OK I have a beautiful little bird close up with a long lens. I am so happy. I understand the rule of thirds. Now I would like to print the bird picture to a nice size, say an 11x14. I want to make the bird the first thing the viewer's eye goes to. However, because it is a small bird I may have cropped too much so the bird in obviously not tack sharp any more. Is there a formula I can use to try and get large, sharpe, focused on the bird prints. ie. how to I get the most bang for the buck. In this case the most bang for the bird?
Thank you all!
My math is always suspect, not really my thing but I tried hard to understand the basic math of printing when I first started in photography. I use a Z8. When I shoot in DX mode the optimal size for a printed photograph (a 1:1 printing ratio), not cropped, would be no larger than 24" x 36" in DX image mode. At 24 x 36 I can print a photo that is 10,800 pixels on the long side by 7,200 pixels on the short side.
It is the number of pixels in the image that counts when printing and that tells you what size of print is optimal without losing image quality. Most printing is done at 300 dpi, although pixels in the camera are referred to as ppi, but the two terms are inter-related.
There are many factors to consider beyond image size, too, general quality of the image being one. If you crop you take the cropped side and multiply it by 300 (or the amount of dpi you plan to use for printing and some people use an amount as low as 240 dpi but most professional printers use 300 dpi) to figure out what the actual pixel size is, so if I cropped to 6900 x 4500 and planned to print at 300 dpi I could, theoretically, print an optimal quality print at 23" x 15."
To make this easier I ran up a list of sizing so I can just glance at it to determine the range of what might work for printing. I normally print at 10 x 15 so I check to ensure that I have an image that is 4500 pixels across on the long side.
Today there are many options to upsize an image to print it larger that work well and I have done this in LrC and have printed high-quality prints quite large using the software and printing through Bay Photo. I hope this has not confused you as it can get a bit tricky in the math.
The short answer is, an 11 x 14 image would need to be 3300 x 4200 pixels across (on the long side) for a quality print, or somewhere around that size.
Below is a chart from the web with some examples: