photoing_blues.txt 090929 2100 ========================== ========================== Technique: You may well note that I use Pentax cameras in many of my examples. That is not because I'm a Pentax fanboy, but because the only gear that I've shot extensively with is Pentax. Unless I suddenly start making enough money from photography to justify buying into a second system, I become a professional reveiwer of photo equipment, or someone loans me their camera for a couple of weeks, I'm simply not going to know enough about other systems to discuss them accurately. The first thing that I discuss is knowing your system. Every piece of gear has it's own ideosyncracies, and you need to know them in order to get the most performance out of your system. ---------------------- Learn your system: Camera user manuals explain, more or less, how the camera is supposed to work, they don't explain what it does. Learning how each camera works at the edges of its performance envelope takes time, experience and even some research. As an example, some people did some research on the Pentax K100D RAW files and there is no change to the electronics at ISOs higher than 800. Shooting ISO 3200 doesn't give you any advantage over underexposing by two stops at ISO 800. =========================== Shoot raw: Compressing data into JPEG format throws away information in the areas of the photo where detail can't be seen. When you are shooting in low light situations, that is exactly the detail that you are trying to recover. =========================== Focusing: Focusing in low light is tough. Autofocus is often more accurate than manual focus, but it's slow and prone to focusing on the wrong thing. ---------------------- Autofocus: There have been tests done to compare the accuracy of autofocus with manual focus that have shown autofocus to be significantly more accurate than manual focus. As with most modern technology, we can expect the gap to widen over time, especially since camera makers place more emphasis on improving automation on cameras, often at the expense of doing the same thing manually. Autofocus has two major flaws. It tends to be slow, especially in low light, and the shutter lag may cause you to miss the shot. The other problem with autofocus is that it is much better at finding something for it to focus on, than it is at knowing what you want to focus on. ---------------------- focus indicators: Most DSLRs have lights in the viewfinder that highlight what is in focus. These can come on when the autofocus locks on to something, or during manual focus, when one of the autofocus sensors detects that something is in focus. You have to be very careful with the focus indicators, they tend to work over a much broader area than you may expect, and the camera could be focusing on grain in the wooden dance floor, or a sign on the wall behind the dancers. This is something that comes with "knowing your camera". ---------------------- Prefocus with autofocus: Many cameras have a way to autofocus when the camera is in manual focus, or to lock out the autofocus temporarily. I have set up my Pentaxes so that the "OK" or the "AF" button will disable the autofocus. When I'm framing a shot of dancers, I'll half press the shutter, allow the camera to get autofocus lock, then press the disable button with my thumb. As long as the dancers don't move (out of the depth of field) I can then take the photo without any shutter lag. ---------------------- Manual focus: Manual focus is arguably the most difficult to do, but I have found myself using it more and more when I photograph dancers, to the point where I use it almost exclusively. As I mentioned in the equipment section, I have katzeye focusing screens in both of my cameras. As much as I love split prism focusing, in extremely low light, I generally can't see well enough to make use of it. However, the microprism ring does seem to work fairly well. Most of the time, I take advantage of the focus acquisition indicators in the viewfinder. The biggest hazard of these is that they don't always indicate focus on what you think they do. Time and again I look at a soft photo, only to find that the grain in the wooden floor is in perfect focus. The autofocus system, which also runs the focus indicators, is not only dumb, but lazy. It will trigger focus on whatever in the view is easiest for it to focus on. This will be whatever shows the best contrast, not necessarily what you find the most interesting. So, take advantage of the focus indicators, but don't make the mistake of thinking that they're looking at the same thing you are. One thing that I'll do when shooting a series of photos, is when I get a break in the action, I'll refocus. This way I'm a lot less likely to get a whole bunch of shots perfectly focused on the wrong thing. ---------------------- Trade resolution for depth of field: The smaller the image of something is on the sensor (the shorter the focal length or the further away the subject is) the greater the depth of field will be. This is why cameras with smaller sensors have more depth of field, to get the same angle of view, they need to use a shorter lens to make the image of the subject smaller, to fit it on the sensor. You can use this to your advantage, by using a shorter lens than you may need, and cropping in post processing. You lose a bit in resolution, but the tradeoff in depth of field may well be worth it. Besides, the shorter focal length can be very handy if the subjects move closer to you. ----------------------- Be aware of the narrow depth of field close to the hyperfocal distance: With a lens of about 30mm focal length, even at f/1.8 you will have a fair amount of depth of field when shooting subjects across the room. However, while it may seem that anything from seven feet to infinity is in focus, it isn't. If you get lazy and just leave the camera focused on infinity, things will look fine in the viewfinder (especially in low light) but very little, if anything, will actually be in focus. ---------------------- Focus trap: I don't know about other brands, but with Pentax you can mount a manual focus (or a quickshift) lens, put the body into autofocus mode, prefocus on a spot, and when the subject moves into focus, the shutter will trigger. This can be very handy when photographing birds, or racecars. However, it seems to have limited use in low light dance photography, because by the time the autofocus can figure out that the subject is in focus in the low light, it has moved out of focus again.