The Photo Focus versus Resolution

One question that has been asked of me is how important is resolution when enlarging a photo for printing. Many photographers want to submit really large photos to make sure their prints are sharp and clear but don’t bother to consider the photo itself.

To give you an example, the other day I was helping the production department at our San Antonio printing studio when one of our customer service reps approached me and said that she had a decorator on the phone who was concerned about the resolution of the images he was having printed on canvas. The order consisted of a large number of stretched and mounted canvas prints with solid colored sides and contained various fruits and vegetables. If I remember correctly most were around 24×24.  I think she said the customer was going to be hanging them on display on the wall of a food vendor at a mall food court . The customer  wanted to make sure the images he supplied were good enough quality for printing and would not look pixilated. If so he wanted to submit higher resolution versions.

I located the order in question and examined the images and saw that they were only around 100 pixels per inch at the sizes being printed , which is a far cry from the golden 300 ppi that most photographers seem to strive for in their prints. While 100 ppi is not at all unusual for many of the images we receive I decided to check out the prints themselves since the customer seemed to be concerned. I wanted to see if it would be better for the customer to resubmit higher resolution images for printing or not.

I located them in the warehouse area we have designated as a spraying center so that the canvas print can be treated with an acrylic coating to protect the inks. They had just been sprayed so I was able to get a good look at the prints when I was about 10 feet away and saw that they looked really good. There was no pixilation and the images looked sharp and clear. I then got closer (about an arm distance away) and noticed the images were not quite as sharp as they appeared at a distance.

The lack of sharpness was not the result of the image being pixilated but simply the fact that the image was enlarged. It was obvious the photographer had the focus too tight on a single spot so details surrounding the subject matter tended to fall out of focus the further away from the center of the focus.  It was not an extreme amount but enough to notice if you know what to look for. The only way they would have looked better is if the photography was shot with a sharper lens or with a change in how the shot was taken. Fortunately the prints were going to be arranged in such a fashion were they would be about 10 feet away from the viewer so this would not be noticeable. The point of all this is that when dealing with large prints any lack of focus in many cases will over shadow a lack of resolution in the image itself. If he had submitted images that were twice or even three times the size there probably would not be much of a difference due to the lack of focus on the shot itself. If you shoot a photograph, it might look really sharp as a 4×5 photo print but once you start to enlarge the image you will see that it is not as sharp, even with very powerful digital cameras. So with larger prints the sharpness of the image will many times deteriorate as you go larger. Images don’t get pixilated so much as they become less sharp. This is absolutely normal. When displaying a large print you will likely display it in a fashion where people will not have to get up close to view it so even if your perfect shot was not as sharp as you would have liked, the print will usually look just fine.

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