Dry Plates Screw Up

I've shot a couple of dozen of the Lane plates so far, and have got some good results. However the consistency hasn't been there. I think most of that might be me. The latest batch came back with very faint images. The sky portion was the darkest but the foreground part was extremely light. Blue Moon processed and suggested I'm not giving them enough light. This is possible. I've been exposure at ISO 2, 1/2 sec., f16--basically using "sunny 16" on sunny days. Exposures seem off by at least one stop, maybe even two. They scanned and I got a printable image. At first I thought the c.1922 Heliar lens in dial set Compur was running slow at 1/2s, but it sounds right and my film (FP4) shots come out well. So, I don't think it's the lens. Should I try adding one more stop to the exposure--i.e. ISO 1? The plates were very, very light.

The last batch I shot had something truly weird going on I've not seen before. They too were very very light but there was an image when I scanned with Epson v700. These appear to have some strange artifacts in them that look like giant bamboo stalks up the center. There's also some strange white streaks radiating from a central point. I load/unload these in a windowless bathroom at night, using a Patterson red light. The red light is usually ~3 feet away and I keep the plates covered as long as possible. Does anyone have any explanation of what's going wrong here? The weird bamboo thing happened to two plates, both shot with a c.1910 100mm Dagor in Compound. I've seen nothing like that on the film shots I took with that lens though. It's just really weird. Anyone have any ideas? I also attached a scan of a plate from same batch, same scene, using the c.1922 Heliar in Compur. There were no weird bamboo tubes in this one, but image was very faint.


Kent in SD

That first one almost looks like a double exposure.

I’d say shoot the rest of what you have at ISO 1. There could be a couple reasons for this: 1) the plate emulsion responds much more strongly to UV levels than panchromatic film. UV can vary enough to affect the results like this, and doing things like adding a haze filter will cut into the effective speed. I don’t think that’s your issue but it’s worth keeping in mind. 2). I don’t know what batch # your plates were from, but as I improved how I make the emulsion I noticed the speed dropped. I fixed this starting with batch 20, but prior to that they seemed to be running a bit thin.

The first looks like a light leak somewhere in your setup. The second looks pretty good. Thin negatives when scanned will start showing the eccentricities of the (very low) base fog from hand-coating. The closest analogy is if you take a picture with a digital camera with the lens cap on, you can stretch the resulting histogram and see the fixed-pattern noise that doesn’t show up in a regular shot. Normal film is like this, too, when underexposed...but the eccentricities are less because modern film has an extra 130 years of production improvements over what I’m doing. Thin plates from the 1880s will have similar artifacts to what you see.

So shoot them at ISO 1 and keep in mind I caught the speed issue and corrected it starting batch #20.

Box says batch 12A. I was suspecting either they weren't ISO 2 or summer haze (or something) was cutting the UV light. On the four I shot yesterday I gave them one stop more exposure. I'll shoot some more today and give some 1 stop more and some 2 stops and see what happens. I have two unopened boxes of batch 14. And no, the weird plate above was not a double exposure. That was my first thought but I didn't photo anything that would have looked like that, and I am very good about flipping dark slides. I don't get double exposures when shooting film. I shot one plate in a dark room (log cabin.) Meter suggested ISO 2, f8, 20s, but I gave it 1 minute. The ISO being 1 instead of 2 explains a lot of what I'm seeing though.


Kent in SD

Kent, just for fun, if you have kept the under exposed plates, see if they work as ambrotypes by placing some black material behind them - I believe with the emulsion side up and the black material against the uncoated side. Ambrotypes are supposed to be about 2 stops under exposed, so you may be able to have some fun with them still.
Let me know because I shot a plate this afternoon, 2 stops under, but haven't processed yet. I shot it specifically to see if ambrotypes are doable with dry plates.

I could put some black paper behind it and scan? There is enough image there that it scans, but with a lot of weird artifacts. I don't have any experience making ambrotype. Do intend to get into wet plate next spring.


Kent in SD

Kent, I was just wondering if your under exposed plates gave the look of ambrotypes to your eyes when laid on a black material, like black construction paper, etc. If they do, then - "voila" - you have experience making ambrotypes.

I know at least one fellow had luck making ambrotypes which seemed to come out well from what I saw.

Also, I’ve had luck coating emulsion onto black anodize aluminum sheets for tintypes, replicating a period correct process from the transitional period between wet plate and widespread acceptance of dry plate. I’m working with the company Modern Collodion to test those and ultimately make those available.

The ironic thing about the speed issue is that it showed up when I made an effort to follow the original recipe more closely.

Developing longer or developing with dilution A will compensate if you need to shoot at ASAa 2, but of course the contrast will be higher.

Cheers,
Jason

I would try the tin types if available. I'm shooting 4x5 and 5x7 now. I just bought a bigger Petzval on ebay last night--an 11 in. Voigtlander. My previous largest was an 8 in. Voigtlander. Now I just need to figure out how to mount a 5 in. flange on a 4.5x4.5 in. Gundlach Korona lensboard. Might have to get with Ritter or someone on this one.


Kent in SD