Hi Mark
Date sent: Thu, 21 Mar 2002 08:28:10 -0700
Subject: Re: OM] Zuiko 100mm varieties
From: Mark Marr-Lyon <markml@xxxxxxx>
To: bj@xxxxxxxxxxxxxxx
> Hi Brian,
>
I noticed your scans have an
> interesting cross-hatch effect. Do you scan the print at the full
> resolution of your scanner, then resize when you're done tweaking? Do
> you see the same effect in the larger scans?
I haven't seen the cross-hatch effect on my screen. (Moire?)
No, I daren't scan at the full capabilities of my scanner. Even though it is a
real budget model, it will do 4800dpi and I doubt my hard drive could cope. I
seem to be getting OK results from it now. There is a learning process and I
think I downloaded newer drivers and installed them. Scans go better if I take
the HP 5L Laserjet printer off the line. Typically I scan somewhere between
72 and 144 DPI; depending on whether I believe at that moment what people
say about scanning at some exact multiple of the screen resolution and
such stuff, and how big I want the image to be. <g>
>
> I noticed on my lens that I can't focus beyond infinity, like with the
> 300/4.5. Does yours?
Yes mine does sometimes, that's why I mentioned it. To find that was a
surprise. It doesn't do it consistently, so now, as for the 300, I focus for
sharpness for far subjects as routine. Just as for closer.
I haven't checked yet if infinity really is
> infinity though. The aperture spring does seem to be a bit stronger
> than on other lenses too, but there also seems to be more damping too.
> I'm not sure if it should be there, or if it's helicoid grease
> migrating. I'm not sure if a strong return spring would contribute to
> vibration or not. It seems that the biggest effect would be the
> aperture slamming open harder, which should only happen after the
> shutter is closed. Of course, it certainly could increase vibration
> too, say when the camera's mechanism hits the opening lever...
>
I suspect there could at least be a torque (twisting) effect.
What I've started doing, when I remember, is to close the DOF button with
my little finger (hand-held shots) before the shutter; but I think some people
have said that could cause more bad vibes as the lever rams against its stop.
I'm going to look into this and see it some foam pad could be needed. In any
case the moving mass and the torque would both be less.
Brian
> Mark.
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