Correcting shutter speed strobing effect

[Guest]

Archived from groups: rec.video.desktop (More info?)

My camera Panasonic PV-DV953 doesn't have a built in Neutral Density
Filter, but I'm determined to get
low DOF by opening the iris to the maximm. I live in the interior of
Brazil and it's impossible to get a 43 mm ND here in less than a
month.
I can get the iris full open by increasing the shutter speed though.
And then comes the strobbing effect.

Now the question: Is there any kind of virtualdub filter or pos
processing tool that would correct the strobing effect so i can get a
smooth
video with low DOF and without a ND filter? Is it possible anyway?

Thanks.

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

"Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
news:e299b146.0404250612.43beecb@posting.google.com...

> My camera Panasonic PV-DV953 doesn't have a built in Neutral Density
> Filter, but I'm determined to get
> low DOF by opening the iris to the maximm. I live in the interior of
> Brazil and it's impossible to get a 43 mm ND here in less than a
> month.
> I can get the iris full open by increasing the shutter speed though.
> And then comes the strobbing effect.
>
> Now the question: Is there any kind of virtualdub filter or pos
> processing tool that would correct the strobing effect so i can get a
> smooth
> video with low DOF and without a ND filter? Is it possible anyway?

You can apply a gaussian filter during movement parts
that show the problem (or "frame blending", if you can
get that to work...;-) while editing, but that is no fun...
Adding two polarizers can make a variable-density
ND filter, and AWB can neutralize their color bias (use
only a linear type on the outside, furthest away from the
lens...). I have used this to permit daylight IR shooting
with cameras that lock the setting to widest aperture and
1/60th (NTSC) shutter when "nightshot" is engaged...
--
David Ruether
rpn1@cornell.edu
http://www.ferrario.com/ruether

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

"David Ruether" <rpn1@no-junk.cornell.edu> wrote in message news:<B3Qic.19834$eK3.15811@nwrdny01.gnilink.net>...
> "Z? Carioca" <joaosilva5435@hotmail.com> wrote in message
> news:e299b146.0404250612.43beecb@posting.google.com...
>
> > My camera Panasonic PV-DV953 doesn't have a built in Neutral Density
> > Filter, but I'm determined to get
> > low DOF by opening the iris to the maximm. I live in the interior of
> > Brazil and it's impossible to get a 43 mm ND here in less than a
> > month.
> > I can get the iris full open by increasing the shutter speed though.
> > And then comes the strobbing effect.
> >
> > Now the question: Is there any kind of virtualdub filter or pos
> > processing tool that would correct the strobing effect so i can get a
> > smooth
> > video with low DOF and without a ND filter? Is it possible anyway?
>
> You can apply a gaussian filter during movement parts
> that show the problem (or "frame blending", if you can
> get that to work...;-) while editing, but that is no fun...
> Adding two polarizers can make a variable-density
> ND filter, and AWB can neutralize their color bias (use
> only a linear type on the outside, furthest away from the
> lens...). I have used this to permit daylight IR shooting
> with cameras that lock the setting to widest aperture and
> 1/60th (NTSC) shutter when "nightshot" is engaged...

I'll try those on my next shooting. Meanwhile i'm ready to order a ND
filter.
Which grade do you suggest 0.6 or 0.9 ? In some tests i had to
increase the shutter speed to > 1/1000 to get the iris wide open.

Thanks.

 

[Guest]

Archived from groups: rec.video.desktop (More info?)

On 25 Apr 2004 21:23:09 -0700, joaosilva5435@hotmail.com (Z? Carioca)
wrote:

>Which grade do you suggest 0.6 or 0.9 ? In some tests i had to
>increase the shutter speed to > 1/1000 to get the iris wide open.

Did you have to go back to < 1/1000 for most of your test? Or was it
occasionaly? Going back to 1/1000 is like 4 stops, so you would even
need a 1.2 for that. If it was occasionaly, you might be better of
with a .9. Alternatively, you can combine the ND with a polariser
to have a bit extra control, or if you have the money, you can get
a set of ND's. There are handy little filter-trays you can mount
to the front of your lens, where you can slide in a few filters.
If you use one of them, it is important to cover the sides where you
slide the filter in to block out the light, as you will see light
scattering in via the filters. Don't get tempted to tape the filters
together, unless you are a big fan of Newton rings ;-).

cheers

-martin-

--
filmmaker/DP/editor/filmschool techie
Sydney, Australia

"The world is on the move. Adopt, adapt, survive."