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|Jun 19, 2008, 11:08 PM||#1|
Join Date: Jun 2008
I just purchased Sony DSC-H50 not to long ago. I have been exploring its funtions for the past week but being that I have never had a camera with so many capabilities Im completely lost! So i have some questions and hoping you guys had some answers or suggestions.
1.) When I am increasing the shutter speed on the "S"mode,why does the picture seem to be getting darker? I also noticed that in high light there seems to be a bright line that apears on the picture when increasing the speed.
-I was attemping to take a picture of my dog playing in the sprinkler but didnt want the water to seem like a continuous flow. I wanted the water and my dog to be frozen in the moment.
2.) I know there is a mode on the camera where if I wanted to take a picture of an object, I could have it completely focused on with the entire background out of focus. I think the indicator on the dail has a little man thats white and the one in back is just outline in white with dark on the inside. If the camera is in this mode will it do everything needed or should I take certain outside parameters into consideration? Any settings that I would need to be watching for? Can this function also be preformed in high action(sport games..below link)shots?
3.) I want to invest in a telephoto lens and wide angle lens in the near future.I know both of these dont do alot, but if you had to suggest one to be purchased first, which one?
I know these are probably dumb questions but any answers would be greatful!
|Jun 20, 2008, 1:08 AM||#2|
Join Date: Jul 2005
Ok, AAK wrote a paper about the earlier members of the H series and while it does not cover the H50 yet it does cover the H9 and most of that will apply.
Read it here.
As for why the picture was getting darker, well, the correct exposure is a balance between three things, the aperture, the shutter speed and the sensitivity of the sensor to light, ISO.
Shutter speed, the faster the shutter speed the less light gets in. The camera will then try to either increase the sensitivity of the sensor (increase the iso) or open the lens further (aperture) to let more light in.
A point and shoot like the H50 has a rather limited range of values the aperture and ISO can take, compared to a Dslr, so when you say the picture became darker it simply meantyou increased the shutter speed so far, the camera could not compensate anymore, and you underexposed the shot.
Aperture, the opening of the iris diaphragmthat sits behind the lens and opens and shuts to let more or less light into the camera.
Rather confusingly a larger aperture has a smaller number (measured as an fstop)
So f/2 is a larger aperture than f/2.8 indeed each f stop as in the picture below, lets in only half the light of the previous stop.
So if you were at f2.8 and closed down the lens to f/5.6 you would have reduced the light entering the lens to only 25% of the previous amount.
ISO, in the old days film was your sensor, as it got darker, you put in faster film, where the chemicals reacted to light faster but with the trade off that the pictures had "grain", the graininess increasing as the film got faster.
Since we can't swap out the digital sensor the signal is "boosted", but this boost also amps the noise in the signal, rather like turning up a weak radio station also increases the hiss and static. (this is a very very simplified explanation)
The higher the boost the more noise, blobs of random color, false speckles, etc ultimately reducing the image to a mess, where the picture looks more like a blurred watercolor that a photo.
The effect you are looking for, main subject sharp, background blurred is harder to achieve on a point and shoot due to thetiny sensor, compared to a dslr which has a vastly larger sensor.
The effect is based around the control of the depth of field (dof), where you want the object and a small region around it to appear to be in good sharp focus and the rest, the background to be out of focus giving a beautiful blur.
Read about depth of field etc in AAKs whitepaper see Chapter 8 - Esthetics: Zoom, POV, Depth of Field and Bokeh
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