Some mirror lenses turn past 'infinity' to allow for temperature changes in
focusing performance.
--
Jim Brokaw
OM-'s of all sorts, and no OM-oney...
on 5/30/03 1:40 PM, Piers Hemy at piers@xxxxxxxx wrote:
> I'm still not sure I'm with you Dan. Past infinity? Surely not - we'll
> have someone chiming in with Buzz Lightyear comments if we ain't careful!
>
> Perhaps what you are seeing is the ability to bring the lens into focus on
> something in the distance, and then go out of focus again - but that would
> be because "in the distance" actually isn't at infinity. That's a
> phenomenon I experienced when first using a 500mm mirror lens - it's as if
> infinity has syuddenly jumped back a mile or ten. But not a 'fault' with
> either lens or camera.
>
> Piers
>
> -----Original Message-----
> From: owner-olympus@xxxxxxxxxxxxxxx [mailto:owner-olympus@xxxxxxxxxxxxxxx]
> On Behalf Of daniel
> Sent: 30 May 2003 20:26
> To: olympus@xxxxxxxxxxxxxxx
> Subject: RE: [OM] Focusing Screens
>
>
> What focus screen are you using?
> Dan
>
> I think its fine, just getting the right screen I think.
> It will go just a bit past infinity in focus, after reaching it, I can still
> go a little more noticing the focus screen split image shift.
> Common for Tamrons?
> Just took some pictures but maybe I need to get use to it because it sure is
> sweet and handy lens.
> Seems that the lens is critical it focus much like a macro that can cause
> everything around it to be out of focus quickly.
> That must be how it achieves that out of focus look around a portrait so
> well?
> Dan
>
> In a message dated 5/30/2003 3:17:45 PM Eastern Daylight Time,
> om@xxxxxxxxxxxxxxxx writes:
>
>
>
>
> I borrowed a 180/2.5 that wouldn't reach infinity. Perhaps it's a common
> problem with the lenses?
>
> Skip
>
>
> I'll chime in. It's my 180 that Skip borrowed and found unable to focus to
> infinity. After Skip alerted me to the problem, I sent it off to Tamron,
> who said the focusing helicoid had been damaged and needed to be replaced.
> I had it done (it did cost a few), but the lens works fine now. I never
> really checked infinity focus on it before because I use it more as a long
> macro lens.
>
> So maybe it is a problem unique to this lens. Its worth fixing, though.
> Takes great images.
>
> Best,
>
> Greg L.
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