There is some thing about 5D original

Started Mar 11, 2013 | Discussions thread
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There is some thing about 5D original
Mar 11, 2013

There was a very lively thread on the subject of resolution of a particular camera+lens combination. OP did a great job in conveying his message.

http://forums.dpreview.com/forums/thread/3396841

What has been discussed is mostly common knowledge, nobody argues about them.

1. No lens is perfect.

2. Better lenses do better irrespective of the pixel count of a camera or other factors such as the efficiency of the AA filter.

3. Law of Diminishing Return is merciless. Linear relationship between increasing megapixel and resolution is hardly a reality. Better lenses will realize the potential of higher resolution cameras better, although not to the extent suggested by pixel count.

Disagreement came when OP, based on DXO measurements, said that crop cameras with higher MP (such as 7D) may have worse resolution compared to a lower MP FF camera (such as 5D) when a cheap and not so good lens is mounted on them. OP's claim was based on a new (but not so original, read on) concept of resolution/sharpness introduced by DXO called 'Perceptual megapixel' (P-mpix). Although based on MTF (of lens or a lens camera combination) it introduces variables such as visual acuity. The idea is not new. Scientists of Kodak lab thought about it in 70s and came up with a concept called SQF.

http://www.bobatkins.com/photography/technical/mtf/mtf4.html

The point of contention was how resolution should be measured when a crop sensor camera was compared with a FF sensor camera. One quarter insisted that when comparing resolution, subject to camera distance should be increased for a crop camera to capture the same area of the scene (probably the method employed by DXO, as opposed DPR's method) while others thought it was unfair and camera to subject distance should be the same (my position, although I am a FF user). So, I decided to take crop sensor cameras out of the equation and just look at the P-mpix values of the FF cameras from DXO database. This is what I found.

5DI sensor (resolution) resists degradation by lesser lenses more than other cameras. There is something about 5D1 sensor.

Let's take Canon 16-35 II for example. This lens didn't do very well in DXO test. With this lens

5DI scores 10P-mpix, minimal loss of resolution

5DII scores 12P-mpix, huge loss of resolution.

Similar results with popular (but mediocre in DXO score) Canon 24-105.

What about a better lens? Let's take Canon 100/2.8

5DI scores 12P-mpix, no resolution loss

5DII, 15P-mpix, substantial resolution loss.

Things get interesting when you take the sharpest Canon lens, 300/2.8II

5DI scoes 13 P-mpix, as if its perceived resolution has increased, only camera to do this as far as I have seen.

5DII, 21P-mpix, no resolution loss.

At this point I thought 12MP probably was a sweet spot for the sensor with regard to resisting resolution degradation and preserving it. As there was no other Canon FF camera with same (similar) resolution in DXO database, I looked at Nikon D90, a 12 MP camera. This is what I found.

When mounted with Nikkor 17-35mm f/2.8D IF-ED

D90 scores 5P-mpix (compared to 10P-mpix of 5DI with a similar lens), more than 50% resolution loss.

And when mounted with Nikkor 24-70/2.8 it scores 7, whereas 5DI scores 10 with 24-70/2.8I (many consider Nikon to be a better lens).

Even with the best Nikon lens DXO tested, 85mm/1.8G, D90 scores 9P-mpix. Some resolution loss (as opposed to 5DI's gain with Canon 300/2.8II).

So, 12MP is not a sweet spot. There has to be something about 5D1 sensor that resists degradation by cheaper lenses and maintains (even improves) its resolution with better lenses.

I wonder what it is? Microlens? Efficient AA? Some other design? Maybe, there was a reason I was yearning for a 5DI like camera.

http://forums.dpreview.com/forums/thread/3390770

(OMG, I wrote such a long post! I miss Mikael, there is no one to talk about banding!:))

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Canon EOS 5D Canon EOS 5D Mark II Canon EOS 7D Nikon D90
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