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Well, step 1 is to put it on your camera.... :-) Actually, there are a couple of things for you to keep in mind when using a telephoto lens (and this of course is a telephoto zoom lens). Mainly, due to the apparent magnification you need to be more concerned about blur due to motion. The motion can be either of the subject (the race car speeding by) your you (your body's natural shake and rhythm just standing as still as you can due to heartbeat, etc.) To counteract these potential problems, you need to either use a fast enough shutter speed or a solid support (a/k/a tripod); the latter is always of value. To give you an idea of how fast is fast enough - the rule of thumb is the slowest shutter speed you should use is 1 over (the focal length of the lens times 1.5). In the 35MM film world, that 'crop factor of 1.5 wasn't there - so using a 300MM lens essentially meant that the slowest speed you'd want to handhold was 1/300th of a second. But since the crop factor of the DSLR is 1.5, that 300MM lens behaves as if it were a 450MM lens on the film camera (due to narrower angle of view - but let's not get technical here), so the slowest you should handhold at 300MM is 1/450th (or 1/500th) second. Of course, this might entail a lot of ambient light and/or a high ISO setting given the speed of that lens (f5.6 at the long end). If your subject is moving (kid on bike, dog running, whatever) then you might want to take shots at slower speeds while "panning" the camera - that is, moving the camera in the direction of the subject's motion. When timed right (i.e. -when you get lucky) this can make the subject somewhat sharp while the background smears into a motion blur of color that doesn't distract the eye. Since you have a digital camera and film costs aren't an issue, there's no harm in practicing on all kinds of subjects. You could try slow shutter speeds while actually zooming the lens in (or out) to see what kinds of effect you get that way, too. Also, for what it's worth, though the effect on that camera/lens combination is not major, the longer a lens is the shallower its depth of field at a given f-stop. This means that while your wide angle lens might give you 5 feet to infinity in focus at f8, the 300Mm lens DOF is much slimmer. Hope that helps - now get out there and play!
April 03, 2007
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