Whole plate format is 6.5×8.5″, lodged somewhere between 5×7″ and 8×10″.
Rounded this comes out to 165x216mm. This gives you an aspect ratio of 1.30.
So what happened to this format? It’s still around, you can buy some film cut in whole plate size, so these old plate cameras aren’t out of use. You tape the film onto the plate and load the holder (the glass plates were a whole lot thicker than film, and this has to be compensated for.)
There were quite a lot more formats, whole plate was just one of the more common. Really in the early days of photography, you could make your cameras to be whatever size you wanted, so standardisation was slow to set in.
But what about the plates themselves? Of course sheet film pretty much obliterated pictorial glass plates, but for scientific purposes they’re still used. Holography especially, and until the 90′s they were quite often used in astronomy. The reason is they have high resolving power, and are a lot more permanent than anything else on the market. Since a properly developed and fixed image is just silver on glass, it’s reasonable to assume they’ll outlive you and your grandkids by a long way.
That is, if you don’t drop them.
The only place I know to get sensitised glass plates [is from Slavich], they are aimed at holography and not of whole-plate size. There is an interesting point from the HARMAN website though, parent company of Ilford…
Photographic Glass Plates
In the early days of photography, glass plates were in general use, but they were so fragile and heavy that they were quickly superseded by film for most purposes. Nevertheless, some glass plates are still used.
HARMAN has a coating machine specifically designed for coating on glass plates, and produces specialist plates for scientific uses – nuclear plates for particle physics, and Q-plates for mass spectrography. We also have the capability of producing photographic glass plate equivalents of some of our film products, though these are not routinely available.
Also from Kodak:
KODAK T-MAX 100 PROFESSIONAL PLATE
The KODAK T-MAX 100 Professional Plate is a continuous-tone panchromatic plate that has the same sensitometric characteristics as KODAK T-MAX 100 Professional Film / TMX. It is especially useful for photomicrography, electron micrography, and laser recording, as well as solar and astronomical photography. It provides maximum image quality for detailed subjects. You can process this plate in KODAK T-MAX RS Developer and Replenisher, KODAK XTOL Developer, KODAK HC-110 Developer (Dilution B), or KODAK Developer D-76. For ordering information, see a dealer who sells KODAK PROFESSIONAL Products.
So if enough people wanted it…
But for the purpose of the glass plate camera project, I intent to cut and coat my own plates on a 2mm thick base.