How Do you Use a Light Meter and 18% Grey, photographing Art?

Hello,

I've been told to use an 18% grey card
when using my Canon T70's built-in light meter
to photograph my paintings.

But that if i get a light meter, i don't
need the 18% grey card anymore, right?
Because the meter instead reads the light
falling on the subject, right? I just plug in
the ISO and Aperture, and out comes the shutter
speed, right? So it really shouldn't matter what
color the subject is (or how dark or light).

Additionally, i bought Fuji64T, and i plan
to get the tungsten lamps (2x500watts should be enough?).

But i was wondering if these lamps would be usable
with my 4Mpixel digital camera when it arrives. Or
would it look like crap?

Thanks in advance.


Slick

http://www.drslick.org/

 

Word has it that on 2 Sep 2003 23:02:41 -0700, in this august forum,
(Dr. Slick) said:

Yes, that's good advice.

You will if you need to do white balance correction, which you probably
will if you're photographing paintings & need accurate colour.

Likely no better or worse than it would with a film camera.

 

You have a light meter, it's part of your camera. A hand held light
meter has the same issues (other than white balance and some also have that)
as does the one built into the camera. It is possible to measure the actual
light illuminating the subject rather than the light from subject so you
would not need the gray card.

 

By all means, use a gray card and a hand held meter to check the
lighting. By moving the gray card to every corner of the painting, you
can check verify that the illumination is completely even. By including
the gray card in the photo, you have a known reference point for color
and density. By using the gray card as a reference for white light
balance, you have a known standard for balance.

I also use a Macbeth ColorChecker card along with a gray card. I use
the gray card to set the white balance with my Nikon D100, and then
shoot the gray card until the histogram shows that the exposure is
perfect. Next I shoot the Macbeth ColorChecker to have an accurate
color/density reference in the photo. Then, without changing any camera
settings, I remove the gray card and colorchecker from the scene and
shoot the actual scene (usually bracketing). Finally, in Photoshop, I
use the image with the gray card and colorchecker to adjust the levels
and curves and color balance.

 

Yes. Meter in spot or centre weighted. Get up close enough that the
grey card covers the metering area and a bit more.

<snip>


Yes. But: A grey card will give you accurate results regardless of the
lens mounted. A light meter will give you accurate results but will not
account for minor differences in light loss between lenses. Your in
camera meter will compensate for this.

Yes, place the lamps at 45 deg angles wrt to the painting, each side of,
and level with the camera. Ensure that no light from the lamps gets
directly to the camera lens (any mirrors around?). The distance from
the lamps to the work should be several multiples of the size of the
painting to ensure even illumination. The further away, the more even
the lighting.

After you have determined the exposure, consider the exposure range of
the image. "survey" the paintings darkest and lightest areas (using the
in camera spot or ctr-wtd meter) and see how far off the readings are
from your chosen exposure.

Paintings have, at most, +/- 2 stops of scene latitude. This will
squeeze in nicely onto that film. If the shot is for scanning, consider
overexposing slightly (1/3 to 1/2 stop) to thin out the slide and make
it easier for the scanner to cope with. For projection expose normally.
(shoot one of each).

_If_ you are unsure, bracket in 1/2 stops on each side of the grey card
reading (5 shots per painting). (This will yield at least one slide for
projection and one slide for scanning in any case).

Use the tungsten setting of the camera or filters: 81A (household
tungsten lights) or 81B (white photoflood). These will cost you about
1/2 stop of light (your in camera meter will compensate for this, your
handheld meter will not).

Other:

--WHAT LENS? AVOID USING A ZOOM (or find the FL at which it has the
least distortion). 50, 85, 100mm prime lens' are ideal for this.
--TRIPOD
--CABLE RELEASE
--SHOOT AT 3 STOPS CLOSED FROM WIDE OPEN FOR BEST SHARPNESS
--MIRROR LOCKUP or TIMER WITH MIRROR LOCKUP (if you have it)
--AVOID SHOOTING 1/15 sec to 1/125 SEC IF YOU DON'T HAVE MIRROR LOCKUP
--REMOVE THE "UV" or "Sky" filters.

If shooting at 3 stops from wide open puts you in the 1/15 to 1/125
range, then close down 1 more stop and move your lights further away
until the speed is slower than 1/15 (Tripod and cable release are
essential).

 

What they mean is to use the camera's meter, but do manual metering. To
do this, hold card up in front of painting, and then read what the meter
says the exposure is. Now, using manual metering/exposure, remove card
and set camera for that exposure, shooting the painting.

 

You mean measure the illuminating light with the camera? By
placing the camera where the subject would normally be? hmmm...

I think i'm gonna try the 18% grey, because the light meters seem
a bit expensive. Does anyone recommend a good light meter, that is
fairly cheap too?


Slick

 

Photographing paintings is the primary use of my 35mm and 4x5 camera.
I use a light meter with both to measure incident light falling on the
canvas.
Fujichrome 64T is great for copy work. I have two Lowel 750w Omni lights
setup at 45 degrees to the painting for even illumination. I have not needed
a gray card.
Results are excellent. My meter is a Gossen Luna Star F digital. Its
important to have
the correct angle on the lights to control reflections, particularly on oil
paintings.

Good luck,

JimW

 

ebay. I was really shocked when I went shopping for one, to tell you
the truth. In fact, I never did get one. Here's a page with prices and
links to reviews:
http://www.photographyreview.com/Light,Meters/PLS_3115_913crx.aspx

There's about 300 listed on ebay. So you can use the above to compare
with what's available.

Watch out. If you get too much money wrapped up, you'll be obligated to
drop your paint brushes and take up photography, just to cap on your
investment. Just kidding.

