What’s medium format?

Last week, we ran an article by Contributing and News Editor James Booth entitled "What's an SLR?" This week, we continue our series of photography basics article by explaining a term some folks have heard of, but not everyone's familiar with: medium format.

So why use medium format? In one word: quality.

If none of the pictures you take are going to be printed larger than 5x7 inches, then by all means, stick with 35mm. You would reap little benefit by spending the money to upgrade to medium format. On the other hand, if your images are routinely printed at 8x10 or larger, then you should really consider the upgrade. By the way, we'll be talking about film through much of this article, but I'll also mention some digital medium format issues.

A negative image

In photography, image quality is directly related to the size of the original image. Therefore, a larger image surface on the negative or image sensor will mean more sharpness, color saturation, tonality, and detail in the finished image.

Although there are several sizes of camera available in medium format, I think the most widely used is probably the 6x4.5cm, or 645. Developed by Mamiya in 1975, cameras in the 645 format are also available from Pentax, Bronica, Contax, Fuji, and of course Hasselblad. Figure A shows the Mamiya 645 Pro.

The 645 format is closer to the "ideal format" than 35mm. What this means is that a 645 negative requires very little cropping in order make an 8x10 inch print. By contrast, a 35mm negative needs significant cropping in order to achieve the correct ratio for an 8x10 inch print, sacrificing a large portion of the image. Of all the medium format sizes, 6x7cm is actually the closest to "ideal format," requiring almost no cropping when enlarged to an 8x10 inch print.

The simplest way to explain the difference in quality is with the size of the negatives. A 645 negative is almost three times larger than a 35mm negative. To put it in a little better perspective, a 35mm negative has to be enlarged eight times to make an 8x10. A 645 only has to be enlarged four times. Obviously, the less enlarging a negative requires, the better the resulting image quality will be. Figure B has a visual comparison of the sizes of the two negatives.

Figure C compares an actual 645 negative and a 35mm negative side-by-side.

You may think...well, if bigger is better, why not use 6x7? Now you're getting into a different area of tradeoff: quality vs. portability. 6x7 format cameras are very heavy. They are basically designed for studio use, whereas a 645 camera will offer you the same portability as a high-end 35mm SLR camera. It's almost impossible to hand shoot a 6x7.

I've seen my father drag his Mamiya RB67 around on vacations. After having that thing hanging around his neck for a couple of hours, he could barely stand up straight.

If you do strictly tripod-mounted studio work, and are considering medium format, then take a look at 6x7. But if there's ever the possibility you'll shoot handheld, opt for something a little more portable.

Versatility

Have you ever wished you could change films mid-roll with your 35mm? You can with medium format cameras. Have you ever wished you could see what the picture would look like before wasting your film? You can with medium format.

These features are pretty much moot if you're shooting digital as there's no film involved, and most digital cameras offer a preview screen. But wouldn't it be nice to be able to switch between color and black and white film mid-roll? Or between negative and transparency? Or to be able to change from one film speed to another? What about shooting 120, 35mm, and Polaroid all with one camera? You can do all of this with medium format.

Most medium format cameras have removable film backs, allowing you to pre-load them with different films and put them on the camera when needed. This is also how you can put a digital back on a traditional film camera, although digital backs for medium format cameras are extremely expensive, starting at around $6000. Figure D shows some of the many film backs available with medium format cameras.

Regardless of whether the camera is 645, 6x6, or 6x7, they all use the same 120 film. They can also take 220, which is twice as long as 120. With some medium format cameras you can get a 35mm back for panoramic shots. With a Polaroid back, you can get an instant proof of what your shot will look like to test the lighting and composition.

Medium format cameras that have leaf shutters are also able to synch the flash at all speeds. Most cameras will only synch the flash at either 1/60th or 1/125th, some at 1/250th. Not all medium format cameras have leaf shutters though. With some, it's an option that's available with alternative lenses.

So why would you want to synch the flash at higher speeds? It's necessary for things like fill-flash in bright sunlight and for freezing movement on specialty shots, like splashing water.

Conclusion

So who uses medium format? Professional photographers like Andrew Eccles, a freelance photographer that has worked with Robert Mapplethorpe and Annie Leibovitz, or Mark Seliger, chief photographer for Rolling Stone magazine, a position once held by Annie Leibovitz.

Do you have to be a professional to use medium format? No, certainly not. I'm no professional, but my photography has improved dramatically since moving up to medium format. Is it for the average photographer? No, not really. But if you're an advanced amateur that would like to go professional, consider trading up. Assignment editors and art directors for ad agencies and publications need the largest original image possible.

Stock photography is another income staple for professional photographers. Stock houses pay more for larger source images. Medium format is also the choice of most wedding, portrait and studio photographers and offers versatility that is unequalled in 35mm. If you're not sure whether or not medium format is for you, many companies will rent out equipment so you can try before you buy. Good luck and good shooting.

James Booth is a self-taught PC and Palm device user that dabbles in graphics and photography. He can be reached at lizardworks@mchsi.com.