Size matters … sort of

As promised this is my fourth report in my search for a replacement camera.  For those of  you who have followed my posts, you know that I enjoy the nostalgia of photographing old buildings.  I belong to a group which produces art with the theme of “old buildings and ruins.”  You’ll find some of our work here.  As always, we appreciate a print purchase if you like the image enough, but we also ask you to share the image on the social networks to which you belong as that helps us too.

But back to size … sensor size.  The question is how large should the camera sensor be?  The answer is not so straight forward, and in the end is essentially personal preferences and the use to which the images will be put.  This is how I figured the issue out … others with more knowledge will come to different conclusions I am sure.  The bottom line is the result of the printed image … which depends on the desired image size, resolution or sensor size, lens performance, and printer capabilities.  I’m not an expert on lenses so I’ll just assume that your lens works adequately for your needs.

Commercial work is normally requested at a 300 dots per inch (dpi) or pixels per inch (ppi) resolution.  That allows the publisher’s art department to do what I believe is a maximum of cropping 25% of the image away and still getting a good result.

When I worked with 35mm film and slides, the maximum print I ever made was a 20×30″ landscape taken in Arizona.  But if you only print a maximum of an 8×10″ photo, your sensor resolution needs will be much smaller – just don’t expect much quality if you upsize.

As far as printers go, my photo editing software warns if printing less than 220 dpi, and on various Epson models I have made superb prints at 150dpi.  A lot of that depends on the quality of printer you have and the paper you use (I use Ilford, a carryover from my film days I guess).

So if I were to make another 20×30″ image to sell commercially at 300dpi I would need a sensor size of 54 Mpixels; to make that same image on a 220 dpi printer I would need 29 Mpixels, and to print the image on what has worked for me in the past I would need 13.5 Mpixels.  If I intended to crop these images first by say 20% all of those numbers would need to be increased proportionately.   By the way, cropping is essentially electronic zoom so for those of you with a 5x electronic zoom you need a lot of pixels.  On the other hand, if I never intended to print or work with an image larger than 8×10″, those numbers are drastically reduced: 7.2MP, 3.9MP, and 1.8MP – with the appropriate allowances for cropping or electronic zoom.

For my purposes then, I needed to look at 18 million pixel sensor sizes and above … but others could do great jobs with much smaller sensors.

Some reports say that larger sensor sizes do make a difference when the camera is asked to work at the extremes of its iso settings (very high and very low light).  Again, I am no expert so I will leave you to research that yourself.

Next … camera religious wars.


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