Last Week – Follow Up
Last week I discussed aspect ratios when printing and I said that you should pretty much always expect to crop at least a little when printing. Someone asked about doing custom print sizes. If you find a printer that will do custom print sizes then that would eliminate the need to crop your photo. However, if you are framing the photo, you would need to have a custom frame ordered as well. This can get pretty expensive, but possible. This brings to mind printing on canvas, which eliminates the need for a frame. Most canvas printers have standard sizes/ratios that you have to crop to. However, you can find some canvas printers out there that can do custom sizes.
The other main question folks have when printing is how large can they print. The answer to this question does not have a definitive answer. Much depends on personal preference when it comes to sharpness. You lose sharpness (resolution) the larger you blow an image up to print. Two things to keep in mind are:
- The dimensions of your digital image
- PPI (pixels per inch, or resolution)
Each camera will have different image dimensions depending on the number of megapixels, etc. My Canon 6D shoots at 5472 x 3648 pixels. Based on last week’s discussion, if I want to prepare an image for an 8x10 print, I’ll need to crop my photo. Cropping obviously reduces the dimensions of my photo. The more I crop a photo, the more blurry it will look when I blow it up super large.
In very simple terms, this is the amount of clarity or sharpness your photo has. Photographers vary on what they say is the minimum amount of resolution you need when printing. Some say you need as high as 300 ppi (pixels per inch). Others say that they print no higher than 240 ppi and often go lower than that. Really, the resolution you want will depend on what the print is for. If it’s for a huge billboard, people are going to be pretty far away from it so you can get away with a lower ppi. If people are going to be inspecting the print up close and personal, then you might want 240 ppi. I would say that a good rule of thumb is to be somewhere around 200 ppi.
The Bottom Line
If you know your image dimensions and the minimum resolution that you are willing to tolerate, then it’s just a matter of math from there. Take my picture (uncropped) at 5472 x 3648 pixels. Say I am willing to go with a 200 ppi resolution. Then I just divide my picture dimensions by 200.
5472 / 200 = 27.36
3648 / 200 = 18.24
In other words, I could print my photo at a size of about 18x27 inches. As that is not a standard print size, I would want to crop my photo first to the desired ratio, and then recalculate.
Phtoshop and Lightroom can help you do these calculations. Below is a picture that I have cropped to a 4x5 ratio. Its dimensions are 4194 x 3355 pixels (just trust me that it is 4x5). At a 4x5 ratio, the standard sizes that I can print are 8x10, 16x20, and 24x30. So how large can I print this without losing too much resolution?
I’m using Photoshop Elements, but this is similar for Lightroom and other programs. Under the “Image” tab on the top menu, I go to “Resize” and then “Image Size”
As you can see from the picture above, if I print an 8x10, the resolution will be 419.4 ppi. This is way higher than the 200 ppi rule of thumb that I discussed earlier. We can go bigger!
So I just type in a 20 where the 10 inch width is and everything else recalculates automatically for me. It says that a 16x20 inch print has a ppi of 209.7. Right in the sweet spot.
I was printing this on a canvas for a customer and I knew that 16x20 was going to be too small. I really wanted to go at least 24x30 inches. Again, changing the width to 30, everything else calculates (see below):
At 24x30, the resolution is now only 139.8 ppi. I was worried that the resolution would be too low, but knowing that size was an important factor, I decided to print the 24x30 anyway and inspect for quality before delivering to the customer. When the print arrived, the resolution quality looked great to me especially knowing that the print would not be viewed up close with a magnifying glass. Success!
If you would like to see a short video tutorial on this topic, Scott Kelby has a great 2 minute summary:
In summary, while there is no definite answer on how large you can print something, hopefully this discussion has helped you understand the relationship between the dimensions of your image and the resolution. Knowing a rough rule of thumb for your target resolution (remember the 200 ppi general target) you should be able to make an informed decision on how big you can print.
Next week we’ll discuss some more useful editing tricks in Photoshop Elements that might make your life a little easier.
Do you have any success or horror stories? Feel free to post your comments and questions to this post and I’ll be happy to discuss them. Happy shooting!
Bryan Rasmussen owns Chiseled Light Photography and is also a freelance photographer for a local newspaper. Follow him at www.facebook.com/ChiseledLight. He is also on Instagram, Flickr, and Fine Art America.