Sensor Resolution

An ongoing conundrum we face in life is separating our wants from our needs… in photography that can manifest itself with sensor resolution. How much resolution do we actually need for the work we do? I can’t answer that question for you, nor can you determine that for me.

The objective of this article is simply to explain why the 20.4 MP sensors in my OM-D cameras have more than enough resolution to meet my specific needs.

NOTE: Click on images to enlarge. Photographs have been added to serve as visual breaks.

Olympus OM-D E-M1X + M.Zuiko PRO 12-100 f/4 IS @ 100 mm, efov 200 mm, f/5.6, -0.7 step, 1/800, ISO-320

When it comes to displaying our work online almost any camera or smartphone has sufficient resolution. For example, the images on this website are resized to 1200 pixels on the long end.

I use a pair of 27” monitors in my home office and when I click on an image in one of my articles it displays at a width of 34.5 centimetres (~13.5 inches). To my eye the images look sufficiently detailed to communicate effectively.

Olympus TG-5 @ 18 mm, efov 100 mm, f/4.9, 1/100, ISO-1250, microscopic mode

From a pragmatic standpoint resizing my photographs to 1200 pixels helps to keep my website costs in line, and also helps discourage intellectual piracy. So, 20.4 MP is more than sufficient for my online use. Heck, even the 12 MP sensor in my Olympus TG-5 is often sufficient.

The images used in my various photography eBooks have all been resized to between 2048 to 2400 pixels on the long end and work well for their intended use.

Olympus OM-D E-M1X + M.Zuiko PRO 7-14 mm f/2.8 @ 14 mm, efov 28 mm, f/5.6, 1/100, ISO-200

Another sensor resolution consideration is printing. When printing photographs at a standard 300 dpi (dots per inch) the actual difference in print sizes that different resolution sensors produce is often not as big as we may think it will be.

Let’s have a look at three comparisons based on full resolution files from different cameras that I have owned and used, all printed at a standard 300 dpi.

  • Nikon 1 J5 20.8 MP 1″ sensor (5568 x 3712 pixels) would produce a 18.56 x 12.37 inch (47.1 x 31.4 cm) print
  • E-M1X 20.4 MP M4/3 sensor (5184 x 3888 pixels) would produce a 17.28 x 12.96 inches (~43.9 x 32.9 cm) print
  • D800 36 MP full frame sensor (7310 x 4912 pixels) would produce a 24.37 x 16.37 inch (61.9 x 41.6 cm) print
Nikon 1 J5 + 1 Nikkor 10-100 mm f/4-5.6 @ 15.2 mm, efov 41 mm, f/8, 1/320, ISO-160

So, there is a difference when you examine the numbers at face value. It is interesting to note that even though my D800’s sensor had 76% more MP than my E-M1X, the actual width of a full resolution print is only about 18 cm (~7 inches) wider.

When comparing the potential visual impact of print sizes, an interesting test is to actually cut out these various sizes and tape them to a wall. When this is done, the size differences often do not look that significant from normal viewing distances.

Given the wall space that we may have available to display our work, and the cost of custom framing prints, producing very large size prints may not be practical or make economic sense.

Nikon 1 V2 + 1 Nikkor CX 70-300 mm f/4.5-5.6 @ 300 mm, efov 810 mm, f/5.6, 1/3200, ISO-1000

I seldom print and display my photographs in my home. I do have four motivational posters that I created many years ago displayed in my home office. These four posters each measure approximately 43 x 56 centimetres (~17 x 22 inches) and look perfectly fine from their intended viewing distance of about 2 metres (~6.6 feet).

All of the photographs in these posters were captured over 15 years ago during trips to New Zealand and Australia with a 4 MP Kodak DX6490 zoom camera. That camera had a minuscule 5.75 x 4.32 mm sensor.

French Polynesia, Kodak DX6490, 6 mm, efov 38 mm, f/5.6, 1/750, ISO-80

These 4 posters help to illustrate the importance of viewing distance. The amount of resolution (i.e. dpi) that is needed at various viewing distances varies significantly. We’ll get back to this issue a bit later on in this article.

From a business perspective we’ve sold 12 x 18 inch (30.5 x 45.7 cm) image size prints (and larger) captured with Nikon 1 gear and have never had a client complain about image quality.

Many of the photographs used in our safety, wellness, and respectful workplace business posters were created many years ago with a very small sensor camera.

Obviously some care was taken in terms of using studio lights and a tripod so we could shoot at base ISO. These photographs are reproduced to a width of 16.5 inches (~41.9 cm) on our business posters and our clients have always been pleased with the quality of our posters.

Olympus OM-D E-M1X + M.Zuiko PRO 40-150 mm f/2.8 @ 150 mm, efov 300 mm, f/2.8, 1/320, ISO-200, subject distance 780 mm

Let’s consider the standard dots per inch used to produce various types of materials that are printed commercially.

Billboards are typically printed at 15 dpi. Bus wraps and similar materials are usually printed between 72 dpi and 100 dpi. Glossy magazine spreads are done at 150 dpi. Even fine art prints are often done at 240 dpi.

