[LargeFormat] Elgeet Update

[Clive Warren]

At 03:18 04/03/2003 -0800, Les Newcomer wrote:

>On Tuesday, March 4, 2003, at 02:31 AM, Clive Warren wrote:
>
>>Alan,
>>
>>Richard may have mentioned this earlier, but in1962 the Elgeet 'firm=20
>>acquired ownership of the ancient establishment of Steinheil in Munich'=20
>>(from Kingslake).
>
>>The only mention of large format lenses I can find is the Elgeet=20
>>Anastigmat f4.5 250mm which is of course your lens. Be wary that the=20
>>circle of illumination is probably larger than the useful image circle.
>>
>>Cheers,
>>            Clive
>
>Looking up Steinheil in  my '39 ed of "Handbook of Photography"  I find=20
>they made a 250mm f4.5 Unofocal lens.  This was similar to the Celor and=20
>Aviar, and later the Artar.  It has 4 symetrical air spaced elements  with=
=20
>an angle of view of 60=B0, and is the basis of most process lenses.
>
>If we let a=3D the radius of the coverage angle, then 2a=3D 2[focal length=
 x=20
>Tan (half the angle of view)]  will give us the circle of coverage.  Thus
>
>2a=3D2(10 x Tan 30=B0)
>
>2a=3D 2 x 5.7735"
>
>2a=3D11.54"

Don't you just love it when Les gets all technical?  Now we're getting=20
somewhere. My bet is that the Elgeet Anastigmat and the Steinheil Unofocal=
=20
f4.5 250mm are one and the same lens and it will cover 8x10 with about=20
3/4"movement available. Given the design of the lens, the quality of the=20
image should be very good and the contrast adequate with eight glass to air=
=20
surfaces - better if the individual elements are coated.

The final test of this is down to you Alan - how many reflections in each=20
lens cell? If there are two from the front and two from the back then we=20
have solved the mystery :-)

Cheers,
            Clive