what should i trust

[foon]

i just received my luna pro today and it even comes with the battery adapter 😀

i took some readings and they are really close to what the sunny-16 rule

but my nikon fm2n is telling me that's about a stop under....
i've been using my nikon for quite a while, have taken slides with it, i think the slides came out fine,
and that makes me always curious about the sunny 16 rule coz it always tell me to use f8 or f11 for 1/500 of a second(using 400 film)

now i'm metering a blank wall in front of me..
just so the metering area won't make a difference
and my nikon and gossen are giving me two different value
(and my contax tvs is giving me a third value)

i'm totally confused here :bang:

 

[zpuskas]

Your Luna Pro could be off. I'd check both against each other and whichever seems closest to perfection is the correct reading. You should be able to adjust the LP to correction anyway.
Another idea, find another meter, preferable hand held, and check that against what you have.

 

[jlw]

I have never seen two meters that read EXACTLY alike unless they have been calibrated to match each other (as is necessary in a commercial photography studio, for example.)

When setting up their meters, different manufacturers use different standards for the average reflectance of the scene, color temperature of the light source (the color sensitivity of the meter cell never exactly matches the sensitivity of the film), the user's preference for negative or slide film, etc. This causes the meters to give different readings even when pointed at the same scene.

Also, metering circuits are not perfectly linear, so even if you encounter two different meters that happen to read the same under one lighting condition, they probably will not read the same under brighter or dimmer light.

So, what to do? If your Luna-Pro only reads 1 stop different from your other meter, that suggests that it is working correctly. How do you adjust for the difference? Take pictures with your new meter, using whatever metering technique you prefer to use, and note how you like the results you get. If you feel your pictures need a bit more exposure, set the meter to a lower film speed; if you feel you need less exposure, set the meter to a higher film speed. Eventually you will derive a personal metering index that will give you results you like with that meter.

This used to be routine procedure for every serious photographer. Now, in the digital age, people seem to have the false expectation that everything will be exact and repeatable -- but when dealing with the natural world of light and human preference, that's seldom the case!

 

[Sonnar Brian]

I would tend to trust the SIlicon Photo Diodes in the Nikon over an older CDS cell. DO the readings "disagree" across the range, from room light to bright sunlight? Or do they disagree by a constant amount no matter what the lighting conditions? In other words, are both meters "linear with an offset" or do they agree at some light levels, but not at others? CDS cells tend to lose sensitivity at the extremes when they get old.

I tend to use an F2AS that has never given me reason to doubt its accuracy, and then adjust other meters to agree with it if they are way-off. Within a Stop, I let it ride.

 

[foon]

hmm,
thanks for your advice

maybe i should go get a couple rolls of slide film and take some pictures with the LP reading

is that a good idea?

 

[Gabriel M.A.]

Use the Force, Luke. Trust your instincts...

seriously, if you're metering a white wall, you're metering through the lens, and I would say that that would be actually one or two stops underexposed; if you're using your Luna light meter to meter *ambient* light, then I would guess that's about two stops of what you're getting from the same reading from your Nikon off the white wall.

 

[foon]

I would tend to trust the SIlicon Photo Diodes in the Nikon over an older CDS cell. DO the readings "disagree" across the range, from room light to bright sunlight? Or do they disagree by a constant amount no matter what the lighting conditions? In other words, are both meters "linear with an offset" or do they agree at some light levels, but not at others? CDS cells tend to lose sensitivity at the extremes when they get old.

I tend to use an F2AS that has never given me reason to doubt its accuracy, and then adjust other meters to agree with it if they are way-off. Within a Stop, I let it ride.

some readings they get really close
and some about a stop off

not extreme conditions though

 

[foon]

Use the Force, Luke. Trust your instincts...

seriously, if you're metering a white wall, you're metering through the lens, and I would say that that would be actually one or two stops underexposed; if you're using your Luna light meter to meter *ambient* light, then I would guess that's about two stops of what you're getting from the same reading from your Nikon off the white wall.

i was actaully measuring the reflected light by moving that little white thing aside, so both of the reading should be pretty close, shouldn't it?
of course if they are accurate that would be about two stops underexposed

 

[Todd.Hanz]

I think the Luna pro reads a 30* angle with the dome slid off the cell, I think that translates to a 90mm focal length. If your using a different focal length than 90mm there may be some discrepancy.


Todd

 

[Sonnar Brian]

I would just load some slide film and ry out the meter. If they agree on some conditions and not in others it could be a number of things like spectral response, field-of-view, and even response time. CDS tends to respond slower than SPD's. If the difference is 1 stop at the worst of it, I would not expect much better. You will not see too many meters/cameras agree with each other under all lighting conditions much better than 1 stop.

 

[FrankS]

Is It A White Wall? 🙂

 

[Roger Hicks]

Read a completely 'average' scene with both -- a blank wall isn't an 'average' scene.

Better still, as you suggest yourself, use the Lunapro/Lunasix with a couple of slide films and see what you get. Use INCIDENT mode -- otherwise there's little or no advantage over the camera meter.

Cheers,

Roger (www.rogerandfrances.com)



Cheers,

Roger

 

[foon]

Is It A White Wall? 🙂

it was pretty white i guess 😀

but does that matter? coz both the meter and the nikon is measuring the same thing

 

[foon]

Read a completely 'average' scene with both -- a blank wall isn't an 'average' scene.

Better still, as you suggest yourself, use the Lunapro/Lunasix with a couple of slide films and see what you get. Use INCIDENT mode -- otherwise there's little or no advantage over the camera meter.

Cheers,

Roger (www.rogerandfrances.com)



Cheers,

Roger

i only have a 50mm or 105mm for my nikon, so that's actually wider or narrower area than the metering area of the lunapro
and the nikon is center weighted too, so that would even be harder to tell how it is metering the scene

i just want a handheld meter for my meterless cameras, that's why i bought one

 

[Roger Hicks]

Dear Foon,

Well, for slides, incident is still better anyway.

For negs, use reflected and favour the darker parts of the scene.

Cheers,

Roger

 

[foon]

Dear Foon,

Well, for slides, incident is still better anyway.

For negs, use reflected and favour the darker parts of the scene.

Cheers,

Roger

Dear Roger,

Thanks for your suggestion,
I haven't really tried to use an incident light meter before,
that may worth a try

Foon