Olympus OM-D E-M1X + M.Zuiko 60 mm f/2.8, f/8, 1/250, ISO-200, macro flash used

Let’s think about an E-M1X full resolution M4/3 file used on a billboard. At 15 dpi It would be blown-up to 28.8 feet wide (~8.77 metres) and could still be perfectly acceptable for a billboard application.

Joe Edelman does some incredible work with fashion photography. Six months after he made the switch from full frame equipment to Olympus M4/3 gear, Joe posted a video on YouTube.

In this video he described the reasons why he made the switch, and at the 12:19 mark in the video Joe shows one of his images that was used in an Olympus trade show booth. It was blown-up to 6 x 8 feet (~1.83 x 2.44 metres) and looks spectacular.

Deirbhile’s Twist, Ireland, Nikon 1 J5 + 1 Nikkor 6.7-13 mm f/3.5-5.6 @ 6.7 mm, efov 18 mm, f/8, 1/320, ISO-160

When holding a smaller print in our hands a typical viewing distance is about 18 to 24 inches (~46 to 60 cm). So printing at 300 dpi for smaller sized prints is the norm.

As prints increase in size we need to put them down and physically back up so we can view them from a more comfortable viewing distance. Under these conditions we do not have to use 300 dpi since our distance from the print would not allow us to discern as many visual differences in print image quality, as when the same print is viewed closer up.

Nikon 1 J5 + 1 Nikon 10-100mm f/4-5.6 @ 10mm, efov 27mm, f/8, 1/640, ISO-160

Let’s look at some of the minimum dpi values that can be used for prints based on various intended viewing distances.

  • 1 metre (~3.3 feet), 180 dpi
  • 1.5 metres (~4.9 feet), 120 dpi
  • 2 metres (~6.6 feet) 90 dpi
  • 3 metres (~9.9 feet) 60 dpi
  • 5 metres (16.4 feet) 35 dpi
  • 10 metres (32.8 feet) 18 dpi

Obviously higher dpi values can be used than the ones shown. The point is that using those higher dpi values would likely not result in any significant increase in perceived image quality at those intended viewing distances. We could be wasting money printing at higher dpi values than are actually needed based on intended viewing distances. Our eyes can only perceive what they can perceive.

Nikon 1 J5 + 1 Nikkor 6.7-13mm f/3.5-5.6 @ 13mm, efov 35mm, f/8, 1/320, ISO-400

Cycling back to our E-M1X example… an image that is intended to be viewed at 1  metre, and printed at 180 dpi, would produce an acceptable print measuring 28.8 x 21.6 inches (73.2 x 54.9 cm).

At an intended viewing distance of 1.5 metres, printed at 120 dpi, an acceptable print measuring 43.2 x 32.4 inches (109.8 x 82.3 cm) would be produced.

And, at an intended 2 metre viewing distance, the photograph could be printed at 90 dpi. This would result in an acceptable print measuring 57.6 x 43.2 inches (146.3 x 109.7 cm).

Purakaunui Falls, Nikon 1 J5 + 1 Nikon 6.7-13 mm, f/3.5-5.6 mm @ 8 mm, efov 21 mm, f/8, 1/4, ISO-160

Not separating our actual needs from our wants when it comes to sensor resolution can result in us buying more expensive, higher resolution cameras than we actually need for the work that we do.

We can spend countless hours examining images on a pixel peeping basis… and forget that the differences we may see at the pixel level are irrelevant when viewing the same photograph displayed in normal viewing formats, and at normal viewing distances.

Olympus OM-D E-M1X + M.Zuiko PRO 40-150 mm f/2.8 with MC-20 teleconverter, 270 mm, efov 540 mm, f/5.6, 1/200, ISO-200, Olympus FL-700 WR Flash used, subject distance 1.6 metres

We can also clog up our computer hard drives with additional megapixels that we don’t really need. And, we can waste a lot of time in post processing working on these larger-than-necessary files. Using high resolution files may necessitate upgrading our computer processor, motherboard, and RAM.

When I owned my D800 I needed to buy larger capacity, and more expensive, memory cards. As is often stated in the articles on this website… everything photographic comes with some kind of trade-off.

Our money is usually much better spent on higher quality lenses, than on higher resolution sensor cameras… regardless of the camera format that we may prefer.

Olympus OM-D E-M1X + M.Zuiko 60 mm f/2.8 macro, f/2.8, 1/250, ISO-320, handheld focus stacking used, subject distance 580 mm, out-of-camera jpeg

If we had the opportunity to view the Mona Lisa… Leonardo da Vinci’s masterpiece… would we take a magnifying glass with us so we could put our noses up to the painting and examine each individual brush stroke?

We would miss the beauty of his artistry if we did. It is a parallel experience when we get fixated with pixel peeping to find visual  differences with sensor resolution that may be completely irrelevant for the work that we actually do.

Technical Note

Photographs were captured hand-held using camera gear and technology as noted in the EXIF data. Images were produced from RAW files using my standard process.

