Comparison of Telephoto Lens Sharpness

I’ve written previously about the Panasonic GH-3 micro four thirds camera and the 100-300 mm lens. 1, 2  We were certainly delighted with the results we obtained during our recent visit to Africa. But how would it stack up against my professional Nikon 200-400 f4.0 lens? Furthermore, how would it measure up to the new Nikon 80-400 mm zoom?

I decided to put these lenses, as well as a Sigma 150-500 mm zoom, to the test. The question was, how would I test them? Some people claim to be able to see minute differences between photographs taken with different lenses. I’m not one of them. I can tell the difference between a great lens and a crappy one, but can I tell the difference between a great lens and a good one? I’m not so sure. I needed a more objective method for testing them. (I know, I could go read the reviews in Popular Photography and DxO data, but where’s the fun in that.) And then it struck me. How does my eye doctor test my visual acuity? With an eye chart! I decided to create an eye chart for my lenses.

So here is what I created. A bunch of lorem ipsum text in fonts that ranged from 8 to 20 point that I printed out on my laser printer. I attached the chart to a clipboard to hold it flat and then mounted the whole thing on the fence in our backyard. I set up my tripod about 50 feet away.

Scan at 1200 dpi-Edit-1

An “eye chart” for my camera.

Actual shot of "eye chart" with a 400 mm lens.

Actual shot of “eye chart” with a 400 mm lens at 50 ft.

The four lenses that I tested were:

  • Nikon 200-400 mm f 4.0
  • Nikon 80-400 mm f 4.5-5.6
  • Sigma 150-500 mm f 5.0-6.3
  • Panasonic 100-300 mm f 4.0-5.6

The first 3 lenses are full frame (FX) lenses which I mounted on a D610 camera body for the test. All were adjusted to a focal length of 400 mm. The Panasonic lens is a micro 4/3s format with a crop factor of 2.0. (The Panasonic lens was tested at 200 mm, the equivalent of 400 mm in an FX camera.) In all four tests the cameras were mounted on a tripod. Ambient light was measured with an incident light meter and the exposures set manually. The settings were 1/60th sec., f8.0 and ISO 400. The shutter was triggered with the camera’s self timer to minimize shake. As the photo of the clipboard shows, the target type was very small. I was wondering if anything would show up.

I imported the photos into Lightroom. I did no adjustments to the images other than to crop them to the same size for comparative viewing. Immediately upon viewing the photos I could see a difference between lenses. For presentation here I am only showing portions of the 20 point type and 8 point type.

Click on image to enlarge

Comparison of 20 pt. fonts.

Comparison of 20 pt. fonts.

The 20 pt. type shows a significant difference in sharpness between lenses. Not surprisingly the Nikon 200-400 gives the best, sharpest results, followed by the 80-400, the Panasonic 100-300, with the Sigma coming in last.

Comparison of 8 pt. fonts

Comparison of 8 pt. fonts

The 8 pt. data are a bit harder to interpret. Again, I was impressed that any of the lenses resolve the 8 pt. fonts at 50 ft. Once again, the Nikon 200-400 mm lens was the winner. However, the Panasonic lens appears to have beaten out the 80-400 mm lens slightly. All three gave amazing results, however. The Sigma…not so good!

Conclusion

So what does all this tell me?

  1. The Nikon 200-400 is still the best lens that I own and represents the gold standard of quality.
  2. The Panasonic GH-3 / 100-300 mm lens combination is a viable alternative to lugging around the heavier pro gear when weight and size are an issue.
  3. The new Nikon 80-400 mm lens offers excellent results that are close to the 200-400 mm lens in a much smaller and lighter package. Combined with the D610 body it is an excellent wildlife/action combo.
  4. We may have to consider what the future has in store for the Sigma 150-500 lens.

Footnotes:

  1. Panasonic GH-3 Passes the Test, https://pembertonphoto.wordpress.com/2013/08/28/panasonic-gh-3-passes-the-test/
  2. Panasonic Lumix GH3 Review by NE Explorers Mark & Cathy Pemberton, http://www.naturalexposures.com/panasonic-gh3-review/
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