Saturday, 27 February 2010

Nikon to m4/3 adapter

One of the benefits of the Micro Four Thirds format is the short register distance. Since virtually all other formats have a longer register distance, it is possible to make adapters for other lenses to be used on Micro Four Thirds.

Here is one of many adapters available:

It attaches to the camera just as a Micro Four Thirds lens. Here is a video showing how to attach the adapter to the Panasonic Lumix GH1.

It reads "NIK-M4/3", and can be used to mount Nikon F mount lenses to a Micro Four Thirds camera. These kind of adapters are simple, meaning that they only provide a means to mount the lens, and no control over the aperture or focus is possible from the camera. On the positive side, they are rather inexpensive, and can be purchased for around US$30-40.





When using a third party adapter like this, the camera has no electronic confirmation that a lens is actually connected. For the camera to still operate, you need to set the menu item "shoot without lens". This is found under the "Custom" menu, indicated by a "C" with a wrench icon. Here is the menu item from the GH2 camera:


In the picture below, the adapter is used to mount a Nikkor 200mm f/4 AIS tele lens to the Panasonic Lumix GH1. When using this legacy lens on a Four Thirds camera, the field of view becomes equivalent to a 400mm lens. With a long tele like this, using a tripod is a necessity. While you can choose fast shutter speeds and capture an image without blurring due to camera shake, framing the subject is very difficult when handholding this combination. Recording video without a tripod is virtually impossible with such a long lens.



This lens has an aperture ring. Since the camera cannot control the aperture, it needs to be set manually. The presence of an aperture ring makes this operation easier. Some more expensive adapters have a means for controlling the aperture also for lenses without the aperture ring, e.g., the Nikon G mount lenses.

Many newer lenses do not have aperture rings, and require an adapters with a lever to stop the lens down. This goes for both Nikon and Pentax lenses.

Focus confirmation

There is some talk on the internet about adapters that provide focus confirmation for legacy lenses. To my knowledge, such a thing is not possible with Micro Four Thirds cameras. The cameras cannot confirm the focus when using non-compatible lenses. In fact, with the current cameras, the only way for the camera to know that the image is in focus, is to use a Micro Four Thirds lens, or one of the CDAF compatible Four Thirds lenses.

To be able to confirm the focus, the camera must jog the focus back and forth to find the optimum contrast. This is not possible with manual focus lenses, of course, since the camera cannot control the focus at all. So focus confirm adapters for Micro Four Thirds simply make no sense at all.

Size

A fun fact is that the adapter is larger than the Panasonic Lumix 20mm f/1.7 pancake lens. (The lens to the right below.)


Example images

Here are two example pictures taken at f/4:



And an example video:

video

I have also looked into an adapter for Pentax K lenses.

Monday, 8 February 2010

Panasonic Lumix GH1

When the Panasonic Lumix G1 was launched in the autumn 2008, it was the first camera in the Micro Four Thirds system. While it was an innovative camera, it had one feature missing: Video recording. The lack of video was seen as very strange, as the sensor was obviously capable of sending live video feed to the display.

It was not surprising that when the second Panasonic Micro Four Thirds camera was launched in the spring 2009, it did indeed feature video recording. One year on, it is still the only consumer video capable camera with exchangeable lenses, that also feature continuous autofocus during filming, and a tiltable display, features that I would say are essential.


During most of the camera life time, it was only sold as a kit with the superzoom lens Lumix G HD 14-140mm.

Improvement potential

There are a number of good GH1 reviews out there, and there is not much point in making another one. Let me mention a few features that I would have liked to see on this camera, though. While it is a very good camera, there are also some areas where it could have been further improved.

I think that the focus selector is awkwardly placed, on the top left side. This selector is usually placed on the front, next to the lens mount, where it is easier to operate with the left hand.

Generally, I prefer a thumb click wheel to a finger wheel. Having both is of course the best, but having to choose one, I would choose the thumb wheel. The GF1 has got a thumb click wheel.

The video recording is well integrated into the picture taking functions. However, there are some inconsistencies. For example, leaving the camera in AF Single mode will make it do continuous autofocus during filming. There is no mode that will autofocus when initiating filming, but not during filming. Also, the P, A, S, M-modes do not apply when filming. Rather, you need to select a special "Creative movie mode", and then go into a deep menu to choose from the P, A, S and M alternatives. Wouldn't it be easier to just use the mode dial for this selection for video recording as well? A final drawback is that it is not possible to take still images while filming.

Some image processing features could have been added. For example in-camera RAW conversion, and the ability to delete only the RAW image, or alternatively, only the JPEG image. As the camera works now, you can choose to delete a picture all together, but not only one version of it.

The hood will block the built in flash in most cases, with the exception of extreme tele. Even without the hood, the kit lens will block the flash in a wide range of wide angle to normal focal lengths.

There is no supplied software that does video editing with the AVCHD format. For a premium video camera kit, this is rather disappointing.

The camera is not weather protected, as one would expect from a camera in this price range.

