Tintype Exposure Guide?
So I recently took a class at my University in alternative processes... and fell in love with a great many of them-- but nothing struck me as much as when we got France Osterman to come do a collodion workshop with us
So, predictably, I decided to start working on my own in collodion and am currently waiting for UPS to drop off all the chemicals... I am bouncing in excitement!
My question is about exposures... I am aware that positives in collodion require less exposure than negatives (I'll be doing plates, but for the ease of not having to clean glass at the moment, I'm starting with tintype plates). I can't find any sort of recommendation on exposure. I am aware that collodion is sensitive to more UV spectrum light, and thus light meters (at least France told us) are pretty useless.
Is there any sort of guide or rule of thumb I can use for a starting point? I am willing to experiment to find exposures, but I'm looking for a starting point.
Exposure for Collodion
It all depends on how much light you have to shoot with. Collodion is very slow, and not terribly sensitive to much of the visible spectrum. Are you making images outside with natural light or inside with studio lights? How fast is your lens? The last time I shot outside my exposure was about 3 seconds at roughly f/8ish in dappled light. You should start to see your highlights between 8-12 seconds after you have covered your plate with developer. If it comes up before that, its over exposed, if you are waiting for 20-25 seconds to see a highlight appear, its under exposed. Hope this helped, have fun with a great process. I have found the folks at Bostick & Sullivan quite helpful with this stuff