PDA

View Full Version : Optiocal Glasses



Bill_1856
30-Dec-2004, 09:51
Has there been any really significant changes in optical glasses since they started using trace rare elements over 50 years ago?

Alan Davenport
30-Dec-2004, 10:04
Yeah, they stopped using trace rare elements. The radioactive ones, anyhow.

David A. Goldfarb
30-Dec-2004, 10:22
They've figured out how to make clear glass without bubbles.

ED and LD glass seems to have come in more common usage in the 1970s some time.

Plastic aspheric elements are fairly recent. Anyone know if any LF lenses use plastic in this way?

martin_4668
30-Dec-2004, 10:31
It is only Leica that has the technology to manufacture aspherical surfaces out of one piece of glass material. all others use a glass element and cementes a plastic aspherical onto it.

The newest is from Zeiss led-free glass sorts. E.g. ther new Biogon 905SWC is completely led-free.

I am sure all serious photografic lens manufacturers are using new materails, new way of thinking, new computing of lenses etc. All to make the world a better place for us, the crazy imaging loving people (and perhaps to make up new needs to make a buck, but hey ! - thats OK with me)

Arne Croell
30-Dec-2004, 10:46
The introduction of lead-, arsenic, and antimony-free glasses for environmental reasons (toxic slurry during grinding and polishing of the older types - there is no problem for the user with those glasses) happened in the 1990's. The Schneider Apo-Symmar L line as well as the latest edition of the Zeiss Biogon as mentioned above use those glasses.

I don't know exactly when they were introduced, but glasses with high titanium oxide content came after the rare earth ones.

Bob Salomon
30-Dec-2004, 12:12
"It is only Leica that has the technology to manufacture aspherical surfaces out of one piece of glass material. all others use a glass element and cementes a plastic aspherical onto it."

Nonsense. Rodenstock has been making all glass aspheric elements for years. They use a Rank Pneumo Precision MSG 325 diamond turning machine. This rests on a sprung 32 ton concreate block to isolate the machine from any external vibration. It is also used in a room at a constant temperature that fluctuate 0.2 degrees C.

Now, the Rodenstock lenses are used for Digital and large format applications with pro cameras. They are not P&S optics or optics used in hand held digital cameras.

Virtually all 35mm zoom lens P&S cameras from all manufacturers, German or far East branded, have a pressed aspheriic acrylic surface in the lens system. That includes Leica and Rollei. The same is true for the P&S digital cameras.

Witold Grabiec
31-Dec-2004, 08:08
This may never make it into LF lenses, but I just read about Ceramic Lenses. An apparently new material developed in 2001, which has been employed by Casio in one of its little Exilim digital cameras. It is said to have optical glass qualities, yet with much greater refractive index. Apparently the latter makes it possible to make much thinner (more compact) lens with same specs.

Arne Croell
31-Dec-2004, 14:54
Another development that has not yet made its way to LF lenses are gradient index (GRIN) glasses. And then there are diffractive optics, like the one in some Canon 35mm lenses.

Dan Fromm
2-Jan-2005, 06:53
Gee, Dan, that's odd. Mine returns "ignoramus" for "Leica enthusiast."