aadesh116

I'm trying to take product shots and was told I need a grey card. I was like OK, it's cheap and looks simple. So I have this card here and it had no instructions. I hate to ask a lame question, but how in the world are you supposed to use a grey card?

Just to confirm, this thing is supposed to help me get the same white balance in all my shots?

Thank you for the help!

tailskid

My Feedback: (34)

Now that's one question I would have to learn the answer to!

049flyer

My Feedback: (18)

I have used a gray card in film photography to normalize exposure settings, usually with a manual camera or an automatic camera in manual mode.

Depending on what part of the frame your light sensor is monitoring, and the orientation of your subject with the available light, your image may come out over or under exposed, even when the light meter indicates the settings are correct. In this case you would determine the proper exposure by focusing on your gray card, note the f stop and shutter speed for a correct exposure of the card, and then using those settings for your desired subject.

Often this procedure is required in less than ideal lighting situations such as bright light behind the subject, which would likely cause your subject to be under exposed.

049flyer

My Feedback: (18)

I am not a professional photographer so take what I say with a healthy dose of caution.

Few amateur photographers consider the light source when snapping a photo, but the source, direction and amount of light is hugely important because, after all, the reflection of the light off of your subject is exactly what you are trying to record.

Different light sources are often subtly different in their color, incandescent light makes things appear yellow, fluorescent lights sometimes blue or green. Furthermore, different films, if you are using film, react differently to different light sources and produce slight hues in the image. Ideally you want sunlight to illuminate your subject, which renders the best colors, but you can often use filters to correct for off white light sources, or you could even use a flash to help correct for color.

Low light situations are much more challenging as it’s often difficult to get enough light to properly expose the image at the shutter speed you need. Again a flash is often the answer but your shutter speed will be limited to a relatively slow speed. You could try a faster film or higher ASA rating on your digital camera with means the film or sensor is more sensitive to light, which is what you need for low light photos. Generally, low light photography is difficult or impossible with high shutter speeds. There just isn’t enough light to get the job done.

I suspect your needs are far beyond my rudimentary knowledge. I think you would be better off posing questions on a message board frequented by serious photographers.

Scarebird

The human eye/brain combo is very adept at making corrections to what we see, and adjust accordingly. As has already mentioned, light comes in a variety of colours that normally we don't notice because our brain makes the necessary correction, but cameras are not quite so good at doing this. What this means is that unless you set the colour balance on your camera to exactly match the colour balance of the light on your subject, your resulting images will have a slight colour cast. Obviously this is undesirable if shooting products that need to be shown in their true colours.

To correct this, you should take a shot of a grey card under the lighting conditions that you will be using. Obviously, if the lighting conditions change, you should take additional shots of the grey card.

In post processing you should sample the grey card in the relevant image to determine what colour correction you will need to make to show the true colours, and then apply that correction to all the images you took under the same lighting.