Spot Metering Automatic Vs. Manual

[Alexr25]

While the Pentax camera was called the "Spotmatic" the metering it actually used was simple through-the-lens stop-down averaging metering. I seem to recall that the pre-production model did have spot metering but by the time it went on sale they had changed the metering back to average metering since they doubted that the average amateur would be able to make sensible use of spot metering.
So the Spotmatic was neither 'spot' nor auto'matic'.

 

[FLCKeats]

I thought as much.

Thanks for everyone's replies.

 

[Bebulamar]

You can use any meter mode with any exposure mode but when using spot metering it's best to use manual exposure mode. The reason that when you point the meter on something you may not want to make that spot as medium tone. You may want to make the spot darker or lighter than medium tone.

 

[pgriz]

I suspect your friend either skipped a few chapters, or speed-read through the sections about how the various exposure methods worked. I use it in manual mode when I'm "sampling" the scene to get an idea of the dynamic range I'm looking at.

 

[fmw]

Let's go back and and take a look at the purpose for spot metering. The benefit the photographer gains from spot metering is the measurement of dynamic range. By having a narrow field, the photographer can measure highlights and shadows separately to have a measurement of the number of stops between the two. He can then decide on an overall exposure setting to include as much as possible of that range or determine what parts of that range were most important. The photographer would then have to use manual mode to set the shutter and aperture.

I suppose a photographer could try to choose a 15% gray area in the subject to spot meter with auto exposure but it would be easier and probably more accurate to use a matrix mode. In other words, the matrix mode will evaluate the subject overall and calculate something akin to what the photographer in the first paragraph would determine with the measurement of the dynamic range. Spot metering in auto mode would produce an exposure based on where the spot was set on the subject, not an evaluative calculation.

So I would say there is no reason at all to use spot metering with auto exposure. There are better approaches. Let's not forget that the photographer should operate the camera. We don't want the camera operating the photographer. If the photographer doesn't have the experience to use spot metering, he or she shouldn't use it at all.

 

[fmw]

I should have noted above that there is yet another option and it is the option I prefer. That is incident light metering. I'm not aware of any cameras having a built in incident meter but most hand held meters have the function.

Remember that reflected light is affected not only the brightness of the light falling on the subject but also the subject's reflectivity. Incident metering eliminates the effect of reflectivity. It will provide about the same exposure calculation as spot metering shadow and highlight and splitting the difference. I find incident metering to be a little fussy but the most foolproof approach for subjects that don't move and can use it.

 

[pgriz]

So I would say there is no reason at all to use spot metering with auto exposure.

If you have the scenario of rapidly changing light, and you MUST get the primary subject correctly exposed, then using the spot meter on automatic would do the job. For example, you're photographing someone underneath a canopy of leaves on a bright but windy day, with the sunlight filtering down through the leaves in a rapid and constantly changing pattern. Assuming you cannot find (or don't have the time to find) a better spot, then a spot meter reading on automatic will allow you to do the best under the circumstances.

 

[fmw]

So I would say there is no reason at all to use spot metering with auto exposure.

If you have the scenario of rapidly changing light, and you MUST get the primary subject correctly exposed, then using the spot meter on automatic would do the job. For example, you're photographing someone underneath a canopy of leaves on a bright but windy day, with the sunlight filtering down through the leaves in a rapid and constantly changing pattern. Assuming you cannot find (or don't have the time to find) a better spot, then a spot meter reading on automatic will allow you to do the best under the circumstances.

OK, if that works for you then fine. But I think a matrix mode will work better for most photographers in those situations.

 

[Dave Colangelo]

The best of the best spot meter in manual mode...

 

[Braineack]

Her explanation was that: " [if] You ... use spot-metering on automatic ... when you meter on the 'spot' you want, the automatic exposure compensates and corrects the rest of the image, as where on manual, you have to go in and fix everything else once that one spot is correctly metered."

on the surface this isn't technically wrong. but there's a reason it's called "manual" exposure...you know, because you have to manually "fix" everything once you've metered the scene [with any metering method], if you choose to.