How do you focus HD broadcast camcorders?

[Mxsmanic]

In the old days (I haven't used broadcast equipment in ages), an analog
broadcast camcorder had a small but very high-quality CRT in the viewfinder,
and you focused the image on the CRT to focus the camera. But with digital
camcorders and high definition, how do you focus the camera to make sure that
the image is as sharp as possible? Does the viewfinder display contain all
2,000,000+ pixels so that you can get the sharpest possible focus, or what?
You can't get exact focus unless the viewfinder has at least as good a
resolution as the final image is supposed to have. So what is the current
method?

[Martin Heffels]

On Tue, 22 Mar 2011 10:32:53 +0100, Mxsmanic <***@gmail.com> wrote:

Image enhancement which makes the edges "pop" into place, or a pushbutton
which electronically enlarges the image 5-10x so you have a better idea about
focus. And the latter works good.

[Mxsmanic]

Post by Martin Heffels
Image enhancement which makes the edges "pop" into place, or a pushbutton
which electronically enlarges the image 5-10x so you have a better idea about
focus. And the latter works good.

I guess that sounds practical. It would be interesting to try. As I recall, on
analog camcorders, if your vision was good, the resolution on the CRT matched
what the camcorder could produce, so the best focus you could get in the
viewfinder was also the best focus the camera could produce, so no problem.

Of course the CRT had to be in perfect adjustment.

[mike]

Post by Mxsmanic

Post by Martin Heffels
Image enhancement which makes the edges "pop" into place, or a pushbutton
which electronically enlarges the image 5-10x so you have a better idea about
focus. And the latter works good.

I guess that sounds practical. It would be interesting to try. As I recall, on
analog camcorders, if your vision was good, the resolution on the CRT matched
what the camcorder could produce, so the best focus you could get in the
viewfinder was also the best focus the camera could produce, so no problem.
Of course the CRT had to be in perfect adjustment.

And that's why you pay the extra money for a good hi-res viewfinder.
The CRTs on my (almost) 10 yr. old JVCs (DV-550) are still crisp.
My new JVCs (HM-700) use a 4.3" flip-out LCD panel as well as an 0.45"
LCD viewfinder.
The camera has a feature called "focus assist" which turns the display
from colour to black and white and all objects which are in focus take
on a (user selectable) colored edge.
It sounded too strange to work effectively but, to my surprise, it
really does its job.

Mike

[ushere]

Post by mike

Post by Mxsmanic

Post by Martin Heffels
Image enhancement which makes the edges "pop" into place, or a pushbutton
which electronically enlarges the image 5-10x so you have a better idea about
focus. And the latter works good.

I guess that sounds practical. It would be interesting to try. As I recall, on
analog camcorders, if your vision was good, the resolution on the CRT matched
what the camcorder could produce, so the best focus you could get in the
viewfinder was also the best focus the camera could produce, so no problem.
Of course the CRT had to be in perfect adjustment.

And that's why you pay the extra money for a good hi-res viewfinder.
The CRTs on my (almost) 10 yr. old JVCs (DV-550) are still crisp.
My new JVCs (HM-700) use a 4.3" flip-out LCD panel as well as an 0.45"
LCD viewfinder.
The camera has a feature called "focus assist" which turns the display
from colour to black and white and all objects which are in focus take
on a (user selectable) colored edge.
It sounded too strange to work effectively but, to my surprise, it
really does its job.
Mike

like mike i use 'peaking' more than anything else. it's proved very
efficient.

[Mxsmanic]

Post by mike
The camera has a feature called "focus assist" which turns the display
from colour to black and white and all objects which are in focus take
on a (user selectable) colored edge.

How does the camera know what's in focus and what isn't?

[Mike Kujbida]

Post by Mxsmanic

Post by mike
The camera has a feature called "focus assist" which turns the display
from colour to black and white and all objects which are in focus take
on a (user selectable) colored edge.

How does the camera know what's in focus and what isn't?

The camera has no idea.
It's showing the operator (by using a peaking circuit) what is in focus
by the use of the green (or red or blue) outline.

Mike

[Mxsmanic]

Post by Mike Kujbida
It's showing the operator (by using a peaking circuit) what is in focus
by the use of the green (or red or blue) outline.

What sort of peak is it looking at?

[meagain]

Post by Mxsmanic
How does the camera know what's in focus and what isn't?

