Shooting Art Part 2 – Camera Bodies and Resolution

When people learn I shoot art professionally one of the first three questions they ask is “How high a resolution camera do I need to do that?” (The other two top questions are – ‘Will people really pay for that?’ and ‘How much do you charge?’)

My answer to their first question is a question: “How big a copy does your customer want to make, and do they wish to print it, or just show it on the web?” You’ve seen perfectly good images of artwork on the web that were taken with a 4 megapixel (or less) camera. However, you probably haven’t seen art prints of any size from that camera. (The answer to the other two questions – “Will people really pay?” and “How much?” are “Yes,” and “It depends…” (More on the last question in a future post.))

Let’s cut to the chase and do some quick calculations about camera resolution and what it means for final image size – both printed and web:

What really matters is pixels-per-inch (or centimeter) sent to the output device. Note that this is NOT the DOTS per inch your printer brags about, its PIXELS per inch, the little dots that make up the image.) For printing, you need to send at least 150 (bare minimum), and preferably 240-300 pixels per inch to a good quality printer to achieve crisp results. Over 300 DPI, and most observers aren’t going to be able to see it (and many printers won’t print it any clearer). For on-screen viewing (web, slide shows, conversion to video) you only need 72-96 DPI (dots per inch).  Here is a quick way to calculate how well your current camera meets your needs:

1)      Determine the number of pixels your camera records horizontally and vertically. (tip: check the EXIF info – FastStone and Irfanview are free programs that make this easy. Recent versions of Windows will also reveal this for JPG files, but not camera raw.) Round these dimensions down to the nearest 100.

2)      Divide each dimension by 150. The results are the LARGEST PRINT you can make and (probably) still have a satisfied customer.

3)      Divide by 300 to get the largest using “best resolution” techniques. (Yes, it’s half the size, or just one quarter the area of the 150 pixel version.)

Example:

Let’s use a Canon 20D, an older prosumer camera body now available for about $300-$400 used. It records a 2336×3504 pixel image. At 300 ppi you have 2300/300 = 7.6” and 3500/300 = 11.6. That is, you can make a very high quality reproduction up to about 8”x10”. Going to the lower quality limit of 150 ppi will get you to about 15”x22”. This assumes your artwork fits proportionally into the frame. Images with different proportions will obviously not fill the frame, resulting in a smaller maximum size in one dimension. Since you need SOME border, these sizes are a maximum.

Now Let’s talk about photographing work for screen display. Suddenly, your resolution needs are much MUCH lower. Like cameras, monitors work in pixels. And compared to camera sensors, monitors are small. Even a high res monitor (QSXGA spec) only has 2560×2048 pixels. So you can easily do full-screen images with an 8 meg camera, and even have some pixels available for cropping. For display purposes on commerce sites you are only displaying about 800×800 pixels, or 0.7 megapixels. So even a 4 megapixel camera is more than adequate!

Bottom line? You probably do NOT need to invest in a new, high resolution camera (Darn! There goes THAT excuse!)  BUT (aha, you knew a “but” was coming, didn’t you?) there are real, sometimes significant advantages to a better, more current technology camera body with a larger sensor. This is especially true if your current gear is a Point and Shoot camera (P&S) rather than a DSLR with interchangeable lenses.

These advantages include:

1)      All camera sensors  are NOT created equal. A Point-and-shoot camera with a 12 mp sensor  often will not take as sharp a photo as an 8 mp DSLR.

2)      Larger high quality prints. (A 21 megapixel 5D2 from canon has 5616 x3744 pixels. At 300 pixels per inch this yields a high resolution print size of 18” x 12”. (Since larger prints are typically viewed from further away, the 150 pixel per inch is likely to yield a very satisfactory result – this means a 36” x 24” print is quite feasible.)

3)      Newer sensors are (generally) better – creating less noise, clearer resolution, and truer color. (e.g. You get what you pay for.)

4)      The higher resolution image means a larger print size, and the ability to “grab” detailed callouts  from a single shot, rather than having to shoot each callout separately.

5)      Greater zooming depth: When using tools like Flash that let viewers zoom into a photo, higher resolution images gives you more zooming depth.

6)      More space in the frame:  With extra pixels you can include small color charts in the border area. This makes each image easy to calibrate, even if you change exposure parameters such as f/stop, shutter speed, and/or lighting. This is especially handy if you are shooting in natural light. Sunlight, even indirect, changes with passing clouds and the passage of time.

7)      The ability to work “tethered” – Newer cameras allow you to easily hook up to an external monitor, displaying your shoot “live,” making decisions about framing, focus, and depth of field much easier. (WARNING – Do NOT make color or exposure correction decisions based upon the art object’s appearance on an external monitor unless you’ve calibrated it – even then it may not reflect “truth” as it will appear in the captured RAW file.)

8)      Your results are also greatly affected by lens quality – something you can’t change on a P&S but which you can on a DSLR. It IS possible to take good web shots of artwork with a P&S camera. But P&S camera lenses are typically not designed for close copy work. Instead the camera’s designers focused on the user wanting good snapshots of people 5’ to 20’ away.

9)      If you have a P&S camera you may not have full manual control of the focus, f-stop, shutter speed, white balance, and image capture type (RAW vs JPEG).

For an excellent technical discussion of the details of sensor size, see Cambridge in Colour – Digital Camera Sensor Sizes.

To see more of Ria de Neeve’s artwork, visit her site at: www.iamariver.org

My thanks to both Ria de Neeve and Gary Carpenter for permission to reproduce their work here.

Now you have determined the limits of your camera body. Next time we’ll talk about Glass: Part III – Picking Lenses.

PLEASE NOTE: All Photos on this site are Copyrighted and may not be used without written permission.