kipper wrote:....the black background was a total fluke. I'm not entirely sure how you get these sort of effects as I've seen them many a times before.
Can anybody else give us some insight on what causes it, and how to repeat the effect everytime when shooting a subject like this?
I like to have black backgrounds on my macro shots if I want just the subject and nothing else to show. It is generally just a matter of making sure your backgound is at least 5 or 6 stops below the illumination on your subject. This can be by having the background in heavy shadow, and sunlight on your subject as you did, but that can be hard to control sometimes.
Using a flash will give you more control, and as was posted earlier, using a small aperture does work, but more importantly is to make sure you have nothing close behind the subject. You can have a white wall back a few metres when using flash for close up macro, and the background will still be black, just make sure the wall or other objects are far enough back to be at least 5 or 6 stops underexposed.
One important thing to remember when using flash in these circumstances is that if the subject does not fill an reasonably large part of your frame, then you will need to use exposure compensation for auto flash (TTL with the D70) metering. Anything up to 4 or 5 stops for a very small subject. The camera is assuming a subject of 18% grey filling the metering area, so if you only have a small fraction of that area illuminated and the rest of the scene is black, then the camera will tell the flash to pump out more light to give the "correct" amount of light refected back to the meter. You then end up with the subject blown right out, overexposed by several stops. Using spot metering will sometimes help a bit, but the largest part of the subject is not always in the centre of the frame, epsecially with some insects! Check out some of the pics I posted in the "why I bought the 105" thread.
Of course manual flash and trial and error works very well too, having instant access to the histogram takes the guesswork out of it
Gordon