DIY ULF Lenses - 3D printing resin, epoxy casting or sand casting?

[Tin Can]

Lots on YouTube


ULF DIY LENS

Many ways

[Paul Ron]

when i was a kid (15yr old) i helped a friend move. us kids had to ride in the back with the furniture. as we went, i noticed images on the walls. i can see the other cars and trees going by. the source of the images were missing pop rivets... it blew me away n gave me an idea to make a camera from a cardboard refrigerator box and using 11x14 printing paper. it was fun doing paper negatives making contact prints with them. i especially enjoyed being in the box while taking my pictures.

[Maris Rusis]

Hi Maris, I'm watching a series of instructional videos on optical design currently.
I wonder if your design would have a very high number aperture (slow lens)
Thanks for the reply ...

High aperture number? Yes. About f45 for the example I quoted. The limitation of the "opposing dioptres" approach is the scarcity of large diameter matched pairs of lenses.

[Oslolens]

High aperture number? Yes. About f45 for the example I quoted. The limitation of the "opposing dioptres" approach is the scarcity of large diameter matched pairs of lenses.

Max i found is 138mm, and those needed a holder, but at a cost of $400 per lens. Good enough reason to limit one self to 95mm.

Sent fra min SM-G975F via Tapatalk

[r_a_feldman]

I recently ran across a seller on eBay called “Mittenpaw” with individual Burke & James “laboratory optics” lenses in bi-convex, plano-convex, positive meniscus and negative meniscus, multiple diameters and focal lengths, that might be useful for home-made lenses. I have not bought any of them and have no connection to the seller.

[Nodda Duma]

Hi Kevin,

I think you emailed me similar question but I think my reply bounced. So I’m glad you posted here so I can share my thoughts.

This is not meant yo dissuade you in any way, but you should understand the challenges that you need to overcome. They are far greater than fabricating glass lenses.

Plastic lenses are of course injection molded and used for imaging lenses. However, due to the limited types of plastics (limited selection of optical properties), the ability to design high performance optics is severely constrained. This is why photographic use is typically constrained to low resolution disposable cameras and similar.

For simple optics, it’s theoretically feasible. *theoretically* Of course, the fun is in the difference between theoretical and the real-world. (It might seem shocking that a lens designer / engineering person mentions real world, but engineers are all about making actual things that have to work).

More important than the properties of plastic itself is understanding how it changes dimensionally when it is made. This is practically an art form in the injection molding world, and particularly critical for optics. It is not a linear relationship, so it can’t be modeled. In other words, what you end up with isn’t what you designed. You have to iterate, changing the modeled curvatures and dimensions until you get what you want. This includes surface accuracy, which should be a few fringes (repeatable).

For even the best 3D printers, the surface accuracy required isn’t sufficient to meet useable surface roughness. Optical surface roughness in the visible should be around 50 Angstroms. 3D printers provide a roughness about 2 orders of magnitude larger. So expect to post-polish (polishing plastic can be nightmarish). In addition, homogeneity (uniformity of optical properties in the bulk material) will be a problem. I don’t think 3D printers control the building up of layers sufficiently uniform to provide necessary bulk material uniformity.

Not to say it can’t be done, just want to make sure that you’re jumping in with eyes wide open if you want something a bit beyond the barely functioning piles of imaging goo typically seen in YouTube videos.

There is a lot of work and trial and error involved in figuring it out, and a lot of labor involved in getting it working even after printing (or molding) is complete. Plastic lenses — molded or printed — are not easier to make than glass lenses. That shouldn’t dissuade you, as anything worthy requires time and effort. It is useful to understand the challenges to overcome.

Cheers,
Jason

[Tin Can]

Water lenses?

[Qeb]

Thanks Tin Can, I'll keep looking maybe

~~~
Paul Ron, that's an awesome story!
My Uncle found a camera while on vacation and gave it to my dad who then gave it to me in Grade 6. hehehe
~~~

Thanks Maris Rusis!
I would like to do portraits so f/5.6 or as close to that is the goal
~~~

Thanks Oslolens for the prices and advice
~~~

Hey r_a_feldman!
I took a look at their ebay store page.
I'm not sure if this is the route to go.
I really wanted to make a lens with super large coverage
but also very large in diameter for speed.
Thanks again
~~~

Hey Nodda Duma!
Thank you for replying with a very detailed and caring post!

Okay, hmm, I'm not sure then how to move forward.
Maybe I will start looking for those rare 1800mm lenses.
I've been saving up for a few years for restoring a classic car,
but if I can find, let's say, one rare Nikkor 1800mm f/14, I would
invest in that and take my time on a DIY lens.
This would give me the most options in terms of the direction
in my art I want to take.

Maybe I should post in the "Wanted To Buy" section then... anyone have any leads? hahah

Okay, thanks everyone for the input!

[Nodda Duma]

Qeb,

I’d start by reaching out to Surplus Shed and asking if they have a meniscus lens in your desired focal length with a diameter capable of giving you an f/16 lens. Then, fabricate an f/22 diameter aperture (a hole) and play with the spacing between the meniscus and the aperture until the off axis bokeh looks pleasing. Concave side towards the aperture. This is a basic f/22 landscape lens and will be a good start. You ask for a larger lens so that you don’t vignette.

[Qeb]

Hey Nodda Duma,

Thanks for the reply, sorry for my slow one.

Could I ask you something?

Would a lens break the laws of physics if it could cover a square image of 50 inch by 50 inch at focus at infinity? (and have an aperture closer to f/5.6?)

Though I have an degree in art, I'm trying to work on a online tech platform.
So, if I make money with it, maybe there are companies out there that can do a custom lens.
I am assuming this would cost a lot of money, but it's for art!

Okay, I will send Surplus Shed a message as I didn't find anything with the search function.

Thanks so much again!
Cheers