The Lumix G 100-300mm tele zoom lens is a very long one, useful for birds, wildlife, events, sports, and so on. When recording video with the Panasonic GH2, you can use the ETC, Extended Tele Converter mode, which uses the centre of the sensor only, for an additional 2.6x factor on the effective focal length. At 300mm, this gives a staggering 1560mm equivalent focal length, when comparing with the traditional 35mm film format.
I have made some example video clips at 300mm, including the 2.6x ETC mode. The following video contains four segments, from the May 17th Constitution Day parade in Oslo. Notice that with the 1560mm effective focal length, the perspective is very compressed.
A stable tripod is needed. My tripod is not too stable, and just pressing the button made the video wobble. So the first seconds of footage was always unusable, while the camera and lens settled down.
Notice how the video flickers quite a bit, especially in clip number two and three. This is due to atmospheric disturbances. All the people in the parade generate heat, and it affects the path of the light. The first clip is from the very start of the parade, and the air is much more calm.
This can be seen in still images as well. Here is an image taken from the same point with f=300mm, ISO 160, 1/200s, f/7.1, tripod mounted:
An 1:1 crop of the centre of the image illustrates the blurring caused by the atmospheric disturbances even better:
Please note that this blurring could not have been fixed by the usual measures: Lower ISO, faster shutter speed, smaller aperture, tripod, or even a better lens. It is simply a physical phenomenon which affects an image when the light travels a long distance across air with different temperatures. The only ways to avoid it would be to move closer, or to take the image when the air is more neutral, possibly early morning. But in this case, I wanted the compressed perspective, and rising early was not an option since the parade had not started at that time.
In my review of the tele zoom lens, I noted that it loses a bit of contrast at 300mm in strong sun light, due to flare. I think this happens in my example video as well. It could have been corrected a bit by adjusting the curves in the video, but I left it as is.
Conclusion
The ETC mode, when combined with a long lens, allows for a very significant reach for videos, and a very compressed perspective. However, be sure to have a stable tripod, and beware that atmospheric disturbances may make your video footage less usable.
Most of the Micro Four Thirds lenses need geometric distortion correction applied for the output images to become rectilinear. This is done totally seamlessly by the camera and software, both for JPEG and RAW images. So the user never notices that the image, as seen by the camera through the lens, is not rectilinear in the first place.
This is in contrast to older DSLR systems. In these systems, there is an optical viewfinder, in which the users sees exactly what the sensor sees, through the lens. With a DSLR system, the lens must be rectilinear, otherwise, the user will be appalled by the geometric distortion when using the camera.
Here is an illustration of two basic kinds of distortion: Pincushion distortion (left) and barrel distortion (right):
In reality, the geometric distortion might very well be more complicated than what is illustrated by these simple models.
Again, I have done the tests by taking a pictures of a tiled wall. The images look like this:
Since I am only interested in the geometric distortion, I have increased the contrast so that the images become monochrome. I also superimposed the corrected out of camera JPEG images (black) onto the original RAW uncorrected images (red).
I included the appropriate adjustment needed. The adjustment numbers in percent refer to the "Lens Distortion" filter in The Gimp, an image processing software. Of course, to become rectilinear, some lenses might require more complicated adjustment than the simple model given by the "Lens Distortion" filter. So these figures are just intended to be approximate relative indicators of the degree of distortion. A positive figure indicated barrel distortion, while a negative figure indicates pincushion distortion.
Here is a comparison of the uncorrected and corrected images for some lenses.
There is a significant barrel distortion, which is corrected in the in-camera JPEG image. However, there is some residual barrel distortion even in the corrected image. I have noticed this previously. In fact, the lens is rectilinear (after correction) at long focus distances, but has some barrel distortion at close focus distances. In this example, we see the barrel distortion at close focus distance. This is not an uncommon behavior for lenses that feature internal focus.
No distortion correction at all. It looks like there is a small amount of pincushion distortion, though, so perhaps there should have been some in-camera correction done by the camera.
We see that wide angle lenses and zooms typically feature barrel distortion (negative figure) in the wide end. On the other hand, longer lenses are often not corrected, or are corrected for a small amount of pincushion distortion (positive figure). The in-camera distortion correction is some times insufficient, for example we've seen that the Olympus M.ZD 45mm f/1.8 and Lumix G 14mm f/2.5 pancake lenses feature some geometric distortion in the short focus range, while behaving better at infinity focus.
