AG, you're right about the coffee, but I think I was pondering the stern of
my boat and what shuTTer speed would stop the ruDDer. :~) My 100 f/2.8 does
exactly the same thing (f4).
Hmmm. Coffee, eh?
Richard
----- Original Message -----
From: "AG Schnozz" <agschnozz@xxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Tuesday, May 14, 2002 7:34 PM
Subject: Re: [OM] Shuddering over 100/2.8 (was: 135mm f3.5 better than tests
show?)
> > Help me here. What are you referring to as "serrated". What I
> > mean is, where are the serrations?
>
> With the lens off your camera and no caps in place, put the
> aperature at F4. Press the DOF button and watch the iris close
> down. In my lens, the iris blades leave little serrated edges
> at F4 and F5.6. (at F4, the serrations are quite large)
>
> > And one other thing, don't all shudders
> > such as the
> > OM's produce a starred effect as the lens opens up?
>
> Shudders are usually caused by consuming too much coffee. The
> star effect happens with most lenses as you close the iris down.
> It is caused by the defraction of light past the edges of the
> iris blades. Some lenses star better than others. I had one
> non-Zuiko zoom lens that had nine blades. The star effect was
> downright grotty. (everything else was nice about that lens,
> though).
>
> Most 100mm lenses will not produce much of a star effect, as
> this is more common with wide-angle lenses. Mine has more stars
> than the average galaxy.
>
> AG-Schnozz
>
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