Any Lens Designers /Grinders Here?
Hello to All,
I have been toying with the idea of grinding my own lenses and even designing my own compound lenses. I know that some amateur astronomers do this for there telescopes. I wonder if anyone dose it for cameras.
I don't of much GIY activity. Lens elements are cheap enough on the surplus market that grinding doesn't make much sense.
Reinhold makes and sells meniscus landscape lenses using stock elements. Astro lenses are, needless to say, very narrow field - though people do play around using the objective lenses from old binoculars.
The book Primitive Photography has quite a bit of discussion on the topic of making lenses from stock elements. http://www.amazon.com/Primitive-Phot.../dp/0240804619
I've often thought of going through the Petzval patent and designing a lens using standard elements from Anchor Optics or the Surplus Shack.
The Oslo lens design program has a free educational version for lenses with 10 or fewer surfaces - enough for 90% of non-zoom photographic lens types - http://lambdares.com/education/oslo_edu/
Kingslake's book goes through the classical lens design methods - Petzval sums, thin lens formula and such - http://www.amazon.com/Design-Fundame...ke+lens+design
I woul say that designing is one thing, grinding a lens so the correct specifications is another story. OLSO is great for design but won't help you to get the real lens. And don't forget that for each lens, you have 2 faces to grind in a concentric way.
Astronomers don't grind lens but mirrors: 1 face to polish instead of 2. Surface accuracy has to be much higher but the Foucault method of control is rather easy to implement (even if some parameters has to be well choosen and measurements have taken seriously).
"The problem with photography is that it only deals with appearances." Duane Michals
"Only weak pictures need perfection." David Vestal
I like the IDEA of grinding my own lenses. At least in theory it should be possible to grind something for large format use,particularly if you welcome softness and aberrations. Alas,for me, it is project 138 or something, on my list....
I think the thing to realize with DIY lenses isn't that one is trying to make a good lens but an interestingly bad lens.
A plano-convex achromat, flat side to the subject with a stop a 1/3 of a focal length ahead of the lens should, I think, produce a good first pass at a soft focus lens. And since everyone likes to fiddle and diddle it might be interesting to make the stop position adjustable (or it might not - that's the fun of DIY).
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
I read a really interesting article by a guy who wanted to grind his own microscope lenses the way that Dutch guy with the unspellable and unpronounceable name did way back in the 17th century.
Reasoning that he had no access to special grinding grits and so forth, he started with a bucket of sand from the beach. What you do is grind this in a pestle and mortar - then use the principle called levigation. What you do is mix some of the sand up in water and let it stand for a few seconds or minutes - then pour off the liquid into another container. Only the heaviest particles sink to the bottom and stay in the first container. You then let it stand for a bit longer before pouring it off again. The lens maker repeated this six times, giving him sand graded in steps from coarse to very fine...
The primitive simplicity of this appeals to me... And yet he made some very good lenses.
Microscope lenses are TINY. These simple single lenses are, especially. The very small size means a a very small radius of curvature and therefore a very high magnification. That means a lot of problems working in miniature - but the lens maker can tolerate a lot of defects because the field of view is also tiny - you are just projecting into the human eye to focus on the fovea - which is tiny.
Camera lenses are obviously much bigger - which in some ways maybe makes them easier to make, but also they require a reasonable flat field over a relatively big area, so I suppose would require much more accurate grinding. I still like the idea of starting with a sandy beach and a broken battle, though...
Bill, grinding your own lens is sounding friendly but quality lens comes from expensive glasses. BK7 is the cheapest of all but it comes with big sheets and at least transportation costs you a Barnack Leica lens. There are too many old lenses 100 years old around and when they were produced , there were thousands of lens makers. You cant compete with their experience at spherical lenses.
Few ideas you can make ,
A sliding , travelling slide lens for 35 mm panorama pictures.
Cylinderical cut - water jet - lenses for anamorphic record.
Pinhole anamorphic camera which produces 6 x 17 frames.
Multi fractal pattern square pinholes lens sheet which might be corrected at computer but it is faraway better than pinhole , extremelly low f number but records blurry images which must be corrected with same pattern.
3d printing of acrylic lenses if you can handle free lower options lens softwares and produce a stl file and say goodbye to your 500 dollars
Curving a stainless steel thin sheet to a u shape , put a camera in to middle and record UW images.
Inflatable mirror coated film lenses for 500 mm or more
Using a closeup lens filter, attach to a tube and make your tele
Using pinsieves or others , making a ultrawide band spectral camera , using satellite , remote sensing filters , scan multi frames , false color and get satellite pictures like results
Go to zeiss and order one nonspherical lens for 1500 euro etc etc.
Actually, although astronomers mostly make mirrors - it is still possible to buy the necessary to grind your own achromatic lenses. I found another fascinating article on line about grinding an 8" achromatic. It was from about 1925. In those days it would probably have cost a years wages of a typical earner to buy such a lens. Consequently it was worth putting in the hundreds of hours needed to make one. Now it is maybe only a week or a months salary, so less incentive - but the instructions would still work for the enthusiast... There must still be enthusiasts about, because you can still buy the stuff if you shop around