Saturday, November 26, 2011

Selective Focus – gimmick or tool?

I was looking through my archives today, and I found this image – one that I never really liked. It’s a difficult subject, being an incredibly busy scene with algae literally choking the life out of what is known as Mud Lake, a small lake trapped inside the city near the Ottawa River.

The problem, in my opinion, is that the bokeh simply is not smooth. The turtle’s rear end (facing us, that’s the other problem :-) has speculars on it that are not smooth, and the algae itself is quite busy in the transition from sharp to smooth … the middle zone.

So what to do? I published this heavy crop way back in 2007. Shot with the D2Hs (a 4mp professional Nikon body!) and the 300mm f/4 AFS and TC17e 1.7x teleconverter. The latter device is a big part of the problem here, but the reach was needed as the turtle was a long way off …

But today, I thought that this might be one of those rare images that could benefit from selective focus. I generally consider that technique to be gimmicky, and it usually makes an image look amateurish in my opinion. But others quite like it, so who am I to judge?

So I decided to try a bit of a hack with this image. First, I loaded it up into ACR6 and selected the 2010 processing engine instead of the 2003 engine that originally processed this image. I also selected the Adobe Camera Neutral profile in order to tame the contrast in the bright sunlight. These are the worst lighting conditions in which to shoot, but that’s when turtles like to sun themselves.

The first version, immediately after conversion, is here. The donut speculars really stand out in this image. Click on any image here to see them at 800px and read the layers. This image has already been fully processed, so I created duplicate images and switched off the processing layers to show you the before images.

The second image switches the lens blur layer back on. I masked off the blur using a gradient from black to white and starting it at the center of the turtle’s head, stretching it to about the tail. With a heavy feathering, the effect I wanted was easy to get after a few tries. I also had to use a brush to make sure that the snout was sharp by painting pure black into the mask (you paint on the image with the mask selected.)

The speculars are tamed now and in fact the whole image looks smooth. The selective focus is pretty obvious and it almost tricks the eye into believing that this is real subject isolation. But that’s the thing with selective focus, it’s always a bit fake. Still, it improves the image because your eye will explore and then come back to the only really interesting point in the image … the turtle’s head.

The image is a bit dark at this point in my opinion, so I do what I usually do with any image … apply a curve to taste.

This restores the “bright, sunny day” look and yet leaves the head clearly visible. I allow the shadows to get a tiny bit darker, yet the contrast to the much lighter sunlit part takes care of the rest of the contrasty lighting effect. The lighter green is much closer to my memory of the algae, so all is well.

The final version, after the ultra-fine output sharpening from the PKSharpener2 tooling.

Not bad. Much, much better than the version I created in 2007. I suppose one can say that selective focus is just a tool … useful when it is needed.