Interesting Article from 1902.... oil filled lenses; the first lens coatings?
So I'm posting this here for lack of a better place. However, since it's from 1902 it undoubtedly deals with large format, right? Ok, good....
This article is from the NY Times archive. It's a quick read about a liquid filled lens invented by Dr. Edward F. Grun of Brighton, England and how it permits shorter exposure, low light photography.... "Never before in photographic history has there been a lens so rapid as this."!
I found this article very intriguing, and the mention about increasing the speed surprised me. I came across this article while searching for liquid filled lens stuff, mainly in hopes of learning more about the panoramic abilities exploited by Thomas Sutton and his water filled, spherical lens (2nd link below).
Would the speed be increased in the same way that "modern" multi-coated lenses have decreased transmission losses in lenses? I'm familiar with the concept that air-to-glass surfaces result in lost transmission, and how Ansel Adam's encourages one to find an effective f-stop, due to these losses.
So I'm just curious, could this be the first example of lens coatings?
Thanks so much!
'Liquid Lens Revolutionizing Photography' 1902
Thomas Sutton's Panoramic Camera
No. Apparantly by filling the gap with this oil the focal length was significantly shortened. Since the diameter of the lens opening didn't change, the aperture (=focal length/diameter) became "faster".
Hmm, hadn't thought about that and that makes sense too. But I don't think a flat "no" is true either, because I believe that one non-coated, air-to-glass surface can absorb up to 7% of the light (or 17%?, not sure). Multiply that by each element...
But ahh... I see... evidenced by Sutton's wide-angle lens, the liquid must indeed shorten the focal length; voila!
I believe both principles must be working in unison.
There is always a reflection when the refractive index in the light path changes. This is not only true for glass - air but also true for glass - oil.
True, but the magnitude of the reflection is much less for glass-oil than for glass-air. The practice of making cemented lenses using oil or canada balsam has been around for a long time, at least in telescope lenses. A few designs have been tried using liquid elements as a cost saving measure. Incidentally, the earliest experiments with anti-reflection coatings were done by depositing soap films on lenses.
Originally Posted by ath
Sponsored Ad. (Subscribers to APUG have the option to remove this ad.)
At the moment lenses are on the market consisting of two liquid phases which are electrostatically focussed.
Originally Posted by 3Dfan
Hi, if it's not too much trouble I'd love to know which lenses you're referring to so that I can try to find out a little more about them.
Originally Posted by AgX
Many years ago I had the idle thought that a hollow plastic lens' focal length might be altered by hydraulic pressure - not as a viable proposition for a camera lens - but I was thinking of spectacle lenses at the time.
Even thought about framing some plastic filters to experiment with - but was always too busy.
For "was always too busy" read "never got around to it."
I think I know what he's referring to. Google "Varioptics". They are small lenses for cell phone cameras and the like. Pretty cool though, could make our cell phone cameras a lot better.