Modern camcorders use computers to check for line and edge
definition the same way you do. Fancy viewfinders can
highlight where it thinks the focus problems are/arenot.

[Frank]

On Tue, 22 Mar 2011 10:32:53 +0100, in 'rec.video.production',
in article <How do you focus HD broadcast camcorders?>,

Post by Mxsmanic
In the old days (I haven't used broadcast equipment in ages), an analog
broadcast camcorder had a small but very high-quality CRT in the viewfinder,
and you focused the image on the CRT to focus the camera.

Right, and CRT viewfinders are still available for some higher end
camcorders ($20K to $60K range), usually black-and-white but also
color sometimes. Such viewfinder options are usually about $5000.

Post by Mxsmanic
But with digital
camcorders and high definition, how do you focus the camera to make sure that
the image is as sharp as possible?

If it's a consumer-grade camcorder, autofocus. If it's a
professional-grade camcorder, operator skill and experience,
especially in run-and-gun situations such as much ENG work.

Note that the EVFs (electronic view finders) that are built in to
contemporary model camcorders consist of either an LCD (Liquid Crystal
Display) panel or an LCOS (Liquid Crystal On Silicon) display.

Post by Mxsmanic
Does the viewfinder display contain all
2,000,000+ pixels so that you can get the sharpest possible focus, or what?

You're as welcome as I am to download manufacturer's PDF product
brochures and spec sheets and manuals and study them (and you'll find
many of them in my Documentation Index, URL in sig), but if you look,
I'm not sure that you'll find a single camcorder, at almost any price
level, that actually has a 1920 by 1080 pixel viewfinder.

Post by Mxsmanic
You can't get exact focus unless the viewfinder has at least as good a
resolution as the final image is supposed to have.

If everyone truly believed that, then I suspect that few to no
camcorders would be sold.

Note that shooting conditions permitting, it's not uncommon to mount
an accessory display panel, typically up to about 7-inches in size, on
the rig so as to get a larger image at which to look, not just for
focusing purposes, but also for more accurate framing.

In higher-end studio shooting situations, it's not unusual to find one
or more larger (say, 17-inch or 25-inch) displays on the set.
Color-accurate displays of this sort are costly, however, usually well
over $10K each. A much lower-cost alternative is the HP LP2480ZX
"DreamColor" display, often used in post production suites.

It's my understanding that it's either impossible or very costly to
put a 1920 by 1080 matrix of pixels on an LCD or LCOS panel that's the
physical size of a typical EVF, at least at the present time. This may
change in the future, of course, as manufacturing technology advances,
but a camcorder design engineer must also consider heat-generation and
power-consumption related issues, not just functionality.

There's also the question of whether 2.01 million pixels, crammed into
the under 0.5-inch size of an EVF, would really provide any real world
benefit to the operator.

Post by Mxsmanic
So what is the current method?

Pray that everything is in correct focus, given that HD footage will
sometimes be viewed, even by ordinary consumers, on screens up to 70
inches in size, where out-of-focus conditions will tend to become
quite obvious to even the casual viewer.

Note that consumer-grade camcorders employ two different types of
autofocus techniques: EIS, or electronic image stabilization, usually
found only in the lower-priced models, and OIS, or optical image
stabilization, usually found only in the higher-priced models.
Professional-grade camcorders, just like film-based motion picture
cameras, typically offer no autofocus capability, instead relying upon
the camera operator, or an assistant, to pull focus.

[J. Clarke]

Post by Frank
On Tue, 22 Mar 2011 10:32:53 +0100, in 'rec.video.production',
in article <How do you focus HD broadcast camcorders?>,

Post by Mxsmanic
In the old days (I haven't used broadcast equipment in ages), an analog
broadcast camcorder had a small but very high-quality CRT in the viewfinder,
and you focused the image on the CRT to focus the camera.

Right, and CRT viewfinders are still available for some higher end
camcorders ($20K to $60K range), usually black-and-white but also
color sometimes. Such viewfinder options are usually about $5000.

Post by Mxsmanic
But with digital
camcorders and high definition, how do you focus the camera to make sure that
the image is as sharp as possible?

If it's a consumer-grade camcorder, autofocus. If it's a
professional-grade camcorder, operator skill and experience,
especially in run-and-gun situations such as much ENG work.
Note that the EVFs (electronic view finders) that are built in to
contemporary model camcorders consist of either an LCD (Liquid Crystal
Display) panel or an LCOS (Liquid Crystal On Silicon) display.

