The Backyard Arthropod Project

Taking pictures of insects, particularly tiny insects, is much different from photographing, say, guests at a wedding reception. The thing is, to get pictures of tiny objects you really need to be pretty darned close, and not all cameras can do this.

So, the big question we have first is, what sort of camera can do this without spending a fortune? Sure, a nice digital SLR with interchangeable lenses would be great for taking fantastic pictures, if you’ve got one or two thousand dollars to drop on it, but is it really necessary? As it turns out, it is possible to take very nice insect pictures with something much cheaper.

I am using a Canon Powershot A95 camera, which is actually kind of obsolete. Most of the things I say will apply to other Powershot A-series cameras, only more so. For example, the Canon Powershot A640 can focus on insects that are standing on the lens!, while my A95 can’t focus much closer than 5 cm. I’ve also seen excellent results from someone who uses a Panasonic Z30 camera, with a Raynox DCR-250 macro lens.

Unmodified Camera
For largeish insects, such as mantises, grasshoppers, butterflies, etc., the built-in macro mode on the Canon Powershot A-series is generally pretty good. Read your camera manual to find out if you have a macro mode and how to activate it (on the Canon cameras, it is indicated by the button with the little stylized flower on it).

Get into macro mode before you do anything else!

After this, the key things to watch out for are:

1. Light levels. You want bright, yet diffused light (direct sunlight makes harsh shadows that obscure detail, while dim light means long shutter times and high likelihood of blurring when your subject moves). And, if you are sneaking up on an insect, try to keep your shadow from falling on them, because this generally alarms them enough that they fly away. As for using the flash in low light, you can do that if you like, but it usually isn’t satisfactory because the flash is overpowered for very close objects, and it tends to wash out (and if you are using any accessories like I will talk about later, they will block the flash anyway).   Sometimes, you can get away with using the flash if, instead of getting right up close to the subject,  you back off a bit and use the camera’s optical zoom to enlarge the image.  So, for example, if you have a 4X optical zoom, the bug will look just about as big from a distance of 20 cm as the un-zoomed image looks from 5 cm.  Sometimes, this is far enough back that the flash is OK. Still, if you need supplemental light, you might be better off with a strong spotlight, although I haven’t managed to make this work very well outdoors yet.

2. Focus. Autofocus performs poorly on close-up macro shots, mainly because it’s hard to make sure the camera is focusing on the insect and not on the background. This is particularly bad if you are trying to photograph an insect on a window, because the autofocus will keep trying to focus on what you see through the window. It helps a lot to use the manual focus mode instead of autofocus, for this reason. It is often hard to tell from the camera’s LCD screen whether you are in focus, though, because your depth of field at close focus is only a few millimeters, so very tiny motions will take your subject out of focus. It helps to get what you think is in focus, then take a series of pictures while moving the camera slightly towards and away from the subject (moving the camera is faster than trying to adjust the manual focus, which on the A95 is a slow process)

3. Stability. Hand-held macro photographs are a lot easier if you have some sort of support. Either bracing against a solid object, or mounting the camera on a monopod or one of those baby tripods, makes it a lot easier to hold your focus, and to tolerate slower shutter speeds when the light levels are low (which is most of the time).

Improvising a Macro Lens
This is all fine and dandy when you are trying to photograph insects “in situ”, but what about when you have some tiny little mite or fly that just isn’t within your camera’s capabilities? What then?

First off, there is the question of magnification. Basically, if you put a magnifying glass in front of your camera, you can obviously enlarge the image quite a bit. As it turns out, most of the Canon A-series cameras will take an adaptor (the A95 takes the LA-DC52D adaptor) that lets you put on additional lenses of the type that screw into the filter threads of the lenses of SLR cameras.

The cheapest kind of additional lens is the “macro lens filter”, which are generally single-element magnifying glasses that can screw into your adaptor. These come in a lot of different sizes, so it is important that they are the right size to fit in your adaptor (the LA-DC52D is a 52 mm thread). These give some magnification, but there might be a better option if you have access to an old SLR lens.

It turns out that if you take the lens from an SLR camera and look through it backwards, it becomes a fairly high-power magnifying lens. You can do this using a “Macro Coupler”, which is an adaptor ring with male threads on both sides. The lens from my old Olympus OM-2 SLR had a 49 mm filter thread, so I needed a 49mm-52mm macro coupler to attach it to the 52 mm LA-DC52D adaptor.

