Info on very early Petzvals?

[Mark Sawyer]

A friend at the University of Arizona's Optical Sciences Department recently queried me about early (1840's) Petzvals as follows:

"I would like to find out where in the early Petzval lenses the diaphragm was located. There are two options: a) near the first lens, b) near the middle between the lenses. The only way to know is by actually examining either:
1) The original Peztval-Voiglander camera
2) One of the replicas built in commemoration of the first
3) Looking at Petzval lenses of around 1841-1849 before the Waterhouse stops came in use."

Can anyone point me/him to some good information? (I've already sent him a link to Dan's Petzval history page.)

[goamules]

Actually, I believe Waterhouse stops were invented in 1856 or 1858 depending on who you believe. So any lens prior to this would be useful. But I'm not sure they had much of a diaphragm, I'll have to look at some of my early, uncut ones, but I think they were smooth barrels inside. The fastest design was certainly what they were after in the Daguerriean age. By the wetplate era of the early 1850s, they needed to stop them down some, and started retrofitting the old Petzvals with slots. So I'd look at any uncut Petzval up til about 1851. You're in luck, I have several!

[Mark Sawyer]

Thanks, Garrett! I'd already told him the early Petzvals may not have had aperture restrictions as the early processes were so slow, and one wouldn't want to trade away aperture for other benefits. But not knowing those very early lenses, I could be wrong...

[goamules]

I just looked at one I have out, a quarterplate NY radial drive uncut, and can't see any internal restrictions.

[Two23]

I have an 1847 Voigtlander Petzval. It has no diaphragm at all. Neither does my 1855 Grubb or 1850s Derogy Petzval. Since Dag-type was so slow, they just shot them wide open. That was the point--fast lens, faster exposure time on their very slow media.

Kent in SD

[maurits]

Mark, Garrett, I have two pre-Waterhouse Hermagis convertible lenses that use internal aperture disks.

The big lens on the left and in the middle has a set of small aperture disks to install in the lens hood when the lens is operated in landscape mode, using only the reversed front group (first image). The disks are held in place by a round steel spring.

Smack in the middle of the lens is another, much larger aperture holding device. These disks are to be used when the lens is in portrait mode. The barrel of the Hermagis convertible conveniently unscrews into two parts. Here, the rear part of the barrel holding the air spaced group is taken off the lens. Don't let the flange mounted on the back side of the lens board confuse you. It is just there as an extra safety measure.

The tiny (160 mm focal length) Hermagis convertible barrel also unscrews into two parts. You can see an internal aperture disk mounted and held secure by a steel spring.

On both lenses, when using the focusing device to retract the lens as far as possible into the camera, the aperture would be exactly on the same plane where the flange meets the lens board.

Maurits




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[maurits]

On the left the internal disk aperture from an early Alexis Millet internal bayonet mini-cone lens. In the middle a Darlot cone lens with a disk aperture installed. On the right the bayonet front group of a Derogy I used to have. It came with (I think) three disks. One can be seen mounted here.

In the case of the last two lenses, I think the disk apertures were primarily meant to be used when in landscape mode.

Maurits

[Jason Greenberg Motamedi]

To my knowledge, there was no way of reducing the aperture of the Voigtlaender cannons. This is based on my playing with one of the "original copies." Previous to the 1850s there may have been washer stops on Petzvals--as there were with landscape lenses--but I can't say I have seen them.

[CCHarrison]

Ditto on what Jason said. The earliest Voigtlander Petzvals had no stops/diaphragms. However, some of the earliest landscape lenses did.

Dan

[Mark Sawyer]

Thanks, all! It sounds like no aperture restrictions were used in the earliest Petzvals, though in Mauritz's "convertible" Hermagis Petzvals there were washer stops for use in the landscape lens configuration.

BTW, was the term "landscape lens" used because landscapes would hold still for very long exposures at small apertures, while people couldn't? (Never thought about it before...)