Thursday, 27 October 2011

Olympus vs Panasonic @ 45mm

The long awaited portrait prime lens for Micro Four Thirds is finally here. Olympus has launched their M.Zuiko Digital 45mm f/1.8 lens. It is compact, fairly light, relatively cheap, and focuses quickly and noiselessly.

Before this lens was available, the closest we had to a portrait lens for the Micro Four Thirds format was the Panasonic Leica 45mm f/2.8 macro lens. While this lens is a good macro lens, it has not been very well received as a portrait lens because of the not so impressive f/2.8 maximum aperture.


Panasonic 45mm f/2.8 macro (left), Olympus 45mm f/1.8 (right)

How do these lenses compare when it comes to sharpness? I have made some tests to find out. The images were shot using the Panasonic GH2 camera, at base ISO 160, on a sturdy tripod, and with OIS turned off for the Panasonic lens. The Olympus lens does not feature any OIS.




Infinity focus

These images were taken at a focus distance of around infinity. The sun is in the upper left corner of the image frame, which makes for a challenging situation for any lens. A strong light source in the image frame can easily lead to flare, loss of contrast and chromatic aberration (CA) artifacts.



PL45 @ f/2.8
Olympus 45 @ f/1.8

Let's take a closer look at some 100% crops from various parts of the image frame. Here's from the centre:


And from the upper left corner, where the contrast is the largest:


And finally from the top right corner:


10m focus

These next set of images were taken at a focus distance of about 10m. These images were rescaled and sharpened. You can click on the images to see them in a larger size.



PL45 @ f/2.8
Olympus 45 @ f/1.8

For better evaluation of the sharpness, I have made crops from the centre of the image. These crops are taken at 100% magnification, meaning that one pixel in the image corresponds to one pixel from the camera. Click for an enlargement:


And here are similar crops from the extreme top right corner:


0.7m focus

And to complete the review, I have also compared the sharpness at a closer focus distance. In this case, the focus is placed on the centre of the ball, which is at approximately 0.7m distance (about two feet). A portrait distance is typically at 1m or more.




PL45 @ f/2.8
Olympus 45 @ f/1.8

And the crops from the centre:


To evaluate the sharpness based on these is probably not so easy. But the image series can be used to look at the out of focus rendering (bokeh):


Just to satisfy my curiosity, I also took these images at f/16. Due to diffraction, you would normally not use such a small aperture, since it will lead to some dullness at pixel level. But if you need a deep depth of focus, and are planning to publish the image on the web, I would say that it could be a reasonable balance between DOF and image quality to use f/16.


Night scene

Here is a night scene. The focus is set on the middle of the branch:




PL45 @ f/2.8
Olympus 45 @ f/1.8

Some closeups of the out of focus rendering of highlight on the top, right corner:


And from the left side:


Conclusion

So, which lens is best in terms of sharpness? I think that the Panasonic lens generally does better. The Panasonic lens appears to render a bit better at f/2.8, in my opinion. At larger apertures, there is no comparison, of course, since the Panasonic lens cannot be opened further.

The Olympus lens does exhibit quite a bit of dullness at f/1.8 and f/2. On the other hand, it could be that the DOF is too thin for this comparison, even at a focus distance of 10m. So the subject for this comparison was perhaps not entirely perfect.

At the largest apertures, the Olympus lens does show some chromatic aberration (CA) artifacts, both in the centre and in the corner. You can see that near objects have a purple outline, while far objects have a green outline. This is quite common, and can be seen also for the older Olympus Zuiko Digital 50mm f/2 macro lens. When stopped down to f/2.8, CA artifacts are no longer a problem.

The Panasonic lens does not exhibit any significant CA artifacts. Perhaps this is because the CA artifacts are removed in software post processing? I have tried to examine this by looking at uncorrected RAW images and JPEG images, and concluded that there are probably no software correction with the PL45.

I think it looks like flare affects the Panasonic lens the most. This is not surprising, since flare is generally a larger problem the more lens surfaces the light passes through. And the Panasonic lens has the most complicated optical design, with 14 lens elements in ten groups, while the Olympus lens has nine lens elements in eight groups.

The Olympus lens does not exhibit much vignetting. The Panasonic lens, on the other hand, has a bit of vignetting wide open, which goes away at f/4. Again, this could be due to software correction to the Olympus lens, I don't know.

