A meter reading which perplexes me

David Lyga

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There are two camera involved: Canon AE-1 (SPD meter cell) and Nikkormat FTN (CDS meter cell). I set each camera for Tri-X, using an EI 250 as normal. Outside, within sunlight, I get a proper EV 17 for both cameras. However, indoors, under artificial light, I get an EV of 9 for the AE-1 and an EV 11 for the Nikkormat.

Is there a difference with the two meters regarding artificial light? Again, outside, the readings are identical. In other words, do CDS meters underexpose under artificial lighting? - David Lyga
 

MattKing

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Indoors the Nikkormat may be reading too high, the AE-1 may be reading too low or they may both be wrong - in different directions.
The two different types of cells do have different spectral sensitivities.
In addition, with two cameras of that vintage, one or both of them may have lost linearity.
 

Sirius Glass

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If all light meters were properly calibrated by a technician, different meters see different spectrum and therefore some of the reading would not agree. That could be settled with soft noodles.
 
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David Lyga

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Sirius Glass said:
If all light meters were properly calibrated by a technician, different meters see different spectrum and therefore some of the reading would not agree. That could be settled with soft noodles.
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Or hard, uncooked ones to stab you with in order to settle the matter. I don't like having other than perfect equipment. - David Lyga
 

Sirius Glass

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David Lyga said:
Or hard, uncooked ones to stab you with in order to settle the matter. I don't like having other than perfect equipment. - David Lyga
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Al dente is perfect condition for pasta. Hard pasta is for storage and not as good as freshly made thus soft pasta. Where did you learn to cook anyway? Hoboken?
 
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David Lyga

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This goes beyond this. The AE-1 reading, indoors, is correct. In younger years, I have ALWAYS had INDOOR underexposure problems with B&W films which are metered with CDS equipment. Maybe this is just a characteristic of such meters. When the SPD meters came out, immediately this all seemed to have been corrected. I don't think many really appreciate how profoundly better these latter meters are. - David Lyga
 

Doremus Scudder

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David Lyga said:
... I have ALWAYS had INDOOR underexposure problems with B&W films which are metered with CDS equipment. Maybe this is just a characteristic of such meters. ...
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Yep, there is no "perfect equipment," you always have to know the limitations and the shortcomings in order to use anything well. Since you know that one meter reads low in artificial light, you can simply determine an exposure adjustment factor and then happily shoot away.

And, since the CDS cells give low readings in the predominantly red artificial lighting, they will likely do so as well when using orange and red filters if you use through-the-lens metering with them, so apply your exposure adjustment with them as well.

Once you've done a few exposure tests with artificial light and the filters, you problem is solved.

Best,

Doremus
 

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2 questions. First, how do the photos look? Is one camera's meter giving you better exposures with artificial light? Second, do you have a hand-held meter? Have it calibrated if possible and use that indoors or at least compare the reading with your cameras' meters so you know how to compensate. I am unsure you can calibrate a built-in meter.
 
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David Lyga

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Sirius Glass said:
Al dente is perfect condition for pasta. Hard pasta is for storage and not as good as freshly made thus soft pasta. Where did you learn to cook anyway? Hoboken?
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I learned to cook at a place called 'necessity'. I am a vegan (almost) and do not eat 'fresh' pasta which is made with eggs. I eat the regular, store bought pasta. - David Lyga
 
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David Lyga

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First, I KNOW how to expose after over 50 years doing so. I KNOW HOW, and DO, compensate after all these decades.

But, it is correct that CDS will give thin negatives in artificial light and SPD will not. That, to me, is a meter achievement which should be heralded. - David Lyga
 
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Pieter12

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So if you know all this, why are you perplexed?
 

MattKing

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I would suggest that it is better to say: "if you are metering with CDS, the tungsten speed of the film will be different (lower) than the daylight speed.
 

Sirius Glass

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David Lyga said:
I learned to cook at a place called 'necessity'. I am a vegan (almost) and do not eat 'fresh' pasta which is made with eggs. I eat the regular, store bought pasta. - David Lyga
Click to expand...

Oh so you are into the college student fare such as Spaghetti with Out Sauce.
 
