5D Mark III vs 7D - Effective Resolution When Cropping and Noise Reduction Applied

Started Oct 28, 2012 | Discussions thread
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kidcharles
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5D Mark III vs 7D - Effective Resolution When Cropping and Noise Reduction Applied
Oct 28, 2012

Hi all, I'm sure someone has done this before but I thought I would share the results of my own test. I bought a 5D Mark III and still have my 7D, but need to decide whether or not to sell it. Basically the only real reason to keep the 7D would be the extra reach due to the crop factor for telephoto bird shooting (the 8 FPS on the 7D vs. 6 FPS on the 5D is not a serious issue for me).

I set up the following test:

Lens: 400mm f/5.6 L (set to f/11)

RAW with Auto Lighting Optimizer and Highlight Tone Priority both OFF

Processed in Lightroom 4. 5D3 shots were upsized to match pixel size of 7D images. No post-sharpening was applied during export.

Test Cases:
ISO 100 - 1/500s
ISO 400 - 1/2000s
ISO 800 - 1/4000s
ISO 1600 - 1/8000s

The target was a bit of a brick building off in the distance with some paint detail.
Observations:

1. In Lightroom it was necessary to boost the exposure on the 7D shots by 0.48 to get the same approximate exposure level compared to the 5D3 shots. This means that ISO 100 actually is significantly less sensitive on the 7D than the 5D so you would have to boost the ISO on the 7D to get the same shot, which is a strike against the 7D. I don't know if this is just in Lightroom or also in other editors.

2. In a direct comparison (without noise reduction) the 7D definitely has more detail, but also has much more noise at any given ISO. (To my eye the 5D3 ISO 1600 shot had the same amount of noise as the 7D ISO 400 shot.)

3. The amount of Lightroom 4 luminance noise reduction necessary on the 7D shots to match the noise level of the equivalent 5D3 shots was:

ISO 100 - 20
ISO 400 - 30
ISO 800 - 30
ISO 1600 - 30

Once this noise reduction was applied, there was noticeably less detail in the 7D images compared with the 5D3 images.

Conclusion:

Based on these results (particularly in light of the non-equivalent ISO mentioned in 1) I have to say that the 5D3 will be able to fully replace my 7D for my bird photography, with the only drawback being the lower FPS rate which I can live with. Field tests showed that the 5D3 autofocus system is at least as good and probably better than the excellent 7D system.

Shots are in this gallery:

http://www.dpreview.com/galleries/6934125313/invite/F226DB7B1F3F4AF18D473CBD135F2FA9



Canon EOS 5D Canon EOS 5D Mark III Canon EOS 7D
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