There are some who have speculated that Leica-branded lenses are not subject to any software corrections. I have looked at the Panasonic Leica 45mm f/2.8 1:1 macro lens, and found no indications of software adjustments to the images. However, I still don't believe that statement. One of the first cameras for which the software corrections were widely discussed online, was the Panasonic Lumix LX3 high end pocked camera from 2008. And it does feature a Leica-branded lens, and quite clearly, there is a significant barrel distortion in the wide end of the zoom, which is corrected by software.
There is no doubt that Canon and Nikon have been competing fiercely in the SLR and DSLR camera segments for many decades. Looking at the most recent decade, Canon made a head start by introducing the affordable models 300D and 350D back in the early 2000's. Then, Nikon launched the D40, which combined a small form factor, low megapixel count and a good high ISO capability. This made Nikon once again the number one in some markets.
With the most recent D3x00 series of cameras, Nikon is again a good seller, especially in Japan. Their most recent announcement, the D3200, packs a massive 24 megapixel resolution. It is worth noting that this is more than Canon have ever had in any DSLR camera.
This development can be illustrated graphically like this:
With the blue line being the Canon entry level models (300D, 350D, 400D, 450D, 500D and 550D), and the red line being the Nikon models D50, D40, D40X, D60, D3000, D3100 and D3200.
It seems that while Nikon has traditionally believed in a moderate megapixel count, they have decided to trump Canon at the megapixel race, believing that the market now wants a high number of megapixels. And perhaps they are right. After all, the recently announced Nikon D800 has generated a lot of interest, with the staggering 36MP sensor.
On the other hand, Nikon has continued their moderate philosophy with the mirrorless Nikon 1 line, with both introduction models only having 10MP. This could be to protect their DSLR line from cannibalization.
The 24MP D3200 model might be a reaction to Sony's mirrorless NEX-7 model, also sporting 24MP. In fact, their sensors might very well be related.
So, what does this mean for the Micro Four Thirds cameras? I'd say it makes it even more probable that future models will sport more megapixels. When the GH2 was launched, it upped the megapixel count of the GH1 from 12MP to 16MP. In an interview, some Panasonic professionals said that this was done largely for market reasons, not because it benefitted the images significantly.
With the competition now re-entering the megapixel race, I think it is more probable that the GH3 will come with a higher megapixel count than the GH2.
It seems that to get a camera with a moderate amount of megapixels, you must look to Nikon's professional D4 model, sporting only 16MP on a full frame sensor.
I have previously looked at how to defish the images from the Samyang 7.5mm f/3.5 fisheye lens. Even with a generic fisheye lens profile, it is easy to defish the output images so that they appear rectilinear. But my example image does not show how wide the output image really is. To illustrate that, I will present the same image taken with an ultra-wide lens.
As is apparent from this table, the fisheye lens has a vastly wider diagonal field of view. However, we also know that the fisheye lens has a more compresses field of view the further we get from the centre. Hence, not all of the 180° diagonal field of view can be used when defishing the image.
This can be illustrated by looking at the defishing process. Here are the same images taken with the Samyang 7.5mm fisheye lens, defished, and taken with the Olympus 9-18mm lens at 9mm:
When it comes to wide lenses, fisheye lenses are the very widest available. The currently widest rectilinear (non-fisheye) lens for the Micro Four Thirds system is the Panasonic Lumix 7-14mm f/4 zoom lens. At the widest setting, it has a diagonal field of view of 114°. This is quite impressive, however, a full frame fisheye lens has a diagonal field of view of 180°.
Two full frame fisheye lenses for the Micro Four Thirds system are the Lumix G 8mm f/3.5 and the Samyang 7.5mm f/3.5. The Lumix lens is rather expensive, but good quality. The Samyang is cheaper, does not feature autofocus, and has good optical qualities.
A disadvantage of fisheye lenses is of course the fisheye projection: They do not feature rectilinear projections like we are used to, but spherical projections. This means that any line not passing through the centre of the frame will appear bent. The further from the centre a line passes, the more bent it becomes.
However, fisheye images can be transformed to rectilinear images, to look more natural. In this article, I use the free software Hugin to transform the image, also called defishing.