Post by Mxsmanic
Does the viewfinder display contain all
2,000,000+ pixels so that you can get the sharpest possible focus, or what?

You're as welcome as I am to download manufacturer's PDF product
brochures and spec sheets and manuals and study them (and you'll find
many of them in my Documentation Index, URL in sig), but if you look,
I'm not sure that you'll find a single camcorder, at almost any price
level, that actually has a 1920 by 1080 pixel viewfinder.

Post by Mxsmanic
You can't get exact focus unless the viewfinder has at least as good a
resolution as the final image is supposed to have.

If everyone truly believed that, then I suspect that few to no
camcorders would be sold.
Note that shooting conditions permitting, it's not uncommon to mount
an accessory display panel, typically up to about 7-inches in size, on
the rig so as to get a larger image at which to look, not just for
focusing purposes, but also for more accurate framing.
In higher-end studio shooting situations, it's not unusual to find one
or more larger (say, 17-inch or 25-inch) displays on the set.
Color-accurate displays of this sort are costly, however, usually well
over $10K each. A much lower-cost alternative is the HP LP2480ZX
"DreamColor" display, often used in post production suites.
It's my understanding that it's either impossible or very costly to
put a 1920 by 1080 matrix of pixels on an LCD or LCOS panel that's the
physical size of a typical EVF, at least at the present time. This may
change in the future, of course, as manufacturing technology advances,
but a camcorder design engineer must also consider heat-generation and
power-consumption related issues, not just functionality.
There's also the question of whether 2.01 million pixels, crammed into
the under 0.5-inch size of an EVF, would really provide any real world
benefit to the operator.

Post by Mxsmanic
So what is the current method?

Pray that everything is in correct focus, given that HD footage will
sometimes be viewed, even by ordinary consumers, on screens up to 70
inches in size, where out-of-focus conditions will tend to become
quite obvious to even the casual viewer.
Note that consumer-grade camcorders employ two different types of
autofocus techniques: EIS, or electronic image stabilization, usually
found only in the lower-priced models, and OIS, or optical image
stabilization, usually found only in the higher-priced models.
Professional-grade camcorders, just like film-based motion picture
cameras, typically offer no autofocus capability, instead relying upon
the camera operator, or an assistant, to pull focus.

If focus was really that difficult then still photographers would be
having huge amounts of trouble. Still cameras today have anywhere from
maybe 8 megapixels for a super cheap consumer model to 18 or so for an
entry-level SLR to 80+ for a large-format.

[Mxsmanic]

Post by J. Clarke
If focus was really that difficult then still photographers would be
having huge amounts of trouble.

They do, if they are stuck with an EVF. That's why the best still cameras have
optical viewfinders, which allow you to see exactly what the lens sees. I
suppose you could put an optical viewfinder on a video camera, which would
allow for very precise focus, but it would deprive you of a lot of information
about the video signal the camera is generating.

Post by J. Clarke
Still cameras today have anywhere from
maybe 8 megapixels for a super cheap consumer model to 18 or so for an
entry-level SLR to 80+ for a large-format.

Or an optical viewfinder for pro cameras. Some have prism focusing aids, too,
which can help a lot. But optical viewfinders wouldn't work for video, as
explained above.

I like the idea of a button that instantly zooms in so that you can check
focus, although I guess it would limit you to checking focus in the center of
the frame (but you could focus, then reframe).

[Martin Heffels]

Post by J. Clarke
If focus was really that difficult then still photographers would be
having huge amounts of trouble. Still cameras today have anywhere from
maybe 8 megapixels for a super cheap consumer model to 18 or so for an
entry-level SLR to 80+ for a large-format.

It's time-consuming if you don't have auto-focus, but not difficult.
I recently shot a bunch of stilsl on a 7D with PL-adapter and ARRI
Ultraprimes. It's a situation where the focus-assist was awfully handy, and
brought some tach-sharp pictures.

[Mxsmanic]

Post by Frank
Right, and CRT viewfinders are still available for some higher end
camcorders ($20K to $60K range), usually black-and-white but also
color sometimes. Such viewfinder options are usually about $5000.

Are they available because they allow more precise focusing, or simply because
some operators prefer CRTs?

