My 'new' old camera

[Dave Wilkinson]

It's arrived - and I love it, already !....my new Fed, that is, but I goofed on my original post, when I said I was waiting for a Fed 3 body, I should have said 2 !, 'cos it's actually a 2b, I guess a 3 will go on my wants list now!!. Having owned a couple of 111f leicas in the past, I think this one handles better, and looks really nice, and I like the wide-base finder, if it had slow speeds, it would be better!, - but I can live with that on this camera. While I'm here- can someone enlighten me about lanthanum glass?....when I got my 90 apo-lanthar ( super lens! ) - the Robert White site said it did not contain lanthanum, as it was no longer allowed...why?, now as I get interested in fsu stuff, I read about Industar lenses, marked ld - (for lanthanum) and I believe these are still being made ? -So whats so special about this mystical stuff ??😕 and more importantly-do these lenses produce nicer results?

Regards Dave🙂

 

[rogue_designer]

I believe lanthanum was radioactive, and less dangerous, less costly, more effective High refractive glass has since been introduced.

 

[hitmanh]

I believe lanthanum was radioactive, and less dangerous, less costly, more effective High refractive glass has since been introduced.

Very midly radioactive, that is barely detectable against the background level of radiation.

 

[wolves3012]

Lanthanum glass contains Lanthanum Oxide which gives an alkali-resistant, low dispersion and high refractive index glass; in other words useful! The radioactivity level is negligible and IIRC it's a beta-emitter, which means that a few centimetres of air or a piece of thin paper is enough to stop it. Nothing to worry about. It's slightly toxic and that may be the reason it's not used now, that or today's paranoia with even the slightest risk from radioactivity.

 

[Xmas]

It was the process workers who were exposed to the dust if the used abrasive were allowed to dry out, you have to pay for the disposal as well. The largest problem was the rare earths tended to be contaminated with thorium and it is hot.
The rare earth allowed a triplet to be made with larger radius of curvature, and hence lower abberations off axis, the triplet needs matched crown and flint glasses, having the ref index high helps improve the lens and makes it easier to make. The earlier matched glasses, had other problems like being real soft.
Noel

 

[reagan]

"It was the process workers who were exposed to the dust if the used abrasive were allowed to dry out, you have to pay for the disposal as well. The largest problem was the rare earths tended to be contaminated with thorium and it is hot. The rare earth allowed a triplet to be made with larger radius of curvature, and hence lower abberations off axis, the triplet needs matched crown and flint glasses, having the ref index high helps improve the lens and makes it easier to make. The earlier matched glasses, had other problems like being real soft."

Well.... I'm sure that explains it.