The bokeh appears to be effective smoothing the background, but my daylight example image was not very challenging for the lenses. With higher contrast, at night, the out of focus rendering is not perfect for either lens. The discs are non round off-center for the Panasonic lens: They are elliptical when the lens is wide open. The Olympus lens gives pretty round discs wide open, but they have a tad bit more tacky edges when stopped down, due to the aperture blades not being as rounded.

The Olympus lens is cheaper and faster than the Panasonic lens. But the larger aperture comes at the expense of worse image quality wide open. At f/2.8, they are pretty comparable, but the Panasonic lens perhaps has the upper hand by a small margin. Despite these findings, the Olympus lens does appear to give a good value for money. For users looking for a portrait lens, or a moderately long and fast prime, this is the only choice at the moment.



Saturday, 22 October 2011

Bokeh comparison @ 200mm and 300mm

I like the long tele zoom Panasonic Lumix G 100-300mm f/4-5.6. It is unexpectedly sharp, considering the price, and generally fun to use.

However, after some use, I see some examples where the background blur is a bit distracting. The bokeh some times exhibit a bit of ringing, which means that it doesn't blur the background as effectively as one could wish for.

I decided to test the bokeh with some out of focus highlights. To do this, I photographed the same subject using three lenses, the Panasonic Lumix G 100-300mm f/4-5.6, Nikkor 200mm f/4 AIS, and Panasonic Lumix G 45-200mm f/4-5.6. The three lenses are shown below:


The Nikkor 200mm f/4 AIS lens in the centre is shown including the adapter needed to connect it to a Micro Four Thirds camera.

@ 200mm

The images were taken at dusk, with the camera on a sturdy tripod, and focused on the tree about 2 meters from the camera. I used ISO 160, the base ISO for the Panasonic GH2 camera. As I took the images late dusk, the lightning changed quickly, and they may have different exposure.

Here are the images, click to enlarge:


Lumix G 45-200mm @ 200mm f/5.6

Nikkor 200mm f/4

Lumix G 100-300mm @ 200mm f/4.9

I have made some enlargements as well. These are 100% crops from the centre of the images.


Bokeh

Based on this study, I cannot see any problems with the bokeh of these lenses. They all look just fine. One problem with the Nikkor 200mm f/4 AIS lens, though, is that the aperture diaphragm blades are not rounded. Hence, when stopping down, the lens gives nine-sided out of focus discs, they don't have a rounded edge:


Sharpness

When it comes to the sharpness, the crops above are not suited for comparing the sharpness across the lenses. The Lumix lenses support autofocus, of course, and after viewing the images on PC, I noticed that the camera has prioritized to get the edge of the tree in focus. When focusing the Nikkor 200mm lens manually, I focused on the centre of the branch. So they are not comparable. However, after looking at the images, my conclusion is the same as before: The Panasonic Lumix G 100-300mm f/4-5.6 is significantly sharper than the Panasonic Lumix G 45-200mm f/4-5.6 at 200mm. The Nikkor 200mm f/4 lens appears to sit between them, in terms of sharpness.

@ 300mm

The Panasonic Lumix G 100-300mm f/4-5.6 is my only lens capable of doing 300mm focal length. So I don't have anything to compare with. But here are a couple of images taken at 300mm f/5.6 and f/8:


Again, the bokeh looks just fine, no perceived problems here.

Conclusion

While I believe the Panasonic Lumix G 100-300mm f/4-5.6 is prone to giving slightly distracting bokeh in certain cases, I could not reveal any in this simple test.

We see clearly that the Nikkor 200mm f/4 AIS lens has non-circular out of focus rendering when stopped down, due to non-rounded aperture diaphragm blades. This is not so good for the resulting pictures.

I think that this simple test illustrates another example that legacy lenses are not perfect for use on modern cameras. While the lens is reasonably good in terms of sharpness, the primitive aperture makes it problematic when stopped down. In a previous study, I saw that the Pentax FA50 f/1.4 normal lens exhibits quite distracting bokeh between f/1.4 and f/2. The whole point of getting a fast legacy normal lens is to use it pretty much wide open, and that example shows that it can be non-optimal for such use.

