Treading The Wire: Learning Macro DOF Control

BUZZZZ... now with more Depth Of Field!

Over the last few weeks I’ve done a lot of reading on photography, macro photography in particular and I made a discovery. I had basically been Doing It Wrong. Well not so much as wrong as I had fundamentally misunderstood the effect of aperture size on Depth Of Field and why the largest possible aperture wasn’t always the best idea with macro photography.

Macro lens by their very nature have an extremely shallow depth of field which is all sorts of awesome for doing incredibly sharp shots of a very, very specific area. This is fine when everything you want in focus falls into that very narrow field but gets substantially less fine when you want to take photos of bugs where you want slightly more than just the head in focus.

This was where I had been doing it wrong. I have always been shooting at the largest possible aperture (lowest possible f-stop number) my lens would allow and I have managed to take some pretty awesome shots. I’ve also taken a lot of shots where I was disappointed that less of the subject was in focus than I was expecting.

Enter the smaller aperture size (larger f-stop number) as a method of increasing the Depth Of Field. I won’t go into the full details of the aperture/DOF relationship here but the Wikipedia page does have a good explanation of how it all fits together. There is of course a trade-off for doing this. A smaller aperture means less light getting through to the sensor which results in a slower shutter speed. Not good news for me.


Walking The Wire

My main interest is nature macro photography, particularly critters. This introduces multiple factors out of my control that do not play ball well with a slower shutter speed:

  • Critters are unpredictable and will move when they want to.
  • Wind – the macro photographers nemesis. The slightest of slight breezes is enough to move a subject out of focus, even more so with a slower shutter speed.
  • Changeable light conditions – sun could go behind a cloud, bird casts a sudden shadow etc. Less light usually leads to an even slower shutter speed.

Sure I could do this indoors with a controlled setting but I love the thrill of the hunt. I love wandering around gardens and finding unexpected things. I love that I have no control over the environment. I throughly enjoy the challenge of having to dynamically adjust for various conditions as well as the certain knowledge that there is no telling what I might find today. Could be the same old bugs I’ve seen a thousand times over, could be an entirely new spider I have never seen before. This means I have to face the challenge head on.

A little pink?

First Steps

So with the new knowledge it was time to walk the wire. I headed down to the botanic gardens, set the camera into aperture priority mode and went critter hunting. Most of the reading I had been doing indicated the f/8 was a good “sweet spot” with which to start experimenting. Unfortunately for me the wind was up and it was an extremely frustrating time. I lost a lot of really nice potential shots to the combination of slower shutter speed and wind movement and nearly threw it in a few times.

But I pushed on and after a few hours I ended up with several hundred shots, only four of which I was happy with (all of them are in this post). It was enough however to show me the potential of using the smaller aperture and gaining the larger depth of field.

Please don't attack my face...

Edging Over The Abyss

As uncomfortable as those first steps were I’m glad to have done them and I have a much better understanding of the aperture/DOF relationship. As a “learn by doing” sort of person I’ll be practicing this for a while before introducing other important factors into the mix. For example the next step will likely be to get myself a macro flash. This should help in providing a better, more even lighting for a macro shot and reduce the shutter time Only time and practice will tell how well I go on the wire.