"Analog" Lightmeter Sensitivity.

[xpatUSA]

Recently, as posted here, I bought an oldish Sekonic L-398 - the one that looks like the really old Norwood Director model. After a lot of reading, I found out that the meter doesn't always read actual foot candles: that depends on what you mount on the swivel thingy.

Now, "analog" meters are not very sensitive in low light; in fact, I would be disinclined to believe any reading below about 10fc. However, I've noticed that the meter gives a much higher reading with nothing installed in the swivel - sort of the opposite effect of installing the HIGH slide into the swivel.

Having just bought the latest model L-398A with the "memory" pointer, I put it under some kitchen lighting and took two readings:

Dome on: it read about 20fc . . a 6 Ev scene.
Dome off: it read about 200fc for the same scene.

While I realize that the bare recessed sensor has neither a cardioid (dome) nor a cosine (disk) response, wouldn't it be nice if one could "just" subtract so many Ev and come up with an appropriate exposure?

Like for example the above ratio 200/20 is about 3-1/3 EV - so one would transfer the 200fc and see 9-1/3 Ev in the Ev window and then crank that down until it says 9-1/3 minus 3-1/3 = 6 Ev.

Thus the recommended f/8 @ 1/10 sec becomes f/8 @ 1 sec.

Advice to buy a digital lightmeter will be studiously ignored . .

[rpcrowe]

I have always used meters of this general type with the appropriate domes or disks attached.

[xpatUSA]

I have always used meters of this general type with the appropriate domes or disks attached.

So, for you, it seems that it would be of no use if one could "just" subtract so many Ev and come up with an appropriate [low-light] exposure.

[george013]

Not sure if I understood you. But is that using of the dome not the difference between using the light meter for incident light or reflective light?

George

[xpatUSA]

Not sure if I understood you.

Myself or Richard? If myself, don't worry - I'm used to it.

But is that using of the dome not the difference between using the light meter for incident light or reflective light?

George

Yes, of course the dome is used for incident light.

My post is about using the lightmeter with the dome removed from the swivel.

[george013]

Myself or Richard? If myself, don't worry - I'm used to it.



Yes, of course the dome is used for incident light.

My post is about using the lightmeter with the dome removed from the swivel.

In that case the dome is not much more as a gray filter. It let pass about 18% of the light, or 20 or 12 or something between, depending on the calibration. That's a fixed number. But the use of the meter is different. You never measure the same source.

George

[William W]

Recently, as posted here, I bought an oldish Sekonic L-398 - the one that looks like the really old Norwood Director model. After a lot of reading, I found out that the meter doesn't always read actual foot candles: that depends on what you mount on the swivel thingy.

Now, "analog" meters are not very sensitive in low light; in fact, I would be disinclined to believe any reading below about 10fc. However, I've noticed that the meter gives a much higher reading with nothing installed in the swivel - sort of the opposite effect of installing the HIGH slide into the swivel.

Having just bought the latest model L-398A with the "memory" pointer, I put it under some kitchen lighting and took two readings:

Dome on: it read about 20fc . . a 6 Ev scene.
Dome off: it read about 200fc for the same scene.

While I realize that the bare recessed sensor has neither a cardioid (dome) nor a cosine (disk) response, wouldn't it be nice if one could "just" subtract so many Ev and come up with an appropriate exposure?

Like for example the above ratio 200/20 is about 3-1/3 EV - so one would transfer the 200fc and see 9-1/3 Ev in the Ev window and then crank that down until it says 9-1/3 minus 3-1/3 = 6 Ev.

Thus the recommended f/8 @ 1/10 sec becomes f/8 @ 1 sec.

Advice to buy a digital lightmeter will be studiously ignored . .

Source unknown, probably wiki: "The Sekonic Studio Deluxe L-398 is a series of hand held light meter released in 1976 . . ."

Yer talking Filum Gear -

there's slippage - it's "sort of", "round about", "approximately" ... yer make up for all that in the processing of the neg.

My advice is to just enjoy the journey . . .

WW

[xpatUSA]

In that case the dome is not much more [than] a gray filter.

The comment is off-topic and displays your knowledge of incident light metering quite well.

May I suggest:

http://dougkerr.net/Pumpkin/articles/Norwoods_Dome.pdf

It let pass about 18% of the light, or 20 or 12 or something between, depending on the calibration. That's a fixed number.

Pure obfuscation. You appear to be deliberately confusing the so-called meter "calibration" with the light-transmission property of the dome material.

But the use of the meter is different. You never measure the same source.

I don't understand the point. These sound like truisms and are of no help to this thread.