Having read many sites and posts about proper focusing techniques for macro photography it is apparent this issue is not settled at all. Some photographers insist that manual focus is The-Road-To-Glory™, whilst others proclaim divine guidance that auto-focus is The-True-Path™.
This post introduces another method – It is called The-Threefold-Way™
First some technical bits. This methods works with cameras that have focus locking ability. This permits camera to focus, then stays at that focus distance even when cameras moves relative to subject. This is done by half pressing shutter button and keeping it pressed. On Canon DSLRs this mode is called One Shot focus. Second item is having auto-focus lens (duh!) that has full time manual override. Full time manual override allows user to manually focus camera even though AF (auto-Focus) is turned on. Many lenses have this including both 100mm f2.8 macro lenses from Canon and Nikon’s 105mm f2.8 lenses. Other lens manufacturers may or may not have this feature.
To recap – One shot focus mode on camera and AF lens with manual override.
First place focusing mode to One Shot or equivalent on your camera body. Make sure auto-focus is engaged on lens. Also make sure your diopter setting is correct. Refer to your manual on how to achieve this. Next three sections details each part of The-Threefold-Way
This one is obvious. Simply auto-focus on or near subject.
Below is shot where auto-focus will not easily get subject because subject is surrounded by twigs.
With photograph above one can see that auto-focus will probably fail. This brings up second part of method.
With shutter still half pressed, locking focus on whatever AF found, one now uses manual focus to get Insect subject in better focus. Though manual focus is actually quite good it is sometimes hard to get a specific part of Insect, or Insect face correct. This is where third part of The-Threefold-Way comes in.
We have now got approximate auto-focus ameliorated with fairly good manual focus. Rocking is third step to getting hard to achieve perfection 🙂
Rocking simply means rocking back and forth very small amounts to get specific part of face (or whatever) into perfect focus. Rocking can be done crouched, standing, or even with monopod (Broomopod!) or tripod. This technique also gives approximate depth of field distance allowing photographer to select where depth of field will fall over subject. Even wide open (usually at f2.8) lenses will give some indication of where depth of field distance is relative to subject. One can also depress Depth of Field Preview button for more accurate readings. Again refer to manual on how to do this with your camera body. Rocking replaces macro rail when one is not using tripod.
Above is Yours Truly again rocking into Jumping Spider. Photograph by Diane Bruce.
This three step method will permit focusing on very difficult or difficultly situated subjects.
Have fun 🙂