It does not feature any infra red receivers, and hence, there are no simple remote controls available. Some third party remotes can be used.

When focusing manually, an enlarged view comes up, to make precise focusing possible. To go back to the full view, you can tap the shutter release button. However, it would be good to have a dedicated button to bring up the enlarged view. This would be useful if you want to check the focus without turning the focusing ring. Or when using a legacy lens on an adapter. On the other hand, the enlarged view is available through pressing two buttons in a sequence, so this is not a big issue.

Most lenses for this camera do not have a focus scale. The exceptions are some Four Thirds lenses that can be attached through an adapter. Furthermore, there is no focus distance indication on the camera. You will see that premium Panasonic compact cameras, for example the LX3, do feature focus distance information in the LCD display. The fact that Micro Four Thirds cameras all lack this feature leads me to think that the focus distance information is probably never communicated from the lens to the camera at all.

When using autofocus, the lack of a focus distance indicator is no big deal. However, there are some times when you want to prefocus at a certain distance, and shoot quickly in manual focus mode for speed and/or stealth. In these cases, it is a bit awkward to know at what distance the lens is focused.

While the Olympus Micro Four Thirds cameras can autofocus with Four Thirds DSLR lenses on an adapter, the Panasonic cameras can only do this with a select few. One example is the Olympus 50mm f/2 macro lens. One could guess that this is not due to technical limitations of the Panasonic equipment, but rather due to an agreement between Panasonic and Olympus. Also, when using manual focus, there is no focus confirmation in the viewfinder. This would have been useful, especially for legacy lenses used on adapters.

When using the front wheel to change aperture, turning the click wheel one way yields different outcomes in P and M mode, respectively. This inconsistency of the aperture input is annoying and unnecessary.

In P mode, you can not adjust the aperture using the index finger wheel until the camera has achieved focus. So to adjust the aperture, you first need to half press the shutter to get focus, and then operate the click wheel.

Sunday, 7 February 2010

GH1 video recording at slow shutter speed

A little documented fact is that the Panasonic Lumix GH1 can record video at slow shutter speeds. To do this, you will need a recent firmware, v1.1 or later. The first firmware did not allow this feature.

Normally, the slowest shutter speed when recording movies is 1/30's second. Using the techinque I will inform about here, you can use as slow shutter speeds as 1/2 second.

The camera will only record at such shutter speeds with a number of features turned off. Follow this list:

  1. In the video recording menu, set the video recording mode to Motion JPEG, i.e., you can not use AVCHD.
  2. In the same submenu, define the Creative Movie Mode to give full manual control.
  3. Choose the Creative Movie Mode from the top mode dial, and select Manual Focus (MF). If you want, you can use autofocus when framing the subject, and go back to manual focus before starting to record the movie.
After having done this, you can start to record movies with shutter speeds between 1/2 and 1/30's second. As well as the faster speeds, of course. You can use the click-wheel to adjust the shutter speed, and the aperture.

In the example below, the aperture is f/16, shutter speed is set 1/6's second, and the ISO is 100. After having done the steps above, you must set the exposure manually, by looking at the histogram. You can also adjust the ISO manually, if needed.

In the Creative Movie Mode, recording videos can be started and stopped by pressing the shutter key. Alternatively, you can also use the dedicated red movie button.

Example videos

Here are three videos feature LEGO figures on a turntable, filmed at 1/2 second, 1/10 second and 1/60 second shutter speed. You'll notice that with a slower shutter speed, the number of frames is also smaller.

video
1/2 second exposure





video
1/10 second exposure





video
1/60 second exposure


Fireworks example

Here is an example using the GH2 to capture fireworks at 1/4 second shutter speed.



Shutter speed and motion blur

As a general rule, you'll want to keep the shutter speed not too fast when filming. Professional movies are generally filmed at around 1/50-1/60 second shutter speed. The purpose of keeping the shutter speed fairly slow, is to give some blurring to moving objects. If the speed is significantly faster than this, movement looks strange, because there will be little motion blur. Any items moving will show up at different places in each frame, and with no motion blur, the human eye will be confused.

ND filters

This is the reason why some video cameras have ND filters built in. In strong sunshine, it may be difficult to use a large aperture in combination with a shutter speed of 1/60 second. A Neutral Density (ND) filter will limit the amount of light passing through, without altering the aperture, hence allowing for a slow shutter speed. Using a smaller aperture is not always desirable, since it will give a wide depth of field, ruining the "cinematic" look.

The Panasonic GH1 does not have any built in function to provide ND filters between the lens mount and the sensor in strong light situations. If you want to use ND filters, they must be added to the front thread of the lens.

The upcoming professional Panasonic camcorder AG-AF100, to use the Micro Four Thirds mount, will feature built in ND filters.

Technical implementation

When taking pictures, the Panasonic Lumix G series, as well as the Olympus PEN cameras, use a mechanical shutter. When you press the shutter release button, the shutter first closes, and then opens for the specified shutter speed, and then closes and opens again for continued live view.

When recording videos, the shutter stays open all the time, and the shutter speed implementation is done electronically.