Sunday, 30 September 2012

Air show video using the Lumix 100-300

During the September 1st Royal Norwegian Air Force 100 year anniversary, I tried to video record some of the air plane flybys. This was the very first time I had tried to video record air plane, and I brought the longest lens I have, the Lumix G 100-300mm f/4-5.6 with the Panasonic GH2 camera.

I did not bring any tripod or extra microphone, as I would be standing in a crowd of people, and needed to be fairly agile.

Most of the time, I used the lens in the longest setting, at 300mm, and stopped down the aperture a bit to f/6.3. I could do this at ISO160, the base ISO, and still have a healthy shutter speed of about 1/500s, even when dialing in about +1/3 to 2/3 of exposure compensation. I needed the exposure compensation, as I was mostly shooting into the sun, or close to the sun.

Here I have edited the footage into a video stream of about three minutes with some of the footage:



I used Kdenlive to edit the stream, and I added a bit of post process image stabilization to the video. This was needed, even though I used the OIS feature of the lens. Perhaps I would have been able to go without the extra image stabilization had I used a tripod.

Some things to note about the video:

  • There is quite clearly still some vignetting, even though I did stop down an extra 1/3 of an aperture stop.

  • You can see the lens OIS working, as the brightest central disc area moves about in the frame.

  • The focus is mostly ok. Some times, the camera loses focus for a short period, but it is not a big problem. I had the AF-S mode selected.

  • The sound is not very good. An external microphone would probably have improved it.

  • You can see the evidence of rolling shutter distortion. Here is a frame from a video, where the helicopter blade is bent due to the rolling video shutter:


    When using the mechanical shutter for still images, though, there is virtually no rolling shutter effect:


    This is because the mechanical shutter travels faster than the electronic line by line readout of the sensor is.

Friday, 28 September 2012

Using a +10 macro lens

There are many ways to achieve macro photo capabilities. The easiest is of course to buy a dedicated macro lens, like the Panasonic-Leica 45mm f/2.8 1:1 macro. However, that is an expensive lens, and I am often looking to test cheaper alternatives. I have looked into a number of options, see the table at the end of this article for a list.

Some macro options involve offsetting the lens further away from the camera, or reversing it, effectively cutting off the electrical communications between the camera and the lens. This has the negative side effect of removing the possibility to control the focus and the aperture of the lens.

Probably the cheapest and the simplest solution is to buy a close up filter to be screwed into the front threads of a lens you already have. These are typically rated as +1, +2, +4 and +10. I decided to try the most extreme, the one rated as +10:





One strange thing about the macro filter I got, is that the glass extends beyond the rear side of the metal ring. This means that when screwing it into a lens, the glass elements might meet, potentially damaging either. To avoid this, I used a 46mm stand off ring between the macro ring and the lens. Here they are mounted to the Lumix X 45-175mm f/4-5.6:


When using the +10 close up filter, the Lumix X 45-175mm f/4-5.6, the lens becomes 1:2 capable at 45mm, and 1:0.6 at 175mm. The working distance is 8cm through the focal length range. Here is a typical setup at 175mm focal length:


And the result image, taken with an aperture of f/13:


Sadly, the image quality is rather poor. As you can see, there are some significant chromatic aberration artefacts. Perhaps close up filters with a lower rating, e.g., +2, provide a better quality. But then again, they also give less magnification.

One big advantage with this method is that you can control the aperture from the camera. The focus can also be controlled, however, at this magnification, you are limited to very small fine tuning of the focus distance only. You must do the focusing by moving the object into focus.

Used on the Sigma 30mm f/2.8

I also tried to use the close up filter on the Sigma 30mm f/2.8 EX DN lens, which shares the 46mm filter thread.

In this case, I could do without the stand off ring. However, I could not screw the close up filter completely into the filter threads, as the glass surfaces would meet, which I don't like.

Using this solution, I was able to get a 1:2 magnification, with a 6cm working distance. Here is the output image:


In this case, I did not see any severe chromatic aberration artefacts, but then again, the enlargement is not nearly as large.