So take care if you buy older manual lenses for use on Micro Four Thirds: Do some pre purchase research to make sure the lens fits your needs.

Wednesday, 5 October 2011

Sharpness comparisons @ 100mm and 200mm

Panasonic has got several Micro Four Thirds lenses that span the tele focus range, with the Lumix G 45-200mm f/4-5.6, Lumix G HD 14-140mm f/4-5.8, and Lumix G 100-300mm f/4-5.6 being three of them. The last one is the recently announced powerzoom capable Lumix X PZ 45-175mm f/4-5.6.

The Lumix G 45-200mm f/4-5.6 is a value tele zoom lens, with a useful focus range reaching from the typical portait to long tele area. It gives a good value for money for those who want to try out the tele range.

Marketed as a video optimized lens, the Lumix G HD 14-140mm f/4-5.8 is in fact versatile superzoom lens for photo and video use alike. It is large, expensive, and generally regarded as being very good.

The largest of the three, the Lumix G 100-300mm f/4-5.6, is a very long tele zoom, useful for various event photography, like spectator sports, birdwatching, safari, and so on. For this use, the price is in fact rather reasonable.

The three lenses are seen below:


But how do their sharpness compare? To try to answer this, I've tried to compare them where they overlap. In this experiment, I put the camera on a sturdy tripod, shot at ISO 160 with the Panasonic GH2, and used a delayed shutter to avoid camera shake. I also turned off OIS. I set the white balance to "overcast" for all the images.

I left the exposure at auto at all time, and sadly, the exposure turned out to be slightly different for some of the images. That's a bit negative for this comparison, but I think we can live with it.

Sharpness at 100mm

Here are the full images shot at 100mm, scaled down and sharpened. Click for larger images.




Lumix 45-200 @ 100mm f/4.7Lumix 100-300 @ 100mm f/4Lumix 14-140mm @ 100mm f/5.8

To better compare the sharpness, let's look at 100% crops. I have not applied any sharpening to these 1:1 images. These are taken from the image center. Click for larger images.

As it was a bit windy, I recommend that you don't look at the leaves to evaluate the sharpness. They may be negatively affected by motion blur due to the wind.


Sharpness at 200mm

Here are the full images shot at 200mm, scaled down and sharpened. Click for larger images.



Lumix 45-200 @ 200mm f/5.6Lumix 100-300 @ 200mm f/4.9

To better compare the sharpness, let's look at 100% crops. I have not applied any sharpening to these 1:1 images. These are taken from the image center. Click for larger images.


And from the top right corner:


Conclusion

Based on this study, it is quite clear that the Lumix G 100-300mm f/4-5.6 is the sharpest of the three lenses. It appears to be quite sharp even wide open. On the other hand, one could say that this is not surprising: It was used in the shorter end in this study, compared with the Lumix G 45-200mm f/4-5.6 which was used in the longer end of its zoom range. Also, the Lumix G 100-300mm lens has the lowest zoom ratio, which allows the designers to make less compromises.

The Lumix G HD 14-140mm f/4-5.8 disappoints a bit. But then again, it is a well known fact that it is not at its sharpest in the longer end, and 100mm is surely a long focal length for this lens.

The bokeh appears to be comparable between the 45-200mm lens and the 100-300mm lens. Perhaps one could say that the Lumix G 45-200mm is slightly more busy with the longer of these lenses, with some more "ringing" around the out of focus highlights. But they are pretty similar.

Monday, 3 October 2011

Lumix G 100-300mm f/4-5.6

The Panasonic Lumix G 100-300mm f/4-5.6 Mega O.I.S. is a long tele zoom. This kind of lens would normally be used by people who are interested in photographing birds, wildlife, spectator sports, safaris, and so on.


More mature DSLR camera systems are, generally speaking, better suited for these applications. This is due to a better continuous autofocus, which is possible with the PDAF system used in DSLR cameras. Hence, people with these interests, are probably using Canon and Nikon cameras, rather than Micro Four Thirds. However, with the introduction of the Lumix G 100-300mm, M4/3 users have a possibility to check this out.

There is an alternative lens with a similar focal range as well, the Olympus M.Zuiko Digital ED 75-300mm f/4.8-6.7. The Olympus lens does not feature built in image stabilization, and for that reason it is not so well suited for use on Panasonic Micro Four Thirds cameras.

