Indian Art Work

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11-10-2012, 12:43 AM
krstahl

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Indian Art Work

I have been documenting American Indian art work on sandstone walls in Montana. The color pictographs (paintings) are fairly easy to photo and PP through ImageJ software. However, some of the other art work is nothing more than very shallow scratches (similar to a petroglyph) on the surface of the sandstone. ImageJ only works on photos with a color substrate (paint). A "straight on" photo does not show the scratches well at all. The shoot locations are several miles from the nearest gravel or dirt road, and wheeled vehicles are not allowed, so dragging in a bunch of side lighting gear would not be practical. The best I have been able to do, so far, is to shoot several macros and then stitch them together. However, the results are still not satisfactory for proper documention. Does anyone have any ideas on how to shoot these shallow scratches so that they show up. Because the scratches are not based with color paints, shooting B&W would be OK but not preferred. I shoot with either a Canon 7D w/ 24-70mm f2.8 L USM lens or I use my Canon S100.

I have attached two photos of what I am trying to capture. The type of art I am trying to capture is inside the red circles I have added PP. Both pics are in color even though the first looks like it is BW (it was in sort of a cave). I bracketed both shots for +/- 1/3 stop, these are the best that came out at -1/3 stop - no flash. Flash seems to burn them out at such close range of about 12 - 24 inches. There is not enough room in the cave to back up any farther.

Attachment 1556 Attachment 1557
11-10-2012, 12:47 AM
Mark Elberson

You need side light (90 degrees to the scratches). You could try a flashlight or an off camera flash. That will exaggerate the scratches.
11-10-2012, 12:55 AM
krstahl

Quote:

Originally Posted by Mark Elberson

You need side light (90 degrees to the scratches). You could try a flashlight or an off camera flash. That will exaggerate the scratches.

Thanks, I have considered that and it might work. I did not have a flashlight with me that day. The only drawback is that the sandstone faces are not flat and a lot of surface distortion such that the side light might not highlight all the scratches. I don't own any filters, yet. Is there a filter set that might work?
11-10-2012, 10:57 AM
Busted Knuckles

Filters can't create more contrast on the same material/same light. sometimes slightly over/under exposing can provide some perceived contrast.

You have effectively a monochrome environment.

Side light is the best solution - the further to the side the more "relief" will be shown. Depending on the shape of the scratch - the scratch provide both a shadow line (side nearest the flash) and a bright line (part of the scratch that is reflecting directly at the camera. Moving the flash off camera just an arms length can have a surprisingly dramatic effect on a flat surface. Try it at home with some flat material (sorry early in the morning all I can think of is some cheese) carve the same depth scratch in the cheese (couple of cheap sandwich slices & fork/toothpick? - no sense getting a 30lb wheel of cheese). Try some angles, and see the effect - the cheese won't have the same sandy texture, but you can see the shadow/reflectively interplay w/o having to schlep gear further than your kitchen.

It is way to early in the morning and my coffee hasn't kicked in so take this advice with a chuckle and several hunks of salt.

Quote:

Originally Posted by krstahl

Thanks, I have considered that and it might work. I did not have a flashlight with me that day. The only drawback is that the sandstone faces are not flat and a lot of surface distortion such that the side light might not highlight all the scratches. I don't own any filters, yet. Is there a filter set that might work?
11-10-2012, 04:40 PM
krstahl

It will be a difficult shot to get side lighting because of the cramped spaces under the large boulders. However, that sounds like the commonly suggested method. I have a 750 lumen flood headlamp, as well as my flash unit, to work with. Next time I am out there I'll take both and give them a try. There is not even room for a tripod and I have to take one of the shots lying on my side. I'll probably need an assistant to hold the light(s) for me. Thanks to both Mark Elberson and Busted Knuckles for their response. I like the idea of trying to replicate the shot at home before going out to the field. I actually have slabs of sand stone in my yard that I can scratch on. BK, are you either a pipe fitter or a mechanic? - seems like it with your ID and sign-off.