GH2, built-in flash for macro use

Lightning is critical for macro photography. To illustrate this, I will present a scene I tried to photograph. I used the Panasonic Leica Lumix DG Macro-Elmarit 45mm f/2.8 1:1 Macro lens. To make sure I used the maximum magnification, I selected manual focus (MF), and moved the focus ring until I reached the closest focus distance. Then I placed the camera so that the subject came in focus. This way, I was sure that I used 1:1 macro, which means that the subject is the same size as the sensor area, 17.3mm x 13.0mm.

As a test subject, I originally intended to use a bee. However, I found that chasing a bee around while it was visiting flowers, was much too difficult. Therefore, I found a bee that had been killed by a spider's web. With the bee being suspended, it was much easier to photograph in a controlled fashion.

First, let's consider what aperture to use. The PL45 lens has a maximum aperture of f/2.8, which has been criticized as being too small. Many would have preferred it to be f/2, to make the lens more useful for portraits. In this case, I want to have some depth of field, so I try to set it to f/5.6, a point at which many Micro Four Thirds lenses reach their optimum performance.

Here is the image at f/5.6, 1/60s, ISO 3200:

As you can see, the image is in fact not very good. One wing is in focus, the other is not. The rear part of the bee is in focus, but not the front. We can easily conclude that the depth of focus is too thin: Only parts of the insect is in focus.

To get a better depth of field, let's set the aperture to f/13. Some may worry that f/13 is too small, and will give some dullness due to diffraction. That is true, but as long as you don't make a big magnification of the print, that should not be a problem. For web use, f/13 is no problem at all, and you could even try to use f/16 if needed. I have studied the diffraction effects here.

I took ten images at f/13, 1/15s, ISO 3200, and this one is the most successful:

There are some problems here. First, you can see that the image is not framed very well. I was handholding the camera, which makes framing hard. Also, while the image has much better depth of focus than the previous, it now has some motion blur effects. The shutter speed, 1/15s, is much too slow to handhold the camera, even with Optical Image Stabilization (OIS). Finally, the high ISO at 3200 makes the image a bit noisy.

There is an easy way to solve all these problems: Just use the built-in flash. It turns out that the small built-in flash does cover the entire frame when using the PL45 lens at the closest focus range. The illustration below explains why.

In the illustration, a LEGO figure is placed at the minimum focus distance of the lens. At 1:1 magnification, the distance from the front lens element is 7cm. The built-in flash covers the focal length of 14mm, which corresponds to 75° diagonal field of view.

The resulting image is this:

As you can see, the entire image frame is illuminated by the built-in flash, even at maximum magnification.

A note about the lens hood: I don't like the supplied hood. It is much too wide, and does not do a good job at keeping out stray light. So I made my own hood, composed out of three elements: A 46mm stand off ring (glassless filter), a 46mm-37mm step down ring, and finally a 37mm-28mm step down ring. This gives the ultimate protection against stray light (in my opinion), and also good protection against objects touching the front lens element accidentally.

If you use the original hood, the light from the flash will be blocked by the hood, and you cannot use the built-in flash with macro images.

Back to our bee example. Here is the same image taken with the on-board flash, at f/13, 1/60s, ISO 160:

Using the flash allows for base ISO (160), and there is no problem with camera shake. The flash light is very quick, and freezes the image instantly. We clearly see that this image is much more sharp.

On the other hand, this method is not perfect for macro images: We see that the background has become very dark. This is because the flash light spreads out, and becomes less powerful for the background at a larger distance. Also, the flash light coming from a single light source does give a "flatness" to the image, which is not optimal. The nature of the image changes completely when using the flash.

Using the built-in flash for macro is a quick and easy way to get usable macro images.

Panasonic Lumix DMW-FL360 flash unit

The FL360 flash unit from Panasonic is a medium sized flash gun. It is functionally similar to the Olympus FL-36 flash unit.


