What color temperature illumination to use to view Kodacrome slides?

[retro film]

Hi,
What color temperature illumination am I supposed to use to view Kodachrome slides(what were they designed to be viewed with)?

Thanks

 

[wiltw]

Kodachrome original was launched by Kodak in 1935. The first practical fluorescent lighting was developed by a group of General Electric scientists researching an improved and practical fluorescent lamp. Under pressure from many competing companies the team designed the first practical and viable fluorescent lamp (U.S. Patent No. 2,259,040) that was first sold in 1938.

So the only available light source for viewboxes back then would probably have been incandescent.

 

[retro film]

ok thanks for the response,

 

[retro film]

so 2,700-3,300K would be the the color temperature used back then? Wouldnt this make the slides have a yellowy orange overcast to them?

 

[cliveh]

so 2,700-3,300K would be the the color temperature used back then? Wouldnt this make the slides have a yellowy orange overcast to them?

I think you may be confusing the colour temperature response of the film during exposure with viewing light. I would suggest you view them by whatever light makes them look good for you.

 

[retro film]

No, I know the difference. Both the light used to expose a scene for exposure and light used to view slides (projector or viewbox) both have a specific color temperature to them. Im interested in the optimal color temperature bulb for VIEWING a slide. using different color termperature bulbs on a projector will have a difference on the white balance of the projected image for example. Im assuming all slides I view were exposed under the correct lighting conditions (daylight) or indoor using a filter.

if incandescent bulbs were what they used for viewing slides when kodachrome first came out, then they would have 2500-3300K color temperature which is an yellow-orangey colored light. Also to be clear, Im more interested in the modern Kodachrome that recently got discontinued. I understand that the recent Kodachrome is different than the Kodachrome from the 1930s. So I would imagine the viewing illuminant requirements would be different.

Im interested in what the correct viewing illuminant would be in Kelvins (Im a calibration freak btw, so I dont want to just eyeball the best looking one)

 

[benjiboy]

Daylight balanced illumination, (i.e.. about 5,600 degrees Kelvin), the better quality light boxes have daylight balanced illumination.

 

[Prof_Pixel]

When projecting slides in the dark, the illuminant used isn't too important as the eye will adapt to the white point; viewing transparencies on a light box where there is additional illumination is a different matter.

 

[cliveh]

When projecting slides in the dark, the illuminant used isn't too important as the eye will adapt to the white point; viewing transparencies on a light box where there is additional illumination is a different matter.

Prof Pixel, your statement is also true for a light box in the dark. Are you confusing the issue by suggesting additional light that shows the slide by reflected light as well as transmitted?

 

[MartinP]

I suspect Prof_Pixel means that to make your eye see a colour-cast, even where there is none, is relatively easy when there are different light-sources around. As an example, the lightbox might be a perfect daylight temperature, but if everything else in the room is bright but warmer, then the slides can easily appear blue. However, when the slide is the only light around (projection in the dark, for example) then the eye does it's adaptation thing quite nicely.

 

[Prof_Pixel]

Basically, the human visual system assumes the brightest thing it sees is white; thus you can project color slides, that under daylight have a color cast, in a dark room and they will appear OK. Viewing slides/transparencies in a room with other lights present will negate this.

 

[retro film]

Thank you benjiboy for your answer, that color temperature would make sense since it is approximately neutral in color (not too cool, not too warm, so it should render a neutral color for grey areas in the film slide when viewed.

And what Prof-Pixel is reffering to is called chromatic adaptation.

 

[Poisson Du Jour]

5500° LED lightbox.

 

[DREW WILEY]

There is no one fixed answer. It's more important to have a full spectrum mid-range light source with a very high CRI. But the industry standard
when comparing on sample to another is 5000K. But a 5000K bulb does not produce a 5000K viewing light because the diffuser inevitably has
a slightly warm cast to it. Color pros will have different light sources available, since they want to match the display or reproduction conditions
of a specific client's needs. I use a variety of light sources in the darkroom so I can evaluate prints analogously. But my personal standard is
4200K because it is a nice compromise between daylight and tungsten illumination. Might lightbox for critical colorwork is very close to true
5000K, with are CRI around 98. Macbeath markets color booths, lightboxes, and targets for industry standard work, which might be informative to study. But casual viewing does not need this kind of accuracy. Critical viewing for precise color reproduction might.

 

[DREW WILEY]

Hello again Mr Pixel ... back before I could afford my own color darkroom, or even large format film, one trick I'd use when projecting slides was
was to use a slightly gray neutral gray background rather than an ordinary white projector screen. By tricking the eye in this manner, the
saturation of hues seemed to pop a lot more. One still thought white was white, but it no longer glared and competed. ... same reason many
museums choose a light neutral gray wall paint, though in this case they have to absorb the cold tones of ambient surrounding light, so generally add something to created an subtle warm neutral, which cumulatively comes out looking neutral gray, even though it isn't. During my
ole color consultant days I worked up formulas for a few museums. In one instance they failed to rotate their inventory and had an ancient
5-gal bucket which they wanted to use up before ordering more. So they decided to use it in the back room just in case there was some kind
of mismatch. Now it turns out the paint had gone completely rancid and stunk like sour milk, and that the room they used it in held the
central air conditioner for the entire museum, where the air intake was! So they had to shut the whole thing down for two weeks, paint over
the stinky paint with shellac, and air everything out. I was pretty humorous (not for them, and I'm sure the painter was looking for a new
employer!).