Friday, October 18, 2013

THE DOMES AND DEPTH OF FIELD

Whenever I haven't taken my camera out for a week or so, I start feeling compelled to do some shooting.  I think I may have a bit of an addiction going.  In any event, even when I'm not feeling inspired, I can almost always find something of interest at the Mitchell Domes.  So Friday morning I grabbed my camera and macro lens and made yet another trip there.

This time I decided to focus (figuratively) on depth of field.  With macro depth of field is critical, so I generally keep my camera set to Aperture Priority so that I have control over that variable.  And since I am using a tripod with my macro lens, shutter speed is generally not much of an issue, unless there is a breeze that is moving the plants around.

One of the first opportunities in the Desert Dome was a group of barrel cacti that were catching some of the morning sunlight.  I decided to shoot the cacti from a low level to capture the top of the closest cactus, which was getting some backlighting, and that is where I set the focus.  That meant that I had to position the camera about a foot off the ground.  I also wanted to include the cacti behind the subject cactus for context.  Here is the first shot I took, at f/10.


I liked that the background cacti were somewhat out of focus but still recognizable, and I was happy with the amount of detail available in the needles on top.  However, I decided I would also like to see what the shot would look like at different apertures.  Here is one at a wide-open f/3.2.


I thought this shot really lost something.  The background cacti were a little more out of focus, and that was OK.  The problem was with the needles of the foreground cactus.  I thought their blurriness was just too distracting.  Next I tried a much narrower aperture, this time f/32.


The background cacti are now in much better focus, but I think that is a problem.  The foreground needles are getting lost.  So my choice here was the first shot.

Another subject in the Desert Dome was some sort of succulent that I have shot a number of times in the past.  This plant has very three-dimensional "leaves" that are perhaps a foot high.  They start out green but then turn yellow and eventually black as they die off.  I wanted to highlight a dead leaf against a green and yellow background.  Here is the first shot.


This was taken at a relatively wide open aperture of f/5.6.  As a result, the background leaves are pretty much blurred out.  They provide a pleasant background, but it is difficult to identify them as other leaves in different stages.  Moreover, the spike at the top of the leaf is somewhat out of focus.  Here is a second shot taken at f/11.


Now the background is more intelligible.  In addition, the spike at the top of the foreground leaf is in better focus.  Finally, here is a shot taken at f/22.


Here the black leaf is in a bit better focus but there is still some blurriness in the background leaves.  I finally decided that I liked this shot the best of the three.  The black leaf is interesting . . . sort of . . . but it's not the worst thing to have the background in sufficient focus to be part of the subject matter.

One of the things I keep trying to do is to focus on just a leaf edge, allowing the remainder of the leaf to fall out of focus.  Here is one of my attempts, shot at an aperture of f/22.


This seems like a  very narrow aperture that should keep a lot of the image in pretty good focus.  But in this case I was extremely close (maybe 2-3 inches) from the ledge of the leaf edge, and, as a result, the depth of field was still extremely shallow.  The composition's just too simple, I think.

Here is another leaf shot.  In this case I was focusing on the closer edge at an aperture of f/8, taken from a distance of perhaps 10-12 inches.


A more interesting composition, I think.  In these situations it becomes important to find a stretch of edge that is relatively straight so that when I position the lens an an angle perpendicular to the line of the leaf edge, I am able to keep a reasonable length of the leaf edge in good focus.  Having "live view" really helps in situations like this.

Here is a shot of the petal of an orchid that illustrates that same idea.


This was taken at an aperture of f/8 but at a very close distance from the petal's edge.  Even though the edge of the petal is meandering, much of the front edge is at about the same distance from the lens.  Here I was just interested in creating an abstract, so I didn't care that the remainder of the flower had fallen out of focus.  This shot is cropped some so that the distance across the image is only perhaps 1-1/2 inches.

Here is another orchid shot.


Because orchids tend to be so "three-dimensional," it is hard to keep everything in focus at close range.  This was taken at f/45.

And finally here is a clump of bright daisy-like flowers from the Show Dome.  Here I just wanted to flood the image with flowers from edge to edge.


This was taken from a much greater distance than those above, so depth of field was not as much of an issue.  Even so, I took this at f/16.

John

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