Defishing photos
Here is an example image taken with the Samyang 7.5mm f/3.5 at f/5.6. It features Sergels Torg in Stockholm, with straight lines in three directions in the tiles (click to enlarge):
As you can see, the lines that pass near the centre of the frame are the least bent.
To transform the image to rectilinear, I use the Hugin program to defish it. Hugin can do panorama stitching, but in this case, I use it solely to defish an image.
First, click the "Load images..." dialogue button, and load your image into the program:
Next, insert the details about the lens. Here, I am using a Full Frame Fisheye, with a focal length of 7.5mm and a 2x crop factor:
In my experience, using the lens type "Orthographic" also gives good results. Having done this, it is time to tell the program what kind of output projection we want. This can be done by clicking the "Fast Preview panorama" button in the middle top of the window:
This brings up the dialogue window where you can choose the output projection and field of view. Choose "Rectilinear" projection, and a field of view of something like 140° by 110° in the "Projection" tab:
Finally, it is time to save the output file, which is done in the "Stitcher" interface, since this program is, after all, a panorama stitcher program. First, click "Calculate Optimal Size", and then "Stitch Now...":
This brings up a file save dialogue window. Note that the output file will be enormous, and you need to open it in an image editing program, e.g., The Gimp, to crop and resize it. After cropping and resizing, the image looks like this:
There are a lot of things to note about the defished image:
The lines are now (fairly) straight. I did not use a specialized profile for the Samyang 7.5mm f/3.5 fisheye lens, but a generic profile. So the output image is perhaps not perfectly rectilinear. But it is good enough for most uses, I think.
Also, note that the aspect ratio of the image changed. The original image had an aspect ratio of 1.33 (4/3). The defished image has an aspect ratio of 1.92. This is not a mistake. Keep in mind that the fisheye image is more compressed the further from the centre we get. Hence, in the fisheye projection, we pack more angle of view the further from the centre we get. Since the original image was rectangular, this gets exaggerated after defishing.
Finally, the corners of the defished image have been stretched a lot, and the effective resolution is smaller in the corners than in the centre. This can be illustrated by looking at 100% crops from both the original and defished images, from the lower left corner:
Contrary to intuition, perhaps, the fisheye image actually looks more natural in the corner.
In the corner, we also see that the Chromatic Aberration artifacts get exaggerated after defishing. We can see a more pronounced green fringing around the black figure in the image above.
My example above looked at defishing a still image. It is also possible to defish video. I have used the Kdenlive video editing software for this effect. Right click on the video timeline, and select "Defish":
This brings up the "Defish" video effect settings:
I've found that using the "Equiarea" type, and an amount of 855 works well. Alternatively, use "Stereographic" and an amount of 825. Or you can experiment and see what you like the most.
Using this technique, I have made an example of a video sequence both without and with defishing. The video shows the street gamblers often seen in the Stockholm old city:
Again, we see that the output video is almost rectilinear. For most practical purposes, this is good enough. Also, in the corners, the resolution is not as good as in the centre, just as we saw in the image example above. This is especially evident when viewing the video at 1080p.
Conclusion
Defishing image and video is easy. The output images are not perfect, but considering how extremely wide they are, I'd say they are pretty good.
To avoid the stretched look in the corners, you could apply somewhat less defishing effect. This will leave some residual barrel distortion, but also leave more resolution in the corners. This could be an option if you have an image with few straight lines.
The Samyang 7.5mm f/3.5 fisheye lens, also marketed as Rokinon and Bower, is special in that it is one of the first third party lens designs made specially for Micro Four Thirds. Some other manual focus lenses for Micro Four Thirds are older designs with a new mount.
The Samyang fisheye lens is an alternative to the native Panasonic Lumix G 8mm f/3.5 fisheye lens, so it makes sense to compare them. Here they are, with lens caps:
They have different type caps. The Samyang, on the left, has a cap held in place with clips, operated by pressing the side tabs. The Lumix's cap is held in place with friction only. I prefer the latter, since the Samyang cap must be inserted correctly rotated, which is somewhat more awkward.
There are many ways to achieve macro possibilities. The simplest is of course to buy a dedicated macro lens, like the Leica-Lumix 45mm f/2.8 1:1 macro. This lens does macro very good, and is easy and fun to use. The only negative side is that it is rather expensive, probably in part because of the premium Leica branding.
