Using old lenses - guidance from 100 years ago

[goamules]

I found this article in the 1912 Bulletin of Photography. Very interesting reading how 100 years ago they were explaining when and how to use the "old" lenses from the 1800s. Taking the aperture out of a landscape meniscus to make a soft focus is mentioned. The relative cost of a Dallmeyer 3B versus 3A is addressed. And some fascinating other ideas for soft focus by using uncorrected early lenses are brought up. Maybe chemical focus is why a couple of my early ones haven't seemed that sharp, I'm just not focusing them right.

http://books.google.com/books?id=xvj...20lens&f=false

A little small, try the above link too:

[Bill_1856]

Waa-Hoo!

[Sandeha]

Read it with a slightly modern 'voice' and it could be anyguy's blog from yesterday.

[Steven Tribe]

The problems of visual and chemical raised applies to all the original Petzval productions and was well known at the time. These are the ones with a double convex lens as the last one in the cell and concave/convex (with the convex surface facing forward) inner lens.
Voigtländer suggests a scale of adjustment for the early type with specific values for the individual size no (that is, focal length). Their modified Petzval - no longer needing the adjustment - came first in 1877 I think.
The need for adjusting for chemical focus was so universal that catalogues didn't mention it! It was only in objectives like the late developed Rodenstock Bistigmat, which retained and automated the focus change, against the then current "mainstream" , that clear instructions were available.

[goamules]

Lerebours modified the Petzval design as Voigtlander was making it in the late 1840s (if I recall the date), correcting the chemical/visual focus problem. The others all followed.

[Steven Tribe]

Checking the description of the Voigtländer Petzvals on offer in 1861, it is obvious that the visual/chemical focus problem has been solved by then. They just refer to the need for taking the difference into account for "older Voigtländer objectives".
A comparison of the x section of the 1840's/1850's model compared with the 1861 type shows that the air distance between the rear pair has been increased at least threefold.

[MIke Sherck]

It says there that some of these old lenses were worth $7-$25 each. I think you guys are paying too much!

Mike

[goamules]

But a dollar was worth about $21 in today's value. So up to $525 we should be paying!