E F Grun 6" Focus Liquid Lens Oil Filled

[Dr Klaus Schmitt]

A rare bird indeed I would say ... 170554763656

Any experiences here?

[goamules]

No direct experience, but I've read it was a failed design attempt. A gimmick.

[CCHarrison]

more here http://www.liveauctioneers.com/item/2668551

and lots of google books on this cool lens

http://www.google.com/search?tbs=bks:1,cdr:1,cd_min:Jan%203_2%201,cd_max:Dec%2031_2%201910&tbo=p&q=grun+liquid+lens&num=10


Dan

[goamules]

Thanks Dan. That was as good a description as what I'd read last time one came up:

"...the two rear elements were separated by a layer of oil in place of air. The doctor, knowing little about optics, assumed that this would improve the lens in a way similar to the way the oil-immersion microscope lens functions. It did, however, not perform even as well as a conventional Petzval lens of the same focal length and aperture. Desptie extensive initial publicity, sales were minimal and by 1903 the lens had apparently been discontinued."

"mmmm....lens with a liquid center...aaahhhh...." (Said in Homer voice)

[jnantz]

everything is a gimmick, unless you unlock its secrets.

[Nodda Duma]

Some of the best most highly sought after refractive astronomical telescopes available on the market today are oil-space apochromatics by Roland Christen of Astro-Physics.

It helps to consider the refractive index of oil in the design of the optics, which I highly doubt was done for this lens.

[LabRat]

Some less lens surface to air spaces inside???

Steve K

[Mark Sawyer]

I believe that Fram made a lens of similar construction...

[Jim Galli]

I had a Protar once that had badly crazed on one element of the 4 and it came apart in my hands. Cleaned with acetone and put a drop of Wesson cooking oil where the glue had once been, put it back together and it was wonderful. Of course that's a little different than oil becoming the entire element. :0

[Greg]

I had a Protar once that had badly crazed on one element of the 4 and it came apart in my hands. Cleaned with acetone and put a drop of Wesson cooking oil where the glue had once been, put it back together and it was wonderful. Of course that's a little different than oil becoming the entire element. :0

Recently bought, at a bargain price, a classic uncoated lens in which the front element is badly crazed. Did some research and read that you can use Turtle Wax One Step Headlight Cleaner and Sealant to clean up scratches. Has anybody had any experience using a cleaner and sealant like that on a scratched glass optic? If there is a method for "covering up" scratches, I'd love to know what it is... have seen many a lens with scratches on the front elements up for auction being finally sold for ridiculously low prices. Have read a lot of descriptions of lenses being scratched and the seller stating that the scratch "does not affect the performance"... disagree based on personal experience.

[Jac@stafford.net]

I imagine there will be auctions for distressed optics! Creative imaging from gravity impact, ageing effects, truly random, one-of-a-kind! Two-story Dagor drops, heavenly haze, finest fungus, beautiful balsam separation, unpredictable apertures, slippery shutter speeds, 'can bokeh be broken? ... submit your recommendations here.

Gads, we should dive into the trash for jewels! The world is waiting!

[Dan Fromm]

Recently bought, at a bargain price, a classic uncoated lens in which the front element is badly crazed. Did some research and read that you can use Turtle Wax One Step Headlight Cleaner and Sealant to clean up scratches. Has anybody had any experience using a cleaner and sealant like that on a scratched glass optic? If there is a method for "covering up" scratches, I'd love to know what it is... have seen many a lens with scratches on the front elements up for auction being finally sold for ridiculously low prices. Have read a lot of descriptions of lenses being scratched and the seller stating that the scratch "does not affect the performance"... disagree based on personal experience.

I dunno. Is your crazed lens plastic, like your dull headlight covers?

The usual remedy for scratches is india ink.

[LabRat]

The big problem with fine surface scratches/rubs is like what you see with a old plastic pair of glasses, where the OOF haze lightens everything up and cuts contrast, and if a series of rubs, you get that sleek highlight look you see when looking out of an old train or bus window...

Rubbing nose grease into one lens' scratches, and carefully cleaning the remaining surfaces helped one a little, but one lens got the element dipped in a gelatin solution, and surfaces polished helped another a little...

I have also filled chips on projector condensers with superglue, that vanished...

Steve K

[Mark Sawyer]

The usual remedy for scratches is india ink.

Yup, the theory being that if the scratches are filled in with an opaque material, the light is simply blocked instead of being scattered through the lens, softening the image. In my experience, even deep scratches have little to no effect unless there are a lot of them, or if you're shooting into the light.

[Dan Fromm]

Mark, pardon my failing memory. Did I buy a set of 210/5.6 Fujinon-W cells from you?

The lens had been dropped, it seems, on hard sharp objects and the front cell had a number of deep gouges. Lotsa very bright spots as well as more diffuse stray light. This made the lens unusable for most purposes. The price I paid reflected that. India ink rescued it. Its still too large and heavy, though, and there's no way to add lightness ...

[Jim Galli]

Its still too large and heavy, though, and there's no way to add lightness ...

Most of the weight is glass. Keep chipping and inking until it gets to a weight you like Dan.

[Jac@stafford.net]

Traveling away from the point ... I have an 8x10 soft focus lens, and have defeated its mechanical limitations so that one can dial-in more softness than the maker intended. I has a huge gash on the front element. Huge! So when I sell it (and I will), I will mention the gash with the comment, "After all, it is a soft focus. Could the gash hurt?" Would it?

I tried India ink but it would not take.

Lens rim marking: Wollensak Velostigmat Series II ƒ4.5 Focus US 1 4 FT N W 2 3 55 20 5
At this time it is just a dust cap to a studio camera.

It is nonsense to me.