09-07-2015 01:43 PM - edited 09-07-2015 01:47 PM
Canon Powershot SX520 HS
You are exceeding the aperture range of the camera. It is too bright at low shutter speeds because the camera can't close the aperture far enough for a proper exposure. It is too dark at fast shutter speeds because the camera can not open the aperture far enough for a proper exposure.
Do a Google search on: Digital Photography 1 on 1: Episode 16: Exposure
09-07-2015 03:58 PM
09-07-2015 04:21 PM
My explanation above of what you are seeing is correct.
Until you understand the interaction of shutter speed, aperture, and ISO, I would suggest you use P (program) mode instead of Tv or M modes. You can still increase and decrease your shutter speed, but, only to those values that will give you a proper exposure. If you can't set the camera to the shutter speed you want in P mode, you probably shouldn't set the camera to that shutter speed in Tv or M modes.
09-07-2015 04:31 PM
You have stated no reason to be in Manual mode. That just creates issues as you have to balance shutter, aperture and ISO all yourself, and unless you are doing some kind of strobist work or going for a certain effect in studio, it probably has no upside for you that could offset the negatives of having messed-up exposures.
Even TV shutter priority is subject to the aperture limits of your Powershot's variable f/3.4 to f/6.0 max aperture lens. Outdoors in sunlight, on TV mode, I hope you are getting good results. Indoors, you will struggle, and your ISO will need to be high. I shot my family at a couple of local restaurants lately, and they don't seem too dim to the eye but to the camera it is very dim. I have to shoot ISO 1600 or ISO 3200 even with a bright f/1.4 prime lens wide open just to get a decent shutter speed of 1/60th to 1/100th.
The f/1.4 lens lets in between 3 stops to over 4 stops more light than your lens admits, depending on whether you are zoomed in or out. That is between EIGHT and more than SIXTEEN TIMES more light getting to the DSLR's sensor with a bright/fast lens mounted. So if a DSLR with an f/1.4 lens is shooting at f/1600 and getting proper exposure with a 1/60th shutter speed, your Powershot would have to be at ISO 128,000 zoomed out or ISO 256,000 zoomed in to give you the same exposure.
If if you are not already totally familiar with exposure, I'd suggest watching 2 or 3 free Short videos on "the exposure triangle" on YouTube. I also highly recommend the Book Understanding Exposure by Bryan Petersen.
09-07-2015 09:26 PM