Other options

Here is a summary of various ways to achieve a macro ability:

Methodmagnificationworking distanceaperturefocus
Using a dedicated macro lens, the PL451:1 max6cmautoauto
Macro extension rings, and a legacy normal lens1.4:1 in my example6cmmanual, if the lens has an aperture ringno focus possibilty
Macro reverser ring, with Lumix 14-42mm2.5:1 - 1.15:12-4cmno control of aperture from camerano focus possibilty
Olympus ZD 50mm f/2 lens with extra 65mm extension2:13cmno control of aperture from camerano focus possibilty
Lumix G 45-200mm with reversed normal lens3.5:15cmautoauto, but only small adjustments
Lumix X 45-175mm with +10 close up filter (this article)1:2 (45mm), 1.7:1 (175mm)8cmautoauto, but only small adjustments

Conclusion

This study perhaps shows that there are no free lunches. The cheap macro front filter lens is simple to use, but gives poor image quality. For the ultimate in image quality and simplicity, the best is probably to buy the Panasonic-Leica 45mm f/2.8 1:1 macro. in the first place.





Thursday, 20 September 2012

3D video recording with the Lumix 12.5mm f/12 3D lens

I have already written a review of the Lumix G 12.5mm f/12 3D lens. In the review, I concluded that you should not buy the lens. One of the reasons was the lack of the possibility to record 3D videos, which is a strange omission.


However, it is of course possible to fool the camera into believing that the 3D lens is not attached, in which case video recording becomes a possibility. The way to do this, is to put some plastic tape over the electrical contacts of the lens. Then, the camera will not be able to communicate with the lens, and fails to notice its 3D properties, treating it like any other lens.

For this to work, you must enable the "shoot without lens" option on the camera:


Here is a video illustrating how to do this:



Be careful, though. If pieces of the plastic tape comes off and falls into the sensor, that can cause big problems.

Video

Using this method on the GH1 camera, I was able to use much more of the sensor than what is being used when taking 3D still images. As illustrated by the image below, I cropped off the centre 120 pixel column, and used the rest to make an anaglyph 3D video:


This uses a total of 94% of the sensor area.

As I wrote in the review, when the 3D lens is used in the conventional way, only 35% of the sensor area is used. Used this way, there is an additional crop ratio of 2.4, meaning that the lens becomes a short tele lens of 30mm, just like the Sigma 30mm f/2.8 EX DN.

The way I use the lens as a video lens, though, the crop ratio is only 1.6, giving a focal length equivalent of 20mm, a slightly short normal lens. So the field of view of the 3D lens becomes more useful with the plastic tape trick.

On the other hand, the resolution of 900x1080 pixels is quite unusual, and it is likely that you need to crop this to actually use it in any sensible way.

Here is an example video. The video is anaglyph, and must be watched with red/cyan glasses.



There is still some vignetting in the corners, but this proves that it is possible to record 3D videos with the Lumix G 12.5mm f/12 3D lens.

Still images

You can use this trick with still images as well. It gives you a larger image to work with, rather than the 1920x1440 3D image pair you normally get. Here is an example image taken when using the plastic tape trick. The areas used by the 3D lens in the conventional way are highlighted with the rectangles:


Using the lens in the conventional way yields this image:


When using the whole sensor frame output, though, you can get a much larger field of view, using 1930x3016 pixels per 3D image:


This shows that when fooling the camera into not knowing that the 3D lens is connected, you can get a larger sensor area to work with. The disadvantage is that you need to compile it into 3D manually, and also, you are stuck with the portrait format, unless you crop it down to landscape format, though. You could also use the RAW file, this way.

Alternative lens

Loreo also produces a 3D lens for Micro Four Thirds. It uses the same principle: Two lenses project an image on the left and right part of the sensor, and they must be combined into a 3D video. Unlike the Lumix 12.5mm 3D lens, though, the Loreo lens has a more sensible distance between the lenses, the stereo base, giving a more pronounced 3D effect:


The Loreo lens uses the same principle as the Lumix G 12.5mm f/12 3D lens. It projects two images side by side on the sensor. The big difference, though, is that the Loreo lens has a much larger stereo base, and uses mirrors to project the images into the relatively small sensor. The Lumix 3D lens, on the other hand, does not use mirrors at all, and places both lenses inside the sensor area.

So you end up with the same problems when using the Loreo lens as well: You are restricted to the portrait format, both when using still images and video. Of course, you can crop the images down to a horizontal landscape format, but then you lose quite a bit of resolution when cropping.

Tuesday, 18 September 2012

GH3 comments

So, the new Panasonic GH3 camera has been announced now, after a long wait. How do I view it?

Of course, by this time, I have no first hand experience of the camera what so ever. My knowledge of the camera is solely based on images, video and text online.

In terms of technical specifications, not so much has changed. We have a higher video FPS rating at 1080p, as expected. And we have a higher video bitrate. Under the hood, there is of course a lot of technical details, for example a higher frame rate used for the contrast detection auto focus system (CDAF), which has the potential for better and faster autofocus. And there is a higher sensitivity, as well as the usual promise of a better dynamic range.

