Photo Technical

Control of shutter powerful, but it moves with aperture – A47

Welcome aboard photo enthusiasts… the list of camera specifications is definitely dwindling down in this seventh edition.  You can find all the specifications for just about any camera on such websites as In order to explain what each specification means, I continue to use the randomly chosen Lumix DMC-FX150 camera, manufactured by Panasonic.  We ended on Flash modes: Auto, Red-Eye Auto, On, Red-Eye On, Red-Eye Slow Sync, Off – the last go around, and move on to:

Exposure compensation: -2 to +2 EV in 0.3 EV steps: This feature I seldom use, although for a pocket camera with no manual controls it could come in handy for you.  It may show up on your camera as EV+/- and when entering this feature in my camera I get a notched horizontal line with ‘0’ at center, -1, -2 on the left and +1, +2 on the right side.  Using the left-right arrow keys I can incrementally go in either direction.

If I go to the positive end I will add to the exposure making things lighter, and going left has the opposite effect.   What’s the point?  Let’s say you plan to take (many) photographs your child at play against a bright background.  The tendency for the camera is to see and meter its settings for balance with the bright background.  The resulting images may then perfectly expose the background and your child is underexposed.

Oh, you have PhotoShop and can fix this (underexposures).  Forget about it.  Nothing ever replaces a perfect exposure, a perfectly taken image.

For a bright background setting the EV to +2 will account for the brightness seen by the camera meter, and adjust the auto settings for an extra 2 stops of light.  The result will be a properly exposed child at play.  The background may not be properly exposed, but do we care?  No.  Again, when taking a series of active photos (to get one great shot), in similar circumstances as just described it is handy to make an EV adjustment.

For just one shot what would you try differently?  Options exist with professional cameras, but just experimenting with my pocket camera I found my only option was going to my meter settings (under the menu button) and selecting spot metering.  This means the camera meter picks a small spot in the center of the frame to set its exposure when the shutter is released.  Keep the spot on the playing child and you should get proper exposures.

This brings up something important that I think is vital in choosing your pocket camera.  From what I read on dpreview the focus is set at the mid way point of pressing the shutter, but not the exposure.  Unfortunately this (if not a misprint) significantly limits compositional creativity.

With my pocket camera pressing this half way point on the shutter also sets my exposure, that is, both focus and proper exposure is set at a half press of the shutter.  Then while keeping the shutter pressed half way I can now change the composition (for instance putting the subject off center to the right side of the frame) and still keep the proper focus and exposure for the subject when pressing the shutter all the way down for the shot.

According to details I read on dpreview about this Lumix specification for metering exposures, the light metering is set when the shutter is pressed all the way down, when taking the shot, or not at the mid-way point in pressing the shutter   This means when you press half way and re-frame your image you will get the right focus, but possibly not the right exposure, as this is only set when actually taking the photo.

Like I mentioned above, hopefully this is a miss-print or miss-interpretation on my part of what was written.  I often use this method of pressing half-way to set my focus and exposure and then changing my composition in my photography.  Check your camera and see how this works for you… I just double checked mine.

Metering: Intelligent multi-segment: I just mentioned (6th paragraph from the top) setting your camera to spot meter, that is, set to check exposure of a small dot area at the center of the frame.  This is one option.  There are normally three options, this being one of them.

A second option would be center weighted.  In this case it is no longer metering a small spot, but instead a larger rectangular area at the center of the frame.  I normally have my camera set to this position, as most subjects photographed generally cover more than a pin point area.

If you’re a landscape photographer you may want to experiment with the third option, which is the matrix grid.  Here the entire screen (or frame) is divided into normally nine (9) equal grids.  Each grid provides a numerical figure for exposure; all are combined to calculate a final best exposure for the overall (landscape) scene.

Understanding light metering is vital to great photographs, but for now my space meter has run out and I’ll take permission to go ashore.  Happy sailing!