Spetral sensitivity, tungsten or daylight?

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Helinophoto

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I was looking at some charts online from Ilford fp4+, Fomapan 100 and Fuji Acros, to compare them a little in relation to spectral sensitivity.
I am not well fared into the inner guts of these charts, so I wondered what this mean, when you try to compare two-three films, to see how they seemingly respond to various wavelengths of light.

I noticed that both Ilford and Fomapan display their charts for Tungsten, while Fuji displays the chart for Acros, for daylight.


upload_2018-4-10_14-55-38.png


Does the difference in the actual light-type (tungsten vs daylight) influence the curve?
- does this make a comparison futile?

What values are on the actual Y-axis for Acros, it's floating, while the Foma one also has no value, but is not?

Also, how does blue-sensitivity influence the tones for Red (if, at all) ?

These charts are as funny as they seem to be varied and I am having a hard time understanding what they actually can tell me about a film, if anything. :smile:
 

Old-N-Feeble

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Interesting question... following.
 

AgX

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Does the difference in the actual light-type (tungsten vs daylight) influence the curve?
- does this make a comparison futile?

Yes, of course, as the reaction of the film is dependant of what comes in.

If in the same part of the spectrum one manufacturer has twice the level of radiation than the other manufacturer, even a identical film would yield different spectrophraphs.
This fact is typically overlooked here at Apug.

And even if the same spectrum of radiation is applied then still there is room for interpretation.

So we got various types of spectrographs. Even some who will leave one completely clueless.
 
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AgX

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Manufacturers may go different ways, they can publish as engineer for the engineer, what I prefer, or they can make up some nice, plain graphic.
To the first group only two manufacturers belong, both not shown above.
 
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