Judging by the split-image, infinity comes in properly at both 35mm and
105mm (and other focal lengths in between). I've to recheck, as at 35mm it
should be supposed to focus *past* infinity (given that - while at 35mm - by
focusing a subject set at 20+ meters, the distance scale reads something
like 5m).
Didn't know that focus was supposed to be held only when zooming from 105mm
to 35mm... Anyhow, in that circumstances, my lens doesn't.
Thanks for your help
Ciao
Fabio
On 7/24/06, John Hermanson <omtech1@xxxxxxxxxxx> wrote:
>
>
> Zooms are only supposed to hold focus when zooming from telephoto to
> wide. Does infinity come in properly at 35 and 105? I'm not familiar
> with that specific lens, so can't really comment on how to adjust it.
>
> Closed 7/27 through 8/6
> ___________________________________
> John Hermanson
> Camtech Photo Services, Inc.
> 21 South Lane, Huntington NY 11743
> 631-424-2121 | Olympus OM Service since 1977
> http://www.zuiko.com | omtech1 AT verizon.net
>
>
> Fabio Fiorellato wrote:
> > Hi list,
> >
> > I've recently discovered that my Tamron SP 35-105mm f/2.8, apart from
> > having a mild amount of zoom creep, is not keeping correct focus when
> > zooming from one end to the other.
> >
> > I mean, if I focus a subject when the lens is at 105mm and then zoom
> > the lens backwards to 35mm, the same subject is not in focus anymore
> > (at least judging by the split image in the viewfinder).
> >
> > Of course the same happens when focusing at 35mm and then zooming at
> > 105: the lens is acting as a varifocal lens, although it wasn't
> > supposed to.
> >
> > Furthermore, the distance reading at 35mm are totally wrong: a
> > subject that is focused near infinite (>20m) when at 105mm, turns out
> > to be at 5m or the like when correctly focused at 35mm.
> >
> > Given that years ago I had lost a Zuiko 35-105 with slow diaphragm
> > because of an idiot repairman incompetency, I'd like to know from
> > those of you with much experience in the field (John H. for instance)
> > if repairing a one touch zoom is really that hard.
> >
> > I can live with the problem (my guess is that at 35mm setting I won't
> > focus right up to the minimum focusing distance, while at infinite
> > there is no problem at all except for the bad distance scale
> > readings) but I'm still considering the chance to let the lens be
> > CLA'ed, if that doesn't turn out to be such a hard job.
> >
> > Needless to say, I'll go for another repairman rather than the one
> > that killed my Zuiko 35-105 (R.I.P.).
> >
> > Anyhow, do you think that the focus misalignment should be a direct
> > consequence of the increased zoom creep? When I first bought the lens
> > the latter problem didn't showed, and neither did the misfocusing
> > issue.
> >
> > As usual, thanks for your precious help and hints
> >
> > Ciao!
> >
> > Fabio
>
>
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