F1 versus F5 illuminant?

[Stephen T]

Hello,

Both F1 and F5 are "standard" fluorescent daylight illuminants.
F1 has CCT=6430K and CRI=76.
F5 has CCT=6350K and CRI=72.
What is the difference?


F5 is widely available in ArgyllCMS. F1 is not.

I have some compact flourescent bulbs which are 6500 K Cool daylight and CRI 80. F1 could be a better match than F5 for these? Are the spectra of F5 and F1 very different?


P.S. I do not have a spectrometer to measure the bulbs.

Stephen.

[Michael Darling]

See http://www.cis.rit.edu/research/mcsl2/online/cie.php

Under CIE Standard Illuminant Data, they have A, D65, F1-F12 sampled in 5nm
increments, either on a webpage or in Excel format. If you graph F1 and F5
in Excel, you'll see they are very similar, but slightly different. Same
general shape and peak points, just slightly different amplitude here and
there.

Also see
http://en.wikipedia.org/wiki/Standard_illuminant#Illuminant_series_F

I prefer the home-made Excel graph from RIT's data, as the wikipedia graph
doesn't quite do it for me.

Someone may correct me, but comparing the two, I don't think you will see a
practical difference using F5 or F1 in ArgyllCMS. I think the other
variables will make the difference between the two spectrums
inconsequential.

It seems common practice to include a few of the Fx's but not all of them.
A few other programs that I use that allow you to choose the illuminant
don't have them all, which furthers me believing there's not a real-world
difference between the types they group together. Obviously a bigger
difference when you jump categories, F1-6, F7-9, and F10-12.

Post by Stephen T
Hello,
Both F1 and F5 are "standard" fluorescent daylight illuminants.
F1 has CCT=6430K and CRI=76.
F5 has CCT=6350K and CRI=72.
What is the difference?
F5 is widely available in ArgyllCMS. F1 is not.
I have some compact flourescent bulbs which are 6500 K Cool daylight and
CRI 80. F1 could be a better match than F5 for these? Are the spectra of F5
and F1 very different?
P.S. I do not have a spectrometer to measure the bulbs.
Stephen.

[Graeme Gill]

Post by Stephen T
Both F1 and F5 are "standard" fluorescent daylight illuminants.
F1 has CCT=6430K and CRI=76.
F5 has CCT=6350K and CRI=72.
What is the difference?

Hi,
there seems little information about exactly they represent. Even if
the manufacturer and model numbers was stated, it's unlikely to be much use
since the measurements are old, and models and phosphor formulations have
probably changed.

Post by Stephen T
F5 is widely available in ArgyllCMS. F1 is not.

F5 I take to be a typical cool white "office" lamp, while F8 I take to
be a higher CRI D50 "view booth" type illuminant.

In practice I've found them to be no substitute for measuring your
actual illuminant.

Post by Stephen T
I have some compact flourescent bulbs which are 6500 K Cool daylight and CRI 80.
F1 could be a better match than F5 for these? Are the spectra of F5 and F1 very different?

Attached are the F1, F5 & F8 spectra as ArgyllCMS .sp files. You can view them
using "specplot -c", as well as use them as a viewing illuminant.

Graeme Gill.