Erik

 

In message <uXh5b.32246$>,

The light from the subject tells you nothing at all about how bright the
object is, relatively speaking. The grey card does. I see no point in
using the camera's dumb exposure algorithms in a studio environment with
controlled lighting. Use the grey card as is, or with a fixed
compensation.
--

 

Well no. Imagine, for example that your painting is entirely black. Your
meter doesn't know this so it tells you to overexpose a little - to
lighten things up - because it thinks the light is too low. This would
mean your photo turns out grey.

Now imagine your painting is entirely white. Your meter now tells you to
shut things down a little because the light is too bright - and your photo
turns out grey again. If you expose for grey and use those settings for
boh photos, then the dark painting will be exposed as being dark and the
light painting as being light - which is exactly what you want.

This is similar to what happens 9 times out of 10 when you have photos
processed by a 1 hour mini-lab. Their machine makes adjustments based on a
neutral-colour standard. If you take a photo of a gorgeous red sunset,
chances are your printed photo won't show just how red things were because
the mini-lab machine assumes you buggered up and tones down the redness.

Andy D.

"I'm a great speller - but a hopless tpyist!"

 

Plus be sure to include a shot of just the grey card for the lab (or you) to
use to adjust color balance for the rest of the prints on the roll.
Assuming you're using film and a lab that knows how to adjust color balance.

 

Do you recommend an amatuer who wants professional
results (as close as i can get), but not a lot of $, to
skip the light meter and use a grey card exclusively,
especially at first?


..

Ok, here's a silly question.. My aperture control has
labels for 8 and 11, but there is a "click" in between, at
what i presume to be 9.5 (not labeled).

Is "one stop" considered going from 8 to 11?

And 1/2 stop is considered going form 8 to 9.5?

Right?

Remove the protective/UV filter on the front? Scary!
I don't wanna scratch the lens!

Will it really affect the color?

Slick

 

I've been told to use an 18% grey card

That is correct, but you will need to manually set
the aperture and shutter after metering the gray card.

That is also correct if you use what is called an
incident meter. Most handheld meters have this
capability. Do not use a reflected/spot meter
as this just gets you back to where you were with
the camera meter.

2x500 will be fine. You will need a sturdy tripod and a
shutter release cable at least several inches long to
isolate vibration from your hand. Keep the lights at a 45
degree angle on each side and keep both of the lights and
the camera far enough back so you don't get a direct
reflection of the lights in the picture. You may find
this kind of work simpler with a 100mm or longer lens
because of the working distance and reflection control.

A slight issue is something called "color temperature".
The Fuji64T, which is a good choice, is balanced for
a color temperature of 3100 degrees K. A 500W screw
base "ECT" lamp has a rated color temperature of 3200
degrees which is essentially perfect for Fuji64T. The
more common 500W "EBV" lamps have a 3400 degree rating
and will produce a slightly cool (blue) cast. The
color temperature describes the measured physical
temperature of the filament. Higher physical
temperatures correspond to bluer or "cooler" emotional
colors. Lower temperatures correspond to redder or
"warmer" emotional colors. Standard household bulbs
are much redder than 500W photo lamps. You can use
mismatched lamps and film by filtering with color
correction filters. There are several different
rating systems but as an example, to use EBV lamps
with Fuji64T, you could use an R3 decamired filter
for a perfect match.

Another possibility is to use 4800 degree blue EBW
500W lamps with daylight balanced slide film but in
this case you would probably want to use a B3
decamired filter for perfect color correction with
slide film.

It should look just fine. Most high end digital cameras
let you adjust the color temperature so you can dial it
in directly. The tungstens might actually work better
than flash. Certainly much better than the built in flash.

 

"This is similar to what happens 9 times out of 10 when you have photos
processed by a 1 hour mini-lab. Their machine makes adjustments based on a
neutral-colour standard. If you take a photo of a gorgeous red sunset,
chances are your printed photo won't show just how red things were because
the mini-lab machine assumes you buggered up and tones down the redness. "

So do you ask them to print with no compensation?

Tom - Chicago

 

So you take a grey card pic and tell the lab that that is your standard?

Tom - Chicago

 

No, you ask the person by name...look at the name tag and say,
"Hey, Maria, I have a problem here that you can help me with...."
Explain what you wanted it to look like. If she says she
can't do that...and she might very well not know how to do it...ask if
they had a manager or something. (Learn their name.)
They can do wonderful things with the machines...if they know
how. In Chicago, you should be able to find a one-hour printer who
will give you virtually custom processing.
I shot a roll of negative film on a table top setup. Daylight
film with tungsten lighting. Half-way through the roll, I realized I
had not put the color compensating filter on the lens. I did at that
point.
The first bunch of images were a different color from the
second bunch and all of them were to be published in a series on the
same page.
I went back (Walmart; small southern town) and gave Louise a
print from the end and a print from the beginning and asked her to try
to match the front 8 exposures with anyone following them.
She did, the prints were published, and no one would know what
I had done.
So, learn their names and learn their capabilities...that
makes a one-hour processor a custom finisher. You are lucky to be in
a large city and have many choices.

Ken Cashion

 

Reputable labs will gladly re-print for you to get proper color balance.
Ed

 

The proper way to use a gray card is to set the camera to full manual,
spot meter the gray card under the same lighting that your subject is
going to be under, then shoot the subject, ignoring what your meter
reads. If you are outside and don't have a gray card there are other
things that come close to 18% gray, such as green grass. If you are
Caucasian you can meter the palm of your hand and open up about one
stop.

I would suggest that anyone that wants to learn to do some serious
photography to learn the zone system.

Don

 

Bringing a pan of homemade brownies doesn't hurt, either, Ken.
I'm shameless and transparent: My car mechanics get brownies every time
I bring the car in for an oil change or whatever. I'm their favorite
customer.