Ergonomics

The really big change is the ergonomics. The GH3 is bigger than the GH2:

GH2GH3
Dimensions (w, h, d)124 x 90 x 76 mm133 x 93 x 82 mm
Weight442g540g

The size accommodates a better grip, more space for buttons, three control wheels (the GH2 had one single only), more connectors. As the camera does not really take up that much more space in the bag, I see this as purely a positive thing. The ergonomics of the GH1 and GH2 left quite a bit to be desired. The layout is rather cluttered, and it is easy to press a button by a mistake. The GH3 is going to be much easier to handle, especially with a large lens.

On the flip side, one could argue that the whole purpose of the Micro Four Thirds system was compactness. So why introduce a larger flagship model?

Sensor

The GH3 deviates from the predecessor GH cameras in a significant way: It no longer offers the oversized, multi aspect sensor.

With the multi aspect sensor, the GH1 and GH2 could take photos at 4:3, 3:2 and 16:9 aspect ratios while retaining the same diagonal field of view. This has the advantage of utilizing the lens imaging circle better. More importantly, it could record videos at the 16:9 aspect ratio while retaining the same field of view as well.


Without this feature, the lenses effectively lose some wide angle feature when switching to video. It means that the wide angle property that you were used to when using the GH2 are going be a bit disappointing when switching to the GH3. The difference is not too significant, but noticeable.

When using a fisheye lens on the GH2, for example, you get a 180° diagonal coverage in both photos and videos. With the GH3, though, you get the 180° diagonal field of view only in the 4:3 still image mode, and less than that in video mode. This applies to the Samyang 7.5mm f/3.5 fisheye lens for example.

Conclusion

The GH3 takes the Micro Four Thirds system into the professional territory: With better ergonomics, splash protection, better video bitrate and connectivity. Sadly, it also comes at a significantly higher price point.

While it doesn't live up to all the expectations people had, I am confident that the GH3 will be loved by the users.

Those who are put off by the size increase could still look to the Panasonic G5. While it does not offer quite the same feature set as the GH3, it is still a quite impressive camera given its size.

Saturday, 15 September 2012

Fireworks recorded using GH2 and Samyang 7.5mm f/3.5 fisheye

It was very dark during this firework, so to record it, I had to push the exposure as high as possible. I used the "Creative Movie Mode", with the manual setting ("M"), in which I could dial in ISO 3200 (the maximum), and used the largest aperture on the Samyang 7.5mm fisheye lens: f/3.5.



A little known feature of the Panasonic GH1 and GH2 is that you can record videos with a slower shutter speed than the frames per second setting. I was using the high bit rate 25 fps 1080p mode, and to get sufficient exposure, I set the shutter speed to 1/13s, i.e., slower than 1/25s. This is possible only in the "Creative Movie Mode", in the "M" exposure mode, and with autofocus turned off. Of course, you don't actually get 25 frames per second with a shutter speed of 1/13s, you only get 13 frames per second.

To make the video clip more interesting, I speeded up the video to 200% speed, meaning that the frames per second of the output clip was about 25fps.



I also changed the tempo of the sound, to keep it in sync with the 2x fast video.

Conclusion

The Samyang 7.5mm f/3.5 fisheye lens is very good for recording fireworks. But to get sufficient exposure, you may need to set the shutter speed quite low, lower than 1/30s, giving you fewer frames per second than you are used to. This feature of the Panasonic GH1, GH2 and GH3 cameras is quite useful, and I don't think other Micro Four Thirds cameras can record videos with this slow shutter speeds.

When the GH3 gets released soon, I would guess that it can record videos at ISO 6400, which may solve this issue.

Sunday, 9 September 2012

Lumix X PZ 14-42mm f/3.5-5.6 Review: Compact, but not the best image quality

The Panasonic Lumix G Vario X PX 14-42mm F3.5-5.6 Power OIS is a kit zoom lens in a very compact form factor. It collapses when not in use, in which case it is about the size of the Lumix G 20mm f/1.7 pancake lens.

Both the zoom and focus are the "fly by wire" type, meaning that they can only be operated through levers on the side. This has both positive and negative aspects: The power zoom (PZ) enables smooth zooming during video. For still image photography, though, I would say that a mechanical zoom ring is more useful than the lever operated power zoom.

When looking at this lens, it is natural to compare it with the Lumix G 14-42mm f/3.5, the more basic kit lens. They are both pictured below:


In the foreground: Lumix X 14-42mm (left) and Lumix G 14-42mm (right). In the background: Lumix X 45-175mm (left) and Lumix G 45-200mm (right).