As the name indicates, it has a guide number of 36, which plants it firmly in the "medium flash" category. With the exception of wireless control, it has all the functions you would expect from a modern flash: Auto zoom, TTL, auto exposure mode, FP mode, tilt and swivel head, autofocus assist light. Sadly, the AF assist light does not operate on Micro Four Thirds cameras, only on Four Thirds DSLR cameras.

Using older flash units

People who have previously used another camera system may have an old flash unit lying around. Chances are that you can still use them with your new Micro Four Thirds system.

Using a spare flash unit, rather than the built in on board flash, has many advantages. First of all, the dedicated flash unit usually has significantly more power, and can be used from a larger distance.

There is also the effect of having the flash further away from the lens, which means that you are less likely to get pictures with red eyes, and also makes the shadows somewhat nicer. Last, but not least, the external flash units can often be tilted, so that you can bounce the light off a white ceiling or wall. This will usually give much better lightning when taking pictures of people, as the light comes from a larger area, i.e., the ceiling or wall, and not from a single source.

Here are a couple of old flash units. Let's see how they can be used on the Panasonic Lumix GH1.

To the left is the Metz Mecablitz 36C-2, and to the right is the Nikon Speedlight SB-22s.

The Metz flash unit only has one connecting pin, and hence can only be triggered by the camera. No other communication is possible. The Nikon flash unit, on the other hand, has some more pins, and is capable of autofocus assist light and TTL. However, as this is a rather old flash, these functions can not be used on newer Nikon cameras, and certainly not on Micro Four Thirds cameras.

What can still be used, though, is the auto-function. The auto-function is a bit like TTL, except that the flash measures the light coming back from the subject, and cuts off the light when the exposure is sufficient. In TTL mode, the camera measures the amount of light coming back from the subject Through The Lens (TTL), and shuts off the flash at the correct exposure.

Since there is no communication between the flash and the camera, the flash does not know the ISO and aperture settings on the camera. So you need to give the flash directions manually. The picture shows the Metz flash rear panel, set in auto mode:
In this case, the ISO sensitivity is set to 100, the zoom is set to 85mm, which corresponds to 42mm on Micro Four Thirds. With this setting, the aperture can be set to f/8 (yellow), f/4 (green) or f/2 (red auto mode). Adjusting the ISO slider will give other aperture possibilities.

On the rear panel, you can also see that in this setting, with f/4, ISO 100 and 85mm zoom, the maximum range of the flash is approximately eight meters.

When using the flash in bounce mode, i.e., bouncing the light off a white surface, you generally want to have a wide angle flash zoom, and the effective range becomes smaller.

As for the Nikon flash, the rear panel settings are quite similar:
Again I have selected ISO 100, and with the selected auto mode, the usable aperture is f/2.8. The mode selector can be adjusted, to yield f/4, f/5.6 and f/8 as well, albeit with lower maximum distance as the aperture gets smaller.

Here is the Nikon flash in use, on Panasonic Lumix GH1:
The settings are: ISO 100, f/5.6, 1/160 second, manual exposure mode (M). The lens is the Panasonic Lumix G 45-200mm f/4-5.6 set at 45mm zoom.

I used this combination to take this picture, bouncing the flash off the white ceiling:
This picture showing the Pentax K10D camera with the Sigma 30mm f/1.4 lens, is not very interesting, but the exposure is good. Also, notice that the shadows are soft, due to bouncing the flash light off the white ceiling.

If you use this flash setup, and notice that the images consistently get too dark, then select a slightly larger aperture on the camera, as compared with what the flash rear panel says. And vice versa if the images consistently get too light.

Flash units can be used like this for virtually any camera, of course, as long as you can manually control the ISO, aperture and shutter. You will usually want to set the shutter fairly fast, e.g., 1/60 second, when using an external flash. This is to get a good balance of ambient and flash light in the picture. Normally, you will also need to set the white balance to "flash", to avoid the wrong colour balance.

Warning

Some older flash guns use a high voltage trigger, and could potentially damage the circuitry of the camera. Here is a list to check before using your old flash.