18% grey card

[glen_berry]

I know the advantages of shooting NEF/RAW, but I'd like to know how to properly use an 18% grey card. Everything

I've read suggests you focus on the grey card in the environment in which you intend to photograph and "take your

meter reading from that". That's where I get bogged down. I have a D300 - the 2 lenses I primarily use (for sports) are

the 24-70 and the 70-200VR - both 2.8. I shoot a lot in the school gym, which has recently installed new "bright

white fluorescent" lighting. Here's my take on how to use the grey card - hopefully someone can correct me if this is

not accurate: I'll set the camera to "M", the shutter speed to 1/400, the AV to 2.8, and the WB to either "Auto" or

fluorescent (3 or 5 in the camera menu). I'll set the ISO @ 800 for starters, hold the grey card in front of the camera

and take a shot. I'll tweak the ISO until I get it centered in the histogram in the camera's LCD. Am I on the right

track? Additionally, once I have the correct exposure setting for the 24-70, can I expect the 70-200 to utilize the

same setting, given both lenses are 2.8? Thanks for any help..

[tom_barrance]

Your method seems pretty close to the way I used to use a grey card with a manual film SLR. You could also set it to

aperture priority auto, note the shutter speed it gives you, and then set that with the camera on manual.

 

If you want to be really accurate you need to hold your card where your subject is going to be, though this probably won't

be that different to the light falling closer to the camera if it's fairly flat fluorescent light.

 

If I was trying to get the WB spot on I'd also hold a white card under the light and do test shots with the different

fluorescent options until you get one that looks neutral.

 

If both lenses are 2.8 and Nikon the exposure should be exactly the same.

[Matt Laur]

Sounds about right, Glen. Yes, both of your f/2.8 lenses will see things the same way, pretty much... though because you might be shooting different subjects/scenes with those different focal lengths, your metering priorities might be a little different. There are some other considerations, too. If you're thinking about shooting action on the court, then you need to take into account how the light on the court may be different than at arm's length on the sidelines as you meter against the card. Also: with most of your light coming from overhead, the angle at which you hold the card is going to make a big difference in terms of its apparent brightness. In a perfect world, you'd use something like an incident meter out on the court, or perhaps something like an Expodisk. Both a lot more expensive than the grey card, to be sure.

 

If the light's not changing during the game, and you have a little while to shoot and chimp ahead of time, your method should produce good results. Just keep in mind that as you turn the card on a horizontal access, it will be catching varying amounts of light (just like the uniforms and the tops of heads will), so that's something to experiment with. A two-dimensional card is only a so-so representation of the way light hits three-dimensional basketball players.

[glen_berry]

Thank you both, Tom and Matt. I've shot in that gym before with some good results, I go with S priority, rather than A, as I'm interested in stopping action, more than I'm concerned with DOF. I understand your comment about the overhead lighting, and the angle of the grey card in relation to it as well Matt - I'm anxious to make use of the grey card next week - thanks again for your help.

[vincent_peri]

Thom Hogan has an article on 18% gray cards. See:

 

http://bythom.com/graycards.htm

 

According to him, digital meters read 12% reflectance, not 18%.

[curt wiler]

All reflective meters read about 12% per the industry standard, so a meter reading off a gray card needs to be

adjusted for critical applications. Why not just use an incident meter if you can get close enough to use a gray

card?

[elliot1]

I have never used a gray card but I have shot in numerous gyms and arenas. Lighting typically tends to change from one area of the the venue to another so a setting that works in one area may not be accurate for another.

 

You have two really good tools built into your camera besides a pretty good light meter, the histogram (I would make sure the Highlight option is on) and the monitor. I would use them in addition to the gray card to confirm you have the right exposure.

