Last week I was asked about what objective I use when photographing live insects in the field. I do not always use the same objective, so I will describe the two I most frequently use. Neither do I use what would be the most suitable or state-of-the-art optics.
The camera (Olympus E-M1 mk I)
The camera I use is a mirrorless micro four-thirds camera, which has a smaller sensor than “full frame” cameras. The small sensor has two advantages for this type of photography: an objective of a given focal lens is equivalent to twice the focal length in a full-frame camera. This camera has also effective image stabilisation.
I am rather lazy so I almost never take a tripod to the field and hand hold the camera. Consequently, for macro photography I always enable image stabilisation and very frequently continuous focus. For handheld macro photography continuous focus helps even for static objects as it tracks the inevitable movements of the camera. This is because in many cases depth of (focus) field is only a few millimetres.
Insects can move fast on their own and/or the plants they are standing on may move in the wind. When magnification is high, a shift as small as a millimetre may ruin an image. The number of “hits” tends to be low even when working carefully. One needs to take hundreds of photographs and later select the few worth keeping.
Macro objective (50 mm prime)
The macro objective I own is a Zuiko Digital 50 mm f/2.0 macro for Four Thirds cameras, of Pro grade. Optically is very good, but its age and using it adapted means that focus is very slow. The focal length is equivalent to 100 mm. It can reach 1:2 magnification without use of a macro extension tube and 1:1 magnification with a 25 mm long extension tube, which I also own.
Being a prime (fixed focal length) and in its time being considered the sharpest lens available from any brand, it can produce incredibly good images… as long as the insects are tame and patient. With this focal length if the insects are rather small one has to get very near and and frequently wait for a couple of second until the camera locks focus.
Because of the rather low light level, it would have been difficult to take this image with an objective of longer focal length.
The 50 mm f/2 macro works well together with the 2 x tele converter.
The current M.Zuiko 60 mm f/2.8 micro-four-thirds macro objective with faster focusing and very good resolution would be better for this task. It also weights a lot less.
The advantage of working at close range is that one can hold a flash (or LED light) in one hand and the camera in the other. In the times of low ISO films this was one of the best ways of photographing insects, in which case one would focus by moving the camera very slowly and triggering the shutter some fraction of a second before perfect focus. If the light level is low (cloudy or sun low in the sky) the handheld use of a tele objective as described below becomes very difficult if not impossible.
Tele objective (50-200 mm zoom)
The tele zoom I own is a Zuiko Digital 50-200 mm f/2.8-3.5 SWD for Four Thirds cameras, of Pro grade. Not up to current state of the start in focusing speed but more than fast enough for anything that is not flying. This is the objective I most frequently use for insect photography. To be able to reach high enough magnification, I use in combination with either a tele-converter or the 25 mm macro extension tube.
Image quality with the extension tube is excellent, although not on par with the 50 mm macro described above. With the Olympus 1.4 x tele converter image quality is what I consider good enough, while with the Olympus 2.0 x tele converter only marginally. This last combination is also difficult to use without a tripod. The tele-converter with less magnification provides a maximum focal length of 280 mm, which is equivalent to 560 mm in a full-frame camera. The tele converter with more magnification provides a maximum focal length of 400 mm, which is equivalent to 800 mm in a full-frame camera. The advantage of using a tele converter is that the minimum focusing distance is retained in spite of the increased focal length.
So, what I currently use most frequently for insects is the 50-200 mm tele zoom with the 1.4 x tele converter. It does not provide the best possible image quality but it allows me to obtain more good images as I disturb the insects much less, which allows more time for framing, focusing and for multiple takes of a given subject. This weights about 1.5 kg, has a minimum focusing distance of 1.10 m giving a field of view of xx times xx mm.
In full summer sunlight, the tele zoom plus a tele converter works well.
The tele zoom with an extension tube can be used to advantage, but the working distance is decreased.
If you have a camera with a bigger sensor, then if you want to be able to dispense of a tripod, you will need to use a shorter tele objective than the equivalent focal length of what I am using.
All illustrations, text and measurements are of my own authorship, and copyrighted.
(c) 2017 Pedro J. Aphalo