Camera speed limits your choices in photography. In the old days, it was film speed. Today it is the speed of the image sensor. How far has digital advanced and how far can it go?
I have a beautiful old book on film from the late 1980s. They rated film into the following speed groups.
|Group||Speed in ISO|
|Slow||16 - 50|
|Medium||64 - 125|
|Fast||160 - 800|
|Ultra fast||1000 - 1600|
At the time I purchased the book, 1600 was readily available and mediocre quality 3200 was on the market. I was a kid interested in photography busy developing techniques to double film speed without reducing image quality. I had 1600 film working equally well at 3200. The 3200 film was not good enough to push to 6400. I could then double the speed, for some prints, during the printing stage. The right 3200 print, from a 1600 film, could print as if it were 6400.
Early digital cameras produced massive errors at ISO 800. Today's medium price cameras can produce 800 without problems and a professional camera can produce ISO 1600 images without error. We are currently on the same level as the last of the great films but it is a lot easier to produce the equivalent quality.
Those 1980s high quality fast images were produced with 35 mm cameras. Larger format cameras were too heavy to use in the types of situations where high speed was an advantage. The equivalent today are
full frame cameras including the Canon 5D upwards. The 5D can shoot at 3200 with minimal errors, at 6400 with some errors, then at 12800 and 25600 with unacceptable errors. The 5D is equivalent to the best quality I could produce in the late 1980s by working on the development for extra time then spending an extra ten minutes per print. Today I can get great ISO 3200 images without the work. Somewhere around 2009 digital cameras passed the best of the film equivalents based on speed.
Digital cameras use image elements based on silicon and they could move to gallium to produce images ten times more sensitive to light and 100 times more sensitive to damage from heat and shock. A gallium silicon hybrid could produce ten times the speed without a great increase in failure. An improvement of that order would put digital a long way ahead of film.
Smaller lighter digital SLR cameras use smaller image sensors including ASP-C and smaller. Those smaller image sensors produce more errors for an equivalent speed. Those smaller sensors trail behind the best film but are far easier to use. For most people the convenience of digital results in fewer errors than film.
Film could be sharp and sharpness was related to what you did as a photographer. Today most images are subjected to a weird distortion produced by the Photoshop unsharp mask. Photographers used to learn how to produce sharp images. Now fuzziness is celebrated and the unsharp mask applied on the assumption that the mask will actually fix something, instead of just applying more distortion. If you want to learn about sharp then delete the unsharp mask from your software.
Digital has grain exactly the same as film but software and that horrible destructive JPEG image format are both good at smudging your image to pretend there is no grain. When you grow out of the
Oh look I took a photo stage, you want RAW image processing and a chance to see your image as produced by the camera. Only then will you learn the limitations of digital and why you might want to spend more for a good camera. Meanwhile your mates will remain fascinated by the rubbish produced by the minimal camera in their digital phones.
If you want to learn how to get the best possible image, you have to demand RAW images from your camera.
Contrast could be changed in film cameras by using another film. The maximum digital image contrast is set by the image sensor and the electronics behind the film sensor. The most popular films had contrast sensitivities equivalent to digital image sensors of 10 bit and 12 bit per pixel. Cheap digital cameras record 8 bits and expensive professional cameras record 14 bit. Digital has a wider range overall but each camera is restricted to just one range. One of the differences between a $300 camera and a $3000 camera is the number of bits in each colour of each pixel, which gives you contrast.
Some digital cameras can automatically take a sequence of images at different exposures to be combined in an image editor to give you the equivalent of more pixels per bit. While the technique only works with static landscapes and similar images, you can get 16 bit pixel depth. The multiple exposure technique was used with film but recombining the result was so difficult that few photographers used it.
Digital is now a couple of bits of contrast beyond film. You cannot see the difference in a JPEG image from a camera, you need a RAW image to retain the difference.
Digital covers what was called 35mm and medium format. There is no digital equivalent to large format film. One thing you can do now to emulate large format film is to stitch together multiple digital images. You need a really good tripod and a static scene to take the many pictures required for a large format image. 16 full frame digital images could give you the equivalent of a 5" film format. The old 12" film format would require 10 rows of 9 images or 90 separate images to produce an equivalent. With good quality 35 mm images sitting at 21 megabytes, a 12" equivalent would be close to 2 gigabytes.
Film had a problem where it slowed down when used at the extremes of exposure time. Digital image elements perform better but their error rate goes up. When you try for a very long exposure at low light levels, there is a huge difference in performance between the different pixel sensors. A short exposure produces the same problem. The problem is caused by the computer multiplying inadequate information and effectively multiplying errors. You get the same problem with multiplied errors when shooting in low light levels.
Digital fails here because the manufacturers do not identify the limits of there technology and the points where their computers start guessing what should be in the images.
Black and white
Digital cameras take a monochrome picture, a plain black and white image with a messy colour filter over the top. If you have a 12 megapixel camera, you have a 12 megapixel monochrome image overlayed by a 4 megapixel blue image, a 4 megapixel red image, and an 8 megapixel green image. You cannot get an accurate 12 megapixel monochrome image because of the colour filter. The best you can hope for in colour is 4 megapixel.
The computer in the camera will attempt to smudge the colours of the 4 megapixels over the 12 megapixels in a way that is little more intelligent than 5 year olds finger painting. What we really need is a 32 Mp raw image reduced to 8 Mp by combining the colour information from each set of 4 pixels. We can then confidently edit an 8 Mp image.
Infra red photography was popular with film and digital should be better at capturing infra red. Standard digital cameras do not capture infra red. Specialised surveillance cameras capture poor quality infra red. If you want really good quality interesting infra red shots, go back to film.
With film you had to change film to change the colour balance for different light. Digital cameras can measure the colour balance and adjust with no extra work. Digital is a step ahead here.
Wrong exposures plagued film users. Digital lets us see the results instantly and take another shot if something is wrong. You should still study exposure because touching up exposure in Photoshop is nowhere as good as making the right exposure in the camera. The Ansel Adams Zone system is as applicable to digital as it was to film. A good digital camera can show you graphs of the light recorded by the camera and you can make adjustments in the camera equal to the Zone system processing changes.
Filters have the same use with digital as with film. They let you see things a different way when you take the shot. Polarised filters are especially important. The one time when digital post processing, Gimp, Photoshop, etc, is better is the case where you want a filter applied to the background and not the foreground.
Film is sensitive to the storage environment. Digital images are similarly sensitive. The advantage of digital is simple, you can create several identical copies and store them in different locations. If one melts in a fire, you have the others.
Editing digital images is easier unless the image is covered in error spots caused by shooting outside the range of the camera. The most common mistake is to depend on editing instead of creating the best image in the camera.
Remember that editing can only remove things, it cannot add things that are not recorded in the image. You can, of course, combine two related images to blend the different information recorded across the images.
Filing is much easier with digital because you can add any number of keywords to a digital image.
Duplication of digital files is 100 percent accurate, something you could never do with film. Printing is not 100 percent accurate because every printer is different. Accurate colour reproduction in printing is becoming better and is very close when you stick to the same ink system across all the printers.
Throwing an old photography book in the paper recycling bin is usually a waste of useful knowledge but not when we talk about film. Digital is mostly better than film and is so convenient that you would not step back to film for anything outside of infra red. You still have to learn the same techniques for producing fine images with digital and then digital locks in the quality forever. The ISO speed of digital cameras is now surpassing film and the instant feedback of digital helps you correct mistakes on the spot. Digital is better and faster.