D&K Fairbanks wrote:
>
> I am trying to find out more information on extension tubes. I don't
> understand the purpose of the tubes, and what is the
> difference between
> manual and automatic. There are three different Zuiko
> extension tubes,
> 7, 14, and 25. Are any of these for specific purposes?
>
The tubes allow a lens to focus closer than its built-in focusing mechanism
allows.
The 50mm f/1.8 extends approximately 7mm by itself. Adding the 7mm tube
allows you to focus closer, with no gaps in the focusing range. The
combined extension is 14mm, and so adding the 14mm tube then allows to focus
even closer, again with no gaps in the focusing range.
The 50mm f/3.5 and f/2 macro lenses extend approximately 25mm by themselves,
allowing you to focus at half life size (a subject 48x72mm fills the frame).
Adding the 25mm extension tube allows you to focus at 1:1, so that a 24x36mm
subject fills the frame.
The automatic tubes allow the automatic diaphragm in the lens to work as
normal. With manual tubes, the automatic diaphragm does not work, and you
have to stop down manually.
Alan Wood
http://www.alanwood.net (Unicode, special characters, pesticide names)
==============================================
List usage info: http://www.zuikoholic.com
List nannies: olympusadmin@xxxxxxxxxx
==============================================
|