First, let's look at the specifications:

Lumix X PZ 14-42mmLumix G 14-42mm
Number of aperture blades77
Lens elements912
Lens group89
Exotic elements4 asph, 2 ED1 asph
Minimum focus distance0.2m0.3m
Maximum magnification0.34x0.16x
Weight95g165g
Diameter61mm61mm
Length27mm64mm
Filter thread37mm52mm


Based on the specifications alone, the lenses appear similar: They have the same focal length range, aperture range, and the newer X lens even sports a shorter minimum focus distance. However, be aware that these figures are a bit deceitful. Let's start with the aperture range. While the end points are the same, f/3.5 in the wide end and f/5.6 in the long end, the range between is very different. It can be summarized with this diagram:


This tells us that the newer Lumix X 14-42mm collapsible lens has a smaller maximum aperture for all intermediary focal lengths between the wide and long end. It reaches f/5.6 already at f=32mm, while the older Lumix G 14-42mm lens reaches f/5.6 at f=42mm, the longest end. At f=25mm, the difference is about 1/3 stop. This is not a very large difference, but it shows that in terms of aperture, the newer X lens generally gives you a smaller aperture opening.

Another specification item which is quite misleading is the minimum focus distance. From the table, the newer X lens has the shortest minimum focus distance, which looks all well. However, this applies only at f=14mm, and the distance changes in tele mode:

Lumix X PZ 14-42mmLumix G 14-42mm
Minimum focus distance @ 14mm0.2m0.3m
Minimum focus distance @ 42mm0.5m0.4m

Generally, one gets the largest magnification in the longest tele setting. However, in this case, the older Lumix G 14-42mm lens has the shortest focus distance at 42mm, which would enable you to photograph smaller images at 42mm with the older lens.

Physical appearance

The outer barrel of the lens is plastic. There are two levers on the side, one for focus, and one for the power zoom:


The levers operate very smoothly, and have a high quality feel. The lens mount is metal, unlike the older Lumix G 14-42mm lens, which has a plastic lens mount. Personally, I don't think this makes any difference for small lenses like this. But the metal mount generally makes people feel more confident with their lens.


When extending the lens, the inner barrel is exposed. This barrel is made of eloxed aluminum. When extended, the inner barrel is very stable, it feels solid with no play at all:


The lens extends when you turn on the camera. The extension takes two seconds. Hence, there is always a two second delay before you can use the camera. This is of course not a lot. The Sigma 30mm f/2.8 EX DN, for example, has a start up delay of three seconds, even though it has no extending section at all.

If you accidentally turn on the camera while it is in a bag, with no room for the lens extension, then the camera notices this, and gives up, leaving the lens unextended. When entering power save mode, the camera will collapse the lens. This is perhaps a bit counter intuitive, as it needs to extend again before being ready after waking from the sleep mode.

Finally, if you connect the camera to a computer, and turn it on to transfer files using the USB cable, the lens will extend, even when the camera is in file transfer mode.

The rear exit pupil of the lens is stationary, even when the lens extends, and during zooming. This is contrary to the older Lumix G 14-42mm f/3.5-5.6 lens, in which the rear element moves forward when zooming in. One could speculate that the Lumix X 14-42mm lens does not create any dust problems when zooming, as the rear element, facing the sensor, is not moving back and forth at all.

Hood

No hood is supplied with this lens. I guess a hood would defy the purpose of the lens, which is to be very compact. I still prefer to have some small, simple hood on my lenses, so I used a 37mm stand off ring:


This probably doesn't do much in terms of keeping out stray light, but it makes me feel safer when I handle the lens, as there is some protection against objects touching the front lens element accidentally. This solution does not add any unwanted vignetting.

Autofocus speed

I tested the focus speed of both lenses by turning on the camera, a Lumix GH2, and then seeing how long time it takes for it to lock on a subject 0.5m away. The lightning was at around 11 EV, quite bright. I did the test at 14mm and 42mm:

Lumix X PZ 14-42mmLumix G 14-42mm
Focus delay @ 14mm0.14s0.24s
Focus delay @ 42mm0.40s0.28s

You can see the test here:



One could say that this test is a bit unfair towards the newer X lens. Usually, you will see that the focus speed goes down quite a bit when working in the boundaries of the focus distance range. And the Lumix X lens is at the very closest focus distance possible at 0.5m, while the older Lumix G lens still has some margin down to its closest focus distance at 0.4m.