To see how this lens is different from the smaller tele zooms (Lumix G 45-200mm f/4-5.6, Lumix X HD PZ 45-175mm f/4-5.6) and the superzoom (Lumix G HD 14-140mm f/4-5.8), take a look at this diagram:


In this picture, we have the focal length as the x-axis, and the maximum aperture as the y-axis. What we see, is that the 100-300mm lens covers longer focal lengths, of course, but also that it achieves a larger maximum aperture where it overlaps with the other lenses. So using the 100-300mm lens gives you the possibility to get a faster shutter speed, and more selective focus than the other lenses, for longer focal lengths.

Build and ergonomics

At the time of writing, the Panasonic Lumix G 100-300mm f/4-5.6 Mega O.I.S. tele zoom lens is the largest Micro Four Thirds lens available. It is a long tele zoom, and as you can see from the comparison below, it is significantly larger that the smaller brother Lumix G 45-200mm f/4-5.6:


And the difference is even larger when the zoom is extended to the max:


The Lumix 100-300mm lens has a filter thread diameter of 67mm. This is larger than the Lumix G HD 14-140mm f/4-5.8, which measures 62mm. The diameter of the front lens element is also larger with the 100-300mm lens.

Both lenses are supplied with hoods, and I recommend using them. The pictures above show the lenses without the hoods.

The Lumix 100-300mm lens appears to have a good build quality. Just like most Panasonic lenses, it has a metal lens mount, and the rest of the construction is based on various plastic compounds. I think this is a sensible material to use for such a lens.

Gripping the front end of the lens reveals that it is slightly loose, also when the zoom is not extended. This is normal for zoom lenses.

The zoom ring is a bit stiff, especially from the middle to long end of the zoom range. This makes smooth zooming very difficult. From what I have read, the zoom ring is a bit stiff on new lenses, and becomes smoother with use. So this doesn't worry me much. The zoom ring is covered with a ribbed rubber-like cylinder, which is thick and allows for a good grip.

The lens is heavy, heavier than the Lumix G 45-200mm f/4-5.6 and Lumix G HD 14-140mm f/4-5.8 lenses. I am using the lens on the Panasonic GH2 camera, and find that they go well together. It is fairly easy to hold the camera and lens due to the generous grip on the camera. With smaller M4/3 cameras, I think you might find the operation more difficult. Especially with cameras like the GF2 and GF3, which do not have any significant grip.

The zoom ring is wide and has a rubbery substance which makes it well suited for holding. It is natural to hold the camera with the right hand, and hold the left hand around the zoom ring. I found that I often touched the focus ring accidentally, causing the camera to go into focus assist mode with a zoomed view. However, half pressing the shutter button brings the camera back to the ordinary view mode, so this is no problem.

Autofocus

Just like the other Panasonic zoom lenses, the autofocus is very fast and silent.

One disadvantage with the smaller brother, the Lumix G 45-200mm f/4-5.6, is that it loses focus when zooming. The Lumix G 100-300mm lens is advertised to have some technology that makes it easier to retain focus during zooming. So does it mean that the lens is parfocal, that the focus is maintained when zooming? It looks like it is more parfocal, at least.

Here is a video example which illustrates the autofocus while zooming. The clip was recorded while holding the camera without using a tripod or any support. The distance to the squirrel was about 2m, close to the minimum focus distance of 1.5m. I started with the lens in 100mm, and zoomed slowly in to 300mm. Then I zoomed back out to 100mm:



What we see here, is that the focus is not perfect while zooming. It is not until I stop zooming at 300mm that the focus is regained perfectly, and then it takes a couple of seconds. The same can be seen when zooming out.

Of course, one should normally be careful zooming while video recording, since it is very difficult to zoom smoothly. But this video shows that perfect focus while zooming cannot be expected. Again, however, it is much better than when using the Lumix G 45-200mm f/4-5.6 lens.

Image stabilization

I have not done any scientific studies, but to me it appears that the OIS is more efficient than the Lumix G 45-200mm f/4-5.6 lens, especially during video recording.

Here is an example video, recorded handheld at 300mm. I left autofocus on. In retrospect, it would probably have been better to focus once, and then turn AF off. You can see that the focus is cycled now and then during the video, which is a bit distracting:



Note that the helicopter rotor blades look bent in the video. This is due to the rolling shutter effect.

