Whole-plate camera back dimensions needed for a DIY wetplate holder project

I'd like to make an ABS wetplate holder for my whole-plate cameras but have run into a couple design problems. If you have a whole-plate camera (or reducing back), I'd like to compile some measurements of the rear box to aid designing a couple pieces.

I have 3 different whole plate cameras, an Eastman #2, a ROC Universal, and a ROC Carleton. I also have at least 4 different-sized plate or film holders in that format!

I've read several posts on APUG and this forum about the lack of standardization for this format, both in the past and present day even with new holders coming from Chamonix, Ebony, Lotus, S&S, and AWB. It sounds like a somewhat standard t-distance has evolved taken from the ANSI 8x10 standard of 0.260" but the modern variance runs between 0.260" to 0.300" from what I can glean from forum posts. I measured an old Eastman plate holder with film sheath and get about 0.300" to the sheath surface. I have also discovered that not only are the holders different widths with different rib/light baffle designs, but the camera rear box dimensions are not the same between the cameras I own.

I measured the t-distance on the other various holders I have. Here's what I came up with:

Eastman Portrait Film Holder #2 for Empire State, ROC Universal, Carleton, and Premo cameras - one side averaged about 0.254" and the other 0.245"... call it 0.250" I guess.
a second Eastman Plate Holder was also just under 0.300"
ROC film holder was ~ 0.310"
ROC plate holder w/film sheath was ~0.280"
older Blair plate holder was ~0.290"
Poco film holder was ~0.300"

I'd like to attempt making a wetplate holder for the whole-plate format but face the dilemma of where to put the focal plane due to the different t-distances and, more importantly, my amateurish machining skills and tools. There's no way I can presently stuff a rigid darkslide and set of plate supporting corners in little over a quarter-inch. Half-inch, maybe. As a result, I've decided the path I'm going to take is to make my own adapter back and set the focal plane where I can have a reasonable chance of success constructing the holder.

It seems the current 2 or 3 US wetplate camera manufacturers are so busy that they no longer wish to make adapter backs. Justifiably, they would rather spend their time crafting entire cameras rather than retrofitting those made elsewhere. And to date, In Camera Industries' recently introduced wetplate holders are manufactured only to fit the common modern formats of 4x5 and 8x10 (with 11x14 on the way). Lund Photographics does make whole-plate, half-plate, and 10x12 plate holders, but these are earmarked for older dryplate cameras and as such, have slightly different design considerations than a wetplate or film holder does. As a result, there seems to be a great resurgence in wetplate collodion occurring with more demand for new equipment than there are suppliers, and whole-plate photographers lacking any choice at all other than using a larger format camera with reducing insert.

I wonder if some sort of universal adapter back made out of ABS could be designed to fit different cameras yet still use the same holder? Not only would this help those wanting to do wetplate in historic size cameras, but such a scheme would be a way to keep any camera safe from silver nitrate stains and corrosion. I think I have such an adapter back worked out for my particular cameras, but I wonder if there is a much wider variation considering all whole-plate cameras.

If you are using a whole-plate camera I'm hoping you could measure the rear box and let me know what the dimensions are so I can get some idea of the range adapter backs would need to cover. Here's what I have so far for my cameras:

The rear box of the Eastman #2 camera is 10” square with a rabbeted light baffle 1/8” deep and 1/4” wide (i.e., the 1/4” thickness of the box stock).

The ROC Universal and ROC Carleton cameras have rear boxes 10 3/16” square with similar light baffle to the #2 Eastman.

What size is yours? :eek:

Would regular Whole Plate glass plate holders work? Or do you need something different for wet plate plates?

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Originally Posted by Bill_1856

Would regular Whole Plate glass plate holders work? Or do you need something different for wet plate plates?

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Dryplate holders could be used but wouldn't last very long if the plate contacted the (usually cardboard) septum. In contrast, a collodion wetplate is loaded from the back of the holder and is suspended within the dedicated wetplate holder to allow minimal contact with the plate. As more surface contacts the plate, corrosive silver nitrate solution from sensitization wicks around from the back to the image side and causes many of the artifacts you see in some wetplate images posted on the forums. If you look closely at a wetplate image you'll discover that most have marks in the four corners from being suspended using wire or small triangular pieces.

Attachment 77065

This linked image shows an original 1866 wetplate holder. Notice how robust it is and how the silver nitrate solution has left metallic and black stains all over it. You can clearly see the corners used to position the image plate. The wetplate would be placed emulsion side down onto those corners and the once the door is closed, the attached spring pushes the plate against those 4 corners holding it in place. To remove the wetplate you simply open the door and lift the plate out or put your palm against the back of the plate and turn the holder over so it falls onto your palm.

If a dryplate holder was used I would suspect a few other things could happen. First, it would be a lot messier getting a lot of silver nitrate inside the holder. Second, most dryplate holders are spring-loaded and you must push the plate against the spring at the bottom of the dryplate holder and drop it onto the septum at that point so that when the spring is released, the top of the plate slides under the holder frame and is held in place. To remove it the loading procedure is reversed. Both occasions increase the potential for a fingernail slipping and tearing the fragile plate image. I would also suspect the capillary force caused by the contact between the septum and reverse of the plate would make it much more difficult to unload a collodion wetplate from dryplate holder.

Using dryplate holders or converted film holders is a bit more awkward as well. Loading and unloading a dedicated wetplate holder is very easy.

So, dryplate holders could be used in a pinch, but I think once someone used an actual dedicated wetplate holder, they would not want to go back.

Just asked because I bought a camera earlier this year which came with a couple of DD glass plate holders. They are really beautiful wood, but don't have film adapters.

Can anyone help me out with the rear box dimensions of their whole-plate camera? Thanks.

I didn't reply earlier since it seemed unlikely that anyone who bought an Ebony SV Wholeplate would bring wet plates near it. However, since you're almost pleading now ( :) ), here are the dimensions.

• Rear "box" 10-5/8 x 10-5/8 inches
• Rabbeted area 10 x 10 inches
• Depth of rabbet 1/8 inch
• Size of reversible back section that protrudes inch into box's rabbet 9-31/32 x 9-31/32 inches
• Depth of reversible back section that protrudes into box's rabbet 1/8 inch

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Originally Posted by Sal Santamaura

I didn't reply earlier since it seemed unlikely that anyone who bought an Ebony SV Wholeplate would bring wet plates near it...

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What about that Zebra dude?

Thanks for the info Sal.

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Originally Posted by Sal Santamaura

I didn't reply earlier since it seemed unlikely that anyone who bought an Ebony SV Wholeplate would bring wet plates near it...

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Originally Posted by Joe Smigiel

What about that Zebra dude?...

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I forgot about Monty and his 20x24 Ebony / wet plates. My perspective as a retiree on a fixed income is probably quite different than that of an NBA ref! :D:D:D

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Originally Posted by Joe Smigiel

...Thanks for the info Sal.

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You're very welcome.