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David Lyga

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Pieter12 said:
So if you know all this, why are you perplexed?
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To be honest, I 'knew' this in a subliminal sense without stating it objectively. I simply had thought, all along, that it was simply a quirk of artificial light being not quite sensitive enough to film. With this thread, I am solidifying my findings after decades of playing make believe and convenient conjecture. I am not too perfect. - David Lyga
 
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David Lyga

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MattKing said:
I would suggest that it is better to say: "if you are metering with CDS, the tungsten speed of the film will be different (lower) than the daylight speed.
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No, I like things to be theoretically viable, and that reasoning falls short of that superlative. The FILM is not less sensitive under tungsten light. The METER is faulty under tungsten light. I KNOW that, either way, either explanation would deliver the same result, but it is 'purer' here to state the truth and disclose 'who' is at fault.

But, yes, to lower the film speed when using a CDS is OK as far as the final result is concerned. - David Lyga
 
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David Lyga

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Sirius Glass said:
Oh so you are into the college student fare such as Spaghetti with Out Sauce.
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"Out" sauce seems to indicate homosexual tendencies with food. This is not a very savory culinary aspect with regard to something as pedestrian as sex. Spaghetti with tomatoes or garlic is more to my preference. I prefer to leave the sex part out of the equation.

To clarify: do not leave the sauce OUT. Leave it in and leave out the ulterior motives. - David Lyga
 

MattKing

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I'll use the same phrase, with a very small change: "if you are metering with CDS, the tungsten speed setting for the film will be different (lower) than the daylight speed setting."
 
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David Lyga

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MattKing said:
I'll use the same phrase, with a very small change: "if you are metering with CDS, the tungsten speed setting for the film will be different (lower) than the daylight speed setting."
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Yes, again, but for sanity reasons, just remember that it is NOT the film that is slower, but the meter that is registering too high. Keeping that in mind assures proper perspective when this anomaly is being explained to others. - David Lyga
 

MattKing

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David Lyga said:
Yes, again, but for sanity reasons, just remember that it is NOT the film that is slower, but the meter that is registering too high. Keeping that in mind assures proper perspective when this anomaly is being explained to others. - David Lyga
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We are at risk of getting into a semantic dispute.
If you are using your CDS meter, the speed setting on that meter for that film in tungsten light is that lower setting.
We aren't doing sensitometric tests with calibrated equipment here. We are measuring the light with the tools we have at hand.
You probably remember the days when many films came with two ASA ratings - one for tungsten, the other for daylight.
The film didn't magically change with the light. Its sensitivity was fixed, but the measurement of the two types of light needed to be dealt with differently.
There is a very good chance that at least part of the difference between those two ratings was due to the meters available at that time - some (most?) of them CDS meters.
 
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David Lyga

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Semantics rules. The meter's film speed IS set lower but that does NOT indicate that the film is deficient in speed. Yes, it is purely semantics but I like to keep the theory intact.

The meter is set lower because the METER is not behaving and NOT because the film is not living up to its promises.

Semantics rules.

And, yes, I do remember dual film speeds. And that was the era of when developers could be kept in non airtight tanks with merely a floating cover to delay the onset of oxidation. And Kodak offered premixed developer not only in cans, but also with keys soldered onto those cans so one would not have to use the kitchen can opener to open them. I am very, very OLD. Remember, the year I was born Bette Davis stared in All About Eve and that was also the year that The Third Man (Joseph Cotten, Orson Wells, Alida Valli) opened in the USA. - David Lyga
 
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MattKing

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What is the tungsten speed of the film David?
It will be an EI, not an ISO speed. ISO speeds aren't measured using tungsten light.
It will depend on what you use to measure it with. Some meters might work best with an EI close to or even identical with the ISO speed - it depends on their spectral sensitivity and how they are calibrated.
 

Sirius Glass

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I will spell it out for you.
  1. It has nothing to do with sex.
  2. "with Out Sauce" means "without sauce". We are talking about college students.
 
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David Lyga

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The tungsten speed of Tri-X is the same as it is for daylight. The CDS meter measures tungsten, erroneously, as being about two stops less than it should. - David Lyga
 

Oddscy

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hi im sorry this isnt related to the topic at all but i cant seem to find the option to create a post. any help is appreciated thanks in advance and sorry
 
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