Focus and the TG4/5

The Olympus Tough TG4 and TG5 are two camera models that you’ll see a lot of around the macro dive sites.  They’re relatively cheap and have an awesome macro mode.

Like most compact cameras, the TGs have a single large focus point in the center of the frame.  It makes focusing a bit of a challenge sometimes.  Here are some techniques to help you out.

Focus, Hold, and Reframe.

This is a typical way that people work around the fixed focus point with a compact camera.  It works like this:

  • Select a focus target.
  • Half-press the shutter button to get an initial focus.  You’ll see the focus square in the LCD change to the color green and the camera will beep.  The beep is hard to hear when the camera is in a housing and underwater.
  • Keep holding the shutter button at half-press to keep the focus locked.  Don’t let go and don’t push it all the way to take the shot.
  • Reframe the picture.
  • Check to make sure that the right part of the picture is in focus.  Move the camera back and forth to move the focus.
  • Push the shutter button all the way down to take the shot.

So for something like a nudibranch’s rhinophores (their “horns” or “eyes” or “sensor stalks” or whatever you what to call them), you will always have problems getting them in focus with a compact camera because the area between the rhinophores is empty space.  So focus on one rhinophore, hold the focus, reframe to put both rhinophores in focus and the subject in the frame, and snap the shot.

One problem with this technique is that when you change the framing you might move the camera in or out a little bit which changes your focus.  So right before after I reframe, I do one split-second check that my focus didn’t move.

Focus Lock

Both models of TG camera have a highly undocumented focus lock feature.  The way you set it:

  • Select a focus target.
  • Half-press the shutter button to get an initial focus AND HOLD IT THAT WAY.  You’ll see the focus square in the LCD change to the color green and the camera will beep.  The beep is hard to hear when the camera is in a housing and underwater.
  • Push the “OK” button on the back of the camera to lock the focus.  Now the camera works the same as with Back Button Focus.  If you didn’t hold the shutter button at halfway, pressing “OK” will take you to the quick settings menu.
  • Take pictures using the locked focus.  Move the camera back and forth to change the focus point to put it exactly where you want it.  Pivot around the subject to change the angle of the focal plane.
  • Continue to take pictures with the locked focus.  You can now take pictures a lot faster than with the focus, hold, and reframe technique.
  • To unlock the focus, hit the “OK” button again.

Going back to our nudibranch example.  Focus on the flat spot between their rhinophores, lock focus, then usually you back off a tiny bit to put the rhinophores into focus.

Manual Focus Adjustment

Most compact cameras do not have manual focus.  But the TG4/5 supports it, although strangely.  You lock the focus just like described before.  Then you can use the up and down arrows on the keypad to move the focus point forward and back.  A shrewd reader will discover that they can use focus lock and the down arrow to move the focus as close to the front of the lens as possible and this lets you to take shots where tiny subjects fill the frame.  You’re welcome.

See you underwater!!

–Mike

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