Understanding Film Formats

While all of the different film formats may seem daunting at first, its really quite easy. In understanding film formats, all you need to remember is two principles. The first, is that bigger is always better. And the second, that smaller is easier.

To make a print, your image must be enlarged from the original negative. A 35mm negaitve, for example, is approximately 1.5 inches by 1 inch. Medium format (also known as 2 1/4), is some 3-5 times bigger than 35mm. And large format, starting at 4x5, is some 14 times bigger than a full 35mm frame. So why does medium and large format look so much better than 35mm? Its very simple. Since its bigger, it doesn't need to be enlarged as much. That's it.

So the resolution of your print depends on the enlargement factor -ie, how much you blowup the original. An 8x10 chrome, for example, doesnt even need to be enlarged at all for an 8x10 print because its already some 8 x 10 inches in size. A 35mm negative however, would need to be enlarged almost 60 times to make that print, while a 6x7 neg would only be enlarged 13 times. But, for a 1 inch sized print, a 35 mm frame would look just as good as that 8x10 neg would. So remember: resolution is only relative to the final print size you need.

However, with size, you pay a big price. Larger film is more expensive, the equipment heavier, slower, and usually less versatile. Certain subjects are near impossible for the bigger formats. With Large Format, you must shoot and load one piece of film at a time. That's why 35mm is usually appropriate for fast paced action environments, while Large Format is really only suited for slower, very controlled setups that the photographer controls. Medium format is popular because it straddles somewhere in between the two, providing both quality and versatility.

Format	Area (approx)	Times bigger than 35mm
35mm	1 sq"	-
645	4 sq"	2.7x
6x7	6 sq"	4.5x
4x5	19 sq"	14x
8x10	79 sq"	59x

Print:	35mm	645	6x7	4x5	8x10
5x7	26x	9x	6x	1x	-
8x10	59x	22x	13x	2x	1x
11x14	114x	41x	25x	8x	2x
16x20	237x	86x	51x	17x	4x
20x24	356x	130x	77x	25x	6x
30x40	890x	324x	192x	63x	15x

So, the next time you hear on the internet how so and so can blowup a 35mm neg or a 6MP DSLR file to 11x14 and it looks just fantastic, or as good as medium format.... you now know what he's claiming. He's essentially saying that he somehow can enlarge his picture approximately 114 times -and yet claims it looks as good as something that only needs to be enlarged 25 times! The point is, that anything can be enlarged or upsampled in Photoshop to make a print as big as you want. But the enlargement factor will tell you how good its really going to look. Keeping enlargement to around 50x is usually a good rule of thumb for best results, as shown by the bolder figures in the chart above.

The same principles apply to digital photography as well. The Canon XL1, a well known DV camera, has only 0.25 megapixels of information with its 1/3 Inch chip. And even professional DV Formats, like DVCAM, still dont even have a full Megapixel of information. But professional still cameras in the 6 megapixel range, like the Nikon D1x or D100, have more than 25 times the number of pixels. That's why DV might look OK on a television set, but terrible in print form, and awful in the movie theatre. And high end medium format backs, like the Phase One H25, have 22 Megapixels of information for glossy magazines and posters.

So, once again, size is king, whether film or digital. The bigger the sensor, the better the overall quality. The only real difference is that per square inch, digital is actually superior to film. It's been proven that digital sensors smaller than their film counterparts actually outproduce bigger pieces of film. For example, the full 35mm frame of the Canon 1ds has image quality comparable to medium format film -even though it is some 2.5 x smaller than a 645 neg. Likewise, the 645 frame of the Phase One 22 MP H25 acts much like a 4x5 piece of film. Thus, digital sensors seem to "jump" ahead into the next category of quality. To learn more about digital photography and what kind of image quality you can expect, please goto: The Digital Advantage: Why Digital Has Caught Up To Film.

Print Size versus Enlargement Factor