"R. Westermeyer" <rwestermeyer@earthlink.net> wrote in message

news:4aq1605cq4fp0vk6j0evf00d766saq6osi@4ax.com...

> On Tue, 23 Mar 2004 22:27:42 GMT, "David Ruether"

> <rpn1@no-junk.cornell.edu> wrote:

> <snip>

> >Differences of scale of subject

> >parts resulting from changing FLs may appear to have this effect due

> >to the fixed number of scan lines

> <snip>

> Appreciate your response.

>

> If you don't mind, would you translate the above statement for this

> relative newbie?

Due to the way TV images are made and displayed (with a distinct

number of scan lines in the vertical direction), anything in the subject

that is not well displayed due to scale of detail or other characteristics

(like a lot of near-horizontal contrasty edges, which can result in

"stair-stepping" and jittering) can look bad on TV. If you change the

FL of the lens (by zooming or by adding a WA converter) or if you

move relative to the subject with the camera, you are changing the

relative size of subject elements in the image, and this *can* result in

more (or less) of a problem with scan-line interference in the displayed

TV image.

With DV, compression artifacts resulting from sharply-recorded

fine detail and patterns can also be affected (+ or -) by the same

changes in scale relative to subject elements. Reducing picture

resolution and contrast at the input by avoiding contrasty lighting

or by adding a diffusion filter to the lens (or by later filtering in the

camera or during editing) can reduce these image problems, but the

image will look less sharp (I prefer a sharper-looking image - video

is too low in resolution already to use sharpness-reducing methods

as a solution to this problem...;-).

--

David Ruether

d_ruether@hotmail.com

http://www.David-Ruether-Photography.com