Macro Photography for Beginners: Flash.

When the camera gets very close to the subject that also means the flash will be very close, this brings up a whole new set of problems. A flash mounted on the camera, either inbuilt or slid into the hotshoe, is not usually suitable. When very close the lens will shadow the subject therefore the flash has to be off the camera, held to the side and/or above the camera.
Ring flashes are often pushed as the best way to do macro, but all they provide is convenience and very flat, uninteresting lighting plus weird highlights if there are water drops present. Also, because the flash is right on the lens front, the light falloff is very noticeable towards the background - foreground very bright, subject OK, background very dark. A very unnatural illumination. It is best to persevere with the single or twin flash setup, it is more flexible and the results look better, and it`s usually cheaper than a ring flash. Ring flashes were really designed to give flat lighting for medical work.

The calculations involved in getting a manual flash to give the correct illumination can be a little daunting so the only sensible way to attack macro photography with flash is to employ a dedicated flash that can be extended with the appropriate cord and give proper TTL flash operation. For the beginners, this means that the circuitry in the camera will measure the light received in the camera via the lens during the exposure and send a signal to turn the flash off when enough light has been received. This way means that no calculations have to be done by you and the success rate improves dramatically.

With manual flashes (full output at each firing) there needs to be many wasted test photographs getting it right, and that will only be right for that exact same setup each time. Or you can buy an expensive flash meter to see what output the flash gives and set the appropriate aperture, but this also has complications because when you focus closer in the macro area the aperture of the lens is effectively made smaller thus not agreeing with the markings on the lens. Some more modern cameras will show you the true aperture on their LCD readout, but if the camera is that advanced you should be using the TTL flash operation anyway so you don`t need to know the true aperture.

One feature of using the flash very close to the subject is that closer than maybe 600mm (2`) with some close-up and aperture combinations the flash may not be able to turn off fast enough and will cause overexposure. This is usually fixed by always using very small apertures when using flash very close and/or by maybe backing off the flash a bit further and/or adding some diffusing material (tracing paper or milk bottle plastic) to lessen the flash intensity.

Another thing with flash is that the quality of the light will now be bright where it`s needed but have very dark shadows thereby creating an artificial look to the macro scene. Reflectors made of white cardboard or aluminium kitchen foil can be placed to reflect light back into the shadow areas. This may be easy for table top ventures but gets harder when chasing active insects. The normal solution to this is to add a second flash wired up to the first to achieve full TTL operation for both and position the second flash so that it gives slightly less illumination and now the shadow area from the primary flash is not too dense or not too light.

For convenience these two flashes should be mounted on a custom made bracket fixed to the camera so you can move about and use only the normal number of hands to control everything. I didn`t say this was going to be easy!

Upside. Well illuminated shots if done properly. Can approach a "natural" look.
Downside. Costly if done properly. Some effort required to make custom brackets to hold everything.