I have read on a lot of places that the crop sensor bodies give you an extra reach over the full frame bodies when using the same lens. For example over here: http://www.slrlounge.com/school/cropped-sensor-vs-full-frame-sensor-tips-in-2 - "For example, this can be very useful when shooting sports, wildlife, and other types of photojournalism. Just imagine that on a Canon crop frame body such as a Canon 7D; your Canon 70-200mm f/2.8 lens is effectively a 112-320mm lens!"

So, after reading all of that, I have got the following setup:

  • Canon 5D MKIII, 70-200L IS and Canon 2x extender
  • Canon 450D, 70-200L IS and Canon 2x extender

But my question is - on both of those setups the maximum reach I'm getting is 400mm - should I not be getting more on my cropped 450D?

I'm checking the EXIF data in Lightroom.

  • \$\begingroup\$ See the question linked. But, the quick answer is that while the real focal length does not change, the field of view is narrower, and since the smaller sensor has higher pixel density, this may give you more detail than you would get cropping from an image from a full-frame camera. \$\endgroup\$
    – mattdm
    Apr 6, 2014 at 9:36
  • \$\begingroup\$ Also see What is “angle of view” in photography? for some background understanding on what is going on. \$\endgroup\$
    – mattdm
    Apr 6, 2014 at 9:42
  • \$\begingroup\$ Also! Since you have that setup, you are in a perfect position to do a real experiment to see if you are really getting more detail. I bet, since you are comparing a recent 22mpix full-frame body to a much older 12mpix APS-C camera, you won't. But it'd be great to see the experiment — not with the metadata, but with real photographs. \$\endgroup\$
    – mattdm
    Apr 6, 2014 at 9:48
  • \$\begingroup\$ Thanks Matt, and sorry, I probably missed that duplicate. Your answer on that question is very helpful too. But yes, this comparison might not be the best but will still be worth doing - I'll post a follow up! \$\endgroup\$
    – Ambuj
    Apr 6, 2014 at 13:19

1 Answer 1


Try this: Take the same picture from the same spot with each camera and the 70-200mm lens + 2X extender. You will see that the angle of view is narrower for the APS-C camera than the Full Frame camera. If both images are then displayed at the same size, the image from the APS-C camera will have been magnified to a greater degree than the image from the FF camera. That is what the article you linked to in your question is referring to: images from cameras with smaller sensors must be magnified to a greater degree than images from a larger sensor to reach the same display size.

Another way to look at it: take the image from the 5D mark III and crop it so that only the part that was captured by the center 40% of the sensor (that equates to an APS-C sized sensor). Then display it at the same size as the full image. You will see that it looks like the cropped print was zoomed in by a factor of 1.6x. What you give up in the case of cropping the same image is resolution. The original file is 21.1MP, the cropped image is about 8.24MP. That is lower resolution than your 12MP APS-C 450D.

  • \$\begingroup\$ Thanks Michael, that's the best explanation I have seen anywhere! Makes sense now. \$\endgroup\$
    – Ambuj
    Apr 6, 2014 at 11:36
  • 2
    \$\begingroup\$ Yeah — the open questions is whether that 12MP image actually contains more meaningful data than the 8MP one. \$\endgroup\$
    – mattdm
    Apr 6, 2014 at 13:47
  • \$\begingroup\$ @mattdm When doing such a comparison be sure to use the latest available RAW convertors on both .cr2 files. The older camera might surprise you. \$\endgroup\$
    – Michael C
    Apr 6, 2014 at 23:01

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