View Full Version : Playing with the Av mode
2007 July 22nd, 23:51
I was playing with the Av mode yesterday while my clients are working with the photographer. By adjusting the F-stop values of the aperture, I can archieve the following results,
Depth of Field - Check out the background gets blury when I increase the size of the aperture.
Silky Water Flow - Check out the water flow becomes silky when I decrease the size of the aperture. You can really see how it turns from splashing water to silky water in the video too. Pretty cool
2007 July 23rd, 11:28
The DOF is indeed directly affected by the aperture, but the silky water is caused by the camera decreasing the shutter speed (longer exposure) to compensate for stopping down the aperture (and thus letting in less light). Just thought you might like to know.
2007 July 23rd, 11:30
um3k, thanks for pointing that out. Good to learn something. So, is it true that, since I am in the aperture priority mode, the camera automatically adjust the shutter value to accomodate the change that casuing the silking water flow?
2007 July 23rd, 11:47
That's right. The HV20 wants to maintain a constant exposure, so as you change the aperture, the shutter speed is changed to ensure 'correct' exposure.
Wide aperture --> faster shutter.
Narrow Aperture -> slow shutter.
2007 July 23rd, 11:48
In other words, I can also set it to Tv mode and achieve the same effect. Correct?
2007 July 23rd, 11:48
Although you see a difference in the water (and yes, your assumptions is correct) we can never get the wonderful "angel's hair" water effect that you can with a DSLR as your shutter speed needs to be in excess of 1/2 second, even multi seconds.
The way to do this is to have the (SLR/DSLR) camera on a tripod (naturally), shoot at the lowest ISO you can and use ND filters to further reduce the light entering the lens. Sometimes, depending on the amount of light present, a polarizer will do instead of an ND filter. Typically, you'll want to be in Shutter Priority mode to set the shutter speed to, say, 1 second, or in Aperture mode and choose a small aperture, say f11 or f16 (going higher such as f22 may introduce diffraction which will degrade the image).
Done correctly, it gives a beautiful, ethereal effect as the water's motion "paints" it's way through the image as the shutter is open. (Of course my wife insists that the water should be captured frozen by high shutter speed... oh well... we live under tyranny!)
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