Here's how I see it.
Originally Posted by Leigh B
Matt's trying to understand whether a Zone VI modified meter is worth looking into. It is alleged to have a better correlation to film in the extended regions.
He saw a website that debunks the modified meter. That external referenced site makes a convincing case that the meter modification is useless. I defended Fred Picker on a problem I saw in the tests.
You and I have been disconnected since then even though I am sure we agree.
Actually, I am trying to figure out how important the spectral sensitivity issue is, because of an outside APUG discussion wherein it was asserted that the Zone VI modified meter is essential, because all other meters were markedly incorrect or unreliable, due to the issue.
Originally Posted by Bill Burk
OK. Yes, I think we do agree.
The disconnect happened at post #14 where you were talking about the article (which I have not read).
Apparently it relied on the Macbeth chart for out-of-range analysis.
As I've stated repeatedly that's not a proper use of the product.
My concern with the use of 'live' subjects for analysis is lack of consistency. This is why the Macbeeth chart exists.
You can easily shoot a landscape and produce a photo. Try moving that landscape into a studio to shoot under strobes.
This is the purpose of the Macbeth chart. It can be moved inside with minimal effort.
And the Macbeth chart will yield the same results five years from now. I challenge you to guarantee that with any landscape.
I replace my Macbeth chart every ten years, and cannot tell the difference between any of them.
That is patently incorrect, based on my 50+ years of shooting, mostly black&white.
Originally Posted by MattKing
Most meters are quite accurate. I use a "modified" zone system, spot metering particular areas of interest if I think they are significantly different from what I would expect, thus requiring exposure adjustment.
Some folks will go ballistic if they think a meter reading is off by 1/10th of a stop (I don't know how they know that).
This is total hog wash. The film and the rest of the process would never notice such an error.
As to the actual magnitude of the UV/IR problem, let's look at the solar spectrum at the Earth's surface (red curve):
Ref: Wikipedia Sunlight/Composition: http://en.wikipedia.org/wiki/Sunlight#Composition
Note the UV/Visible/Infrared captions at the upper left of the graphic.
Note also the extremely low amplitude of the UV energy as compared with the visible.
Infrared energy extends quite a distance below visible, but that greatly exceeds the spectral sensitivity of general-purpose film.
The film sensitivity curves that PE posted in #4 and those that Bill posted in #5 show no sensitivity below 700nm.
If any UV/IR sensitivity exists, the available energy is only a small fraction of the visible energy that controls the meter.
My assessment: Picker found a solution looking for a problem, and provided biased analysis to support his product sales.
Yes, there might be a slight difference between meter readings in the general case, but not enough to worry about.
Couple of years ago I did this graph of the spectral sensivity of my Gossen Spotmaster 2 meter simply by placing spectral response curves of some films above the exposure meter's curve.
The difference was smaller than I thought forehand.
Yes, we agree and that's what happened.
Originally Posted by Leigh B
My best advice on the subject Matt from someone who has been shooting film for more than fifty years is to not tie yourself up in knots with the technicalitys, just go out and shoot film and enjoy it.
I couldn't agree more.
But after 40 plus years of shooting, it is fun to stumble upon an issue that hadn't really seemed too important before, and wonder if I should pay more attention.
I think I remain most curious though about how the various types of meters compare, and whether I should be more careful about switching back and forth.
And Ralph, thanks for that.