[LargeFormat] aero ektar

[Clive Warren]

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
>  >
snip
>   Reports from users over the last few years are variable.
>Some get good performance, some complain of poor color
>correction. The performance graphs shown in Smith indicate
>the chromatic correction should be good. Its possible that
huge snip
>   I would also like to hear from anyone who has actually
>used one especially as to the color correction and whether
>anyone has observed browning.
>   The evidence is that although somewhat radioactive they
>are not dangerous.
>   There are some articals on the web about the Aero Ektar,
>I'm surprized a Google search didn't turn them up.

Thnakd for the information Richard - as usual you have added to my 
knowledge about lenses.

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 have three of the 7" lenses and a set of the original aero colour 
filters (for B&W), one of the lenses is in an Alphax shutter and 
appears to have been factory fitted. See 
http://www.f32.net/cgi-local/discus/show.cgi?tpc=6&post=346#POST346 
for photos of the Alphax shuttered version and earlier in the thread 
for a helicoid mounted version.

All of the lenses I have show the brown damaged glass to the rear 
element and the radiation is emitted from the rear elements that 
contain Thorium. This radiation can be measured and is of the variety 
that goes through most solid objects! Michael will explain the 
physics, but the general effect is that radiation changes its nature 
and increases over time (years) and becomes more unpleasant.

I would imagine that the effects of the browned glass with colour 
will be the equivalent of a warm-up filter. Michael has suggested 
that the speed of the lens may also be compromised.

There is also a photo in the f32.net Discussion Forum of the 
shuttered version sitting on a Graphic II waiting for the clouds to 
disperse for a meteor shot that never happened - hey I live in 
England........
http://www.f32.net/cgi-local/discus/show.cgi?tpc=13&post=1854#POST1854

I keep the lenses as far away from me as possible in the office.

Cheers,
        Clive