Another way is to get a cheap legacy lens, and some macro extension rings. If the lens has a mechanical aperture ring and focus ring, then it is quite easy to use with macro. Of course, you must control the focus and aperture manually on the ring, and there is no EXIF information to the camera. For even better control, you could buy some macro bellows, for stepless extension distance.
A third method would be to buy a macro lens to put into the filter threads of the lens. There are a number of third party macro filters to buy, and Panasonic has even launched their own, which can be used with the Lumix G 14mm f/2.5 pancake, and the Lumix G X PZ 14-42mm powerzoom pancake kit lens. I have not tried any of these.
A fourth method is to buy a macro reverser ring. A reverser ring is quite simply an attachment which allows mounting a lens reversed on the camera. I have tried one such ring, easily available on various auction sites for around US$10. It is a simple thing. On one side, it has a Micro Four Thirds lens mount. The red dot makes mounting easy:
On the other side, it has a 52mm lens thread:
The 52mm threads is a good choice, since it fits a number of lenses.
Here is the adapter mounted to the Panasonic GH2. It will of course fit any Micro Four Thirds camera.
Mounting a Nikkor 24mm f/2 AIS lens
I have got an old, rather banged up Nikkor 24mm f/2 AIS lens. It has got a 52mm front lens thread, and hence fits well onto the adapter. Here is a video showing how to mount it:
After mounting the lens, you can still control the aperture with the mechanical aperture ring, which is a good thing. When used like this, the lens has a very short focus distance, good for macro, but it also has a very thin depth of focus. Hence, you will normally want to stop down the aperture to at least f/5.6 to get more in focus. Normally, you will focus at f/2 (for the best focus accuracy), and stop down to f/5.6 (or more) before taking the picture.
I took this test picture of a ruler (in millimeter) to test the magnification:
The test picture shows that the magnification is 17.3:13 (with 17.3mm being the horizontal width of the Four Thirds sensor, and 13mm being the width of the object depicted). This corresponds to 1:0.75 magnification, also written as 1.33x. This is slightly more magnification than what is possible with the Leica-Lumix 45mm f/2.8 1:1 macro. On the other hand, no focus is possible at all with this solution. You can only take pictures at 1.33x magnification.
Mounting a Lumix G 14-42mm f/3.5-5.6 kit zoom lens
The Lumix G 14-42mm kit zoom lens also has a 52mm front thread. Hence, you can mount it to this adapter. Here is a video showing how to mount it:
Using this is quite different from the manual Nikkor 24mm f/2. First of all, the negative sides: The Lumix G 14-42mm lens does not have an aperture ring. Hence, you cannot easily adjust the aperture. This makes macro use difficult, since you will normally need to stop down the aperture for more depth of focus (DOF).
The positive side is that you can use the zoom ring for changing the magnification rate. The focus distance is also changed at the same time, but at this enlargement, it makes more sense to use the word "magnification" than "focus". At 14mm, you get the maximum magnification, and the minimum at 42mm. Let's take a look at this.
@14mm
Again, I photograph the ruler to find the magnification:
The ruler shows 7mm, hence the magnification is 1:0.4, or 2.5x:
The working distance is 2cm, which is quite short. I try to photograph a LEGO figure here, and as you can see, the subject is almost touching the rear end of the lens:
Here is the result, at 14mm f/3.5. I focused on the eye, but due to the very thin DOF, only one eye is in focus:
@42mm
Here is the photo of the ruler, showing a 1:0.87 or 1.15x magnification ratio:
At 42mm, the working distance is 4cm:
And here is the result, at 42mm f/5.6:
Example image
This is a picture a tooth brush, and was taken at 14mm, f/14. I could probably have stopped down the lens even more for more depth of focus.
Also note the dots throughout the image. They are probably dust particles on the sensor, and come into focus when using extremely small apertures, like in this case. Otherwise, they don't cause any negative effects.
Mounting a Lumix G 45-200mm f/4-5.6 tele zoom lens
However, when mounted reversed, it focuses near infinity at 45mm, and nowhere at longer focal lengths. Hence, it is useless for reverse macro use.
Mounting other lenses
Both these lenses have a front thread of 52mm, making them easy to mount. But let's say you have the Lumix G 20mm f/1.7, with a front thread of 46mm. What to do?
You can get a step up ring. Mount a 46mm-52mm step up ring to the front of the lens, and then mount the front of the step up ring to the adapter. A step up ring is very cheap to get on various auction sites.
