lens making or assembly

Discussion in 'Large Format' started by tacocharly, Jan 4, 2004.

  1. im slightly perplexed as to why there are so many people that use
    photo.net that are scientists in their own right, yet somhow it seems
    that there is nobody assembling their own lenses, not even simple
    tessars, or at least not talking about it. i became interested while
    building an 8x10 view camera over my winter break from college, where
    i am a failing physics major. i havent taken the right classes for
    compound lens design yet, dont know if i ever will, but ordered a
    textbook on classical and modern optics for 3 bucks off
    bigwords.com. it should give walkthroughs of classical lens formulas
    such as tessar's.

    can it be that hard to do? there are tons of places online where i
    can buy the elements so i dont have to grind them myself. has anyone
    built a compound lens before? for any sized camera? know anyone who
    has? know anything i dont know?
  2. Some people who want "funky" lenses are making their own, perhaps using a two element achromat purchased from a surplus dealer. However, I think you will find making a state-of-the-art lens a daunting do-it-yourself project. Suppose you design you own Tessar-type lens: you will have selected four glasses (you will use their refractive index and dispersion in the design calculations), four thicknesses and eight curvatures. These characteristics and the spacings will have precise intended values. The chance that you will find these four glass pieces available off-the-shelf (i.e., pre-made) are about nil. If you should manage to find the four elements, or you design a lens around available elements, then you will need to design and make a mounting barrel that centers and spaces them to high accuracy. This all can be done with 19th technology, so in principle an individual could make their own Tessar, grinding and polishing the elements and machining the mount. But the amount of work would be staggering compared to the price of a new one, and especially to the price of a used one. Your hobby would be lens making rather than photography!

    With LF lenses being so available on the used market, I can see making a lens or having a lens custom made only for very special cases: wanting a simple, funky lens or to create an otherwise unobtainable lens, e.g., a wide-angle for an extreme ultra-large format.

    The book "Lens Design Fundamentals" by Rudolf Kingslake has some examples in which lens are designed with explanations of the design steps and considerations. Perhaps some version of one of the simplest designs could be made with off-the-shelf components, e.g., something like the narrow-field "portrait" lens that Kingslake shows on page 227.
  3. Because I'd rather make photographs.
  4. Good speech Michael!<BR><BR>Just to obtain a hunk of some weird glass types to make your own lens is very difficult; but possible if you work in an optical shop that makes custom lenses; ie military stuff. While touring Infrared Industries in California two decades ago; they had some engineers who tinkered with oddball designs; some for work; some for play. This was Warren Smiths place of work then; the guy who has written many books; and has decades of experience. The glass lens grinding process is bloody slow; messy; abit funky; with the elements on orbital globes. The radii checking is labor intensive; and requires alot of equipment. The raw lens elements have no edge ground; and are razor sharp. One can cut the living daylights of ones fingers on those buggers. I did this! (only once; I learned!) The edge grinding requires centering; ie more fixtures too. <BR><BR>Amateur telescope makers often grind their own mirrors; but rarely make their own lenses. Often surplus lenses are used. <BR><BR>Only can buy achromats from Edmund salvage; ie Edmund; and play around to make homemade telephoto lenses. The raw elements of a Tessar are not going to be found; unless it is a surplus Tessar that has been junked. <BR><BR>It is a long haul to make one's own custome 4 element Tessar lenses; abit like saying one will build a new car from scratch; starting with making ones own steel; and digging one's own iron ore.
  5. I figure if astronomers can build their own telescopes and achieve satisfactory results, then you atleast have a decent chance.
    I'd like to see a DIY Petzval lens. For what it is, they are way too much money.. Atleast the ones i've been lucky enough to come across.

    I honestly don't think you could whip up a 90mm Fujinon-W (or 99.999% of the population) but portrait lenses and simple things might not be so bad at all. I say go for it! The worst that can happen is you lose a bit of money and you learn something along the way.
  6. Folks don't make their own lenses because it isn't an economical use of their time. That's why I don't iron my own shirts - the nice lady at the laundry does it better for a fair price. Plenty of decent LF lenses are available for $200 - $300, including a shutter. I'm building my own copy of the Cambo Wide, but that only makes sense because the original is expensive and the necessary parts came around cheaply. I'd guess that most of the folks here would rather be making pictures than making a lens.
  7. "...astronomers can build their own telescopes and achieve satisfactory results..."

    True, but 99% of the time these are mirror telescopes with just one precision ground reflecting surface. And the large size of that mirror (typically 8-14" diameter) does forgive some imperfections.
  8. Grinding your own:
    I have a book called lens-work for amateurs by Henry Orford that covers equipment, tools and toolmaking and detailed instructions for grinding, mounting and testing various lenses including a camera lens ( a double anastigmat from memory ), and even the figuring of an aspherical surface!!. Lens manufacture was essentially a manual process undertaking by craftsmen, the author attempts to demystify the process and reassures that it is not beyond the abilities of an enthusiast.

    The book was originally published in 1895 and reprinted a few times. There are a few copies on ABEbooks, it's an interesting read if nothing else.


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