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[OM] IS-30 features; follow-focus

Subject: [OM] IS-30 features; follow-focus
From: William Sommerwerck <williams@xxxxxxxxxx>
Date: Tue, 09 Mar 1999 05:52:04 -0800
"For ease of focusing in low light there is an "auxiliary flash activation"
available at distances up to 8m (IS-200: 5m). What is meant by that? Is the
built-in flash used to help the AF system in low light? With my IS-3000 there is
the red AF illuminator that automatically lights up in low light, but maybe the
smaller IS cameras has a somewhat different method of helping the AF system?"

When the light is so dim the autofocus won't work, the IS-10 and -20 pulse the
flash very rapidly (as they do for red-eye reduction). I presume there isn't
enough room in the camera body for a separate focus illuminator, so they use the
flash. There's no way to turn off this battery-draining feature, so I'm grateful
the IS-30 will need to use it less often.

To answer another question... the IS-30 is a camera in the IS-10/20 series. It
is not a new version of the IS-3.


"What does follow-focus mean or represent...?"

"Follow-focus" is the act of keeping the main subject in focus as it moves
toward or away from the camera. You normally do this "by hand," but a camera
with continuous autofocus does it automatically (as long as the autofocus sensor
remains on the object).

It's difficult to rapidly twist the focus ring of long lenses to keep quickly
moving objects in focus. That's why Novoflex came up with their system in which
you simply squeeze a grip to change focus. Novoflex lenses have been around at
least 40 years, I think.


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