Light meter or grey card? Do I need one?

[glockhq]

sorry for this completely novice questions but I just picked up a 10D w/ a fixed 50mm lense. I have seen the grey card and the light meters but I do not know what they will or will not allow me to do or what they will help with. My thought is the light meter might tell me what fstop I need to set to take an accurate photo?? Thanks in advance for your replies!

[eosster]

Your camera has light meter, I would buy a gray card.

[PacAce]

sorry for this completely novice questions but I just picked up a 10D w/ a fixed 50mm lense. I have seen the grey card and the light meters but I do not know what they will or will not allow me to do or what they will help with. My thought is the light meter might tell me what fstop I need to set to take an accurate photo?? Thanks in advance for your replies!
You don't really need either although both could allow for more accurate exposures sometimes compared to being without them. Having said that, however, a gray card isn't going to do you much good if you're sitting on a bleacher halfway up an indoor stadium and you're tyring to meter the lighting where the action is down below. And, in the same situation, an external light meter wouldn't necessarily perform better than the built-in one either.

[Mike H]

I'm going to assume that you're talking about a hand held incident light meter. Incident light meters are less commonly used now that digital cameras are so ubiquitous. And yet, some of us who are old enough to have them still use them. What follows is a short description of how and why.

Your in-camera reads light reflected from your subject. In the earliest meters, the camera would be set up to read the level of light coming through the lens and then choose the combination of aperture and shutter speed that would allow enough exposure to give you a medium grey tone for the picture overall. Why medium grey? If you took a large sampling of pictures, it turns out that more photos have all of their dark and light tones average out to a medium grey than photos that would average out to something lighter or darker. Hence, more often than not, you would get a reasonably good exposure. Of course, not all photos average out to a medium tone. If you used an automated system of this type to shoot a white, a black, and a medium grey sheet of paper, your three shots would reproduce as three medium grey sheets!

As computers and cameras became more sophisticated, companies started to make "center-weighted" averaging meters, which would average all of the tones in a shot giving more weight to the tones in the middle, but still give the settings to get a medium grey tone. This worked better because most subjects are in the center of photos. But the systems still weren't perfect.

Then the new "evaluative" meters came out. These have proprietary formulas to set exposure, so consumers don't totally know how they work. But an educated guess is that they are variants of the center weighted meters--they use the focus point in the picture in setting the expsosure, and give less weight to the zones away from the focus point. This is what the camera companies say in their literature, without giving away their precise formulas (of course).

Using an incident meter avoids all of this. The hand-held incident meter measures light falling on the subject, rather than reflected from the subject. The reading will not be influenced by the subject's reflectivity. Hence, if you meter in front of the three sheets (white, black, and grey), it will give you the same reading for each if they are in the same light, and the exposure will be right on. I still use my incident meter for portraits.

The grey card lets you do two things. The first is that you can take a spot reading with your camera's reflected meter (assuming that you fill the field that the meter's sensor sees) and get the same reading that you would get from the incident meter.

The other thing that the grey card does is let you set a custom color balance for a particular scene. It's a reference point for the camera--like having a musician's tuning fork, except for color. See your camera's manual for the custom white balance setting instructions. With all of Canon's current digital camera models this will let you get the colors very precisely set (so that your reds are really red, etc.). The manuals all say to use a white object for this, but then say that it works better with a grey card. It tends to do this because using the grey card with the meter on automatic will get you exposure that's right on, whereas in shooting the white card people will often have the exposure off one way or the other, and a less accurate exposure means a less accurate white balance.

You can get away without an incident meter just by learning how to use the histogram on your camera (see the manual), so most people don't buy them. The grey card is a good buy, though. I set a custom white balance whenever I shoot outdoors. Canon's auto white balance setting works well enough outdoors that I don't bother to set a custom white balance outdoors.

I hope this helps.

Mike H

[thomasrhee]

IMO, light meters are unneccessary with a DSLR. You already have the best tool for evaluating proper exposure already built-in to your camera... a histogram.

As for a gray card, IMO, it's essential. Even though you can adjust white balance in post processing if you shoot RAW, I still prefer to get it as perfect as possible in camera. In order to do this, especially in artificial lighting, you really need to use custom white balance using a gray card.

On a side note, there are alternatives to using a gray card. Some people swear by the ExpoDisk while others use coffee filters or Pringles caps.

[Mark_48]

For what a good lightmeter is going for on Ebay, I would say go for it (Gossen for example). I've used my old Gossen Luna Pro several times with my 20D, partly because I was slightly in doubt of the cameras metering and then again I sort of like doing things manually as well (old timers have a hard time kicking old habits).
I view the lightmeter and grey card as good inexpensive learning tools. It helps better understand what the aperature and shutter are really doing. Using the cameras metering, probably few people are cognizant of what aperature and shutter settings they used other than looking at the EXIF file afterwards.


Mark........

[robertwgross]

When I am shooting a wedding, I do not bother with a gray card. Everything is moving pretty fast, and there just isn't time.

On the other hand, if the same B&G showed up for a studio portrait, it would be different. There, I would expect to control lighting more accurately, and time is not so critical. I would likely have them hold up a gray card for me to double check my exposure with the histogram view.

---Bob Gross---

[jcsorensen]

Not to mention if you are using multiple flashes, the light meter allows you to set the appropriate ratios between key lights and other lights. Pretty hard, if not impossible, to do without a light meter

Also, if you don't have a grey card, you can use other items in the seen which reflect around 18% light. During a recent wrestling tournament, I could not find an acceptable White Balance option on my 10D when I noticed one of the mats was pretty close to the grey in a grey card. I set my Custom White Balance to the mat, and my shots turned out perfect (at least the color was perfect).

[Longwatcher]

The only reason I got a light meter was because it allows me to better control studio lighting if I am setting up on location. In a permanent studio, I take enough pictures that I know already what and where to set my strobes.
For location though I might not be able to set the strobes in the same relative locations, but want the same ratios, thus the light meter. The camera's is good enough for most purposes, but the light meter gives me more precision when needed.

Just my opinion,