Nikon 1 V3 + 1 Nikkor 70-300 mm f/4.5-5.6 @ 300 mm, efov 810 mm, f/5.6, 1/1000, ISO-1800

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10 thoughts on “Sensor Resolution”

  1. The MP size is such an easy trap to fall into. But some of my most impressive images (only 14MP) have come from my Nikon 1 AW-1 with the UW kit zoom -simply because it allowed me to compose and position the camera regardless of being above or under the water to get a different perspective. On the other hand , as you mentioned above, the High Res mode that Olympus offers ( on my E-M1 MkII) allows me to shoot a 50MP still life that just blows me away with the colour fidelity and detail. And then factor in modern software like AI Gigapixel and you can get very good quality files that are upsized by 2x or 4x – and that avenue is only to improve with time. Which boils down to get your composition and exposure right and you can probably make your image grow to the size “required”.

    1. Hi Mark,

      Thanks for sharing your experiences and perspectives! I couldn’t agree more that getting composition and exposure right are the keys to a great photograph.

      Tom

  2. I’m glad you brought up viewing distance. I did fine-art photography for a decade around the turn of the century, and independently came up with the formulas you presented.

    20 megapixels appear to be the “sweet spot” in terms of angular resolution of the human eye. If you make a big print, people have to back up to view it — it’s very simple!

    But I think I understand the obsession with more pixels — beyond the puerile “pull down the zippers and get out the rulers” aspect.

    I went on a photo club hike to a shore bird sanctuary. I had my trusty OM Zuiko 500mm ƒ/8 Reflex, which is nearly pocketable. I got decent-sized buffleheads in the frame that were half-way across the bay, hand-held.

    The guys with the huge Fool Frame cameras and monster 70-210mm ƒ/2.8 zooms were all carrying tripods. They were shooting like mad, but there was nothing close enough to get with 210mm!

    “How are you getting anything? They must be just specks!” I asked.

    “Oh, no problem. I’ll go home and crop it,” they replied.

    Amazing. Spend a lot of money on a huge, heavy camera, so you’ll have enough pixels so that you can throw 80% of them away in post!

    And then, make fun of people with “postage-stamp sensors.”

  3. It seems to me that another factor to consider is the vast potential of PP software to “increase sensor size”. In particular, some of the Topaz modules speak to this.

    Having learned photography in the film days, where each snap of the shutter cost 25c, I always tried to get the best possible image in camera. IMHO the use of good technique plus advanced PP software will likely make the sensor size issue of relatively little importance in the future.

    1. Thanks for adding your perspectives to the discussion Bill! I’m certainly a member of the choir when it comes to the potential impact of post processing software.

      Imaging technology like Handheld Hi Res mode and regular Tripod mode can also come into play and be utilized in specific situations where a photographer may need additional image resolution. While I seldom need Handheld Hi Res purely from a resolution standpoint, I do find this technology to be very useful when shooting at high ISO values in terms of providing increased dynamic range and reducing noise.

      I do think that we can become fixated on resolution when we don’t need it from a practical standpoint.

      Tom

  4. Hi Thomas,

    Great article as always!
    The biggest reason people chase MP is the “double tap / pinch to zoom” trend seen in computer and mobile screen viewers. Sites like Flickr and social messaging apps have promoted this trend because they show small thumbnails and users are forced to open the image to see the actual size. But now viewers keep expecting that they can tap more and still drill down further.

    To some extent that may be the photographer’s composition error as well. If the viewer feels the urge to zoom into something then the photographer has failed to anticipate and accommodate the viewer’s need for more detail. Or maybe, it’s the equivalent of using a zoom lens, just from a viewer’s perspective.

    Cheers,
    Ray

    1. Hi Ray,

      Thanks for sharing your perspectives and adding to the discussion!

      I don’t know why other folks chase MP, all I can share with readers is my own mistake buying into the ‘more is better’ mantra about sensor size and MP.

      Like some other people I bought into the idea that having a larger sensor camera with more MP, more dynamic range etc. would somehow make my photographs better… and by association make me a better photographer. It didn’t of course. That responsibility was mine.

      I found using larger, heavier full frame gear restricting, cumbersome, and terribly boring. I never felt any kind of connection with my full frame gear. At the end of the day it just didn’t fit how I like to work and experiment creatively.

      It wasn’t until I bought my Nikon 1 kit that my love of photography was reignited. The small size, portability, and some unique features like frame rate allowed me to do more with it. And, most importantly it didn’t get in the way of my creative instincts. It was a liberating experience. The incredible technology provided by my Olympus gear has opened up new creative pathways and opportunities which I love to explore.

      Each of us needs to use whatever equipment fits our style, and stimulates our creativity… rather than impede it.

      Tom

  5. Thanks for this article. Opportunity, preparation, timing, focus, and framing get more attention from me now than sensor size. I’m sticking with m43. But I admit to treating an occasional GAS attack for m43 lenses with a cash outlay.
    Joe

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