More bokeh thoughts

Another example of the 17 lenses ability to produce very practical and nice bokeh.  At F2 it shows obvious drop off of depth of field, but the left and right sides of the image look pleasantly coherent. The good central sharpness, enhanced by good micro contrast, allow the front of the rail to stand out well against the immediate background of the wall and the areas further away are well and logically rendered. Notice how your eye can stray to other parts of the image where you expect sharpness and may feel you find it (back edge of the wall front), but when you look back to the hand rail holder, the sharpness jumps at you a bit. this allows the image to transition effortlessly from the point of best focus, to other areas of the image without calling out the focus/sharpness difference. In other words, you can tell a story with the whole image area without worrying about micro differences in focus point accuracy, but also prioritise the prime focal point slightly over the supporting elements. 

A focus miss is a miss, but how the lens renders those misses is part of it's character and practical benefit.

OMD EM5 17mm f2 (35mm f4 on a full frame)

OMD EM5 17mm f2 (35mm f4 on a full frame)

In practical terms, I found the Panasonic 20mm lacking (on EM5's) because it lagged in auto and manual focus speed (meaning in real terms accuracy) and it's bokeh had the more in vogue fast drop-off of focus, showing misses in all of their glory. I would not hesitate to shoot with the 17mm at f1.8-2.8 if needs must, knowing that the lens is very forgiving in it's depth of field transition. The 20mm lens would be used in a more considered way, applying wider apertures only to highlight sharp to blurred areas of an image. it would also require a lot more accuracy and smaller apertures when applying fixed "zone" focusing like below. In my kit, the 25mm f1.8 fills the role of the preferred 20mm focal length as I feel it does what that lens does only better, being a little longer. It is not that I like 25mm more than 20mm (I like 20-40mm equiv the most of all focal lengths), but I like the 25mm's perspective better in the way the two lenses render and the 17mm at what it does.

EM5 17mm f4, zone focussed at about 5 feet. It is perceived as sharp from the gloved hand to the car in the background. I would usually use f5-6-7.1 for zone focus application, but even f2.8 works ok. If I am forced to use a wider aperture, I switch to AF on this lens.

EM5 17mm f4, zone focussed at about 5 feet. It is perceived as sharp from the gloved hand to the car in the background. I would usually use f5-6-7.1 for zone focus application, but even f2.8 works ok. If I am forced to use a wider aperture, I switch to AF on this lens.

EM5 17mm f1.8. Focus fell on the phone and chain. I snuck 3 images in a row, with focus landing in different places with each. This was the one I liked the most, but all of them were ok. Notice how clearly the sleepers are rendered even at f1.8 at a close distance. They support, but do not compete with the main subject. His hair is not completely sharp, but a little clarity added with the brush tool helped. When studying this image I have felt I needed to fight the slight urge to lean back when transitioning from the rear people to the man leaning in. The lens also shows excellent contrast at ISO 1600, wide open.

EM5 17mm f1.8. Focus fell on the phone and chain. I snuck 3 images in a row, with focus landing in different places with each. This was the one I liked the most, but all of them were ok. Notice how clearly the sleepers are rendered even at f1.8 at a close distance. They support, but do not compete with the main subject. His hair is not completely sharp, but a little clarity added with the brush tool helped. When studying this image I have felt I needed to fight the slight urge to lean back when transitioning from the rear people to the man leaning in. The lens also shows excellent contrast at ISO 1600, wide open.

Pen F 12-40 at about 25mm f4 (slightly more DOF than 17mm f2). This image is busy, but with the 17mm lens it would be worse. Better to shoot at f4 with that lens, going for an all in focus look.

Pen F 12-40 at about 25mm f4 (slightly more DOF than 17mm f2). This image is busy, but with the 17mm lens it would be worse. Better to shoot at f4 with that lens, going for an all in focus look.

By comparison, the 12-40 zoom with it's "portrait" bokeh drops sharpness away faster and more dramatically and provides more "blobby" smoothness, considered by many to be the bokeh ideal. I will do better/closer comparison images at some point.

The 12-40 would have made the above (hand rail) image more fashionably sharp/soft, taking away some of the story telling ability the 17mm provides.