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.



8 comments:

  1. Do you have a night scene bokeh comparison shot with the Olympus lens at f/2.8? It would be interesting to see the bokeh at the same aperture...

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  2. I will probably upload more comparison images in later articles. In the mean time, you can note that the Panasonic Leica 45mm lens always gives elliptical bokeh discs outside the centre of the image.

    The Olympus lens, on the other hand, has a more round shape across the image, but has slightly more jagged edges due to not as rounded aperture blades.

    In this respect, I think the Olympus lens is probably preferable.

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  3. Thanks, that was a another comparision that i had been looking for and exactly delivered what i needed to know!

    And after reading, clicking and blinking i know: there is no ideal lens, one is a bit sharper, is stabilized and has a macro range - while the other has decidedly more bokeh swish, even at the price of less sharp focussed areas.

    Blurry!

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  4. If you look carefully at the leaves in the top series you can see that the focus point for the Olympus lens is farther back than the Panasonic. The focus points need to be the same.

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  5. I would agree with the previous comment with respect to the first forest picture. The focus points for the two lenses do not appear to be the same. At first glance the PL45 appears to render the tree trunks with much more detail than the OLY45.

    I would suggest using a point focus (or manual focus) on one of the tree trunks for both lenses. This would put the two lenses on an even playing field.

    Regards,
    AJW

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  6. When it comes to choosing between these using ones head the olympus wins. But using ones heart the Panasonic renders much nicer images, in my opinion an outstanding difference. One can see that clearly in the night shot here above. The only problem with the Panasonic its the slow focus speed and its higher price.

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  7. Yes, I agree with you that for night shots, the Olympus 45mm f/1.8 lens is not always optimal. The high contrast is generally better handled by the smaller aperture lenses, like the Panasonic 45mm f/2.8 1:1 macro, and the Sigma 30mm f/2.8.

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  8. So, I was in my local camera shop the other day, taking comparison shots with the Panasonic 14-45mm at 45mm at f5.6, the Panasonic 45-200mm at 45mm at f4.0 and the Olympus 45mm at f1.8.

    Shooting in AWB, the Panasonic lenses both color balanced bluish, and the Olympus color corrected orangish. However, using any manual WB mode instead of AWB, the Olympus and Panasonic lenses corrected nearly identically.

    I got an Olympus 12mm f2 out of the case and it had the same issue. Same as the Panasonic lenses in manual WB modes, but very much warmer in AWB mode.

    So, do you know anything more about this issue with the GX1 AWB with Olympus lenses? Do other Panasonic cameras display this discrepancy? Would a lens firmware update address this?

    These test shots have identical white balance. Was this done manually or are the issues I'm having self inflicted? Or, maybe the problems exist on the 14-45mm and 45-200m but not the 45mm Panasonic prime?

    ReplyDelete