Depth of field…

I guess you could describe me as a hack amateur photographer.  I haven’t quite got the artistic eye of my actor brother, or the technical mastery of my graphic designer sister, but I at least know how to composition a shot and have a rudimentary understanding of camera functionality.  For example, from the following two photos were taken last month when I did my track weekend over in NM. 

Aside from the aspect ratio, there’s not a lot of difference between these shots compositionally.  The one of Mark on the Deerslayer  (the one on the left) was taken with Amanda’s Canon EOS Digital Rebel, with the ISO set at 400, f-stop at 5.6, and a 1/1000 second exposure.  The one of Tim on the NSR was shot with my Canon PowerShot SD850IS point and shoot camera, with the ISO set at 80, the F-stop at 5.5, and a 1/400 second exposure.  Of course when I shot both of the images, I had ZERO clue as to what the relevant settings were on either of the cameras.  On the Rebel I turned the mode dial to “Sports”, and on the PowerShot I put the mode dial on “SCN” and selected “Kids&Pets”, since on both cameras, I knew those settings were the ‘best’ to capture fast moving objects.  No clue why, I just knew which automatic mode to use so I wouldn’t get blurry photos.

I did some asking around, and there aren’t too many guys shooting sports stuff at local events, which got me thinking.  I looked at some of the pictures various photographers in the area did for similar events, and while they were valid examples of “this guy was on this bike in this corner”, I didn’t think they ‘spoke’ to me from a biker perspective, in that they don’t inspire the individual who’s in the photo to break into a stunning description of what was going on when it was shot.  They lacked ’emotive presence’.  While I don’t think the two above are stellar shots, they are at least somewhat better than some of the others I’ve seen.  The question is, why?

For starters, being a sportbiker myself, I have a pretty good sense of which mental snapshots get captured as I’m riding.  Thus, the best photos are ones which externally capture something I remember from my time at the track via an internal snapshot.  Jumbled up inside the mish-mash of reference-points, target-points, products, sub-products (see Keith Code’s “A Twist of the Wrist” for explanations of those terms), there’s a string of internal photographs that go with them.  Examples: The first time I ever got a knee down. The first time I got a knee down at the track.  A good session chasing another bike around the track, etc, etc.  Thus, as a photographer, my goal would be to capture those moments externally.  It allows those who don’t do (insert sport/game/event type here) to catch a glimpse of the things which those of us who do ride/play/etc get to experience.  And for those of us who do ride, it allows us to perfect our mental image by providing either rebuttal or reinforcement from an external source. I.e. I did have my knee on the ground that first trackday, but my upper body positioning was all out of whack.  So, what it comes down to with regard to getting ‘the right’ shot, is timing.  How you develop that timing is either by doing the activity (ride, play sports, etc) or by watching it a lot.  I would argue that it takes longer to figure out when ‘the shot’ timing is about to occur by just watching, but you can get it sorted out either way.  This is why I think I can be a decent photographer, since I have a pretty good sense of timing.

Following closely behind timing is image composition.  I’m okay at this.  Not great, but at least okay.  Both images above have a bike on the track, slightly to the left of center, with the horizon line approximately 1/3 of the way down the photo.  Nothing to write home about, but they don’t commit the sin of having the subject at the very bottom of the image, or some ridiculous error like the front half of the front wheel not being in frame. Composition isn’t too difficult to learn, just Google “Photo composition”, and you’ll get a bunch of hits on The Golden Section, The Rule of Thirds, etc, etc.  I’m not going to belabor the point on this one, learning composition just takes practice.  Look at other photos, and just try and emulate them.  The next-level stuff has to do with focus and blur within the image. For example, the bike on the right above is clear while the background has a slight blur, and the background on the left isn’t.  The balance lies between enough blur to give a sense of speed, while not so much that it’s distracting.  The following are a full-frame shot, and a crop from the larger shot taken just with my cellphone camera… showing it’s not really about equipment, but the concept that makes decent photos.  I don’t claim that either of the following are ‘good’, just that they “don’t suck”, even when taken from a cell-phone camera (with some subsequent color-correction and resizing in Photoshop)

Decent:

Better:

