This is WHY the best lenses today only use molded aspherical elements

And the cheapo lenses today use plastic molded aspherics.
Because there is NO way anyone would PAY for properly hand-ground
aspherical elements.

http://cgi.ebay.com/Leica-50mm-f1-2-...QQcmdZViewItem

"RichA" wrote in message
ups.com...
And the cheapo lenses today use plastic molded aspherics.
Because there is NO way anyone would PAY for properly hand-ground
aspherical elements.

http://cgi.ebay.com/Leica-50mm-f1-2-...QQcmdZViewItem


Wkat a skanky seller, only sells to US.

Rita Ä Berkowitz wrote:
Pete D wrote:

And the cheapo lenses today use plastic molded aspherics.
Because there is NO way anyone would PAY for properly hand-ground
aspherical elements.

http://cgi.ebay.com/Leica-50mm-f1-2-...QQcmdZViewItem



Wkat a skanky seller, only sells to US.

Is there anywhere else in the world worth selling to? Hell, I restrict my
sales to the continental US. Screw Hawaii and Alaska since they are worse
than Canada.






Rita

Yeah.. no beer...

Rita Ä Berkowitz wrote:
Pboud wrote:

Is there anywhere else in the world worth selling to? Hell, I
restrict my sales to the continental US. Screw Hawaii and Alaska
since they are worse than Canada.

Yeah.. no beer...

Nonsense! There's plenty of beer!
http://www.geocities.com/ritaberk2007/sacrafice.htm





Rita
I've seen what passes for beer down in the states.. I believe my point
still stands.

On Oct 4, 5:46 pm, Rita Ä Berkowitz ritaberk2O04 @aol.com wrote:
Pete D wrote:
And the cheapo lenses today use plastic molded aspherics.
Because there is NO way anyone would PAY for properly hand-ground
aspherical elements.

http://cgi.ebay.com/Leica-50mm-f1-2-...int-M2-M3-M4-M...

Wkat a skanky seller, only sells to US.

Is there anywhere else in the world worth selling to? Hell, I restrict my
sales to the continental US. Screw Hawaii and Alaska since they are worse
than Canada.

Rita

Why not go all the way and restrict them to Manhattan Island residents
only?

On Oct 4, 5:45 pm, Rita Ä Berkowitz ritaberk2O04 @aol.com wrote:
RichA wrote:
And the cheapo lenses today use plastic molded aspherics.
Because there is NO way anyone would PAY for properly hand-ground
aspherical elements.

DAMN!! I wonder how well that would work on the old Mk III? I am guessing
it will not perform any better than the old 58/1.2 Noct Nikkor on any
camera.

Rita

I read an article in a Leica magazine about that lens. The aspherics
help considerably to control the huge amount of spherical aberration
(which manifests itself as the defocusing blur you see wide open in
such lenses) that such a speed would generate. If the Nikon wasn't
similarly equipped, the Leica would clobber it wide open.

Rita Ä Berkowitz wrote:
Pboud wrote:

Yeah.. no beer...

Nonsense! There's plenty of beer!
http://www.geocities.com/ritaberk2007/sacrafice.htm

I've seen what passes for beer down in the states.. I believe my
point still stands.


I can agree! We have some really nice microbreweries here that do
extremely
well. Trust me, not everyone wants to drink that **** called Sam Adams.






Rita


Actually, I kinda like some of the wines you guys produce.. but when it
comes to beer, you have to have at least *some* alcoholic content..

American beer is like making love in a canoe.

It's f*****g close to water..

On Fri, 05 Oct 2007 12:24:37 -0700, RichA wrote:
: On Oct 4, 5:45 pm, Rita Ä Berkowitz ritaberk2O04 @aol.com wrote:
: RichA wrote:
: And the cheapo lenses today use plastic molded aspherics.
: Because there is NO way anyone would PAY for properly hand-ground
: aspherical elements.
:
: DAMN!! I wonder how well that would work on the old Mk III? I am guessing
: it will not perform any better than the old 58/1.2 Noct Nikkor on any
: camera.
:
: Rita
:
: I read an article in a Leica magazine about that lens. The aspherics
: help considerably to control the huge amount of spherical aberration
: (which manifests itself as the defocusing blur you see wide open in
: such lenses) that such a speed would generate. If the Nikon wasn't
: similarly equipped, the Leica would clobber it wide open.

Help an old man out here, folks. Is "aspherical" just the current term for
non-spherical conic sections, i.e. parabolas and hyperbolas? I thought (glass)
parabolic elements had been common for quite a few years and that most good
film SLR lenses had them. They introduced tiny amounts of coma, but prevented
a lot more spherical aberration.

Or is this something entirely new that I've missed? I suppose it's possible
that the world has simply passed me by. :^|

Bob

On Oct 7, 11:59 am, Robert Coe wrote:
On Fri, 05 Oct 2007 12:24:37 -0700, RichA wrote:

: On Oct 4, 5:45 pm, Rita Ä Berkowitz ritaberk2O04 @aol.com wrote:: RichA wrote:

: And the cheapo lenses today use plastic molded aspherics.
: Because there is NO way anyone would PAY for properly hand-ground
: aspherical elements.
:
: DAMN!! I wonder how well that would work on the old Mk III? I am guessing
: it will not perform any better than the old 58/1.2 Noct Nikkor on any
: camera.
:
: Rita
:
: I read an article in a Leica magazine about that lens. The aspherics
: help considerably to control the huge amount of spherical aberration
: (which manifests itself as the defocusing blur you see wide open in
: such lenses) that such a speed would generate. If the Nikon wasn't
: similarly equipped, the Leica would clobber it wide open.

Help an old man out here, folks. Is "aspherical" just the current term for
non-spherical conic sections, i.e. parabolas and hyperbolas? I thought (glass)
parabolic elements had been common for quite a few years and that most good
film SLR lenses had them. They introduced tiny amounts of coma, but prevented
a lot more spherical aberration.

Or is this something entirely new that I've missed? I suppose it's possible
that the world has simply passed me by. :^|

Bob

Aspheric elements can have complex curves that are not just deviations
from a sphere. In one case (Schmidt-Cassegrain telescopes) the
asphere is formed by sucking a flat plat down into a spherical curve,
griding it flat and releasing the suction, forming a complex "wave"
shape on the glass. The problem with any asphere is that is not a
natural shape and even with computer-controlled machines cannot be
formed easily, hence all high quality aspherics take time to produce.
You can't spend 2 hours on a camera lens element today, it would make
the cost prohibitive.
http://www.photozone.de/3Technology/mtf/aspherical.gif