How large is Big Enough

This is something of a question I have started to ask myself in respect of printing photographs. I had better explain a little first though. I like to produce top quality images and I really like to print my work – large where possible. This begs the question how large does my image need to be to print well at a given size?

The complicated answer would be to calculate how many pixels I need to produce the desired resolution at 300ppi. It’s well known that 300ppi gives photographic reproduction with most inkjet printers so if I want to produce a 20” x 30” print, I need an image 9,000 x 6,000 pixels in dimension. Surely that can’t be right as my Canon 5D MkII doesn’t give anything like that.

Truth is, very few people can tell the difference between a 200dpi image and a 300dpi image unless they are the same photograph and placed side by side. The other ignored factor is the viewing distance. The further away an image is viewed the lower the dpi needed to give the illusion of a photographic quality print. If you don’t believe this take the example of a large billboard where the resolution is typically in the region of 10-20dpi.

Golden rule number one; the only people who will stick their nose right up to your prints are other photographers. The rest of the public will view them from a safe and sensible distance. There is as you would expect a complicated formula to work out the ideal pixel dimensions based on the viewing distance and print size. I will ignore this.

Other factors that also come into play are the image and the paper. Is the image full of sharp detail? If it is, it will benefit from printing at a higher resolution but if not you might be able to get away with less than 200dpi. Paper surface also makes a difference as a gloss finish will always appear sharper and handle detail better than a matte finish. You can therefore get away with a lower resolution and hence larger image when printing on matte.

So, the image here. It was shot on my 14Mpixel Sony NEX-5 and I wanted to see if it would handle enlargement. I increased the resolution to 30” x 20” at 300dpi using Genuine Fractals and then printed a section. Surprisingly, even when viewed close up, it was very sharp and gave a photographic quality. My conclusion is that I should stop worrying about size and just take the pictures. My cameras are more than capable.