DON'T MISS: Italian conceptual portrait photographer Sara Lando coming to US for two weekends of workshops in August.

Tuesday, April 25, 2006

On Assignment: Dealing with TV's and CRT's

A little while back I was assigned to photograph the CEO of a television network which shall remain nameless. We'll just refer to them cryptically as The "D" Channel.

I shot the CEO near a bank of TV's, and I want to take this opportunity to talk about some of the problems and solutions for dealing with the little buggars. (TV's, not CEO's.)

There are several things you have to remember when shooting TVs/CRT's, and I want to walk you through one thought process you can take when you come upon them.

The first two things you need to remember are to (a) kill the ambient, and (b) get to a shutter speed of 1/30th of a second or longer.

The ambient cannot always be controlled. But you want to get it as low as possible because the CRT's are basically light sources. The tone of the "turned off" CRT in the room's existing light is the darkest tone you will possibly be able to get for your richest black on screen when the CRT is turned on.

This is to say that, if the TV is a medium grey value in the room light, that is the deepest black you will be able to get in your lit photo of the functioning TV.

To get the ambient down, turn off the room lights if you can (duh). Also, try to shade any windows by drawing the curtains or blinds.

Once you have the TV (or computer CRT) in as dark an environment as possible, turn it on. Meter through the lens at the TV, with the picture filling the frame.

Here's where the 1/30th comes into play. Set your shutter there, because that is the fastest shutter speed that will get you a complete scan cycle of the cathode ray, which "paints" the screen about 30 times a second. That's why you get little stripes at, say, 1/125th or 1/250th. Luckily, this is not the case for most of the flat-paneled monitors we are using more and more these days. But they are dim enough where the slow shutter speed is usually gong to be used anyway.

Now that you have your shutter speed set, adjust your aperture for best exposure. If you cannot get the f/stop opened enough for a good exposure, drop to a 15th of a second. Or an 8th. You get the idea.

This full-scan, ambient light exposure will be your working exposure for the whole photo. This is why you want the turned-on TV to be the brightest thing in the room. Your subject will be darker, and you will have to adjust your flash to raise the subject to balance with the TV. Fortunately, you are not afraid of a little manual flash now and then, Right?

The last thing to remember about CRT's is that they are rounded, which means you may have to work a little creative lighting geometry to hide the flash's reflections in the screen. One tip is to stick your flash behind the monitor and shoot in profile like we did in the final shot in "Abstract Concrete," earlier.

OK, so back to The "D" Channel lady.

We got the room as dark as possible, which was "not very." This means that my blacks on the monitor were not as rich as I would have preferred. But as long as you know how to do it, that is what is important. The monitors filled the wall on the left, so I brought my Nikon SB-28 strobe (on a stand, in an umbrella) around closer to me (on the right) than I normally might have. This got rid of my flash reflections in the TV's.

The TV's were around 1/30th at 2.8 at 400 ASA, if memory serves. (This is usually about where they hit, and a good starting point for guest-imating.) The actual exposure is less important than knowing how you get there. Then I just dialed the flash down on manual, checking the TFT monitor as I went, until she looked balanced.

I know this sounds like a lot if you are new to it, but it really is not. Here it is again, in a nutshell:

1) Get the room as dark as possible.
2) Using 1/30th as your maximum shutter speed, get your exposure, based on the TV screen - right through the lens.
3) Adjust your flash to balance the subject.
4) Angle your flash to avoid TV reflections.

Computers (and TV screens) are a fact of life, and hardly a week goes by that I do not have to shoot someone in that environment. Learn to do it well, and never worry about it again.


Next: Simple Wall/Snoot Portrait


__________

Brand new to Strobist, or lighting? Start here.
Or, jump right into our free Lighting 101 course.
Connect: Discussion Threads | Reader Photos | Twitter

8 Comments:

Anonymous Anonymous said...

For PAL-land, it'll be 1/25 or slower shutter speed. - YowCH (MY in SG)

April 27, 2006 12:47 AM  
Blogger David said...

Great info on your blog here! I have to shoot tv and monitors doing university work at times, but what really challenges me is when they have projection screens. YIkes!

April 27, 2006 4:31 PM  
Blogger David said...

Hey, "Other David"

Check out "Abstract Concrete" in the "On Assignment" section for one approach.

Short answer is that it is tougher than CRT's. You have to

(a) Kill the ambient
(b) mind your shutter speed for the full scan, and
(c) Keep any ambient (or strobe) light from hitting the screen.

Solution: Create separate zones of light by using snoots.

April 27, 2006 4:37 PM  
Blogger David said...

Using snoots on a remote flash would be great. I will need to try that next time this occurs. Killing the ambiant is rarely an option as I shoot these things on assignments where I can't really interfere much with what's going on(which also can make it hard to set remotes.
Another trouble is that some speakers tend to move around while they talk.
This is a great site. When my work slows down a bit I am going to read through it, might be a couple more weeks though.

May 03, 2006 10:33 AM  
Blogger David Chu said...

9 Paragraphs down, spelling error.

"But they are dim enough where the slow shutter speed is usually gong to be used anyway."

"gong".

February 09, 2008 10:36 PM  
Blogger Alex Russel said...

Something to consider for the more computer-technical: While TVs (at least in NTSC land ;) are always 60Hz, CRT monitors have variable refresh rate frequencies that can be set from the operating system.

Since your selection of available shutter speeds is limited to certain mathematical factors and multiples of the refresh rate, by changing the refresh rate you can open up almost any shutter speed you want.

For example, for some reason you need a shutter speed higher than 1/100... The closest multiple is 1/120, so at 60Hz 1/125 sort of works, but not well enough. Change the monitor refresh rate to 80Hz (common on many monitors) and suddenly you have 1/160 available (as well as 1/320, 1/640, 1/800, 1/1600.... if you can sync that high!)

Keep in mind that lower screen resolutions have higher refresh rates, and you can get screens cranked up to 120Hz or higher!

Once you've set the computer, look up the selected refresh rate on a table of divisors or a table of multiples and you'll see all the available shutter speeds.

Fun!

September 11, 2008 1:54 PM  
Blogger Matt R. said...

You wrote, "a complete scan cycle of the cathode ray, which 'paints' the screen about 30 times a second."

In reality, it "paints" 60 times per second, because each frame of NTSC video includes two FIELDS of information. First, the odd scan lines are drawn, then the even scan lines. You're really seeing 60 images per second, not 30 as is commonly thought.

So, that is what causes stripes at higher shutter speeds. You're not allowing allowing the entire two-field frame to "burn in."

September 21, 2009 5:15 PM  
Blogger David Wiltshire said...

I love these CRT Televisions...Too bad the new LCD and Plasma TVs are taking over.


http://mcanetworkacademy.com/rangel86/do-you-remember-the-big-old-crt-television

August 04, 2013 1:59 AM  

Post a Comment

<< Home