View Full Version : Bausch Lomb Tessar 1C 5x7 Focus Length??

7-Dec-2008, 18:39
New to large format photography and picked up a lens on the cheap today, but it doesn't list the focal length. I've found some ways to find the focal length, but was wondering if anyone already knows?

Bausch Lomb Tessar Series 1c Pat. Feb 24, 1903 No 2632694

I've also seen a reference to a book by Woody Woodsen, but can't seem to find a copy at any of the libraries near me.

Thanks in advance for the help.

7-Dec-2008, 20:40
looks like about 7 1/2 inches.

check here (http://www.cameraeccentric.com/html/info/bauschlomb_1.html)

Emmanuel BIGLER
8-Dec-2008, 03:45
Hello from France !
You can guess-stimate your focal length by forming the image of a bright window on the palm of your hand ;-) and measure the distance with a ruler.
For the tessar the distance between the middle of the lens and the focal plane is very close to the actual focal length.
For 13x18cm alias 5x7" the standard focal length equal to the diagonal of the format is 210mm = 8"-1/4 and tessars existed in this f.l... but may be not the one you have.
7"1/2 is about 190 mm which does make sense as well for a tessar covering 5x7".

Dan Fromm
8-Dec-2008, 07:08
Look here http://www.cameraeccentric.com/html/info/bauschlomb_5.html , then measure

8-Dec-2008, 09:27
Thanks everyone. The link to the B&L catalog was exactly what I was looking for. Great resource to have on the web.