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-   -   Focus assist strangeness???? (https://www.dvinfo.net/forum/panasonic-p2hd-dvcpro-hd-camcorders/91923-focus-assist-strangeness.html)

Stephen Pruitt April 19th, 2007 09:46 PM

Focus assist strangeness????
Hi all. . .

I was just trying to use my focus assist on the HVX to see if I could discern any differences between 720 and 1080. And it looked like 1080 was clearly sharper. UNTIL I NOTICED THAT THE FOCUS ASSIST ACTUALLY IS AT A HIGHER POWER AT 1080 THAN IT IS AT 720!

Is this normal? I mean, whereas the focus assist looks 100% larger at 720, it is probably that much closer to 150% or even more at 1080. Is this normal??? And there is no doubt about this. . . it is zoomed in much more at 1080 than at 720.

Thanks much.


Benjamin Hill April 20th, 2007 10:35 PM

I'll venture a guess that it is tied to the fact that the 1080 frame is quite larger than the 720 frame.

Stephen Pruitt April 20th, 2007 10:50 PM

Thanks for the idea, Benjamin, but it isn't true. The frame sizes for both 1080 and 720 are identical. Only the lines of resolution are different. The image is the same.


Barry Green April 20th, 2007 11:07 PM

The frame size for 1080 is much larger than the frame size for 720. 1080 uses twice as many pixels as 720.

And yes, 1080 is significantly sharper than 720. Not twice as sharp, but around 20% sharper.

Stephen Pruitt April 21st, 2007 08:09 AM

Okay. I am obviously not making myself clear here. But it doesn't really matter. It was more of a question of curiousity of an observation I had not noticed before.

When focusing upon any object, at least with my camera (which otherwise seems to work just fine), the image area shown in the view finder is IDENTICAL (to the millimeter) regardless of whether I am in 720p or 1080p/i. This is not the case when using focus assist, however. Focus assist in 1080 shows an image about half as large as in 720. If focus assist is designed to show a set number of pixels (which is the same for both resolutions), then I can understand why I'd see much less of the image in the focus assist window. Since the resolution is higher, the same number of pixels would occupy a smaller part of the image in 1080. My original assumption, however, was that focus assist simply magnified a set physical area of the viewfinder, in which case the part of the area magnified would have been the same.

But thanks for the input.


Benjamin Hill April 21st, 2007 12:31 PM

You made yourself CRYSTAL clear the first time, Stephen. My HVX does the exact same thing.

The idea that focus assist pulls up a prescribed number of pixels, whether in 1080 or 720, could perfectly well explain what happens-- but it echoes what I said about it being tied to resolution (expressed, of course, as frame size). Always glad to help!

Stephen Pruitt April 21st, 2007 03:15 PM

You're right, Benjamin. . . but when I read "frame" I heard "screen image". However, since the screen images are the same size, it almost certainly points to the fact the number of pixels pulled up by focus assist must be the same.

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