Ross - for Cartes de Visite/ Small Petzval's

[Sven Schroder]

Hi
Having found the Ross/petzval I need for some portraits of Glacial Erratics (yes big Limestone ones) with Swirly bokeh. Typically it was found without any waterhouse stops so speed is a problem f3 wide open, I like what I see wide open but how much do petzval users stop down f8 ? also how low with the film speed as I want shallow DOF?

So the lens I have is a Ross petzval "for cartes de visite" in focal lenght of approx 6", I intend to shoot on 5x7/halfplate the swirl shows up well on this size. There is little info on vademecum to help determine the speed of the lens just "Quick acting for cartes de visite" which of course is not insribed on the lens, so is my estimation of f3.7 correct?

As for exposures I will have a look at front mounting a packard as I don't have much room inside the camera ( a Gandolfi ) I am used shooting with barrels at f32 or so but not F3.7 or so.
Thanks and Regards

Sven

Well not for cartes de visite, unless the Glacial Erratics need to introduce themselves.

[Jason Greenberg Motamedi]

Sven,

I don't know anything about Glacial Erratics, but I do know that a 6" Petzval will not cover 5x7 or half-plate without vignetting the corners. You are correct that a 6" lens was intended for CdV (65x90mm), however I think what you need for 1/2 plate is a lens for cabinet portraits (100x140mm), these will provide you with the swirls and fall off, but no extreme vignetting like the 6" lens. The Cabinet lenses were usually 8".

Most Petzvals marked "Quick Acting" were f3.6-3.8. To reduce the aperture you will need to make a waterhouse stop (assuming the lens was slotted). These aren't difficult to make with thin brass or matboard, look on the web for images.

[Sanders McNew]

Even a ten-inch Petzval will vignette at 5x7 -- at least mine does. I shoot a ten-inch Hermagis Portrait Lens (see my avatar!), a Petzval design, stopped down to f/10. Sanders.

[domenico Foschi]

Why don't you adapt it to a Speed Grafic?
It won't be a 5x 7 , but you will be able to use it at full aperture for shallow DOF.

[Sven Schroder]

Jason

Well its a good job Glacial Erratics and petzvals come in different sizes. The erractics are rocks left by the last ice age and very in size, so this lens should do for the small ones on 5x4, the erratics vary from under meter high to larger ones a couple of meters high and the same in diameter. My project is in the early stages so nothing lost, the vignetting didn't look that bad on the ground glass but this will also depend on distance to the subject. So you're right and I am not shooting at portrait distances so I will need to be carefull with lens choice.

Thanks again

Sven

[Sven Schroder]

Sanders

I don't mind some vignetting as aims are simlar to making portaits in that the focus is centralized on the subject with fall off rendering the trees surrounding the rock less well but just enough. I may also look at the gradual loss of detail seen in the outer image circle of Rapid Rectilinear's.

domenico

I have a front mounting neumatic shutter that I can use in the studio it offers Instant or time only, a speed graphic would work but I have 5x4 pinned down to lightweight system.

Thanks again

Sven