Aargh ... plz help ... depth of field issue

[krusty]

I'm hoping for a little advice as I am new to macro photography. Although I absolutely love taking macro shots with my new lens, I am having trouble with the extremely shallow depth of field regardless of my aperature setting. I've read several articles and viewed many examples of some remarkable shots taken with the same lens I use, however I've also noticed that these examples don't seem to suffer the same depth of field issues I'm faced with and I need some insight into how to correct this. As an example, on this site there are some macro shots of mushrooms where the subjects (mushroom sprouts) are entirely in focus. When I try the same thing, I am only able to get one section of one mushroom head into focus and the remaining subjects fall into a blur. What am I doing wrong? I'm using a Canon 40D w/ 100mm f/2.8 canon macro lens.

Any input would be appreciated. Thanks!

[wulf]

The first thing to do is get a better idea of what DoF options you have available. You could look this up online but it is probably better to do an experiment.

Set up your camera on a tripod and use a subject that is easy to measure - a ruler is ideal. Pick a point to focus on and then take a series of pictures working through your aperture range, adjusting shutter speed as required to get a decent exposure.

The end result will be a sequence of pictures that will give you a very clear idea of the capabilities of your lens - you should see a difference between f/2.8 and stopped down to f/11 or f/16. Also, look to see if there is a point of diminishing returns. Stopping down to a tiny pinhole should give you quite a large depth of field but you may hit other optical side-effects (as well as needing a very slow shutter speed).

Let us know how you get on.

Wulf

[krusty]

Thanks for the input. I have done some tests as you suggested, however I am noticing very little difference in the DOF as I stop down. I will try again with a ruler as you suggest.

[oldwolf]

you should see a noticeable difference between f/2.8 and f/11. my first mistake when doing macro was assuming i had to use f/2.8 or f/4.0. i never had more than a little piece of the picture in focus hehe. my wife does a lot of macro photography and corrected me; telling me she uses about f/8ish or even higher.

[wulf]

The ruler makes it easier because of the markings. Because of the angles involved, you would have to use some trigonometry to work out the exact depth of field but it will give a good enough idea.

Remember that you will also get better depth of field if the subject is a bit further away. Moving the camera an inch back should still yield an amazing close-up view but might make things more manageable than having the focal point as close as possible. That gives another set of parameters to test.

Wulf

[krusty]

Ahh ... there's an idea I hadn't tried. Thanks to you both for your input.