Making a lens

[pocketfulladoubles]

If there's a place, this would be it... Have any of you machinists out there tried purchasing raw optical glass from say, Edmunds, and machined the frame to build a compound lens? Or, how about using a CNC and cutting a custom fresnel? I got the itch to try it, but I'm starting down wasted money and failure if this is way to far from practical.

[Bruce Watson]

If there's a place, this would be it... Have any of you machinists out there tried purchasing raw optical glass from say, Edmunds, and machined the frame to build a compound lens? Or, how about using a CNC and cutting a custom fresnel? I got the itch to try it, but I'm starting down wasted money and failure if this is way to far from practical.

Typically it's not the fabrication that's a problem (although you're going to need some pretty tight tolerances and a good understanding of how temperature effects the entire "stack" among myriad other skills). The problem is usually finding a good design (that hasn't already been done). But there are a number of optical programs out there for computer aided design. And you can buy glass from Schott (http://www.us.schott.com/advanced_optics/english/) if Edmunds doesn't have enough selection for you.

[Steven Tribe]

To get you excited - or turn you off completely - you should get, or borrow, the enclosed book. Written by an ex-foreman from Dallmeyer (I think). It gives the complete illustrated description of how to make your own Rapid Rectilinear from a lump of glass and brass.

Whilst Edmonds is a very good supplier, you might find more price competitive items on e**y - particulary md-optics (see item 360202173564) . In spite of the name, this is very German. He does list items with faults - usually small edge fractures and slightly yellow glass (gelb). I have no connection etc. other than I have bought from him.

[Dave_B]

We had a long thread on this a couple of years ago. The issue is are you trying to make something that will cost you less than you could buy it for or are you trying to build a lens for the fun of it.

Given the quality, quantity and prices for old glass these days, it is hard to imagine that you could build something for less than you could buy it. As an example, Jim Galli seems to have a garage full of nice lenses that would work as well as any you are likely to make yourself in the $100-$300 dollar range. There are many lenses on Ebay every day that are fine lenses that would be hard to make on your own, starting from scratch. So if you want a lens and want to take pictures, go buy a cheap one and never look back.

However, if you goal is to make a lens yourself for the fun of it, then you could try to build your own but it would require you to be pretty smart and pretty lucky to get a good one in a finite amount of time spending a finite amount of money. A lot of folks spent their lifetimes figuring out how to make good lenses and the likelihood of you doing as well as them as a hobby is remote. The optical setups alone to align and measure what you have would cost a lot of money.

If you want interesting images that are fun like you get with pinhole cameras and lensbabies, this would be relatively easy but if you want AA quality images, you probably will fall short. Depends on what you want to do.

Schott makes fine lenses but they are not cheap and for a custom design usually have a 20-50 part minimum. Edmunds will sell you small numbers but you are limited to what they carry in stock. If you want to try your hand, you might buy a cheap lens, take it apart for the glass and try to rebuild it yourself with a new housing. A before and after look at the lens on the ground glass will give you a good idea of how you are doing.

Cheers,

Dave B.

[Jim C.]

If there's a place, this would be it... Have any of you machinists out there tried purchasing raw optical glass from say, Edmunds, and machined the frame to build a compound lens? Or, how about using a CNC and cutting a custom fresnel? I got the itch to try it, but I'm starting down wasted money and failure if this is way to far from practical.

Depends on whether or not you're going to buy a lathe and mill with tooling
or you already own them or have access to them. If you do then take a
whack at it, all it's going to cost you is time and money for the materials.

Dave_B makes a good point, lots of nice glass available on the 'Bay or here in the
FS section, buy one and shoot, it'll support Kodak and Fuji sheet film divisions ;)

[sun of sand]

maybe try working a compound lens out of ice
that would be very simple so long as you can work in the cold/keep the glass from clouding up or whatever problems inherent in ice
you could make clear ice blanks but no idea if melting it in the shaping process would lead to cloudiness upon refreezing for later assembly

your ice lens would be garbage optically i'd imagine but if you KNOW the configuration will work with optical glass/polycarbonate/lucite all you're doing is practicing the techique/concept


you read about Alexander McKay? recently threaded on? Made good quality optics from whiskey bottles
no doubt he had some tools but he was still using coke bottles
..and you'd learn a neat party trick so it wouldn't be a total waste

[Mark Sawyer]

I doubt that even the most serious "home-builder" could compete with the manufacturers if we're talking about conventional design goals, (flat field, high-resolution corner-to-corner, no distortion, apo-chromatic, near-zero aberrations, minimal flare, high contrast, etc., etc...) The manufaturers' engineers very carefully determine separate glass and surface coatings for each element, and space/collumate/rotate them with very tight tolerances.

But if you have an interest in less-conventional "soft" optics, almost anything goes, as we've seen in a number of threads here. The images from such lenses can be as beautiful and meaningful as from any other lens, and the experience wonderfully satisfying.

[Tim Povlick]

I doubt that even the most serious "home-builder" could compete with the manufacturers if we're talking about conventional design goals, (flat field, high-resolution corner-to-corner, no distortion, apo-chromatic, near-zero aberrations, minimal flare, high contrast, etc., etc...) The manufaturers' engineers very carefully determine separate glass and surface coatings for each element, and space/collumate/rotate them with very tight tolerances.


Actually Dr. Baker was working on a lens that would meet these criteria in his basement at the ripe age of 90. I am told he was working a 15" super-APO triplet with aspherical surfaces. Very impressive! The commercial outfits would have a tough time making such a lens unless they had equipment to handle large blanks and be able to polish asphers. He passed away before completing the project however. Here is some information about him:

http://en.wikipedia.org/wiki/James_Gilbert_Baker

If one is interested in rolling their own lens you can check out this text:

http://www.willbell.com/tm/refractor-telescope.htm

to see if the degree of difficulty is to much. While it's a doublet telecsope lens, the principles to make a smaller camera lens should be similar mainly more lenses. For designs one should be able to consult a Modern Lens text for general information and use available computer programs to generate the final design. Heck, why not make a Petzval?

Best Regards,

Tim