This article explores grain and noise, how they relate and other issues in choosing between film and digital capture.
There are two ways to capture images photographically, use a film camera and scan or use a digital camera.
Film is certainly, on the surface, the cheapest option. You probably
already have a film camera of some sort, but new ones are very
reasonably priced. You will have read that film is so much higher
resolution than any digital camera around. That is true up to a point.
Film is an analogue device, meaning that it is not sampled at fixed
points, like a digital camera does. This does mean that, theoretically,
there is more information in a piece of film. However there are two
things that can get in the way of you having all this data to play with.
Film has a fine structure called grain. It looks like noise. Slow
films, like ISO 100, have smaller, more even grain and so is less
noticeable unless you enlarge massively. Fast films, like ISO 400 and
above, have large grain that is more noticeable at lower enlargement
levels. What this means is that above a certain resolution, determined
by the speed of the film, smooth areas of the image, like skies, become
noisy. There is still information there, it is just noisy.
Another issue with film is what resolution you can scan it at. Now you
can always get the film scanned at very high resolution. The down side
is that this can be expensive and you are not doing it yourself, so you
do not have control. However, this is a very valid approach for many
people. If you scan yourself, the option is to scan the prints or the
film. Scanning the prints is a viable option but don’t believe you are
going to get incredibly high resolutions by scanning this way, even if
your flatbed scanner is capable of it. Prints are a second generation
and is limited by the optical, and increasingly the digital, resolution
of the equipment used to produce them. Anything above 600 dpi is
probably pushing it for most prints, especially drug store ones. You
can buy a film scanner that will go to much higher resolutions.
One last issue with film is dust and scratches. Film is prone to
attract dust and can be easily scratched. Removing these marks can add
significantly to the time you spend scanning images.
The sensors in digital cameras capture a specific amount of
information. A two megapixel camera captures that many pixels, usually
no more and no less. As discussed last issue, you can increase the size
of the image file by interpolation, but you can only do this so far.
Digital camera images have no grain. At a low ISO setting (for cameras
that allow you to vary this) and with fairly short exposures, like in
daylight, the images from a digital camera are beautifully smooth. As
the ISO setting is increased and/or you take longer exposures, noise
starts to appear. You also get more noise the hotter the camera is.
Many cameras now have some sort of noise removal processing built into
the camera, which does help.
Pictures from your digital camera are available immediately. There is
no processing and scanning to do, they are just there. Now this is only
truly the case when your camera is saving the image in a standard file
format, like JPEG or TIFF. Proprietary formats, like RAW, need to be
processed by special software before you can commonly use them in, say,
Photoshop or PhotoPAINT, or processed by Photoshop’s own Camera RAW
plugin. This still takes less time than having film processed but does
add a delay.
Digital camera images are very seductive. Most people find it very hard
to go back to film once they have had a taste of the immediacy and
smoothness of good digital images. But film is cheap (except when you
shoot a lot) and is still in some ways the best to do long duration
trips with. Digital cameras allow you to vary the ISO setting from shot
to shot, something you can’t do with most films. However, you will be
very hard pushed to blow a two megapixel point and shoot digital camera
image up to 1m x 1.5m in size. The higher resolution digitals are very
capable and it is my belief that top end camera, like Canon’s EOS-1Ds
Mark II, with a 16.7Mpixel sensor are the equal of film in a 35mm
The truth is that there are pros and cons with both. Which works for you depends on funds, expectations and usage.
This extreme blowup is from a Nikon
D1x camera set at ISO 100. You can see that the sky is very smooth,
typical of all digital cameras at such a setting.
This shot, taken with a Canon G1, is
a similar extreme close-up and shows the noise that appears in all
digital camera images with very long exposures, here over 4 seconds. In
fact the G1 has handled this better than most.
This extreme blow-up is a tiny
section of an ISO 100 slide. Even here you can see both the grain and
tiny dust particles that stop the sky being nice and smooth, as it
would have been with a digital at a low ISO setting.