The Central Sensor Crop « Arthur Morris/BIRDS AS ART

The Central Sensor Crop

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Common Eider, molting male, Shinnecock Inlet, Hampton Bays, Long Island, NY. Canon 800mm f/5.6L IS lens with the 1.4X II TC and the EOS-1D Mark IV. ISO 800. Evaluative metering -1/3 stop: 1/2000 sec. at f/8 in Av mode.

The Central Sensor Crop

When I am using the 800 with the 1.4X II TC and the Mark IV, I have autofocus but only the central sensor is active. This greatly limits your compositional choices, especially when you are working with moving subjects and AI Servo AF. There are many other situations where you are limited to the central sensor only. Two common ones for me were when I worked with either the 500mm or 600mm f/4L IS lenses, the 2X II TC, and a pro body.

When you are working with the central sensor only with a moving subject that is not large in the frame, the subject will always be in the center of the frame. Thus the “central sensor crop” was born. With the large file sizes of the modern digital bodies, sharp images can stand healthy crops. To execute the central sensor crop, I crop from below the bird and from behind the bird; this places the bird pleasingly near one of the lower corners of the frame in the vicinity of one of the rule of thirds points. I use this crop often with swimming ducks as well as with birds in flight.

Having the bird in the center of a horizontal image rarely works well (unless the bird is flying right at you). You can learn the basics of composition in the original The Art of Bird Photography (soft cover). And you can study advanced composition and image design in the section of the same name in The Art of Bird Photography II (916 pages on CD only). Better yet, you can save $10 by purchasing them together here.

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This is the original image before cropping. Note that with the central sensor on the bird there is no other place for the bird to be but smack dab in the center of the horizontal frame. Bad! A healthy crop from behind and below the bird yielded the opening image in this blog post.

Shopper’s Guide

Here is a list of the gear that I used to create the image above.

Canon 800mm f/5.6L IS lens
Canon EF Teleconverter 1.4X II
Canon EOS-1D Mark IV professional digital camera body

And from the BAA On-line Store:

Gitzo 3530 LS Tripod
Mongoose M3.6 Tripod Head
Delkin 32gb e-Film Pro Compact Flash Card

If you are considering the purchase of a major piece of photographic gear be it a new camera, a long lens, a tripod or a head, or some accessories be sure to check out our complete Shopper’s Guide.

10 comments to The Central Sensor Crop

  • Nate

    Excellent! Have you used this technique for print? If so what was the largest you printed from such crops? Thanks so much!

  • Arthur Morris/BIRDS AS ART

    Gordon, We recommend that all serious photographers use RAW capture 100% of the time. Surely working without a TC gives you lots of opportunities to crop for composition, but that was not Becky’s question. She felt that if you did not use a TC and cropped that the resulting image would be sharper. My gut feeling was that she was wrong. As it turns out, she was wrong and I was right 🙂

    For an explanation, click here.

  • Gordon Lindsay

    I feel that shooting in raw and cropping in PS afterward gives a lot of options for the final image.

  • Arthur Morris/BIRDS AS ART

    Nelson, I will see you at Anhinga Trail in FEB. The workshop sold out so quickly that the woman who organized it now calls me “rock star.”

  • Arthur Morris/BIRDS AS ART



    I think generally I’d rather shoot without an extender and crop than use the extender and not have to crop. Depends on the subject, but do you agree, to a point?

    Nope. When the birds are distant I will go with the 1.4X. Always. I have seen the math on that but do not remember the conclusion. If anybody knows, please chime in with a link.

  • Shinnecock Inlet is Hampton Bays, not Westhampton Beach.

  • P.S. I do realize without the extender you can move the focus from center to right (or left), but my reflexes are best with center focus when it comes to fast moving birds.

  • Artie, I’m so glad to see even the best of pros crop! With the Mark IV and 800 I think generally I’d rather shoot without an extender and crop than use the extender and not have to crop. Depends on the subject, but do you agree, to a point?

  • nelson pont

    thanks artie i used the crop it really looks better with the bird flying into the image see you soon nelson