Supporting and Focusing a Camera/Improvised Macro Lens
An arrangement like this has a very limited range of focal distances, basically it needs to be within about 1 inch of the subject and held very rigidly. The baby tripods I tried using were too tall, so a better solution was an old microscope frame, like this one:

Here we see about 10 pounds of the finest brass machining the 19th century had to offer - the frame from an old dissecting microscope, with the original optics probably having been removed and lost sometime before I was born. It then lurked around in dusty junk-filled cabinets in the lab at work for decades, waiting for its new moment in the sun. It was relatively easy to modify it so that a 1/4-20 thread stainless-steel cap screw could go through it, and thread into the tripod-mount hole on the camera. This sort of modification should be doable with pretty much any microscope frame, even a cheap kids microscope. The beauty of this setup is that the fine adjustments let you put the camera on manual focus, get it coarsely focused on the subject, and then scan the camera slightly up and down for fine focus, just like a microscope.

Lighting
The next thing is the light. I started with a fluorescent lamp that is supposed to be “daylight spectrum”, and can be put very close to the subject. It works better than nothing, but the colors seem a bit washed out and it could be brighter. I then put the whole camera/light assembly into a cardboard box lined with aluminum foil. This captures a lot of the light from the lamp, reflecting it back so it has another chance to illuminate the subject.

(ignore the black furry thing sticking out from behind the box, that’s just a cat). It looks kind of dim in this picture because the sunlight from the window is washing it out, but it is actually pretty bright. This is helping a lot, it fills in most of the shadows and gives more uniform illumination. It also allows me to point in things like desk lamps, to add additional light from a different direction. In the picture, the desk lamp has an incandescent bulb, but this dumped in way too much heat (which the light box retains very effectively). I have since replaced it with a small compact-fluorescent bulb, which runs much cooler. I’ve thought about orienting the box to catch sunlight, but this would put me in the awkward position of depending on the sun to be the same today as it was yesterday, and would probably also turn the little box into a solar oven. This would probably not be a good plan.

Post-Processing
Once you have the pictures, it is nice to be able to clean them up a bit (crop, rotate, resize, maybe adjust the brightness range and contrast, things like that). I guess that, say, Photoshop could do these things, but that would entail spending money. Instead, I use ImageJ, a sofware package that was developed by the National Institutes of Health specifically for the purpose of manipulating and analyzing microscopic images. It is a free, open-source package, and it works pretty well.

Something that I have just gotten to work is a processing technique called “Extended Depth of Field”. The idea is that you take a series of pictures focusing on different levels of your specimen, and then use “wavelet processing” to sort out the bits of each picture that are in focus and use them to assemble a finished picture where everything is in focus simultaneously.

So, I started with a picture focused on the surface the subject was lying on (an Ichneumon wasp, in this case):

then pictures focused on progressively higher levels:

finishing with a picture of the highest parts (the wing and one antenna):

I then used the ImageJ software to assemble these pictures into a “stack”, so they could be handled as a unit.

In order to go further, I needed three plugins for ImageJ: the stackreg and turboreg plugins to “register” the individual pictures in the stack to make sure they were all lined up properly, and the extended depth of field plugin to do the actual generation of the new image.

The stack registration plugins were the things that I needed to have in order to get this to work with my equipment: when I first tried this some months ago with just the Extended Depth of Field plugin, I got crummy results because there are tiny shifts in position between pictures,and I basically ended up with what I can best describe as a “sharply-focused blur”:

Using the stack-registering plugins was pretty simple [2]- I just ran “stackreg”, which went through the whole stack comparing pairs of images with “turboreg” and shifting them back and forth/up and down until everything lined up. Once the stack was registered, it was just a case of starting up the extended depth of field plugin again and letting it run. One point to keep in mind is that, the bigger the images are, the longer it takes and the more memory it sucks down. When I tried it on full-resolution pictures, it never actually finished in periods of up to an hour. So to keep the times reasonable I ended up doing this on images that were 800×600 pixels, which meant that it finished in about a minute.

And here is the result: it isn’t perfect, the upper edge of the wing is a little bit peculiar, and one antenna turned into a blur. The wing problem was probably a case of the sofware selecting the image where the background grid was in focus, and not where the transparent wing was in focus. The antenna issue might have been due to motion between pictures. It obviously could be a better picture, and I need more practice, but it does bring most of the wasp into sharp focus all at once, something that I wasn’t able to do with the original photographs.

Getting Them to Hold Still
Which brings us to the final problem - getting the insects to hold still long enough for a picture. It is extremely frustrating, because the live ones start walking just as you are ready to shoot, while dead ones look, well, dead. It helps a lot to put them in the refrigerator for an hour or two to put them into torpor before starting a photographing session — although this doesn’t always work around here, because our climate is cold enough that a lot of arthropods have adapted to be active at temperatures right down to freezing. It might be possible to anesthetize them with carbon dioxide (a trick that is used in “instrumental insemination” of queen honey bees), I’m thinking of rigging up some sort of CO2 generator with vinegar and baking soda to try this.