Photographing coral skeletons?

[JHemdal]

Hi all,


I'm working on a project to help people ID their corals using voucher specimens. I need to make the process suitable for a variety of camera systems, so I'm looking for a method to take macro images of a cleaned coral frag that is independant (mostly) of camera type.

I have the specimen prep method worked out, but as I expected, the whites in the coral skeleton gets blown out. I have to use a light source because of the need to create shadows to increase the contrast of the skeletal features (like shooting the moon - a full moon does not have the detail of a quarter moon because the shadows in the latter give the peaks and valleys more prominance).
I've tried a huge variety of light sources, including LEDs, backlighting, and using a pen light to "paint" the coral during a long exposure. I've also tried a number of different dyes in order to try and enhance the contrast. In the end, I keep coming back to shooting at around f16 with the coral at 45 degrees to the camera and the flash on a sync cord off to the side that the corallites open up to. Here is a sample:

Does anyone have any advice as to how to better preserve the detail in these types of images and not have the whites blown out?



Thanks,

Jay Hemdal

 

[Reef Bass]

My standard technique for keeping the bright tips of acros from blowing out while shooting live coral is simply to reduce exposure, say -2/3 to -1. You may need to add a touch of brightness during post processing to complensate. I end up with detail preserved in areas that would otherwise be blown.

Good project by the way!

 

[JHemdal]

Reef Bass,

Thanks - I should have mentioned that this shot was done with a -2 exposure compensation. That does help, but I'm looking for more detail still. I'm still learning with my D300, it seems that if I dial the exp. comp. back, the flash just tries to make up the difference. I can set a compensation on the flash also, so maybe I'll try that at the same time.

Because of the nature of what I'm trying to get (the detail of the skeleton) I don't care a bit about the color or exposure, as long as I can end up seeing the structure of the coral. I've tried a number of post-production things, converting to black and white, using flase colors, etc. but none of that seems to help either.


Jay

 

[Reef Bass]

Yeah, now that you mention that, your exposure compensation is listed in the EXIF info which I didn't check. My b.

Uniformity of lighting (lack of bright / hot spots) on light colored objects can be tough to achieve, as you are aware! Normally one would use additional light sources from complementary positions to help to even out the light, but you are explicitly looking for detail which is enhanced by allowing shadows to exist.

Interesting scenario. I got nothing else. Hopefully somebody has something?

 

[Jacob D]

Are you using any modifiers or just bare strobe?

 

[TitusvileSurfer]

I suggested a member turn a 10 gallon tank into a light box earlier. I think you should just make a regular dry light box here.

http://photography-on-the.net/forum/showthread.php?t=281524

 

[JHemdal]

mothra,
I have an SB-600 and I tried using a diffuser on it, but again, I'm thinking I need the harsh shadows to bring out the contrast in the septa. I have a ring flash also - it works great on other macro images, but since it doesn't create any shadow, you can't see much detail in the coral when I use it.

TitusvilleSurfer,
Thanks - I wonder if my ring flash would give about the same results as a light box? Maybe I'm over-thinking this "needing shadows to bring out the contrast" thing....

Jay

 

[TitusvileSurfer]

No a light box is completely different than a single direct flash.