Dual focus

In macro photography, the depth of field is commonly a constraining factor. At high magnification, even using f/16 might not give enough depth of field, if the object is not narrow. And closing down the aperture beyond around f/11 is not adviceable due to diffraction.

One way to get around this, is to take more than one photo, and change the focus distance between them. The photos can then be merged in photo editing software, to yield one single photo where more than normal is in focus. This technique is some times referred to as focus stacking.

When having a lot of photos to merge, it is best to use some software to do the merging automatically, since it involves a lot of tedious, manual work. However, when only merging two photos, it can be done quickly in any photo editing software that feature layers, e.g., The Gimp.

Here is an example. I took this picture of two LEGO minifigures. The figures were placed in a simple macro soft box to get even lightning. I used the Panasonic Lumix Leica 45mm f/2.8 1:1 macro lens for the image, and placed the autofocus area on the figure faces for focus. I used f/5.6, which is far from enough from getting both figures in focus at the same time.

Photo 1: Left figure in focus:



Photo 2: Right figure in focus:



Merging the two images is a matter of loading them both into the same image in two different layers, and then removing the out of focus areas. Note that some lenses will give a different field of view depending on the focus distance. Hence, you may need to rescale one (or more) of the photos when merging.

This merged image would have been impossible to take with only one exposure:

Cheap and simple macro soft box

When taking macro pictures, or pictures of fairly small objects in general, a common problem is to get the lightning right. More even lightning can be achieved by using a "soft box", essentially a contraption that spreads light from one (or a few) light sources over a larger area.

A very cheap and simple soft box is a transparent bucket, like this one:

Preferably, it should have as neutral density as possible. If it has some colour tint, the images will get the wrong white balance. It is of course possible to adjust the white balance later, especially if you're using RAW images, but it is better to have as correct colours as possible from the start.

When photographing the object, place it inside the bucket, with the light source on one side, or from the closed end, like this:

In this case, I used a Panasonic Lumix GH1, with an Olympus 50mm f/2 macro lens. This combination can only be focused manually, which is no problem for macro use.

The light source is simply the sun light coming from the window on the top side of the image. One could also have used a flash pointing towards the side of the bucket, however, an off camera TTL flash would have been preferable, which is probably not so common for people to have for this system.

Here is an example picture, taken with (left) and without (right) the softbox. As you can see, the softbox image has softer contrasts. Besides, the picture taken without the softbox has reflections from the window. The right image also has some shadows next too the feet, which you may need to edit out later.

I used ISO 100, f/5.6 for both images. The shutter speed was 1/3.2 second for the left image, and 1/5 second for the right image, since the softbox steals some light.

Here is another example image, showing a Pelikan M425 piston filler fountain pen. I used f/13 to achieve enough depth of field.