"FSV" - Horseman Exposure Meter

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I bought a used Horseman exposure meter and was able to find a battery for it, but I'm confused about the meaning of "FSV" (full scale value? something else?) and what the indicated shutter speed corresponds to in the context of aperture.

I don't have the manual, but I gather that I'm supposed to set the ISO, take an FSV reading and use the dial to translate this to a shutter speed. But what aperture does this correspond to? How / when do I use the zero adjust control.

Many thanks. This is my last resort as I can't find any data online.

-- Matt Chroust (chroust@jps.net), December 17, 2000


The aperture is the one set on your lens when you take the reading. Pretty simple, huh? I had the same problem when I first tried to use one.

-- Howard Slavitt (info@naturelandscape.com), December 17, 2000.

I've already responded to Matt privately but am reposting it here for the benefit of archive searchers everywhere...

"FSV" stands for "film speed value" and appears to be roughly the same thing as the EV scale. The first thing you do is set the film speed with the rotating dial; then you insert the meter under the ground-glass, open the aperture and take a reading by rotating the knob on the side until the meter needle falls within range of the visible scale. Then you rotate the clear plastic dial on top of the film-speed dial until the thin green line lines up with the FSV shown by the meter ... since you've already picked your aperture, this indicates the correct shutter speed. If you want to use a specific shutter speed and let the aperture fall where it may, you simply work backwards; i.e., you select your preferred shutter speed on the scale, see what FSV is indicated and then adjust your aperture accordingly until you're getting the correct reading on the scale.

BTW, the zero adjust control is used to compensate for changes in the battery voltage ... set the scale to the battery check position, push the test button and use the adjustment screw to center the pointer in the wider band opposite the "0" mark.

-- Jeffrey Goggin (audidudi@mindspring.com), December 17, 2000.

I was just flipping through the copy of the owner's manual that I made for Matt and realized that I erred in my post above regarding the zero adjustment provision. Oops!

It turns out that it's NOT for the battery voltage but for zeroing the meter needle if it somehow gets knocked out of adjustment. It is done by turning the meter off, placing it on a flat surface facing upwards, and twisting the adjustment screw to or fro until the needle indicates zero.

-- Jeffrey Goggin (audidudi@mindspring.com), December 19, 2000.

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