I think this is a really novel idea.. brilliant even.
What happens if you eliminate the "pinhole", and widen the diameter of your aperture to utilize the whole area of epoxy lens?
Imagine if there were ways to affect the lens as it cured... like centrifugal force, temperature, g-forces... you might be able to manipulate the liquid into more ideal lens shapes.
Its interesting that you brought up lens shapes, as one of the more interesting shapes that happened was one droplet that had dried as a concave surface. I thought it was pretty cool, but it wasn't usable as when I was playing with it, the dried glue droplet popped off the aluminum tape.
Creating the bubble style lenses is pretty difficult, I have been trying with a small straw, using mouth blown, and compressed air, but its a bit too delicate. The only way that has worked is to coat the tip of the epoxy tube, and squeeze a bit of air out of the tube and epoxy at the same time and hope you form a bubble. The process is similar to the bubble wand style toys kids play with, you have to coat the wand surface with a layer of soapy water in order to create a bubble with it.
I have been trying to induce different surface shapes by manually pressing on the material as it dries, and also using compressed air to change the surface while it cures into a more viscus fluid, which does seem to kinda work.
I saw an article about doing something similar to create a microscope.
I've never done it but it looks like you would have to get pretty close to the lens to get a decent image. So probably a very small image circle.
I'd expect that just putting the lens on top of a pinhole would just soften the image a bit, I think the trick is to open the pinhole up a bit. Regarding epoxy, it shouldn't shrink on trying much at all. The Duco-branded glue you are using......is it two or one part?
Originally Posted by holmburgers
Anyway, the shape of the lens you create will depend on the surface energy difference of the two surfaces. In other words, how much does the glue wet the surface of the base material. If the base is, say, teflon, it will tend to stay more spherical. The other approach to change the focal length (and shape to a lesser extent) is to simply make a much larger drop. I think this is probably the best bet. I suspect the easiest way would be to form the drops on a sheet of polyethylene, maybe coated with oil, then pop them off and put it onto your pinhole.
I've spent a ton of time at work lately working with very similar things. Also, remember that your drop will not be all that close to a true sphere. In zero-g it would be but stuck here on earth, it will be a flattened sphere....I really son't think that will matter for what you are trying to do except to add more cool distortion!
Well the Duco cement Ive been using is a one part type, so I think I was wrong to call it an epoxy. I think it would be better classified as a glue.
I have tried larger drops to make a bigger lens, but the same problem the glue seems to shrink as it dries and deforms the initial smooth surface. The temporary solution to that was the blow a bubble under it. But I think a true fix would be to find a right material such as a more viscus super glue, or other type of clear drying glue which does not shrink on drying and is not runny. The bubble lenses would create 4 surfaces where light passes through as opposed to 2 if it were a solid lens which probably would be better.
I will try out some of your tricks, maybe coat a sheet of plastic in spray on oil and try to create ones on that, as well as widening the hole when I get a bit more time hopefully this weekend.
I have been thinking about trying to dry them suspended on a bit of floss, such as when water is suspended on a spiders web. But that might get a bit messy, and the shape maybe less spherical when moving to a larger scale.
The shrinking is due to the solvent evaporating. A 2 part epoxy is what you want.....that won't shrink
I love this thread. Using glue as a lens, awesome. What about using half a clear glass marble for lens? Perhaps it's possible to cast the glue in a mold.
What about this, if you have the right shape for the lens, why not make a mold out of silicone? Hobby stores have a kit to make a silicone mold from a hand in order to make a cast from that mold. Perhaps this stuf is acurate enough for making a mold. I don't know if superglue sticks on silicone, I guess not. But epoxy might work.
For thicker grades of cyanoacrylate think woodworking supply.
Technically it is a lens therefore not a pinhole anymore...
This was my first thought when I saw OP. Some may think it is just being pedantic, but there are some pinhole photographers who show wonderful "pinhole images" taken with their pinhole camera, when in fact they are also using a lens over a very small aperture. As the previous post states this is then not a pinhole picture.
Originally Posted by ced