Overall, I'd say the focus speeds of the two lenses is quite comparable. Most kit zoom lenses focus very fast anyway, and for still images, the focus speed is rarely any problem with them.

Manual focus

Manual focus is operated with the focus lever on the side, given that you select the manual focus mode on the camera. This works ok, although it must be said that a real focus ring is much easier to use. I suppose that most users will use autofocus most of the time, so I don't see this as an issue. The focus lever gives you two different focus speeds, depending on how hard you push the lever.

Power zoom

Just like the Lumix X PZ 45-175mm f/4-5.6 tele zoom lens, the Lumix X PZ 14-42mm has power zoom functionality. Unlike the 45-175mm lens, though, the 14-42mm only has the zoom lever, not the zoom ring. This makes the zoom a bit more awkward to operate, in my opinion.

Using the zoom lever, you can operate the motorized zoom at two speeds. These are selectable by pushing the lever more or less hard, just like with the motorized manual focus.

Here is a video which illustrates the use of the Power Zoom feature:



The power zoom feature works well. Personally, I would have preferred to have a zoom ring, but I can see why they chose to put a zoom lever: To save space. And the compactness is one of the key features of this lens.

With some experience and dexterity,  the lever control allows for very precise control of the focal length. For example, there are several intermediary stops possible between 14mm and 15mm focal length.

Image quality

Here is an example image, taken at 14mm with both the 14-42mm lenses. The focus distance was about 0.5m, with the focus area set on the centre of the wooden plank:


Here are 100% crops from both lenses to compare the quality:


This test shows that both lenses have quite good image quality in the centre. The X lens, though, exhibits some quite bad donut shaped bokeh, which is not lost until stopping down well beyond f/5.6.

Here is a rather simple test at f=42mm. Again, the focus distance was about 0.5m:


And here are 100% crops from the upper left corner of the frame:


This test shows that the older Lumix G 14-42mm lens is in fact significantly better in the corner at 42mm. This doesn't surprise me, since I have previously been impressed by the basic kit zoom lens.

In the centre, they are very similar, though.

Here you can find a comparison with the Sigma 30mm f/2.8 at 30mm. As you would expect, the Sigma lens is significantly better. After all, it is a prime lens with a moderate aperture.

The image quality leaves something to be desired for this lens. The bokeh can be problematic, and the image quality is not the best in the corners.

Regarding flare, I have often seen the lens handle high contrast situations poorly, especially when using longer focal lengths. Perhaps a proper hood would help.

Geometric distortion correction

Just like most other Micro Four Thirds lenses, this one relies on in-camera geometric distortion correction to show rectilinear results. My tests indicate that the lens gives barrel distortion in the short end, and pincushion distortion in the long end, quite common for such a lens. With the correction, though, there is little residual distortion.

Example pictures

This image was taken at 14mm, f/5.6, 1/320s, ISO 160:


With some 100% crops from the image:


Another example, taken at f=35mm, f/8, 1/320s, ISO 160:


With some 100% crops from the image:


Example video

This was video recorded using the GH2 camera, in 1080p 25fps, auto everything. The camera was hand held, and the focal length was mostly at 42mm, however, I zoomed a bit out some times using the power zoom.



In this article, you can find a video recorded mostly at 14mm, including some use of the power zoom feature.

Conclusion

The main attraction of the Lumix X PZ 14-42mm f/3.5-5.6 is the size. It is remarkably compact, and as such fits well into the Micro Four Thirds concept. The image quality is good, but not stellar.

Previously, I often put the Lumix G 14mm f/2.5 pancake lens in my pocket when I wanted to have a spare lens in case I needed to go wide. Nowadays, I often bring the Lumix X 14-42mm f/3.5-5.6 for that purpose. It is not much larger, and adds OIS, which is useful for video, as well as the option to zoom in to 42mm. I believe the image quality of the 14mm pancake lens is probably better than that of the Lumix X 14-42mm lens, but the latter adds a lot of flexibility, with a zoom and OIS.

Compared with the older and cheaper Lumix G 14-42mm f/3.5-5.6, I would say that the cheapest lens is the best when evaluating the image quality exclusively. So if you don't care about size, and don't need the power zoom, I'd say get the Lumix G 14-42mm f/3.5-5.6.

For me, the size matters, and I am tending to use the Lumix X 14-42mm f/3.5-5.6 mostly these days. The power zoom feature does come in handy when video recording, I must say, so it adds to the usefulness of the lens.

I'd say that this is a lens you would buy for the ultimate in compactness, not to get the best image quality.