When you spot meter on the black leather and get 1/30 sec, the leather
will come out to be 18 0rey. The shadow button tells the camera that
what you just metered on is actually black (dark) so it makes the shutter
speed faster. Think about it, a faster shutter speed would "under" expose
the "18%" grey leather and it would come out black in the picture. On the
other hand, using the highlight button tells the camera that the item you
just metered was white (light). It compensates by decreasing the shutter
speed. The decreased shutter speed will "over" expose your "18 0rey"
leather and it will come out white in the picture. This stuff is all old hat
to
us needle readers. OM-1(n)'s don't die, they just chug away.
-Chris Riek
> -----Original Message-----
> From: John Hudson [SMTP:jahudson@xxxxxxxxx]
> Sent: Wednesday, June 16, 1999 1:39 PM
> To: LIST - Olympus
> Subject: [OM] OM4T / hightlight & shadow control
>
> Pages 81 thru 84 of my 6" by 4" OM4T instruction book covers the camera's
> highlight and shadow control metering features. The highlight example
> features three all white pieces of table crockery against an off white
> background and the shadow control features an all black telephone against
> a
> grey background.
>
> As an experiment I took a spot reading with my camera from a distance of
> about four feet of the non-polished black leather of an easy chair using
> 100
> ISO film under fairly bright but cloudy lighting conditions. The reading
> was
> 1/30 @ f2.8. The same reading was confirmed by a 15 degree spot reading
> with
> a Lunasix 3 hand held meter.
>
> When I re-spot metered with the camera and then pressed the shadow control
> button the exposure reading changed to 1/200 @ f2.8 which would result in
> a
> photo of a darker shade of black!
>
> I re-spot metered on the same chair and then pressed the highlight button
> and the exposure changed to 1/8 @ f2.8. Now this surprised me because I
> would have thought that for the highlight feature to work properly the
> camera's meter would have had to have sensed something white or highly
> light
> reflective. The longer exposure of 1/8 resulting from pressing the
> highlight
> button even though the normal spot metering showed 1/30 tells me that the
> highlight feature might be mimicking the characteristics of an incident
> light meter. However, in actuality, the mimicking in this case is false
> because the black leather is absorbing rather than reflecting light.
>
> I guess that my question is this: is the combined spot metering and
> highlight control feature an attempt to mimick the results of an incident
> light meter reading and if so how close would two sets of readings [one
> with
> an incident meter and the other using the OM4T spot & highlight feature]be
> in conditions when a straight reflected meter reading would produce false
> results ....... for example off snow or sand in bright sunny conditions
>
> Also, if the spot and shadow control exposure has the effect of mimicking
> an incident reading in reverse, so to speak, in cases where the subject
> matter absorbs as opposed to reflecting an excessive amount of light [like
> the black leather] I wonder whereabouts in the greyscale an off-black
> subject would have to be when the spot and shadow control exposure would
> match a straight spot reading.
>
> I have taken photographs of dark objects and have relied upon spot
> metering
> with my Lunasix 3 or my OM4T and the results have always been properly
> exposed. Now that I have run the spot and shadow control experiment using
> an
> admitedly dark subject [the black leather] and seen a jump in exposure
> from
> 1/30 to 1/200 at the same aperture I am wondering just how accurate the
> combined spot and shadow exposure feature really is..
>
> John Hudson
>
>
>
>
>
>
>
>
>
>
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