Tweet Any period articles or papers on Orthochomic film?

I am very interested in finding a contemporary article or technical paper regarding orthochromic film, especially tests on what colors in the spectrum it was sensitive to.

I heard it only registered blue but am interested in the specifics.

Anyone know of a source(s)?

Thanks in advance.

Darren,
I just looked at Google, and found lots of references. You have the spelling wrong, which might have prevented your finding it. The correct term is orthochromatic.
Good luck.

Ortho stock was SUPPOSED to be sensitive to blue and green light (ie. cyan), but the period stocks were really only sensitive to blue, hence the use of the blue glass for judging contrast in those days. If you use a blue filter, you'll find the same effect. Modern photo paper is ortho by nature, hence the use of a red light in its handling.

This book by Kodak covers the basics quite well:
http://books.google.com/books?id=QvwTAAAAYAAJ

Orthochromatic was sensitive to blue mostly. Panchromatic (emusision sensitive to all colors) only came in 1922.
But they could use some technics to try make it sensitive to some red, and that why tehre are some color system before 1922.

They could expose the orthochromatic film to hydrogen and add some filters to reduce the blue light.


Lumiere brother's autochrome was created before 1922, so it used orthochromatic B&W emulsion. SOme look very good:






Instead of use three B&W negatives for each primary color, Lumiere technic used combined micro filters irect on a single B&W plate. The micro filters was made using grains of potato starch dyed .


When panchromatic film was introduced, they industry did not changed immediately to this emulsion, cause it was a lot more expansive and labs charged more to develop, as it was more difficult to work, since any light color could spoil the virgen film.

Here is an interesting website. ADOX films still make Orthochromatic films in 35mm and other formats and offer some technical data.


http://www.adox.de/english/ADOX%20Films ... tho25.html" target="_blank" target="_blank" target="_blank

You want some ortho motion picture stock?

Simply buy Eastman 2302/5302 print stock. This lab stock has emulsion and exposure characteristics very much like the earliest Nitrate filmstocks with a corresponding sensitivity of about 5-10 ASA, although the stock is not technically rated for ISO/ASA speeds, because it was never intended to be used to directly photograph images, only make prints from negatives.

I have the sneaking suspicion that print stock IS the original formula for motion picture stock (Kodak anyway) and that this emulsion formula has changed very, very little since the 1890's, but that's just my strong suspicion...

Short ends are cheap, you can build a 35mm hand cranked camera and small pin rack, (find yourself a copy of the 1920's "Boy Mechanic" series of books for details) and knock yourself out.


Here, it should be in one of these two: (actually Vol 2 @ pages 198 to 205)

http://www.archive.org/details/theboymechanicvo12655gut" target="_blank
http://www.archive.org/details/boymechanicbook200chic2" target="_blank" target="_blank

thanks!

Technicolor camera, as we know, use beam splitter prisms and color filters to split the light to each B&W strip. But indeed the light is split by a single prism, so we have two splitted images. You may think: "How it got the 3 strips if split just by two???"

What happens is that in one side the camera had in one side a film emulsion sensitive sensitive to Red and Green (orthochrokatic film), in contact with a strip of panchromatic film ( film strips in contact by emulsion side to emulsion side). The ortochromatic film did not get the red light, and a a magenta filter allow just the red and blue light to expose this "two emulsion sandwich of strips" . The green light was capturedby the other splitted light, other side of prism, by a a single strip and a panhromatic filter after a green filter.

Well, it's easier to just lok this schematic:



If wasnt for the ortochromatic emulsion, the technicolor would need to created three splitted beams of light, using extra prisms, and would result in a considerable higher amounts of light than the usual technicolor we knwon that was already quite "light hungry". This would probably nearly invalid the use... So, say tahnks for ortochromatic emulsion for allow all technicolor classics we see today.

No wonder they used successive exposure methods for shooting animation - so much simpler! It wasn't like the cels were moving on their own either, to cause blurring between the color records the way SE turns out when photographing a real subject (as seen in some early color processes.)