This section is from the "Studio Light Incorporating The Aristo Eagle - The Artura Bulletin 1922 " book, by Aristo Motto. Also see Amazon: Studio Light Incorporating The Aristo Eagle - The Artura Bulletin 1922 .
The illustrations of Mr. Bur-gert's experiment with Panchromatic and Portrait Films are shown on pages 6 and 7.
In the Panchromatic Film the professional photographer, especially the commercial or technical worker, has the most plastic of all materials at his command.
It has those qualities that are peculiar to other professional Films and in addition is completely color sensitive. This means that with Panchromatic Film and color filters the photographer can completely correct the faulty rendering of colors given by ordinary materials that are not color-sensitive.
But Panchromatic Film does not merely correct. With the proper filters it permits of partial correction, complete correction or over correction. By complete correction we mean that colors are reproduced in the tones of the print in the same values they have to the eye when we look at the colored object.
If there is a red that is lighter than a blue it is reproduced lighter; if a yellow is darker than a green it is reproduced darker, and so all of the colors are shown in tones that are in correct relation to one another in the print from the negative that has been given complete color correction.
Partial or complete correction is secured by the use of yellow filters. Like all sensitive photographic material, Panchromatic Film can not be made proportionately sensitive to all colors. All photographic materials are most sensitive to blue, so with Panchromatic Film the correct amount of blue light must be eliminated to permit other colors to be photographed in their correct relation to blue.
Print From Eastman Portrait Film Negative, Made At Night 10 Minutes Exposure F.22 Stop.
Mazda Lights. Silks Displayed Are A Shade Of Orange.
Print From Eastman Commercial Panchromatic Film Negative, Made Without A Filter 10 Minutes Exposure F.2s Stop. Same Display Shown On Opposite Page.
It is readily seen how simple a matter it is to get a correct rendering of color by using the correct yellow filter. And it is equally simple to understand how the use of a filter which eliminates the excess of blue light also makes it necessary to increase the exposure in proportion to the amount of light that is cut out.
When only a small amount of color correction is necessary, as is often the case in landscape work, a light yellow filter will separate white clouds from blue sky or give a fair rendering of yellow fields against green and also permit of fairly short exposures.
It is also quite often necessary to over-correct colors or produce color contrasts. When several colors have the same tone or depth and are photographed on Panchromatic Film with a K-3 yellow filter, they are reproduced as though they were of one shade of gray.
When we look at these colors we see a color difference but when we photograph them we reproduce only their tone values which are alike. So it is readily seen that unless the photograph is to be colored some other method must be used if contrast between the colors is desired in the photograph. In producing color contrasts one must decide which colors shall be light and which dark. If the shades of orange and red are desired light, an orange-red filter (the Wratten A) will give such a result. If greens are desired lighter than reds, the Green B filter should be used, while if yellows are to be over-corrected the G filter, which is a strong yellow, should be used.
In explanation of the pleasing results secured by Mr. Burgert, as he states in his letter, without a filter, it is only necessary to explain the nature of the light used.
Mazda lamps produce a light of a yellow color - a light which contains considerably less blue than daylight. As Mr. Burgert's negatives were made at night by mazda lamps, the results were the same as would have been secured with a yellow filter had daylight been used.
The Panchromatic Film is not as fast as Portrait Film under ordinary conditions, but in this case the Panchromatic Film being more sensitive to yellow than Portrait Film, the speeds of the two films were equalized and a good negative was secured with a ten minute exposure in each case. As will be seen by the illustrations, however, the Panchromatic Film gives a correct rendering of the orange-red silks while the Portrait Film, not being sensitive to red, does not.
From this it will be seen that with an artificial light which is deficient in blue, a very good result can be secured on Panchromatic Film without any filter.
In our other illustrations we show a number of comparative results which show very clearly the advantages of using Panchromatic Films and filters in photographing objects containing color.
Print From Portrait Film Negative, No Filter Used. The Red Berries And Flowers Are Too Dark For Coloring.
Print From Eastman Commercial Panchromatic Film Negative. The Red A Filter Has Produced A Result That Is Suitable For Coloring.