View Full Version : PAL SD - stair stepping / NTSC conversion

Bill Brown
August 25th, 2006, 07:41 PM

I've just got an HVX202EN (yes!) and started the first project with it.

I'm shooting SD (the piggy bank should be fat enough for P2 next time).

First test I used Setting F6 and didnt change any of the defaults. I shot 25P.

One subject contained lots of strips of different coloured glass side by side on a bench, and also glass artworks of mosaic like patterns - very challenging.

Pans and zooms produced noticable 'stair-stepping', very lively.

In reading the manual and trawling the forums it seems I should set V detail to Thick not Thin, at the expense of resolution.

The default is Thin - so would that have been that be the main reason for the stair-stepping?

Is there much resolution loss with the Thick setting?

Is there anything else I can do?

Should I try 50i rather than 25P? ( I had assumed that 50i would more likely caused such problems).

Also, there is one particular shade of red that really troubles the camera (noting that I really like the way it handled colour in general - and that red is the most difficult of all) - what can I tweak to try and improve the response to that shade of red?

Finally - the finished product will need go to DVD as a PAL version and an NTSC version.

Generally speaking, when shooting PAL SD with a view to an NTSC conversion, should one shoot 50i or 25p?

When shooting PAL HD - which frame rate would be the best option to cover the NTSC conversion?

(i'm doing post with FCP)


Leonard Levy
August 25th, 2006, 08:14 PM
I don't know anything about PAL.
In NTSC there is what you could call a flaw in the HVX that sounds like what you are describing. However I have only seen it on SD 60i, not on Progressive and not in HD.
This problem looks like excessive interlace artifacts that I describe as jaggies" but maybe the same as what you call "stairstepping.
I see it on contrasty straight lines - especially diagonals and especially when you are moving the camera.
It largely goes away in progressive and has nothing to do with thick or thin.

I would first make sure you were in 25P and double check the thick and thin issue.

Re: shooting 50i vs 25P: I would be wary of shooting anything in SD/60i on an NTSC HVX.

Bill Brown
August 28th, 2006, 05:19 AM
I found a section in the PAL manual (page 101) that says Vert Det Frequency is a setting for when shooting in 576i progressive mode.

Thin and Mid will give higher resolution than Thick.

BUT using Thin and Mid settings when played on a 50i monitoring television you "will see flickers on hoizontal and almost horizontal oblique lines".

I'm not sure what they mean by flickers, but it could be the same characteristic I'm seeing.

This seems to imply that you need select Thick when shooting 560i/25p ??

There's a lot of ambiguity in all that - does anyone know what it really means?

Leonard, I did more tests and confirmed I was on 25p.

I want to shoot more before I can say for sure, but it does seem perhaps that 50i produces more of this undesirable effect .. whether its called stairstepping or jaggies, or whatever.

But I'm also getting it in 25p, I've reduced it I think, but I want to try and eliminate it.