Take care that mounting a wide attachment to the Lumix G 20mm f/1.7 lens can cause the focus mechanism to jam. So don't power the lens with the step up ring attached.
Conclusion
Using the reverser ring adapter, the Lumix G 14-42mm lens can be mounted reversed, and the zoom ring can be used for focusing. The magnification rate is 1.15x-2.5x, which is not a very large range. For comparison, Canon has a specialized macro lens called Canon 65mm MP-E, with a macro focus range of 1x-5x.
Changing the aperture is not very easy with this lens, but it is needed. You cannot photograph macro images using the lens wide open, since the DOF is too thin. To stop down the lens, you can mount it to a camera, and start a long exposure at f/8, 4s, for example. As the camera is exposing, remove the lens. That way, the lens is stopped down to f/8 when you remove it. Do this at your own risk.
This is a cheap way to achieve macro possibilities with the kit lens, a lens that quite many users probably have already. But is is not very easy to use. First of all, the working distance is very short, so you cannot photograph live insects. They will be scared off.
Second, changing the aperture is awkward. And third, the macro range is limited, at 1.15x to 2.5x.
But if you want to experiment with macro images of static objects, than this is a very inexpensive way to do so.
The Samyang 7.5mm f/3.5 fisheye lens is an interesting addition to the Micro Four Thirds lineup. While most third party Micro Four Thirds lenses so far have been existing manual lens designs given a new mount, this lens is designed for the Micro Four Thirds format from ground up.
How can I tell? A full frame fisheye lens has 180° diagonal field of view. Hence, the lens must match the sensor size exactly. If the lens was designed for APS-C, a larger format, then the corners would not correspond to 180° angle of view. A fisheye lens which does not project to 180° in the corners is pretty much useless. Then it is just a wide angle lens with a lot of geometric distortion.
Compared with the existing Lumix G 8mm f/3.5 fisheye lens, the Samyang lens is a much more traditional design, with a manual focus ring and aperture ring.
Some say the Samyang lens features a different projection type, the Stereographic projection. This is supposed to be less distorted than the Spherical projection traditionally associated with fisheye lenses. Let's look into how their projections differ. Here is a picture taken with both lenses, and also using the Olympus Zuiko Digital 9-18mm Four Thirds wide angle zoom at 9mm:
Samyang 7.5mm
Lumix G 8mm
Olympus 9-18mm @ 9mm
By superimposing both the fisheye images in one image, and doing edge detection, we can see how their projections compare:
And let's look at another example:
Samyang 7.5mm
Lumix G 8mm
Olympus 9-18mm @ 9mm
Superimposing the two gives:
(Click for larger images.)
Conclusion
So, what is the conclusion of all this? First of all, from the second example, we observe that both lenses have pretty much the same diagonal field of view. This experiment does not verify that the diagonal field of view is exactly 180°, as it should be, but at least both lenses have around the same maximum diagonal angle. To be more precise, the Samyang lens appears to render a slightly wider diagonal field of view. This might be due to the shorter focal length, 7.5mm versus 8mm.
Regarding the distortion, we can see that the Samyang lens renders objects which are inside the border of the image a little bit smaller. This means that it distorts the images somewhat less. So the rumor is true: The Samyang lens does give less "fisheye distortion".
But surely, the differences are pretty marginal. You're not likely to notice much difference, unless comparing head to head, as I do in this article. So if you're looking at the Samyang 7.5mm lens to avoid the fisheye distortion, you are going to be disappointed.
One thing to note is that if you plan to convert to rectilinear images in post processing, the Samyang lens has the potential for giving you the widest possible rectilinear images of the two fisheye lenses. This process is called defishing, and you can read about the topic here. It is probably not true that the Samyang lens features stereographic projection. It still has fisheye projection, but with slightly less distortion than the Lumix G 8mm f/3.5 fisheye lens.
The Panasonic GH series has comprised the premium camera models for Micro Four Thirds. The Panasonic GH1 and GH2 have had the best video quality among mirrorless cameras at the same time, and they are also considered to have the best sensor for photos. They are not intended to be volume models, but rather to sell at a premium price for those who want the best camera.
Panasonic GH1 (left) and GH2 (right)
The Panasonic GH2 was announced in September 2010. I bought it the very first day it was available in my market, which was in December 2010. Hence, this camera is starting to get old. In this article, I would like to speculate a bit about what we can expect from the GH3.
