Wow! this is cool!

Markok765 · Sep 2, 2006

I just got back my kodacromes and it looks like someone etched a image on the emulsion. how does this happen? this also happens with stand developing.

htmlguru4242 · Sep 30, 2006

Not sure what causes this, but the image appearing in relief on the emulsion side is common with Kodachrome slides; it's one of the ways to identify a Kodachrome from another type of slide.

All of the Kodachrome's that I've seen have this; I'm imagining that the reason lies in the emulsion structure.

I'd bet that PE would know ...

Dave Parker · Sep 30, 2006

it is the reaction of the chemistry that removes the various parts of the emulsion, actually on some of the E6 slides you can see this as well..

Dave

reellis67 · Oct 1, 2006

It's very pronounced on Kodachrome. I've got thousands of stereo slides and they all exhibit that look.

- Randy

dmr · Oct 1, 2006

I noticed this many years ago when I shot my first Kodachrome, which was back in the 70's. I was told that it was due to the way the layers of the dye were formed during the processing. Maybe PE can elaborate on this.

Photo Engineer · Oct 1, 2006

Kodachrome is a very thin film. In fact, it is the thinnest color film ever made.

In that regard, when the dyes form, they form by reaction of 2 ingredients in the color developers, namely coupler and color developing agent.

The formation of this huge molecule causes the emulsion to swell in image areas, and edge effects further enhance this swell, shrink effect thereby forming a relief image on the surface of the film.

PE

reellis67 · Oct 2, 2006

PE, thanks for the details! I've always wondered about it, but never knew what the story was.

- Randy

Earl Dunbar · Oct 12, 2006

Does the thinness of the emulsion contribute to the sharpness? I would have to think it does.

kb244 · Oct 12, 2006

Its possible the way i understood it, is that kodachrome was an additive process (thus why so thin), because the color dyes of the film were added after/during development, as opposed to having the dyes already coupled in the film (ie: ektachrome), its a slightly more complicated process to develop kodachrome than it is to develop ektachrome.

I'm told that kodachrome has excellent dark storage life, where as ektachrome has much better light storage (ie: you can keep kodakchrome's colors for a lot longer in dark storage).

Photo Engineer · Oct 13, 2006

All analog color products are subtractive. They use cyan, magenta and yellow couplers to produce dye.

Kodachrome is sharp due to the thinness of the layer, and grain is low due to the small size of the dye particles.

Dye stability is high due to the method of formation which prevents easy oxidation or reaction with heat and humidity in the dark. Light stability is good as well, it is just not as good as more modern products as it was designed back in the 70s and 80s whereas the current Ektachromes were recently upgraded.

PE

bruce terry · Oct 13, 2006

PE- I'm looking at some super 'edgy' Aug58-dated Kodachrome 10 slides, which always appeared to me 'pleasingly oversharp' compared to the subsequent Kodachrome 25 series. Obviously the 10-film had to be speeded up for the market but God, I've always missed that original stuff, it was so unique!

Bruce

PS - Slightly related here, I have an extremely weird 'keeper' K25 slide that was processed in error by the factory as photomicrography film (if I've got that term right). The edges of everything on the red sports car and throughout the parking lot background are severely sharp, appear partially solarized, and probably are. I sent another roll to Kodak and asked them to make the same 'mistake' again but they refused to!

Wow! this is cool!

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