I'm sure that with some practice, it should be easy to make less shaky videos.

Bokeh

Bokeh is the nature of the rendering of out of focus areas. When leaving some parts of an image out of focus, the rendering of these parts is important: While the photographer usually means to point the attention towards the areas that are in focus, a distracting bokeh can fool the viewer to spend more time looking at the background. So a smooth bokeh is important in blurring the areas that are out of focus, and not causing distractions.

Here are a couple of real life examples. From Washington Square Park, 150mm, f/5.6, ISO 1250, 1/320 second exposure:


By enlarging a part of it, we can study the bokeh more closely:


Here we see that there is some ringing around the highlights. This is not ideal, as it is distracting. In this example, I would say that the bokeh is not perfect, but it is not overly bad either.

Another example, 218mm, f/5.1, ISO 320, 1/500 second exposure:


Looking more closely at the out of focus rendering, it looks pretty normal:


Flare

The lens comes with a hood, and I recommend using it. The hood gives some protection against stray light coming from outside of the image circle (at 100mm focal length), and should reduce some flare problem.

Even with the hood, the lens can be negatively affected by flare, if there is a strong light source in the image frame, or just outside.

Here is an example illustrating this. It was taken at nine o'clock in the morning from East 43rd street 7th Avenue. The sun is just behind the Chrysler Building, and causes the clouds to be very bright (100mm, f/5.6, ISO 160, 1/2000 second):


This is a difficult situation for any lens, and especially a long tele lens. However, I would say the lens handles the backlight pretty well. The contrast is probably reduced a bit, but not much. And there is no significant ghosting or other negative effects.

Let's see how it goes at 300mm (f/5.6, ISO 160, 1/4000 second):


In this case, it looks like there is more significant loss of contrast due to flare. This is not unexpected: Generally it appears that flare is a larger problem the longer the lens is.

To see how the same building looks without the flare, let's view it from the other side, without the backlight (at 100mm and 300mm):


100mm, f/4, ISO 160, 1/2500 second.


300mm, f/5.6, ISO 160, 1/1600 second.

By looking at the difference between these images, it is clear that flare causes a significant loss of contrast, especially at 300mm focal lenght. Of course, the exposure of the building wall is not entirely similar in the two situations: In the backlit photos, the building is less exposed.

Sharpness

Enlarging the images of the Chrysler Building above makes it possible to do a quick assessment of the sharpness of the lens. This is from the image at 100mm, unsharpened (click for larger version):


And at 300mm, also unsharpened (click for larger version):


In these examples, I think the sharpness appears to be quite good, especially considering that they are taken at maximum aperture.

In this test, the lens comes out very well in a comparison between five lenses at 140mm.

In this sharpness comparison at 100mm, the 100-300mm lens comes out very well.

In this comparison, I show that the Lumix G 100-300mm lens is sharper than the Lumix G 45-200mm and Lumix G HD 14-140mm lenses.

Example images

Here are a couple of example images.

From Bronx Zoo, 223mm, f/5.1, ISO 250, 1/500 second:


From Williamsburg, 258mm, f/5.4, ISO 640, 1/125 second:


Both these images could benefit from being cropped a bit, but I show them here as the were taken.

Another example. It was taken at 300mm, f/6.3, 1/640s, ISO 160:


And here is a 100% crop from the centre of the image:


Video

Here is an example video recording of an air show.

Conclusion

This lens appears to tick all the boxes: It focuses quickly, it has effective OIS, it appears to be sharp and has good bokeh. And the price is not unreasonable.

So should you buy it? If you only want one tele zoom lens, then you should rather get the smaller brother, the Lumix G 45-200mm f/4-5.6 lens. Because it is smaller, lighter, cheaper, and most importantly, because it covers a focal length range that you are more likely to need on a daily basis.

The Lumix G 100-300mm lens, on the other hand, is a very long tele lens. Even in the short range of the zoom range, it already has a very narrow field of view. So it is a lens you would bring to special events, like sports, safari, and so on. It is not a lens you would normally leave on the camera while you walk around.

If you need a long tele lens, there are not really any alternatives to this lens. It's good then, that the Lumix G 100-300mm lens gives good image quality, at a reasonable price.