A friend of mine is an American Civil War reenactor, and I'll be taking some digital shots of his group doing a reenactment. I'd like to produce mockups that resemble real Civil War photos. I'm not a Photoshop guru and my knowledge of 1860s photography is even thinner. I would appreciate any advice or pointers to advice.

Nearly all Civil War photos were collodion process plates and albumen prints. The effective ISO was between 2 and 3, and exposure times of 15 to 20 seconds were likely. (Although if I did the math right, that works out to an aperture around f/100 to f/140 with a sunny EV of 15, does that sound right?) I don't have enough ND filters to simulate that, so I'll just take a normal photo.

Here's the post processing I think I need:
- Collodion responded to blue light, so convert to B&W entirely (or almost entirely) on the blue channel.
- Use curves to form a shoulder at the highlight end to reduce dynamic range and lose some detail at that end.
- Collodion plates didn't have an anti-halation layer, so I need to add some halo but I'm not sure how. I think I mostly want to wash out fine details in bright areas. I'm experimenting with copying the layer, bluring it a bit, lightening it, and blending it back in with "lighten" mode. Any ideas?

Something wrong here? Anything else I should do?

Any suggestions for printing?

Old prints always seem to have a sepia tone, but did they look that way when they were first printed?

Should I add light fall-off around the edges?

Any help would be appreciated. Thanks.

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-- Mark