Limited depth of field - What use is it?


We've all seen pictures like the one above, probably taken a few too. This one is with a 50mm f/1.8 Nikkor lens set to f/1.8 on my Nikon D800E. Most of the 36MP are out of focus, so what actually does this achieve?

Following on from the excellent article I posted by Jordan Steele HERE I thought I would take this on and write a piece about fast lenses, wide apertures, limited depth of field and the dreaded "bokeh".

"Fast lenses." These are from film days, mostly for 35mm SLR's and rangefinders, when the notion of a decent image that you could actually distinguish detail in at ISO 1600 and 3200 was just a dream. ISO 200 with colour and ISO 400 with Black and white were pretty much the limits, unless that it is you liked film grain. When we all bought camera outfits in those days, it usually included a tripod and a flash gun. Because how else were we going to take pictures in low light? Those with deep pockets maybe had an f/1.4, f/1.2 or even an f/1 lens. (Canon made a 50mm f/1) It wasn't the whole answer but it helped. The lenses were primarily bought for their light gathering properties. The fact that wide open they weren't that sharp with lots of CA and fringing and the fact that there was limited depth of field were necessary evils, tolerated for those situations when the tripod and the flashgun were unable to be used.

Fast forward to now and that limited depth of field is worshipped in some circles. Now I can't remember ever talking to a single photographer, amateur or professional, who went on about what great results they could get at f/1.2. I have never known anyone who shoots other than a few test pictures at apertures like that, and I don't know anyone who doesn't use a lens with a ridiculously wide aperture wide open without a sense of foreboding. But wedding photographers use it all the time don't they? Well some might put a few pictures on their website but I've never met the bride who wanted a portrait of herself with only her left eye in focus, or with a picture of just a part of the ring on her finger in focus with some blurred things in the background that might possibly be her fingers.

Looked through a (non-photographic) magazine recently? Looked at the commercial, commissioned, editorial and advertising shots. Not many with limited depth of field and "creamy bokeh" are there? And for me that is the whole point. Just what use is limited depth of field other than to be posted on internet forums, published in photographic magazines and discussed down the camera club. "Look at the bokeh on that" "Fantastic, but what is it a picture of ?"

Now I've taken pictures with vast out of focus areas and something sharp somewhere in the image, usually as part of a review, but I've never sent one of them to a picture library. Partly because for what I shoot its completely innapropriate and secondly because they reject them, as neither use nor ornament. Whenever I read about how "artistic" it is to shoot with minimum depth-of-field I think about those poor souls who are macro practitioners. Now even with the lens closed right down to its minimum aperture, depth of field at the macro level is virtually non-existent, hence ring-flashes and all kinds of powerful lighting solutions. People sometimes moan about macro lenses not being fast enough. Anyone out there tried a macro shot at f/2.8? Hope you got better results than me.

Ansel Adams used a 10' x 8' view camera for a lot of his work. The "standard" lens for something like that is 300mm. You probably now understand why he formed the f/64 club! Contrast this with the 25mm standard lens on m4/3. A 300mm lens at f/64 on a 10x8 camera is roughly equivalent to a 25mm lens on a m4/3 camera at f/8. This is why when I write about m4/3 used for landscape I often mention the depth-of-field advantage. As Jordan Steele rightly points out this is because with the smaller sensor you can use lenses that have more depth-of-field to frame the same picture. Its the crop that makes the difference. 

So for the most part photographers have been constantly attempting to get the most depth-of-field at the lowest possible ISO. At least those who make a living selling their pictures do. I guess it is personal preference to a certain extent but I just don't like wide aperture images. I certainly don't find them artistic nor visually interesting. I can see a situation where needs must, but to go out and create images like that on purpose strikes me as pointless and the height of geekery. When someone has their portrait taken don't they have a right to expect the whole of their head to be in focus? Or do people like images of themselves with blurred ears? How many of us would buy a car if the pictures we see of it consisted of the front left headlight in focus and the rest of the image a dreamy mush? And how many of us would go on holiday to a hotel where the pictures consisted of close ups of twigs with limited focus for the actual place we would be staying in?

There is no denying that it does work to have something in sharp focus and a background somewhat softer, but I would argue the extremes of f/2 and below rarely offer us a view of the world that is either aesthetic or useful. Some might argue that it is of course, but I just can't see it. I'm much more interested in images that show their place in the world, that have some context and that have some connection with what we see with our eyes. To me limited depth-of-field pictures are just self-indulgence, often published and posted just to show what deep pockets the photographer has. There is nothing wrong with fast lenses, they can be very useful, and I would argue that fast lenses on m4/3 cameras are more useful than most, because they offer the ablity to gather a lot of light and the ability to render a decent amount of the subject in focus. I see both of these as advantages. And more importantly I see them as useful for creating photographs that are about whats inside the rectangle rather than what the camera / lens combination is able to do. 

Finally bokeh. Now I really don't care about bokeh. I'm just not interested. All those pictures of creamy out of focus nothing just leave me cold, because thats what it looks like to me, nothing. If I want that I can walk around without my glasses on anyway. The last thing I want to do is look at a picture simulating my short sight!

As per usual if you have a view on this pop over to Google+ and air your thoughts. Maybe someone might like to post or link to an image that shows just what marvels limited depth-of-field can create. Who knows, I might even be convinced.


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