On Tue, May 08, 2001 at 01:02:16PM +0000, John A. Lind wrote:
> At 17:01 5/8/01, Frieder Faig wrote:
> >While working with my spreadsheed, it occours more questions than answers.
> >The real focus lenght might differ about +/- 5%.
> > And a lens isn`t a ideal thin lens. When you calculate macro-distances this
> >diffrences values matters.
> >
> >As theoretical ideal 135mm my spreadsheed gives the following values :
> > Auto-Macro-Tubus max. extension (58mm):
> > Distance to film: 64.2 cm
> > working distance: 42.4 cm
> > lenght of equipment 22.0 cm
> >
> >Now I´ve made some measurements:
> >For the 135mm /F 4.5 Macro I've meassued the following:
> > Auto-Macro-Tubus max. extension (58mm):
> > Distance to film: 61.0 cm
> > working distance: 39.2cm
> > lenght of equipment 22.0 cm
I`ve made different setup fo a more accurate meassureing which is closer to the
publishes values:
Auto-Macro-Tubus max. extension (58mm):
Distance to film: 62.0 cm
working distance: 40.6cm
lenght of equipment 22.0 cm
> >Though the 135mm isn`t a thin lens, this values are hard to guess.
> >The best guess is 126mm real focal lenght and 26mm distance between
> >priciple planes
> >(dt. Hauptebenenabstand?).
Now the best guess values have changed to 131mm focal lenght and 4mm difference
of
principle plane.
Frieder Faig
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