. The light has approx. 70° beam angle which is reduced with the snoot but actually most of the light get lost inside the snoot.
A few months after I bought the flashlight, they updated it with a new model. The snoot seems to be identical to mine but they put in 3 lenses to collimate the light better. I tried asking them if I could buy the upgrade but they charged me the same price as the new lamp!

What kind of lenses can I use to try to mimic their upgrade? The inner large snoot diameter is about 22 mm. The inside diameter of the head where the snoot is screwed in is about 25 mm. I had a couple fo plastic fresnel lens diameter 20 mm and focal lenght 50 mm which fits inside the snoot but of course I get only a mess.

Thank you in advance

Henk4U2
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Why not start with some trial and error? First give it a try with a regular magnifying glass.
If that seems about right, look for a countryman with a 3D printer to make you a bezel.

You are a flashaholic if you are forced to come out of the closet, to make room for more flashlights.

kennybobby
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It looks like they are using 3 Plano-Convex lens to collimate and focus the light. You will need to study the dimensions inside the various snoot pieces to determine the diameters and if flanges, spacers or orings are needed to hold them in place, plus measure the lengths to determine the focal lengths you need to order.

What do you photograph with such a beam?

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

Davide
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Thanks for your replies.

I shoot video of small critters or coral polyps. Such beam permits to enlight the subject and maintain a black background. Moreover a thin beam doesn’t enlight small particles/plankton which are always present even in the clearest water. The whole coral bush in this photo is 2”

A friend of mine has a 3D printer so I could even print a different snoot. I’m not interested in the lens #1. It’s too small.

Yes I would start with a trial & error process but with which kind of lens?

Snoot Internal diameter is about 22 mm / 0.87” From the photo it doesn’t seem a fresnel.

Davide
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Since I can’t find loose magnifying glasses, could I disassemble such a loupe?

40 X power and focal distance of 0.5”
Lens diameter is 25 mm

kennybobby
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you can order a plano-convex lens to meet your requirements, do a web search and you will find many vendors of this lens, it is flat on one side and has a spherical surface on the other. A glass or plastic lens would be fine and it may need to have a lip or flange on the edge in order to fit into the light and not interfere with the threads.

i think you will need to make a drawing with accurate measurements to determine the actual dimensions that will fit. Or you can do trial and error and maybe get lucky to find something that fits and works.

Find Plano Convex Lens

10mm example

Now i used to think that i was cool,
drivin' around on fossil fuel,
until i saw what i was doin',
was drivin' down the road to ruin. --JT

Davide
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Location: Italy

Sorry for my late reply. I did not get the notification.

I will follow your suggestions.

Thanks