Film v Digital: Latitude
It’s been said before that there is a specific look to film, and it’s hard to quantify why digital doesn’t reproduce it. Having played with both digital and film for years now I’ve felt that a large part of this difference is actually comes down to how highlights are handled between the two.
Now what is a talk about highlights without bringing up dynamic range and latitude. While the two terms are tossed around often interchangeably, in the photography world they describe two related but distinct qualities of a medium. Dynamic range is a measure of the brightest and darkest that a medium can capture simultaneously, while latitude is the measure of a mediums ability to be over or underexposed and still achieve acceptable results.
Having defined dynamic range and latitude, it is possible to focus in on just a single aspect such as we will be doing with latitude. I chose overexposure latitude this time as it's much easier to both quickly test and then visually see the difference.
SETUP
The next part was to come up with a reasonable scene to photograph that would stress the dynamic range while being analogous to a real world scene. I decided to shoot a high contrast mask in direct sunlight with half the face in shade. Direct sunlight portraits are a very common subject that can often be tricky to get pleasing results, especially with digital cameras. The illuminated side of the face would have a proper [Exposure Value] of 15 while the side in shadow would be properly exposed at 12ev.
For the digital, a D800 was readily available. The camera was set to a constant f8 aperture on a fixed focal length 85mm lens. The shutter speed was then swept from 1/500th of a second down to 1/2th of a second. This would give total range of exposures equivalent to 8 stops or 15ev down to 7ev. The results would be brought into ACR and exported as JPGs once highlight had been recovered.
A F3 using Fuji Superia Film with an ISO value of 200 was available for the film comparison. The film would then be scanned by a V750 Pro using Silver Fast with automatic settings. Unfortunately this was done using the last bit of an unfinished roll so a range of 4 stops was captured with the scene exposed for 12ev down to 8ev. As this covered the overexposed end, and this is quick overview, it shouldn't affect the types of conclusions we might be able to draw.
RESULTS
The results naturally break down into two sides. We have the side of the face in direct sunlight [right side] with a proper exposure of 15ev and the side in shadow [left side] with a proper exposure of approx 12ev. It makes sense to look at each side on it's own to see how many stops overexposed we can go before we clip and start to lose real detail.
For the right side, a range of 5 images presented below cover 4 stops of overexposure as we move from the correct exposure at 15ev to 11ev.
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| Recovered Digital Results 11-15ev |
The image appears to maintain detail at 13ev, and just starts to lose some of the lighter parts of the image at 12ev. Looking closer at the last two stops we can get a more clear visualization of the clipping.
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| Recovered Digital Results 11-13ev close-up |
While there is noticeable loss of detail at 12ev, the image still preserves a more graceful transition to the highlights. Once we hit 11ev it's clear that much of the right side has clipped and no further detail can be recovered.
From the images, the right side of the face appears to have an over exposure latitude of approx 3 stops. The image is still able to be recovered by a reasonable amount, but pushing it a stop further provides to be too much.
Moving to the left side of the face, we have a range of 5 stops captured starting with the approx correct exposure of 12ev.
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| Recovered Digital Results 7-12ev |
At 8 stops there is some overexposure of parts of the image not in direct sunlight on the left side of the face. Moving a single stop further and much of the light parts of the left side of face has clipped. The over exposure latitude from 12ev down to 8ev in which detail is acceptably still maintained would then be 4 stops.
This puts the D800's latitude somewhere between 3-4 stops for overexposure. We can't pull as accurate of an estimate for film since unlike digital it's not clear when detail is actually lost. Putting the images side by side against the digital can help us visualize the difference in films latitude.
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| Recovered Digital(top) compared Film(bottom) |
First impressions make it appear that the film quickly is losing contrast in the highlights from 12ev to 11ev, but as we move all the way down to 8ev the film is still holding onto detail on the right side.
Even at 7 stops it is possible to separate the ear from the mask, color of the pot at both the ear and neck, and the wrinkles on the right side of the face, along with detail on the majority of the nose.
Where does this leave us? Did film beat digital? I wouldn't say so, as the most critical piece of information from this test is that we failed to properly expose the scene, and as long as it wasn't over approx 3-4 stops the scene was recoverable.
That said, the film offers us an opportunity that the digital doesn’t. There is something I like about the over exposed images on film. We are losing the colors, the contrast, and the textures, but the results provide their own unique feel. Had it been digital, I would have deleted them, adjusted, and re-shot. But with the film, on purpose or accident I’m left with something usable, with it's own flat and soft look. I think that's really what can be taken away on the differences between the two.
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