Post by Frank
You're as welcome as I am to download manufacturer's PDF product
brochures and spec sheets and manuals and study them (and you'll find
many of them in my Documentation Index, URL in sig), but if you look,
I'm not sure that you'll find a single camcorder, at almost any price
level, that actually has a 1920 by 1080 pixel viewfinder.

I did look at some specs for a couple of Sony HD broadcast camcorders, but
there was no mention of the resolution of the viewfinders.

Post by Frank
If everyone truly believed that, then I suspect that few to no
camcorders would be sold.

It's not a matter of belief, it's a matter of mathematical fact. You can't
determine if 1920 pixels are sharp if you only have 1000 pixels to look at.
That has long been the problem with all types of electronic viewfinders:
unless they have at least as much resolution as the original image they are
displaying, they cannot allow for maximum precision in focusing.

Post by Frank
It's my understanding that it's either impossible or very costly to
put a 1920 by 1080 matrix of pixels on an LCD or LCOS panel that's the
physical size of a typical EVF, at least at the present time. This may
change in the future, of course, as manufacturing technology advances,
but a camcorder design engineer must also consider heat-generation and
power-consumption related issues, not just functionality.

Well, hopefully it will eventually be fixed. Do standard-resolution camcorders
have the full broadcast resolution in the viewfinders yet?

Post by Frank
There's also the question of whether 2.01 million pixels, crammed into
the under 0.5-inch size of an EVF, would really provide any real world
benefit to the operator.

Since it nearly fills the visual field, it should be at least as easy to
benefit from the resolution as it would be sitting in a room with a wall-sized
HD television set.

Post by Frank
Pray that everything is in correct focus, given that HD footage will
sometimes be viewed, even by ordinary consumers, on screens up to 70
inches in size, where out-of-focus conditions will tend to become
quite obvious to even the casual viewer.

Sounds like a step backwards from older camcorders.

Post by Frank
Note that consumer-grade camcorders employ two different types of
autofocus techniques: EIS, or electronic image stabilization, usually
found only in the lower-priced models, and OIS, or optical image
stabilization, usually found only in the higher-priced models.

Image stabilization and autofocus are different. I don't know how camcorders
handle autofocus, but good still cameras use parallax measurement to adjust
focus, which is very accurate (provided that you point the focus spot in the
right direction).

Post by Frank
Professional-grade camcorders, just like film-based motion picture
cameras, typically offer no autofocus capability, instead relying upon
the camera operator, or an assistant, to pull focus.

I suppose a focus puller would be feasible in studio work, but in ENG, I don't
know. I guess you can just zoom out to the widest possible angle and fudge
things with depth of field. It works for street photography.

[Frank]

On Tue, 22 Mar 2011 20:45:25 +0100, in 'rec.video.production',
in article <Re: How do you focus HD broadcast camcorders?>,

Post by Mxsmanic

Post by Frank
Right, and CRT viewfinders are still available for some higher end
camcorders ($20K to $60K range), usually black-and-white but also
color sometimes. Such viewfinder options are usually about $5000.

Are they available because they allow more precise focusing, or simply because
some operators prefer CRTs?

A bit of both I expect. Some traditions die hard.

Post by Mxsmanic

Post by Frank
You're as welcome as I am to download manufacturer's PDF product
brochures and spec sheets and manuals and study them (and you'll find
many of them in my Documentation Index, URL in sig), but if you look,
I'm not sure that you'll find a single camcorder, at almost any price
level, that actually has a 1920 by 1080 pixel viewfinder.

I did look at some specs for a couple of Sony HD broadcast camcorders, but
there was no mention of the resolution of the viewfinders.

I don't have time right now to look up any, but I would expect that
you'll see this specified more often on pro grade camcorders than on
consumer grade camcorders, so I'm a little bit surprised that you
didn't see it mentioned.

Post by Mxsmanic
If everyone truly believed that, then I suspect that few to no

Post by Frank
camcorders would be sold.

It's not a matter of belief, it's a matter of mathematical fact. You can't
determine if 1920 pixels are sharp if you only have 1000 pixels to look at.
unless they have at least as much resolution as the original image they are
displaying, they cannot allow for maximum precision in focusing.

People make do each day though, although some do use external
displays. But it should be noted that almost none, if any, of these
(usually around 7-inch) display panels have a 1920 by 1080 size.

Also, as far as I know, none of the expensive pro-grade CRT
viewfinders have particularly high res. In fact, some have what I
would describe as low res, despite the high price being asked.