[kelly_flanigan1]

The 18 percent card comes for the graphics arts industry in the 1930's; its FIVE times the reflectance of a piece of paper thats about 90 percent. Since one shot with asa 3 to 6 film with a copy stand camera or process camera; one exposes the lights with a timer; ie many seconds. There was no 12 percent meters then; or even meters in cameras; or even the ASA film speed yet; whcih came out in WW2. The reason one used the white side is somtimes the light is not enough to budge a meter with the grey side ; one metered then with the white side; then used FIVE times the time in seconds as a trial exposure. The reason its FIVE is because folks could multiply it easy; thus thats why the card was MADE to be 18 percent. The meters were so crude then; plus each maker had different film speed systems; the 18 percent card was a starting point for the graphics arts industry; and one used to align earlier meters; before the redefine of the asa system in 1960. Many meters in existance are never calibrated after they leave the factory; the best exposure might be with a card from 5 to 30 percent. In printing the grey card is used more for a neutral balance target; a pro often includes a entire greyscale step target in artwork shots..In reality you do not know if the meter another calibrates is tied to a certain standard; or what color temp is used; or the light levels and points that were checked; or if the target was even card; or just a typical source thats like a bodycap that pops on the body to test an slr.

[diane_madura]

Hi, Glen. I lost you here.

 

"I'll tweak the ISO until I get it centered in the histogram in the camera's LCD."

 

Can you explain further what you meant?

[glen_berry]

First of all - thanks to all who responded - I appreciate the input and the info. Diane - I meant I'd start the ISO @ 800, then increase or decrease it as required until the histogram spike on my camera LCD was approximately in the center, or a tad right of center. That way I should have a pretty good exposure. I'm not explaining this very well, but I hope you understand what I mean.

[studor13]

Glen, I think you are making things really hard for yourself.

 

Like Elliot, I've never used a gray card to work out the metering. I use it occasionally to get the WB if I'm

shooting JPGs. Even then, it's really not that important for me. In post you can simply pull the Blue channel to

get a very good WB.

 

Anyways, the D300 is very accurate with it's metering. Take a shot and then look at the LCD with the histogram.

If you need to adjust the exposure just dial -, or + and that's it.

 

Also, you should start at the highest possible ISO. The reason for changing ISO usually has to do with the

shutter speeds.

 

Lets say you can hand hold 200mm at 1/100. At f4, 1/200 and ISO is at 400 you work normally.When when the light

drops one stop, you don't need to change the ISO. You increase exposure by one stop at the same aperture. So now

you are shooting at f4, 1/100 and ISO is still at 400.

 

When the light drops another stop you can first try f2.8 leaving ISO at 400. Only bump up the ISO when you've no

longer have a bigger aperture, or you really want to shoot something at f4 and the ISO is too low and is

underexposing.

[glen_berry]

Andy - thanks for that thought. When I'm shooting BB or VB in that gym,(where the light is constant) I have to shoot @ 2.8 and have the ISO up around 1000+ so I can shoot @ 1/400 sec. to stop the action. Unfortunately, shooting @ f4, 1/200 sec,and ISO 400 isn't an option for the results I'm looking for, but I do appreciate your rationale and your example. Thanks to all who took the time to respond.

[studor13]

Glen, just one last thing.

 

A number of people have the 50mm f1.4 and they say that it can be used wide open for indoors BB with excellent results.

 

Of course you will need to get closer to the action but the lens is said to be great for many other things as well. I don't have this lens but have the f/1.8 which you may know is extraordinary for the price.

[owen_omeara]

Andy:

 

I have the 50mm f/1.4 and it is outstanding. The clarity, sharpness and contrast are fantastic even wide open. I do not

have the 1.8 to compare but have heard great things about it especially considering the price.

 

-Owen

[tom_barrance]

I have the 1.8. The bokeh isn't very nice (or maybe I'm spoilt - I'm used to using an 85mm Zuiko which is outstanding).

[glen_berry]

Andy - thanks - I do have that lens, it's what I use during foul shots in BB. I'm very pleased with the results from that lens.