The curves below are cuñas sensitométricas made by Madrid Film with Fuji negative stock. On the positive chart, the curves are aligned according to the average of the cuña (value 11). We have pointed out on the curve the values read off the density metre from both negative and positive, over and underexposed 18% gray Kodak card. Conveniently corrected HMI instruments (Minolta IIIF Colour metre) have been used for daytime emulsions, correcting colour temperature and colour corrections at 5500ºK. For the F500T 8572 emulsion, we have used tungsten instruments corrected at 3200ºK. The aperture values were adjusted with a direct light Minolta IIIF and a reflected light Sekonic Spot F appropriately adjusted.





We can see the emulsions´ latitude on the curve and its reaction to colour, whereas we can also appreciate the differences between the density of an 18% card and the values from the laboratory in the pictures below. These differences are considered normal and can occur for different reasons such as the emulsion itself or the lab. On the positive curve we can see the range of F-stops reproduced by them and the colour dominants both in light and in shade.
Generally speaking, emulsions tend to be cyan/green when underexposed and more yellowish green when overexposed. The corrections made in the positive chart for neutral grey determine the deviations on each of the emulsions for the skin tones. We could say that, as a general rule, corrections for overexposure give red/magenta skin tones and that corrections for underexposure give more green/cyan tones to dark skins rather that lighter ones.

F 8562 250D
This is the stock we used most in Nubes de Verano, and the one I like most because of its consistent response with blacks and colour reproduction, which allows you to underexpose in interiors and overexpose in exteriors. Skin tones also look very natural with both Tugsten or HMI lighting.

Contrast
Medium with a 0,51 gamma (slightly over 10 Stops), with a smooth compresión in the highlights as well as the shadows.

Grain
An extremely fine grain which remains acceptable even when strongly underexposed.

Colour Saturation
Colour reproduction close to natural, with intense colours without excessive saturation. It maintains these characteristics even under very extreme exposures. It maintains a good colour balance although with extreme underexposure the blacks tend towards yellowy green. Printing to correct the overexposure to an neutral 18% grey, skin tones tended slightly to the red/magenta. More than 2 F-stop underexposure makes skin tones divert towards green/cyan.







F500D Reala
We didn’t use this emulsion in the end because it was the worst at maintaining colour reproduction and black constants during the under- and over-exposing processes, with really notorious grain. Although I like its soft, pastel palette, its inconsistent response to blacks and colour made me discard it. It’s a film that needs few changes in its exposure to obtain consistent results.

Contrast
Of the three emulsions tested it’s by far the one with less contrast, with an average gamma of 0.46 and a greater latitude up to 1 F-stop more than the F 250D.

Grain
There is a clearly visible grain with normal exposures which increases notoriously when underexposing, which makes it significantly harder to work with than the two other emulsions.

Blacks
Very smooth blacks that become milky when underexposed, which makes them hard to work ith after only one F-stop of underexposures. .

Colour saturation
Very soft, pastel colours with slightly magenta skin tones. The colour balance is not as consistent as the other emulsions and it clearly loses out when underexposed (it doesn’t go beyond 1 F-stop) and overexposed. When overexposed the magenta dominances in the skin tones and in the underexposing the green/yellow tone is specially notorious in the darker skin tones. With the correction of the positive towards a neutral grey when underexposed the blacks tend towards green/cyan and the highlights take a yellowish/green dominance.






F 8572 500T
This emulsion was used for shooting night sequences that required additional sensitivity. Its response was been satisfactory, possessing the highest contrast out of the three emulsions and the most saturated colours, with a clear red dominance in the skin tones that we have easily corrected during colour grading.

Contrast
The emulsion with the highest contrast out of the three with an average gamma of 0.55 ( a bit more than 8 F-stops in latitude ).

Grain
A visible grain, less than the F-500D emulsions, acceptable for a fast emulsion. El grano se mantiene razonable con un stop de subexposición, con dos éste es realmente notorio.

Blacks
The blacks are very intense, a lot more than the F 250D, very contrasted and with fast loss of detail when underexposed.

Colour Saturation
It’s the emulsion with the most saturated colours. It maintains a very reasonable uniformity, during under- and overexposing although after two F-stops of underexposure the first green/cyan dominances start to appear in the blacks, although less than in the two other emulsions. With the corrections on the positive skin tones take a magenta/red dominance and in the overexposing they take a clear red dominance.







In the comparison between the three negatives we can see the difference in contrast between them, as well as the differences in colour reproduction.








In the table we can see the different density values. They are slightly denser in the negative of the photographed card and slightly less dense than in the positive.
With these values one can decide whether to modify the light-metre to adjust it to the lab we are working with and detrmine the values of the positive we are interested in.




The stills
The stills we reproduce here are captured from the positive without being colour graded, so despite the expected differences with what we saw during projection, they give an indication of the emulsion’s response.
Comparison between the three emulsions at the normal exposure. We can see the differences in colour and contrast.