PMW-F3 and EX1R aliasing comparison.

workshops-275 PMW-F3 and EX1R aliasing comparison.
F3-EX1R PMW-F3 and EX1R aliasing comparison.
PMW-F3(top) and PMW-EX1R(bottom)

Here is a roughly done (sorry) comparison of the aliasing from an EX1R at the bottom and my F3 at the top. The F3 had a Nikon 18-135mm zoom, both cameras were set to default settings, 25P. The F3 clearly shows a lot more chroma aliasing appearing as coloured moire rings in both the horizontal, vertical and diagonal axis. The EX1R is not alias free. The chroma aliasing from the F3 is not entirely unexpected as it has a bayer sensor and there is always a trade off between luma resolution and chroma resolution and the point where you set the optical low pass filter. Frankly I find this performance a little disappointing. More real world test are needed to see how much of a problem this is (or is not). To put it in to some perspective the F35 aliases pretty badly too, but that camera is well known for producing beautiful images. I hope I’m being over critical of this particular aspect of the F3’s performance, because in every other respect I think the camera is fantastic.

UPDATE: I’ve taken a look at the MTF curves for the F3 and they are quite revealing showing that an OLPF is in use which is giving an MTF50 of around 800 LW/PH V and 950 LW/PH H. This is not quite as high as an EX1 and are quite reasonable figures for a 1920×1080 camcorder.  This suggests that the aliasing is largely limited to the chroma sampling of the sensor. As this is a bayer (or similar) type sensor the chroma is sampled at a reduced rate compare to luma, which is why coloured moire is not entirely unusual.

Tests performed with a Tokina ATX-Pro 28-70mm lens at 25P

Feeling a bit better about my F3 now 🙂

F3-MTF-H-Tam PMW-F3 and EX1R aliasing comparison.
PMW-F3 Horizontal MTF
F3-MTF-V-Tam PMW-F3 and EX1R aliasing comparison.
PMW-F3 Vertical MTF

5 thoughts on “PMW-F3 and EX1R aliasing comparison.”

    1. The F3 does the de-bayer process internally. With RED the de-bayer is done in software at the edit suite.

    1. The key things to remember about MTF are:

      It is a measure of contrast performance. Without contrast you cannot see the detail in an image.

      MTF50 is where black and white becomes middle grey, so if you had black and white lines, they would both appear as middle grey, so it would be difficult to visibly discern the difference between the lines in a real world image. But MTF50 is not the ultimate finite resolution, this would be around MTF10, so the resolution of the system will be higher than the MTF50 figure, but MTF50 is important as it measures the resolution and contrast that you will actually see in the image.

      The other important thing is the shape of the curve to the left of the MTF50 point. You want a nice big fat area under the curve as this determines how contrasty the image will be. A high contrast image will have a richness and crispness that would not be there in a lower contrast image. This contrast is what often differentiates between cameras that may have similar finite resolution but one just looks richer than the other. This is the verisimilitude (realism or true-to-life) that that you will find in high end cameras and lenses that is lacking in cheaper cameras, even though they may boast similar resolution.

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