7D aliasing - psychiatrist needed?

Barry_Green said:
But the in-camera 720p is extremely more prone to aliasing. The way the camera samples and downconverts, the aliasing artifacts are a lot more prevalent in 720p than they are in 1080p. That's why I gave the (perhaps overly aggressive) recommendation that if you want to avoid aliasing, don't use the 720p mode.

Note, I'm not saying "never use the 720p mode", I'm saying "if you want to avoid aliasing, never use the 720p mode." If you want some slow-mo shots, and you're shooting stuff that doesn't have a tendency to exhibit the effects of aliasing (i.e., shallow-DOF shots, locked-down wides, etc) then you can use the 720p mode all you want. It's not very high-res, it's about standard-def res, but it delivers 60p that can be slowed down and, when used in appropriate circumstances, can make for lovely footage.

But it's much, much more prone to exhibit aliasing artifacts.
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Sorry that I was also perhaps overly aggressive. Thanks for clarifying - this is the kind of constructive criticism and opinion that I have always looked forward to in your posts. I also appreciate and agree with the comments from Rigs and Depth of Phil. It seems that many of us are swept up with the need for HD 'shapness' and have forgotten the quality of the softness with Black Promist and Soft FX filtration and if it helps overcome the aliasing problem, without backing off on the focus, the better it is.
 
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Barry_Green said:
[...]But the in-camera 720p is extremely more prone to aliasing. The way the camera samples and downconverts, the aliasing artifacts are a lot more prevalent in 720p than they are in 1080p.[...]
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So, would it be correct to say this is a software issue that could be rectified with an update?
 
I wouldn't think so; it seems to me it's more likely part and parcel of the way the sensor gets sampled. You have to keep in mind that it's a still-camera sensor that is only designed for 8 frames per second. In order to get 60fps out of it, they can only read little bits of it here and there; as a gross oversimplification, let's just say that they might be reading no more than one out of every 16 pixels in 720p mode (one out of a 4x4 block), and one out of nine in 1080 mode (one out of 3x3). So it's skipping huge gaps on the sensor. The gaps are what cause the aliasing (well, not really; it's the lens passing too much info down to the sensor, but that's getting pedantic; either way, it's seeing a tiny bit of spot detail instead of seeing a properly blended amalgamation of the whole).

So it's a fundamental hardware technique they're using, to make an 8fps sensor deliver 60fps speed. That's not something that's gonna be changed by a firmware update!
 
barry - there could be a way - they could sample as if it is 1080 and then in software downconvert with a low pass filter to at least not introduce new aliasing in 720
 
But if they did, they'd eliminate the entire purpose of why there's a 720p mode at all. 720p is there for the faster frame rate. If they sample it at 1080, they can't have the faster frame rate.
 
well - they could do it at 24 frames - i dont think thats irrelevant - many cameras shoot 720 and 1080
 
Well, yeah, I guess there's that, but ... that wouldn't give you anything you can't get already. At least with the method they're using now, there is a way to get 60 motion samples per second...
 
I shoot 1080p more, but I have shot quite a bit of skateboarding stuff with 720p. And honestly, on the Tamron 17-50 the aliasing is not that bad. It's far more than live able.

On Tokina 11-16 it's really bad at 720, but that's really the only lens that I have really bad problems with Aliasing. On that lens, I tend to stick to 1080 and sometimes soften the focus a bit.

But really... I think the Aliasing is really blown out of proportion. It does happen, but usually it doesn't ruin my day.
 
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