So, I just read through what Alan Robert's had to say about aliasing at 720p with the HPX371:
The camera can be used in 720p mode, which is the only way to get access to “off-speed” shooting. There is clear aliasing in the picture, both horizontally and vertically. This is inevitable in any camera, since the conversion to 720p is a standards conversion, which cannot be done satisfactorily in any camera at an economic price. Resolution is cleanup to about 1280 by 540, with vertical aliasing dominating above 720. The aliasing with a null centre at 1080 (vertically) and 1920 (horizontally) is evidence that there is probably only horizontal optical filtering in the camera, the strong vertical alias would be suppressed if there were vertical filtering as well. The performance is not bad, and is probably acceptable if the need is to shoot off-speed, but for shooting on-speed, it would be better to shoot at 1080 and down-convert externally as part of the post production operation unless the motive for using 720p is to improve motion capture.
Read the whole white paper here: http://www.bbc.co.uk/rd/publications/whitepaper034_add53_panasonic_ag-hpx371.shtml
First of, am I correct in assuming that the HPX250 would perform nearly identically? If so, is there any way to mitigate the aliasing? I'm shooting a verite doc and recording at 24pN at 720p would save a lot of card space, but if the aliasing is too noticeable maybe this is a bad idea. As Alan says, it's "inevitable in any camera," but looking at some of his other tests, it's a lot less noticeable in some higher end cameras.
I'm tempted not to worry about the aliasing and shoot at 720p anyway, but I'd be curious to hear from others with more experience.
If I were to buy enough P2 cards and shoot at 1080, but I also wanted to shoot off-speed occasionally, could I just up-convert the 720p in post? If so, what would a sensible workflow be?
Thanks!
Matt
The camera can be used in 720p mode, which is the only way to get access to “off-speed” shooting. There is clear aliasing in the picture, both horizontally and vertically. This is inevitable in any camera, since the conversion to 720p is a standards conversion, which cannot be done satisfactorily in any camera at an economic price. Resolution is cleanup to about 1280 by 540, with vertical aliasing dominating above 720. The aliasing with a null centre at 1080 (vertically) and 1920 (horizontally) is evidence that there is probably only horizontal optical filtering in the camera, the strong vertical alias would be suppressed if there were vertical filtering as well. The performance is not bad, and is probably acceptable if the need is to shoot off-speed, but for shooting on-speed, it would be better to shoot at 1080 and down-convert externally as part of the post production operation unless the motive for using 720p is to improve motion capture.
Read the whole white paper here: http://www.bbc.co.uk/rd/publications/whitepaper034_add53_panasonic_ag-hpx371.shtml
First of, am I correct in assuming that the HPX250 would perform nearly identically? If so, is there any way to mitigate the aliasing? I'm shooting a verite doc and recording at 24pN at 720p would save a lot of card space, but if the aliasing is too noticeable maybe this is a bad idea. As Alan says, it's "inevitable in any camera," but looking at some of his other tests, it's a lot less noticeable in some higher end cameras.
I'm tempted not to worry about the aliasing and shoot at 720p anyway, but I'd be curious to hear from others with more experience.
If I were to buy enough P2 cards and shoot at 1080, but I also wanted to shoot off-speed occasionally, could I just up-convert the 720p in post? If so, what would a sensible workflow be?
Thanks!
Matt
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