What do you need from resolution?

Newcomers to the digital camera world can be easily overcome by all the technical specification numbers tossed around, doubly so by the off-hand advice given by people who don’t appreciate how confusing all this can be.  Let me help simplify this confusion a bit.

How big do you want to display your image?

It’s one of the first questions you need to think about.  If all you’ll ever do is show your images at full size on a computer monitor or TV screen or print no bigger than 8×10″, just about any camera out there will deliver the image size and quality you need.  6, 8, 10, 12, etc. megapixels – don’t worry about it, you’ll have enough to meet your needs.

Sure, you have to consider all those other choices available in your decision (lens, options, physical size, ease of use, etc.) but few of those will affect the answer you give to the first question.

And if you’re part of the crowd that wants to print bigger than 8×10″?  Well, how much bigger?  11×14, 16×24, 20×30, 30×45, size of your wall – where do you see your limit?  This important because more information in the image means you can print bigger and keep the quality you desire.

For example, my choice of digital camera is the Olympus system.  The sensor Olympus uses is smaller than a traditional 35mm film negative (which is called full frame or full format) and the image size is 10-12 megapixels.  This works very well up to slightly larger than 8×10; larger than that and my software has to “create” pixels from the existing ones to fill in the area created when the image is enlarged.  Various types of software do this differently and some are better than others.  The ones I’ve used enable me to print up to 30×40″ and get a print that looks good from a typical viewing distance of 6-8 feet.

As I am a resolution junkie (also known as a pixel peeper), this is not adequate.  I want good quality at that size from 1-2 feet (yes, I know people don’t stick their nose up to a large print but work with me – I’m a resolution junkie).  So I’m experimenting with film and scanning to create image files with more information.  The bigger the image you start with, the less quality you lose when it is enlarged.

Some data might help.  The Olympus sensor is 17.3mm x 13mm (or 0.68 x 0.51 inch) and mine delivers around 10,000,000 pixels.  My medium format film negative is 60mm x 60mm (2.3 x 2.3 inch) and my large format negative is 4 x 5 inches.  The image area of the medium format negative is 16 times the size and the large format is 57 times the size of the digital sensor.

Here are image examples of the same scene I photographed recently – no adjustments have been made other than converting the digital image to B&W using Lightroom’s standard settings.

Digital Image

Medium Format Image

Large Format Image

Here they all look pretty much alike.  If I enlarge each by 3 times their existing size and take 1″ crops out of each I get this:

Digital Image, 27 Inch Print Size

Medium Format Image, 25 Inch Print Size

Large Format Image, 44 Inch Print Size

Again, not that much difference.  But what if I want to print each the size of the largest (44 inches)?

Digital Image, 44 Inch Print Size

Medium Format Image, 44 Inch Print Size

Large Format Image, 44 Inch Print Size

Now the differences are starting to show up.  The digital and medium format images are less sharp than the large format image (some sharpening will bring out more details but the difference among the three will be unaffected).

So, the final size of the print determines how much information you need in your image to retain the quality you expect.  Most people rarely print so large they need a piece of film 4×5 inches in size but if you expect to print from your digital camera at sizes more than 2-3 times the size of the native image (the size of the image right out of the camera at normal print resolutions) then you need to consider the size of sensor you purchase and the number of pixels it will deliver to your software.

There are other issues to consider (size of pixels, shape of pixels, etc.) but all that is secondary to the sensor size when it comes to determining how big you can print with good quality.

So, size does matter, after a fashion.  Print 4×6″ or 8×10″ to share with friends or family, or show off your images on a computer or TV and you can pick your camera based on other features.  Starting planning some wall art, though, and you need to put in a little more research on the type of camera you buy.

Or, you can just invest in a large format camera and join the rest of us under the black cloth!

 

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2 thoughts on “What do you need from resolution?

  1. Nicely explained. I’ve come across a problem with shape of pixels. When I import my digital still images into my film editing software there is a conflict due to the different shape pixels. Camera pixels are square whereas video pixels are oblong. This means still images get stretched. I’ve yet to figure out how to overcome this. It’s really a big problem when you want to do flashy things with your stills like having them move around on screen, any movement plays havoc with the pixels.

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    • Kate,
      Wasn’t aware of the difference. So if I understand you right, taking a single frame from a high-def video gives you a distorted photograph? Isn’t there something in Photoshop that lets you convert pixel shape? Seem to remember hearing about that in AI but way outside my area of knowledge. Let me know what you discover as a solution – got a friend who just bought a 1080p digital camera hoping to make both stills and video.

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