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David Flockhart
21-Dec-2004, 00:32
I've been given a barrel lens - a No. 6 Ser II Dallmeyer Stigmatic F/6 lens that is marked as 10.7 or 27cm length. Can't seem to find much inf from these archives or google. It covers the 8x10 with some movements (no pics yet, just GG gazing). Any info would be appreciated. How does this design compare in practical usage from say, a Kodak anastigmat where the astigmatism is dealt with. Thank you for your insights.

Dan Fromm
21-Dec-2004, 05:19
According to the Vade Mecum, all of Dallmeyer's Stigmatic lenses are anastigmats. So don't worry about that. Have some text lifted from the VM:

"Stigmatic Series 11 f6.0 3.5-18in (11 foci) Da019 from 1897
It was also listed as 3.25, 4.0, 4.5, 5.3, 6.4, 7.6, 9.0, 10.7, 12.7, 15.1, 18in by Houghton's catalogue. They
suggested to use 4in or longer for 5x4. They emphasise the good angle covered for cameras with movements.
An example was noted as a Stigmatic f6/192mm No74,56x on a 1/2plate Sanderson and others at No69,58x
in a Volute shutter on a Sinclair Una and at No77,20x in a dialset Compur. A late version was noted on a Soho
Precision at No168,xxx in a Compur No3.00 million, form the middle 1930's, such as 1935. The choice may
have been for the convertibility of the Stigmatic since it was an old design by then.
These were separable for longer foci, (1.6 and 2x focus), were less costly and sold well so they are easier to
find today. For 5x4, use 6.4in, at f6.0, 4.0in at f16. In use these seem to be good flat field lenses, the image
gaining contrast at f8 and f11, but better than expected, and covering a really wide field. It could still be a use
lens. It was made into the 1920's and 1930's. When separated, the front is 2x and the rear 1.5x the focus of
the whole. It was rated for 70 at f6.0, and 75-85 at f16. The f6.0 is the commonest of the Stigmatics today,
which suggests the sales were often as a professional lens of about 10in, and then it is followed by the Carfac,
which seems to have sold in smaller sizes probably to amateurs. The mount of the Stigmatic seems to have
been revised about 1900 so that it was easier to dismantle to use separate cells. (B.J.A. 1900, p891, for the
design story see: Photo. Jour. 1897, 21, p167).
Series II was still offered in the 1920's in many sizes, with stress on the convertible nature of the lens and the
great covering power. It was stressed that it was very well corrected for colour and that the front combination
was fully corrected for astigmatism. Sizes were:

Number Focus Format @f6 Format stopped down:

!AA 3.25in for 2.5x2in (1/4plate)

1A 4in for 3.25x2.25 (5x4in)

1 4.5in for 3.25x3.25in 6.5x4.75in

2 5.3in for 4.25x3.25in 8x5in

3 6.4in for 5x4in 8.5x6.5in

4 7.6in for 6.5x4.75in 10x8in

5 9in for 8x5in 12x10in

6 10.7in for 8.5x6.5in 15x12in

7 12.7in for 10x8in 15x15in

8 15.1in for 12x10in 18x16in

9 18in for 15x12in 22x20in."

Mike Phifer
21-Dec-2004, 08:56
David, R. Kingslake (A Hisory of the Photographic Lens, 1989, Academic Press) states that in 1895 Hugh Aldis at Dallmeyer revived the plan of the Zeiss Anastigmats with his series of Stigmatics. He replaced the strong dispersive interface in the front component by the addition of a narrow airspace having the shape of a positive lens. This offered better zonal correction of the spherical aberration.

In the Series II (f 6) this was accomplished by a meniscus lens in the front of the front cell. The middle and rear components were almost identical new-achromat doublets.
The cutaway view looks something like this: (( ()( : )()

I hope this helps. Mike

David Flockhart
21-Dec-2004, 16:00
Thanks for the replies. Dan, I presume the two set of sizes refer to the intended format and then perhaps the image cicrcle. Would this be a good assumption? eg., 6 10.7in for 8.5x6.5in (intended format) 15x12in (image circle). Given the initial looking on the 8x10 it sounds reasonable. I'll test it on the 8x20 and see if I can run out of image. Any users of these lenses?

Dan Fromm
22-Dec-2004, 05:10
David, I think the first size is coverage wide open and the second is coverage stopped well down, whatever that means.

Cheers,

Dan