It's a Ratio Thing

I was recently asked a very good question by a client. 
I felt it would be a good question to discuss here, because it not only applies to clients ordering reprints and enlargements, but it can also apply to the beginning photographer when composing their photographs.


The client asked "I ordered an 8x10, and when I got it back, some of the edges were missing!".


This is because most digital SLR cameras shoot in a format that has an aspect ratio of 3:2.  This creates a "full frame" image in the standard size of 4 by 6 inches.  Most "point and shoot" digital cameras have a ratio of 4:3, because that is (well, used to be, anyway) the ratio of the standard computer monitor.


The 3:2 DSLR aspect ratio is perfect, as long as you're printing 4x6 images.  But if you want different sized images, there will most likely be cropping involved.  How much cropping?  Let's find out by doing some first semester algebra.  Let's say you have a DSLR image that you'd like to make into a 5x7.  How much will be cropped?  You have a frame that is 5 inches wide, but how long will the "long" edge be?


4             5
---   =     ---
6             x                      (6x5)/4 = 7.5


Your final image will be 5X7.5, which means that you will lose a half an inch off the long edge.  That's not much of a crop and can usually be done without any manual  adjustments.  The standard lab will cut .25 inch off of either end for a symmetrical crop.


However, if you wish to get an 8X10 printed, the cropping is more drastic.  For an 8X10 you are going from an aspect ratio of 3:2 to one of 5:4.  If you've done the math, you will see that a "full frame" image would be 8X12, NOT 8X10.  Two inches is quite a chop, and rarely will these images look perfect with a symmetrical chop.  Here's a visual:

This is a standard 3:2 ratio image from the camera:

This is the above image with a "symmetrical" crop, one inch from either end.  This would be the standard crop from most photo labs:

Here is an adjusted crop that will give you a better result.  Now the head is no longer cropped off, but we still end up with the proper ratio for an 8x10.  Many labs will let you adjust this cropping area, but you must first specify where you want your cropping.  If you don't, you will get the standard, symmetrical crop.

Here is the final 8X10 cropped print with the adjusted ratio:

How does this apply to the beginning photographer?  Because when you are taking photographs, keep in mind that you (or someone else) might want an 8x10 of the photo and you may wish to leave some space on the edges for cropping.  This is especially important with large group photos.  When a group is large, the tendency is to stretch the group all the way to the edges.  But this can cause a problem later if 8X10 (or 16X20) enlargements are wanted.

This was the final image AFTER cropping.  I purposely left room on the sides for cropping.

I hope this has been helpful!


JB