I have had many people come up and claim their digital prints match film quality, yet I have a very hard time believing it. The numbers just do not support this conclusion, and the prints I have seen do not get close to film in most cases (those prints which do were either done by professional labs, or by very skilled photographers who invested significant time and money into very high end equipment). Everyone hails the breaking of the 5 megapixel barrier as the beginning of the end of film, yet when you get right down to it, 5 megapixels is still insufficient to match film, which can hold up to 35 megapixels of information on a 35mm negative! Before you rush out and get that digital camera, take a look at the following numbers.
The biggest difficultly people have in comparing digital to film is that they have no way to convert film specs into digital pixels. McBroom's Camera Bluebook to the rescue. Aside from providing an excellent price guide and system information on many of today's used cameras, McBroom included the Rosetta Stone for film to digital comparison. The problem is that film and lenses are often spec'ed in Lines Per Milimeter (lpmm), where digital cameras talk about Megapixels. The following formula allows you to convert lpmm to pixels, so you get a direct comparison of film technology to digital.
(film vertical in mm X # lpmm resolution X 2 pixels/lpmm) X (film horizontal in mm X # lpmm resolution X 2 pixels/lpmm) = resolution in pixels
So for a 35mm negative, the formula is as follows:
(24 X # lpmm res. X 2 pixels/lpmm) X (36 X # lpmm res. X 2 pixels/lpmm) = res. in pixels
The final step is to convert pixels to Megapixels. Since 1 MP = 1,000,000 pixels, the formula is simple:
resolution in pixels / 1,000,000 = Res. in MP
Now comes the fun part - doing the math. For the sake of argument, the calculations are based on using a fine-grain 100 speed film that will resolve 100 lpmm or more. Given today's films (and even those of 10-20 years ago), this is a very easy benchmark for a 100 speed film and virtually every commercially available 100 speed film exceeds this spec (as do a number of 160/200 and 400 speed films). So the limiting factor will be the resolution of the lens used, and NOT the film. What comes out is the following:
| Camera/lens Type: Disposable Point and Shoot SLR - consumer SLR - professional Best Possible |
Resolution in lpmm 40 50 60 65-80 100 |
Megapixel Resolution 5.53 8.68 12.44 14.6-22.12 35 |
So where do we go from here? Does this hardcore evidence nail the coffin in digital cameras? Should we all abandon this foolish digital thing simply because it doesn't match the quality of film? Is digital just useless right now, and should we all just wait for tecnology to improve? FOR HEAVENS SAKE, I JUST SPENT $895 ON A NIKON COOLPIX 5000! DID I SIN AGAINST THE PHOTO GODS?
Well... Hold that thought for a moment. For those of you who have flipped through McBroom's chapter on digital, you will remember that he mentioned something very important. While digital technology may not yet match the theoretical max of film, the usefulness of digital cameras depends greatly on how you plan to use the image. In fact, it is this topic which is perhaps the most important to the debate of film versus digital, and the most useful. And, for some strange reason, it is also the next topic in my exploration of digital photography...
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