The limit to brightness

In article , Steve Thackery
writes
R. Kennedy McEwen wrote:

Fascinating post - thanks.

If it was at the broadcast end then all TV's, including CRTs, would
suffer from it at the same time, on the same images. They don't, so
it isn't at broadcast.

That's the only bit I might disagree with. I've certainly noticed the
occasional "topping out" effect on various TVs, including older CRTs.
I've never, though, had the chance to study them in a row to see if the
effect occurs (or doesn't) at the same time on all of them. Have you
done that? Can you confirm that you've seen it occur on some but not
all screens showing the same picture at the same time?

I have seen it on shop display racks where some sets show the clipping
effects and others don't but never seen it occur on all the sets
simultaneously, even though all are fed from the same source. Now, it
could be that the source wasn't clipping at the times I have been
viewing, and some sets were just badly set up, but I am fairly content
that the vast majority of the problem is down to individual sets rather
than broadcast, or even the STB, sources.
--
Kennedy

R. Kennedy McEwen wrote:

.......but I am fairly content
that the vast majority of the problem is down to individual sets rather
than broadcast, or even the STB, sources.

OK, thanks.

--
SteveT

"Steve Thackery" wrote in message
...
R. Kennedy McEwen wrote:

Fascinating post - thanks.

If it was at the broadcast end then all TV's, including CRTs, would
suffer from it at the same time, on the same images. They don't, so it
isn't at broadcast.

That's the only bit I might disagree with. I've certainly noticed the
occasional "topping out" effect on various TVs, including older CRTs.
I've never, though, had the chance to study them in a row to see if the
effect occurs (or doesn't) at the same time on all of them. Have you done
that? Can you confirm that you've seen it occur on some but not all
screens showing the same picture at the same time?

Yes: I've had my ancient JVC 14" CRT and 10-year-old Panasonic CRT both
tuned to analogue from the same aerial using the same transmitter, and seen
(occasionally) orange faces on the Panasonic but not on the JVC. Maybe the
Panasonic is more sensitive to bad material than the JVC. I think it may
have been "made-on-the-cheap" documentary rather than (eg) news or drama
that provoked it, but it was several years ago that I compared side by side
so I forget he exact details.

A lot of material from Sky box, via HDMI, seems to trigger it on my
fiancee's LCD TV and it's more common and/or more noticeable than via the
TV's built-in DVB decoder or the DVB decoder in her DVB disc recorder via
SCART, though I've not had chance to switch back and forth when I see it on
Sky to compare like with like. I wonder if her TV has separate
brightness/contrast/colour settings for each type of input (internal
analogue, internal DVB, SCART, HDMI).

In article ,
Bill Wright wrote:
You can't simply shoot with natural contrast ratios. The 'system'
simply can't cope with it. You either have to light the foreground to
reduce the contrast, or reduce the brightest parts with filters of
some sort

What sort of filter reduces contract?

A filter across the window of the room you're shooting in. Etc.

--
*Forget the Joneses, I keep us up with the Simpsons.

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Steve Thackery wrote:
You can't simply shoot with natural contrast ratios. The 'system' simply
can't cope with it. You

That's interesting - I don't know any of this stuff.

So basically, then, it means there is too much dynamic range in a "real
life" scene for the cameras and the rest of the broadcast chain? Hence
using fill lighting to bring up the shadows. Have I understood
correctly?

It obviously depends on the weather conditions - but with full sunlight,
yes.

I'm glad we got this discussion going - I love learning new stuff. :-)

Rather obvious on any footie match etc where the stand is shading one side
of the pitch, especially when the players have some white in their strip.

--
*Never kick a cow pat on a hot day *

Dave Plowman London SW
To e-mail, change noise into sound.

On Fri, 31 Aug 2012 11:57:20 +0100, Bill Wright wrote:

You can't simply shoot with natural contrast ratios. The 'system' simply
can't cope with it. You either have to light the foreground to reduce the
contrast, or reduce the brightest parts with filters of some sort

What sort of filter reduces contract?

A fog filter. Thinking framewise, a graduated filter.

Steve Thackery wrote:
Mark Carver wrote:

At least contemporary screens are a lot 'blacker' than they used to be.

Yes, absolutely, and it's well worth remembering. My Sony LCD is very
dark indeed when it's switched off, but I remember some older CRTs had a
very light screen - like an insipid pale brownish colour. No way could
that produce realistic blacks.

Don't forget though that in those days it was assumed that viewing was
done in greatly subdued light. People were used to drawing the curtains
and turning the light out to look at images on a screen, because of
movies and magic lanterns.

Also, no-one watched telly in the daytime, and interior lighting was
usually pretty dull. A single 100W bulb in a shade was as good as it got.

Bill

Dave Plowman (News) wrote:
In article ,
Bill Wright wrote:
You can't simply shoot with natural contrast ratios. The 'system'
simply can't cope with it. You either have to light the foreground to
reduce the contrast, or reduce the brightest parts with filters of
some sort

What sort of filter reduces contract?

A filter across the window of the room you're shooting in. Etc.

A shade then.

Bill

Dave Plowman (News) wrote:
In article ,
Steve Thackery wrote:
You can't simply shoot with natural contrast ratios. The 'system' simply
can't cope with it. You

That's interesting - I don't know any of this stuff.

So basically, then, it means there is too much dynamic range in a "real
life" scene for the cameras and the rest of the broadcast chain? Hence
using fill lighting to bring up the shadows. Have I understood
correctly?

This is the basis of adjusting the exposure of any kind of photography
to favour the gradation in the highlights or the gradation in the
shadows. Since large burnt out areas look terrible most auto exposure
systems take highlights into extra account, even when set for 'averaging'.

Incidentally I was messing around last year with still photography and
found that if I took a contrasty still life scene at several different
exposures using a tripod, it was possible to combine the shots in
PhotoShop and achieve a wider contrast range. This was of course
artificial and unrealistic, but it looked pretty nice.

Photographic paper used to be supplied in several different contrast
grades. Normally you'd print on Grade 3, but film had a wider range than
that paper, so there was always loss of either highlights or shadows
compared to the negative. Grade 2 would fix it, but often the prints
looked a bit flat unless there were significant areas at both ends of
the range.

Bill

In article ,
Bill Wright wrote:
Dave Plowman (News) wrote:
In article ,
Bill Wright wrote:
You can't simply shoot with natural contrast ratios. The 'system'
simply can't cope with it. You either have to light the foreground to
reduce the contrast, or reduce the brightest parts with filters of
some sort

What sort of filter reduces contract?

A filter across the window of the room you're shooting in. Etc.

A shade then.

Not really. It's common (in drama) to fit a filter to a window which is
invisible to the camera, so you can still shoot the window. It simply
reduces the light coming through it.

--
*What am I? Flypaper for freaks!?

Dave Plowman London SW
To e-mail, change noise into sound.