Tuesday, 17 August 2010

Macro photos with the Leica Lumix 45mm f/2.8

The Leica Lumix 45mm f/2.8 1:1 macro may look like an ordinary macro lens on paper. However, while most macro lenses are specified as 1:1, they are related to the 35mm full frame format. So, the 1:1 designation means that they can be used to photograph an object which is the same size as a classic film negative, or 36mm by 24mm.

For the Panasonic Leica 45mm lens, on the other hand, the 1:1 designation means that it can be used to photograph items that are the same size as the sensor, which is about one quarter of the area as a full frame film negative. So you can photograph very small items, probably much smaller than you can see with your own eyes.



For example, I photographed some item on the tiled floor, and when accidentally zooming in on the tiles in the image, I noticed that they had an offset printing pattern. Somewhat naively, I had thought that they were made from natural materials.

Let's verify that the lens is indeed capable of true 1:1 reproduction. I chose the minimum focus distance, and placed a measure band at a distance where it was in focus. This is the resulting image:



We can see that the subject is about 17mm wide, which corresponds to the width of the Four Thirds sensor. So the closest focus does indeed give a 1:1 reproduction, also denoted as 1x.

Let's use this reproduction rate to photograph a common, daily object. I chose the Iphone 3GS. Using a tripod to get a shake free exposure:



And here is the resulting image:



Looking at a 100% crop reveals details that are, perhaps not surprising, but at least interesting:



We see how the LCD display consists of red, green and blue segments. To get white colours, all three are used. Yellow is achieved by combining red and green, and so on.

This principle is used by most imaging and display devices. Image sensor generally use a Bayer pattern, though, where the pixel sites are arranged in a square pattern. One two by two segment consists of two green pixels, and one red and one blue. This mimics the human eye, which is also more sensitive to green colors than to others. See the illustration below of the Bayer pattern:



For comparison, here is also a 100% crop of a 1:1 macro image of my computer monitor. As you can see, it uses the same principle as the Iphone. However, the individual pixels are larger on the monitor:

Thursday, 5 August 2010

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.

It takes two standard AA batteries, which is good, since it makes the flash less bulky. On the other hand, the recycle time is not the best, due to a small power reserve.

The time to recharge the flash supply fully is around 16 seconds with my batteries. This means that if you use the full flash capacity, you can only take one picture every 16 seconds. Usually, you will not use the full flash capacity every time, though. As long as you do not drain the flash power capacity, you can take flash images in rapid succession with this unit.

Zoom

When used on a compatible camera, e.g., a Four Thirds or Micro Four Thirds system camera, the head will autozoom when pointing straight ahead. This means that the flash will select one out of six discreet zoom steps, 12mm, 14mm, 17mm, 25mm, 35mm, 42mm, whichever one is the most suiting for the lens setting. It will select the largest zoom setting which is smaller than or equal to the lens focal length used.

Zooming can be also done manually, e.g., when using a non compatible camera, but also on a Micro Four Thirds camera. The flash head does not change physical form when zoomed, i.e., the zooming is done internally.

If you have a lens which is wider than 12mm, you can flip over a wide angle diffuser. This gives you 8mm flash light coverage.

Tilt and swivel


The head can be tilted a little bit downwards, suitable for closeup focus distances. Tilting downwards gives a warning symbol on the display. It can also be tilted 45°, 60°, 75° and 90° upwards, as you would expect.

The head can be swiveled 30°, 60°, 90°, 120°, 150° and 180° to the left, and 30°, 60° and 90° to the right. Tilt and swivel can be combined.

Tilting upwards or swiveling automatically zooms to 25mm when used on a compatible camera, regardless of the zoom setting on the lens. However, the zoom can still be operated manually during tilt and swivel, if you want to zoom to a different setting than 25mm.


TTL exposure mode

All modern system cameras are expected to offer TTL flash control these days. On film based cameras, this meant that the camera measured how much light bounced off the film, and gave instructions to the flash to shut down when the exposure was correct. This was done using a sensor in front of the film plane.

In modern cameras there is no film, but rather an image sensor. Micro Four Thirds cameras solve this is a slightly different way. Before the actual exposure, a small pre-flash is done. The pre-flash exposure is read by the image sensor, and used to decide how much flash to apply in the actual exposure.

There is a clear advantage with this solution: The camera can study the pre-flash exposure thoroughly before deciding upon the main exposure. In face detection mode, for example, it can take extra care that the faces are correctly exposed. Generally, it is my experience that TTL exposure mode gives very satisfying results.

On the other hand, the method also has a drawback. There is a pre-flash, which is a bit annoying for anyone being photographed. Also, the pre-flash means that the main exposure is slightly delayed. Not by much, but it could be enough for you to miss a crucial timing.

Auto exposure mode

If you have a non-compatible camera, the in-flash auto mode can still be used. In this mode, the flash will measure how much light is returning from the subject, and terminate the flash when the exposure is sufficient. For the flash to do this, you need to feed it information about the lens aperture, and camera ISO setting.

You can also use the auto mode on a compatible camera, in which case it will read the aperture and ISO information directly from the camera. However, TTL is usually preferable when using a compatible camera, since it usually gives more correct exposure. You may choose to use auto mode still, for example to avoid the small TTL pre-flash.

High speed sync mode

On a compatible camera, you can select the FP TTL mode on the flash. This enables you to select shutter speeds faster than 1/160 second on the camera, while using the flash.

When having other flash exposure modes activated, you cannot select any shutter speed faster than 1/160 second on the camera. (The 1/160 second flash sync speed applies to the camera models Panasonic Lumix G1, G2, GH1, GF1, and the Olympus E-PL1. The Olympus E-P2 has a flash sync speed of 1/180 second.)

In FP TTL mode, the flash gun fires a rapid series of flashes during the exposure. For this reason the maximum capacity (guide number) is lower during FP mode than during normal mode.

Conclusion

The Panasonic Lumix DMW-FL360 flash unit is pretty compact, easy and fun to use. It will give you a lot better flash images, compared with the built in flash on the camera. If you can bounce the flash light off a white ceiling, the exposure generally gets even better.

It's too bad that the autofocus assist light does not operate on M4/3 cameras. 16 seconds recycle time sounds pretty bad, however, keep in mind that you don't usually drain the capacity completely with one exposure. So mostly, you can take pictures in rapid succession using the flash unit.

Updated version



In late 2012, Panasonic released an updated version of the flash, the Panasonic Lumix FL360L. It replaces the AF assist light with a more useful continuous LED light for video recording. It also adds wireless flash control, usable with the Panasonic GH3 camera.