View Full Version : 6 1/2 x 8 1/2 (full-plate?) Extreme Wide Angle

Neil Purling
13-Mar-2007, 14:57
I assume this lens is for Full Plate. I won it on ebay and it doesn't seem to have a makers name. It has aperture stops on a wheel and I am finding out if they are of the American or European progression. I have't yet got a figure for the max aperture.
What focal length in mm are we talking about for the diagonal of a full plate?
As to the optical design.....

Ole Tjugen
13-Mar-2007, 15:26
The image diagonal is about 10 1/2", or 265mm or so.

"Extreme wide angle" often means that the image angle is greater than 90°. That corresponds to a focal length of 132.5mm assuming 265mm image circle (at 90°, coverage is 2x focal length).

Assuming the intended coverage is 100° the focal length is at least 113.3mm. More than 100° was often specified, but rarely realistic.

So at a rough guess, what you've bought is an Extreme WA Rectilinear, 5" focal length, f:16.

Or something like that...

Neil Purling
14-Mar-2007, 00:29
It is definitely f16 max aperture, the wheel stops being marked in the Uniform System.
Would a European maker have marked their lens stops thus for export to the US/
This creature is anonymous, no makers name or that of a supplier. The only engraving being "6 1/2 x 8 1/2 Extreme Wide Angle" and the marks on the stops.
Is this lens American or European?? If the lens were European would the maker have supplied it with the lens barrel & flange in a metric thread form or European?
It may be the only way of establishing a place of origin.

Ole Tjugen
14-Mar-2007, 01:28
If you look at the thread dimensions for Compound shutters, you'll have an idea about the probability of European makers using metric threads... :)

The aperture numbers could well be US, but I wouldn't quite discount Stolze either - Stolze 16 is f:12.5, doubling with each stop just like the US.

Ernest Purdum
14-Mar-2007, 10:09
"US" doesn't mean United States, it stands for Uniform System. The (British) Royal Photographic Society pushed for its use for awhile.

Neil Purling
14-Mar-2007, 13:00
Were anonymous lenses a common thing?
I would have thought that a optical manufacturer with any pride in their products would want to put their name to them.
From browsing that auction site I have seen lenses with both a makers name and another which may be a distributor or a camera maker they were supplied with.

Ole Tjugen
14-Mar-2007, 13:24
Anonymous lenses were very common. So were otherwise anonymous lenses marked with a retailer's, camera manufacturer's or importer's name.

The most famous lens makers of a century ago are, not surprisingly, those who marked their lenses...