[LargeFormat] aero ektar

[animal]

Thanks for all your replies.

I tried the lens on a sinar with some close ups and the results did not
disappointed me .Allthough the lens still has the original cameras metal
cone attached to it so it it is about 5 inch in front of the lensboards
there for causing a very short extension and also vignetting with even
little movements.
Some tries are here
http://www.leica-gallery.net/apekop/folder-5075.html
simon jessurun,amsterdam,the netherlands








----- Original Message ----- 





From: "Richard Knoppow" <dickburk@ix.netcom.com>
To: <largeformat@f32.net>
Sent: Wednesday, July 30, 2003 12:03 AM
Subject: Re: [LargeFormat] aero ektar


>
> ----- Original Message ----- 
> From: "Clive Warren" <cocam@blueyonder.co.uk>
> To: <largeformat@f32.net>
> Sent: Tuesday, July 29, 2003 10:28 AM
> Subject: Re: [LargeFormat] aero ektar
>
>
> > At 8:36 am -0700 29/7/03, Richard Knoppow wrote:
> > >----- Original Message -----
> > >From: "animal"
> > >Sent: Monday, July 28, 2003 11:36 PM
> > >
> > >>  Hello i,m new here and hope you can answer my
> question.I,m
> > >looking for test
> > >>  data on a 7 inch 2.5 aero ektar lens.I,ve tried to
> locate
> > >this on the web
> > >>  but had no luck so far.
> > >  > Thanks,simon jessurun,amsterdam,the netherlands
> > >
> > We have a resident expert on the Aero Ektar lenses here in
> the form
> > of Michael Briggs and these lenses have been discussed
> here before.
> > Simon, have a search through the archives - hit any page
> of the
> > http://www.f32.net site and put your search term in the
> box on the
> > top right of the page. The list is searchable from the
> search box.
>
>   I drew a blank on MIchael's name at the time or would have
> posted his site. Sorry Michael, just a senior type memory.
>   BTW, the Thorium in the glass is not, as I have seen
> indicated, accidental or an inpurity. There are a number of
> formulae for NBS and Kodak rare earth glasses in the patent
> literature. Thorium was included in some of them to obtain
> certain optical properties. Its radio active nature was
> either not known or not appreciated at the time. The
> understanding of the long term effects of radiation exposure
> really did not occur until after the bombing of Japan. You
> may remember a scandal and series of law suits regarding the
> health effects of radium poisoning of the women who painted
> fluorescent watch and clock dials. These originally
> contained a small amount of Radium to excite them in the
> dark. These women were taking some of the paint internally
> because they wetted the brushes with their tongues. Problems
> such as those caused by overexposure to medical X-ray were
> also not recognized until sometime later than the Aero Ektar
> was made.
>   Not all Lanthanum glass contains Thorium and not all
> Lanthanum glass is radioactive. This is a good thing because
> lots of Lanthanum glass is used in modern lenses. The
> advantage of this glass is that it has a high index of
> refraction but a relatively low amount of dispersion. This
> allows elements to have less curvature than if lower index
> glass were used but also allows good color correction. As a
> rule the less steep the curvature of the elements in a lens
> the less the aberrations. For conventional glass types the
> higer the index the greater the dispersion, so a type which
> has high index but low dispersion is very useful.
> ---
> Richard Knoppow
> Los Angeles, CA, USA
> dickburk@ix.netcom.com
>
>
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