Knowing Your Camera

July 29, 2013

 

This woman doesn't look stressed (cross-eyed does not mean stressed) as she goes through the menus of her camera. She's probably sitting in a shady spot and has allowed time to make sure that all is correct. She looks to be well-prepared. Being prepared is the secret.

So what’s a good approach to becoming confident? Practice and experiment  often, until you begin to feel that all this is really pretty simple.  And it is simple after you understand only a few key camera settings.  These are: A) camera sensitivity to light (known as ISO setting) B) shutter speed, typically some fraction of a second and C) lens opening, always a fraction, such as 1/16, of a maximum theoretical lens opening (1 means fully open). These openings are known as a fractional opening stops(f-stops). So do a little exercise from the film days, as if you had a camera with no automated capabilities:

About noon on a bright sunny day, set your camera in manual mode (yikes!) by moving the wheel on top of the camera until M clicks into place. Then set your camera ISO to 400, your shutter speed to 400 (1/400 sec.), and your lens opening (aperature) to 16 (1/16 open). AND,turn off autofocus (yikes 2!) and focus manually for these

Go outside and take 12 or so shots of things and scenes around your home.  A flower, a bush, a picture of your car, the house across the street, one of grass or asphalt where the viewfinder/focusing screen is filled by it. Also take a picture of something that’s entirely in the shade with no sunny area in the shot at all.

As you shoot you might see the images show briefly on the screen on the back of the camera.  Do not try to evaluate them here.  It’s too bright and the screen is too small.

What you’ve done here is exercise the old film-days rule of “Sunny 16” which states, on a bright sunny day a good ‘normal’ exposure is aperture f-16 at a shutter speed of 1/ISO – in this case 1/400.

Now go inside, download the images to your computer.  View them full screen and make a list.  Beside each on the list make notes on anything that you think is out of focus or under or over exposed (doesn’t look right).  Most likely, the shot of something completely in the shade will look too dark. This is because your vision compensated at the time, making the object seem brighter than it actually was.

Last, go out the very next time that similar conditions occur outside, preferably right now or the next day, and shoot the same shots with the same camera settings EXCEPT with the dial on top of the camera set to Av, or whatever position that invokes “Aperture Priority” mode.  Make sure that the aperture is set to f-16 and that the ISO setting still 400, and use autofocus if you want.  You should notice while you’re shooting that the shutter speed will vary considerably from shot to shot.  This is because the camera METERING is now active and is trying to get the ‘most pleasing’ exposure.  It’s most likely making the shady shot a little brighter and the brighter subjects a little less so by varying SHUTTER speed to automatically change the exposure.  It MUST use the shutter speed to do this because you have SPECIFIED that aperture remain at f-16 and ISO at 400.  Aperture priority mode is an auto-exposure mode that ‘locks’ the lens opening (an important topic for another chapter). Download and compare the photos to the previous set to see this.  Ask a friend for an opinion/explanation if you are not sure what’s happening.

To be continued...  

 



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