Tuesday, April 29, 2008

Digital prints: Easy, right?

It is fairly typical these days to post our digital images directly to a photo sharing site such as Flickr, Zoomer, pbase, (and the list goes on) and forgo the process of getting them printed. And why shouldn't you? It is the fast way to share your photography with the world. After all your photography is meant to be seen! At some point though every photographer will capture an image(s) that they want to display at home or perhaps at the local Starbucks as a large print. By large, I mean 11"x14" frame and up. Easy, right? Well maybe not.


I have been lucky enough to have my work displayed a few times and in doing so learned a few simple things along the way about prints and framing.

Aspect ratio:

Depending on your camera, digital or film, the resulting image will have a particular aspect ratio. For 35mm film and many DSLR (Canon's lineup anyway) the ratio of the length of the image to its height is 1.5. For example my Canon 20D is an 8.2 MP camera that records 3504 x 2336 pixels and doing the math yields an aspect ratio of 3504/2336=1.5. Of course, there is nothing special about 1.5 and many other cameras have different formats. Some are 1, 1.25, 1.33, and so on. That's great but so what? The aspect ratio becomes important for matting and framing.

Frames and mats:

Standard frames come with matting in 4x6, 5x7, 8x10, 11x14, and 16x20 with aspect ratios 6/4=1.5, 7/5=1.4, 10/8=1.25, 14/11=1.27, and 20/16=1.25 respectively. What's more, is that a 11x14 inch mat opening in a 16x20 inch frame is really 10.5 x 13.5 inches. Ugh, my 20D's sensor has an aspect ratio of 3504/2336=1.5.

Question: How much of the print will be lost by cropping to a 11x14 mat format in a 16 x 20 frame?

Suppose the height of 2336 pixel is maintained and the length is cropped to obtain a 11 x 14 aspect ratio. This means the new length L satisfies L/2336=14/11=1.27 or equivalently L=2966.72 pixels. If the cropped image is printed at 300 dots per inch (dpi)[1] then you have cropped (3504-2966.72)/300=1.79 inches! If you have already composed the photo to maximize the image area in the frame, as I try to do, this amount of cropping may not be desirable or even possible.

[1]Note that technically dots per inch and pixel per inch are two very different quantities.

After coming to grips with aspect ratios of standard frames/mats and your camera there are several options.
  1. Buy a custom frame and custom mat from a framing store.
  2. Buy a standard frame from any store and have a custom mat made at a framing store.
  3. Buy a standard frame from any store and cut the existing mat yourself to the desired aspect ratio.
  4. Buy a standard frame and cut new matting material yourself to the desired aspect ratio.
For a 16 x 20 frame a simplest custom mat will be around $25 dollars. A custom 16 x 20 frame (i.e. not a mass produced off the shelf model) can easily cost over $100 dollars. Then there are different types of glass and so on. Needless to say anything custom is going to be pricey. The first time I framed photos in a 16x20 frame, I printed them at 10 x 15 and I opted for option 2. The frames were about $30 dollars each, $25 dollars per custom mat (with a 3-4 day wait time), by four prints is $220 dollars. The second time around, after some thought, I printed my photos 11x16.5, maintaining their aspect ratio, and cut the mats that came with the frames so I had 1/8 inch overlap over the photo. To do this I bought a mat cutter which worked awesome and even allowed me to cut a 45 degree beveled edge.

Mat cutters:

Mat cutters are roughly divided into two categories, hand held and board mounted. The cost of course will depend on the type, size, and features. I opted for a simple board mounted cutter by Logan graphics which was on sale, less than the cost of four custom mats, at my local art supplies store . You may find the following article Matting: The Why & How of Matting Photographs helpful when deciding what route is right for you.


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