Post by Mxsmanic

Post by Frank
It's my understanding that it's either impossible or very costly to
put a 1920 by 1080 matrix of pixels on an LCD or LCOS panel that's the
physical size of a typical EVF, at least at the present time. This may
change in the future, of course, as manufacturing technology advances,
but a camcorder design engineer must also consider heat-generation and
power-consumption related issues, not just functionality.

Well, hopefully it will eventually be fixed. Do standard-resolution camcorders
have the full broadcast resolution in the viewfinders yet?

I'm surprised that you said "yet". I mean, what manufacturer is
working on a new SD product in 2011?

Post by Mxsmanic

Post by Frank
There's also the question of whether 2.01 million pixels, crammed into
the under 0.5-inch size of an EVF, would really provide any real world
benefit to the operator.

Since it nearly fills the visual field, it should be at least as easy to
benefit from the resolution as it would be sitting in a room with a wall-sized
HD television set.

I don't mean to be argumentative, but each pixel would have to be so
small, and so physically close to its adjacent pixels, that I'm not
sure there would be much benefit.

And for what it's worth, I haven't yet seen a camcorder at any price
point that has a flip-out LCD panel that has a full 1920 by 1080
matrix.

Post by Mxsmanic

Post by Frank
Pray that everything is in correct focus, given that HD footage will
sometimes be viewed, even by ordinary consumers, on screens up to 70
inches in size, where out-of-focus conditions will tend to become
quite obvious to even the casual viewer.

Sounds like a step backwards from older camcorders.

Well, as long as outlets such as CNN continue to use UGC (user
generated content), often shot by amateurs on cell phones, it's not
really an issue. :)

Post by Mxsmanic

Post by Frank
Note that consumer-grade camcorders employ two different types of
autofocus techniques: EIS, or electronic image stabilization, usually
found only in the lower-priced models, and OIS, or optical image
stabilization, usually found only in the higher-priced models.

Image stabilization and autofocus are different.

Well of course they are! Any idiot knows that! I was having a
conversation with someone about EIS versus OIS when I wrote that, and
was still on my first cup of coffee to boot! Mea culpa.

[Mxsmanic]

Post by Frank
I don't have time right now to look up any, but I would expect that
you'll see this specified more often on pro grade camcorders than on
consumer grade camcorders, so I'm a little bit surprised that you
didn't see it mentioned.

So am I. In fact, even the type of viewfinder is not mentioned, and from the
photos, it looks an awful lot like the older CRT viewfinders. Are these
high-end HD camcorders still using CRT viewfinders?

Post by Frank
Also, as far as I know, none of the expensive pro-grade CRT
viewfinders have particularly high res. In fact, some have what I
would describe as low res, despite the high price being asked.

Then I don't see how precise manual focus could be possible without some
special gadget to assist (like a quick zoom function).

Post by Frank
I'm surprised that you said "yet". I mean, what manufacturer is
working on a new SD product in 2011?

I suppose that's true.

Post by Frank
I don't mean to be argumentative, but each pixel would have to be so
small, and so physically close to its adjacent pixels, that I'm not
sure there would be much benefit.

It's okay if the pixels are small. In fact, if they are too small to see
individually, that's ideal. That would allow you to focus as best as your eyes
can manage (within the limits of the camera resolution).

The smallest a pixel can become and still be individually distinguishable is
about 1/6872 of the viewing distance. So if you are looking at a screen that
is six feet away, the smallest pixel you can see would be 6/6872 = 0.3 mm in
size. For a viewfinder, it depends on the visual distance of the image after
manipulation by the optics in the viewfinder.

Anyway, 1920x1080 is far below the resolving power of normal human vision.
It's about 1/3 the resolution that the eye can see at normal viewing distance
("normal" meaning a distance equal to the diagonal of the image, roughly). So
lots of pixels can help with focusing--but there need not be more than the
image actually contains, since focus more precise than that will only provide
details that will be lost, anyway.

Post by Frank
Well, as long as outlets such as CNN continue to use UGC (user
generated content), often shot by amateurs on cell phones, it's not
really an issue. :)

The iReporter stuff? That's an amazing scam. CNN gets all sorts of useful
footage for free, taking advantage of the naivete of viewers. But I've
uploaded stuff to their iReport scam, too--stuff that wouldn't be worth paying
for, anyway.