With the advent of the digital camera, there is really no reason people shouldn’t be able to take pretty decent photographs. For 90+% of the photos the average joe takes, put the camera on “Auto” and just click away.  And for portraits or relatively still objects, timing becomes a non-issue.  So with a digital camera on auto and a ‘normal’ subject, all one has to do is not screw up the composition too horribly… yet somehow it still happens.  But now, assuming you’ve got a decent concept of timing, and a similar grasp of composition, how do you continue to improve?  No, the “Buy one of them thar cameras what let you swap the lenses on the front” is NOT valid.  Yes, with improved electronics, it is less likely that your ineptitude in the basics will overwhelm the camera’s ability to deal with sub-optimal conditions, but that does not mean you will take pictures that are any ‘better’.  What the DSLR camera has over the point-n-shoot is the capability to not rely on just the ‘Auto’ mode of the camera to figure out what you’re trying to take a photo of, and to instead allow the user to control either portions or all of the relevant settings involved with photography since the user already knows what they’re shooting.

Here are the things which govern how a picture comes out, and my rudimentary understanding thereof:

ISO: This is the sensitivity level of the camera to light.  With old film cameras, you had to invest in higher ISO film when you were going to shoot action stuff since the film needed to react to the light faster in order to render an image before the subject moved.  With new digital cameras, this is instantly adjustable from shot to shot, and can be bumped up when you’re shooting through a ‘slower’ lens or somewhere darker, like indoors or in places a flash isn’t allowed.  Some of the newer cameras register ISO values up over 10k, which is well beyond the values used in standard film cameras.  Generally speaking, you want to shoot with the lowest ISO you can in order for your image to have the least amount of ‘noise’  from oversensitivity of the camera sensor pixels.

Shutter speed:  Denoted in seconds or fractions of seconds, shutter speed is the amount of time the shutter inside the camera stays open to allow light to hit the film (or sensor).  Every photographer is different, but at some point you can no longer hold the camera steady offhand, and a tripod is required for the images to expose correctly without blur.  With a higher ISO, a faster shutter speed can be used since it takes less time for the film/sensor to react to the light.  Extremely long shutter speeds can be used to photograph things like stars, but any motion will be blurred, so a tripod is definitely necessary.

Aperture:  This is the size of the ‘pupil’ inside the camera lens, with larger apertures allowing more light, and thus ‘faster’ photos.  Aperture is listed by ‘f-stop’, which is notated by N = f/D where N is the ‘f-number’, f is the focal length of the lens, and D is the diameter of the iris.  A side effect of having a large opening is that the depth of field (thus the title here) gets tighter and tighter, while with a smaller aperture causes more of the image to be in focus.

The crazy thing is that all of these 3 settings interact with each other.  Lower f-stop (bigger opening) means more light, which means you can use a lower ISO (to reduce noise), or a faster shutter speed (to reduce blur).  Higher f-stop means you will get more of the image in focus (depth-wise), but it restricts light, meaning you either have to up the ISO or run a longer shutter opening, or some combination of both.

Examples:

(I left the ISO at 400 for all the below images, since I was experimenting with f-stop and shutter to see how it affected depth of field)

In this first image, the F-stop is at 2.5, which is as big as it will go for the macro lens I was using.  Since there was a bunch of light available, the shutter duration was only 1/50th of a second  Note that the lower bridge is in focus, while the saddles are blurry, even though they’re less than 2″ behind the front of the bridge.

On the other end of the spectrum, we have an image shot with the f-stop set at 32.  The shutter for this shot had to stay open for 8 seconds in order to gather enough light, but at the same time, because the bright spots on the bridge were reflections of the ceiling light, they appear blown out.  While even the strings just past the bridge were blurred in the previous image, this shot has good focus all the way down the guitar neck.

And here is the ‘thing’ about photography: Both of those shots are interesting from a technical standpoint, as they show the opposite ends of the spectrum with regard to depth of field.  However, neither is really that interesting from an aesthetic perspective, because while the ‘bokeh’ (the blurry area caused by a shallow depth of field) is interesting in the first shot, it’s really too much.  And in the second shot, it’s just a shot of a guitar neck.  Kinda evokes the same ‘meh’ as I felt looking at some of the track photos I’ve seen.  So, knowing what we know now, we apply some of the ‘art’ to our science of settings, and try and create an image which evokes some sort of response other than “most of that’s blurry”, or “Yeah, it’s a guitar neck”.  Like I said, I’m a hack amateur, but hopefully exploring stuff like this will eventually lead to being a decent amateur:


f/8, .5 second exposure

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