Lens advice needed for 8x10 fully open in a tight space

[Bernice Loui]

Wet plates with an exposure time of 10-30 seconds, a shutter is moot as a well fitting lens cap will do fine to turn the light to the wet plate on and off. This allows using barrel lenses with little problem.

Given this, skip over the majority of modern plasmats as they are typically f5.6 wide open.

The solution could be found in older vintage lenses of a Tessar, Heliar or similar design. Most Tessars are f4.5, few are f3.5. This is also true for the Heliar which is most common in f4.5 and the rare f3.5. There are a few f4.5 dialyte lenses like the Cooke Aviar and Goerz Dogmar.

That one stop might not appear to be much on paper, it is very significant in actual image making. Moving beyond these lens formulations, there are a number of aero recon lenses that might do. Lenses like the Kodak 12" aero Ektar has a whopping f2.5 and designed to cover 9x9 - 10x10 aero film at infinity.

The Petzval lens formula goes back to the wet plate era as it was one of the first successful large aperture lens designs that was used for wet plate image making. They do have a distinct look and might fit your needs.


Bernice

[jb7]

Laura by joseph - jb7

This is an 11" (270mm) f/3.3 (or 3.5) Petzval, at around 10 feet distance. I'm not sure, based on my reading of the original question, if this is what aople is looking for. In fact, I seriously doubt that it is. I know people claim great coverage for their Petzvals, especially when they're selling them, but none of my Petzvals seem to cover as much as theirs.

I also have a 250mm f/3.5 Tessar, it doesn't come close to covering 8x10 at this distance. A longer lens might, but wouldn't fit the space restrictions that are part of the problem.

[Mark Sawyer]

Just a note that the Aero Ektars make poor wet plate lenses, as the rare earth glass has a yellow cast that cuts the UV light significantly. Tessars, Heliars, and Petzvals all have pretty modest coverage.

The OP's Fujinon covers 8x10 at infinity, so at the 8-10 foot distance she is working at, it should cover her plates fine. I suspect any fall-off is either from taking the lens off-axis with movements, or from uneven lighting (which is pretty easy to have happen when the lights are close to the subject for studio wet plate portraiture).

[Bernice Loui]

No experience what so ever with wet plate image-making. Question is.. what is the spectral sensitivity of wet plates. Given this, would a light source with a spectrum centered to the greatest band of wet plate sensitivity help reduce exposure times?

Knowing the spectral requirements would also help in optics selection.

Aero Ektars are intended to cut UV sensitivity and enhance IR sensitivity as IR is often used in aero imaging to this day. This designed in aspect of aero Ektars would make them a poor choice for UV work.

There are lenses made using optical quartz specifically designed to transmit UV better than normal photographic lenses. Much like lenses made of optical germanium specifically designed to transmit IR better than normal photographic lenses.

Here is a lens coverage chart from the Linhof book published years ago. The 240mm f4.5 Xenar/Tessar has an image circle of 280mm at infinity, 8x10 requires about 312mm to just cover. The Heliar is also listed. Given the working distances involved, the image circle should be just enough. Depth of focus will be small at f4.5.





Bernice

Just a note that the Aero Ektars make poor wet plate lenses, as the rare earth glass has a yellow cast that cuts the UV light significantly. Tessars, Heliars, and Petzvals all have pretty modest coverage.

The OP's Fujinon covers 8x10 at infinity, so at the 8-10 foot distance she is working at, it should cover her plates fine. I suspect any fall-off is either from taking the lens off-axis with movements, or from uneven lighting (which is pretty easy to have happen when the lights are close to the subject for studio wet plate portraiture).

[goamules]

Wetplaters do use artificial lighting that is heavy on the UV and blue end of the scale. Some use black lights. Shooting portraits indoors with strobes or florescent lights for wetplate is just difficult. You ether give the subject a powerful, thermonuclear blast of flash, or make them sit basking in UV radiation for long exposures. Either way, artificial lights make the skin look pasty, and unnatural to me. That's why 1800s studios had huge skylights, sunlight is perfect for wetplate.

In open shade outdoors, I can get a 1-2 second exposure with a normally fast lens. Take the same lens indoors, with a bank or two of compact florescents, and you may need a 30 second exposure.

[aopie]

Thanks again for all the suggestions. In my case, the solution was in my hands (in my camera in fact). Mark was right:

"The OP's Fujinon covers 8x10 at infinity, so at the 8-10 foot distance she is working at, it should cover her plates fine. I suspect any fall-off is either from taking the lens off-axis with movements, or from uneven lighting (which is pretty easy to have happen when the lights are close to the subject for studio wet plate portraiture)."

My lighting was uneven and I was raising the front standard too much. Corrected those things and I'm getting even coverage on the whole 8x10 plate. An example:

On wetplate lighting, since that has been mentioned a few times. I'm using at least 10 of these wonderful, massive fluorescent bulbs 250 watt I believe, as well as a bank of 4' fluorescent tubes and large, open softbox. So, I'm using a lot of light but it's cool and easy for subjects. I have another bank of 4' black light tubes I've used but I find that with some formulas (the spectral sensitivity changes for different formulas and with age) the highlights look terrible so I've shifted away from black light with my current formulas.

Back to lenses, for others searching in the future, I've made a list of the lenses suggested in this thread, hope I didn't miss any. Even though I find my needs are actually set with what I have, I'm going to look into getting the wide field Ektar and keep my eye out for others, can't have too many lens options!

Lenses suggested for fast, even coverage of 8x10 at 8’ to subject
250mm Fujinon W f6.3
240mm Rodenstock 5.6 Apo Sironar-S should work
200mm Grandagon-N
210mm Apo-Sironar W 5.6 (352mm circle)
250mm Fujinon-W f/6.7
210mm Fujinon W f/5.6?
250mm Wide Field Ektar f/6.3 (422mm image circle)
240mm Dagor
222mm Cooke Series VIIb

If you could go to a 12" lens, there are many more options, starting with:
300mm Schneider Xenar f4.5
12" Kodak aero Ektar f2.5
14" Kodak Commercial Ektar (444mm image circle)

Other fast lenses:
Cooke Aviar
Goerz Dogmar
Petzval

[Bob Salomon]

No experience what so ever with wet plate image-making. Question is.. what is the spectral sensitivity of wet plates. Given this, would a light source with a spectrum centered to the greatest band of wet plate sensitivity help reduce exposure times?

Knowing the spectral requirements would also help in optics selection.

Aero Ektars are intended to cut UV sensitivity and enhance IR sensitivity as IR is often used in aero imaging to this day. This designed in aspect of aero Ektars would make them a poor choice for UV work.

There are lenses made using optical quartz specifically designed to transmit UV better than normal photographic lenses. Much like lenses made of optical germanium specifically designed to transmit IR better than normal photographic lenses.

Here is a lens coverage chart from the Linhof book published years ago. The 240mm f4.5 Xenar/Tessar has an image circle of 280mm at infinity, 8x10 requires about 312mm to just cover. The Heliar is also listed. Given the working distances involved, the image circle should be just enough. Depth of focus will be small at f4.5.





Bernice

But these coverages are all at f22 not wide open. Wide open they will cover less. Closer then infinity they will cover more. So, at portrait distances the coverage will be something other then what is listed for f22.

[Mark Sawyer]

Thanks again for all the suggestions. In my case, the solution was in my hands (in my camera in fact). Mark was right...

I'm always right, and I never lie.