Are you taking portraits and selling prints to your clients?  Are you planning ahead for the different types of prints your customers may want?  How can you do that?  What do you need to know?  Lots of questions. A few simple things done during your portrait sessions will make it easier for you to easily provide the size prints your customers want.  It’s all about ratios.  OK, I’m not gonna go into some high level math here as my engineering days are behind me!  But a little ‘math’ knowledge will take you a long way.
Back to film!  What? Back to film! Yeah let’s start there.  35mm film is actually 36mm x 24mm (or 1.5″ wide by 1″ tall if in landscape mode).  So what’s the ratio of width to height?  Divide 1.5″ by 1″ and that equals 1.5 to 1.  Or 36mm divided by 24mm equals 1.5 to 1.  What does that mean?  The length (width) is 1.5 times bigger than the height.  From an Eagle song: “are you with me so far”?
Let’s go to print sizes:
– take a 7″x5″ print. What’s the ratio of width to height?  Take 7 divided by 5 and you get 1.4.  Seven is 1.4 times bigger than 5. Close to your sensor ratio.
– take a 10″x8″ print. What’s the ratio of width to height?  Take 10 divided by 8 and you get 1.25.  Ten is 1.25 times bigger than 8. A lot smaller than your sensor ratio!
– take a digital SLR image file (in my case I’ll use one from the Nikon D600). The file sz is 20″ by 13.3″ or a ratio of…..wait for it….1.5 to 1. Alternatively known as 3:2 ratio for the full frame sensors.
NOTE: all of the above pertains to FULL FRAME CAMERAS (like Nikon D600, D800, D700, Canon 5D, 5DII, 5DIII or the new 6D)

That’s great but what if I’m using an APS-C Sensor camera and Not a full frame?  How does that impact me? Well an APS-C sensor by Canon is 22.2mm by 14.8mm or a 1.5:1 ratio.  Nikon’s APS-C sensor is 23.7mm by 15.7mm or a ratio of 1.5:1. How about that!  Doesn’t matter what DSLR you’re using.

Here’s the question: You take some portraits of a family and they come out great.  Smiling faces and well lit.  You send the images to the clients and they love them.  Now they want a 5×7, an 8×10 and two 16×20 prints.  What happens if you filled the frame with the family? Remember your camera sensor ratio is 1.5 to 1 (width is 1.5 times larger than the height).  What’s an 8×10 ratio?  It’s 1.25 to 1 meaning that they want a print where the width is ONLY 1.25 larger than the height.  Doesn’t match your sensor ratio does it?  So what happens: to make an 8×10 print of your image it’ll have to be cropped such that the sides have to be squeezed in from the left and from the right.  The print ratio (of 1.25:1) is less than the sensor ratio (of 1.5:1). So the family of seven is now down to five!  Ooops!
So, I’m sure I’ve confused the hell out of everyone by now but to reel it all back in a picture is worth a 1,000 words right?  Check the images out below.
Yeah we’d like to ‘get it right in camera’ but what is right?  5×7 ratio or 8×10 or 11×14, etc?  Only your client knows and even then not until they see your images!  The key is to give yourself some room to go from Portraits to Prints!!
Bob Ring


Learn More