Can somebody please explain Grey card please

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Mayer71

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Can somebody please explain to me why and how to use a grey card as i am not familier with this. thanx:shrug:
 
In ye olden days of film the grey card was just about exposure. The meters in cameras make the assumption that the whole world is a grey card. Or to put it another way, a mid tone or mid grey. So the idea is that if you meter off of a grey card, then the camera is looking at exactly what it's calibrated to meter and the exposure will be spot on.

It works well enough if you and the subject are in the same light. You can hold up the card, take a reading and then point at the subject and shoot. If you are one side of a valley or a road and the subject is on the other, it's not always so precise.

These days, grey cards also get used to set the colour profile or colour balance with digi cameras. Shoot with a grey card in the frame and then use that shot to set that grey as a true neutral tone and remove any colour tint.

Hope that makes some sense. :)
 
Thanx a lot dazzajl. I will try it as i sit here. I a preciate it.
 
dazzajl said:
The meters in cameras make the assumption that the whole world is a grey card. Or to put it another way, a mid tone or mid grey.
Click to expand...

18% grey, to be exact.

However, if you(r digital camera has the ability to) shoot in RAW format, you can adjust/correct the exposure after the fact, in post production!

So, against the background of today's spot metering, center-weighted metering, Automatic Exposure Lock ('AEL'), digital accuracy, and RAW, for all intents and purposes the grey card really can be considered to have died quietly together with the film camera.
Afaic you should only be seeing them in photography museums these days.
 
Alfred D. said:
18% grey, to be exact.

However, if you(r digital camera has the ability to) shoot in RAW format, you can adjust/correct the exposure after the fact, in post production!

So, against the background of today's spot metering, center-weighted metering, Automatic Exposure Lock ('AEL'), digital accuracy, and RAW, for all intents and purposes the grey card really can be considered to have died quietly together with the film camera.
Afaic you should only be seeing them in photography museums these days.
Click to expand...

I would love to agree with you there Alfred, as I often have on this board but this time I can't for two very good reasons.

One, I've just finished a fabulous bottle of vintage Rioja...

and two, that's complete pish.

Shooting with film, a grey card is something that can be useful but if you understand how metering works you really don't need one.

In the digital world, if you want correct colour representation you need to set the colour balance for every shoot, or lighting situation. The simple grey card (in 17 or 18% guises) still exists but has also expanded into gretag colour cards and many other products, purely because of the NEED for them in precise digital photography. :)
 
I always use a grey card when possible, guessing at what looks "right" is fair enough in post processing but a guess isn't ever as accurate as sorting WB precisely.
I've made quite a few converts to this extra little step too after comparing results from photoshoots - well worth taking the time imho :thumbs:
 
dazzajl said:
Shooting with film, a grey card is something that can be useful but if you understand how metering works you really don't need one.

In the digital world, if you want correct colour representation you need to set the colour balance for every shoot, or lighting situation. The simple grey card (in 17 or 18% guises) still exists but has also expanded into gretag colour cards and many other products, purely because of the NEED for them in precise digital photography. :)
Click to expand...

Yeah, you shouldn't have had that last glass before you responded, dazzajl. :lol:

I think you're confusing the goals of using a grey card. With film 18% grey cards were convenient to measure and set exposure. Which is about the amount of light. With film grey cards were not used for White Balance. Which is about the quality/color of light. Not about the amount.
With digital we don't need grey cards anymore to set exposure (about the amount of light). We have those other features for that now (RAW, metering, AEL).
For White Balance (about the quality/color of light) you now use another kind of grey card. Where the percentage of 'grey-ness' isn't important, but where the exact colour neutrality is. Irrespective of percentage.

We're talking about two different grey cards here.

Bottoms up!
 
Alfred D. said:
Afaic you should only be seeing them in photography museums these days.
Click to expand...

I saw one for sale in Jessops today - Metro centre, Tyneside.

Given the attitude of the staff it's likely to stay for sale for some time I reckon!
 
I would like some help here too.

Ok, so you've shot a pic and included the grey card in the image. What do you do then? How does the grey card work? Do you put the grey card alongisde the monitor and mess with the setting in PS until the grey on screen matches the card in your hand?

I ask out of ignorance not out of disrespect. I've heard much talk of using a grey card but have no clues how it's done.
 
Mart61 said:
I would like some help here too.

Ok, so you've shot a pic and included the grey card in the image. What do you do then? How does the grey card work? Do you put the grey card alongisde the monitor and mess with the setting in PS until the grey on screen matches the card in your hand?

I ask out of ignorance not out of disrespect. I've heard much talk of using a grey card but have no clues how it's done.
Click to expand...

There's a series of tutorials here ( http://www.whibalhost.com/_Tutorials/WhiBal/01/index.html ) that give a good background on their usage.
Pick from the various "chapters" (01-08) down the left side.

Bob
 
Do you put the grey card alongisde the monitor and mess with the setting in PS until the grey on screen matches the card in your hand?
Click to expand...

Hi Mart,

PS will do that for you. You can use that grey swatch to click on and tell the software that that is 100% neutral. i.e. exactly the same levels of red, green and blue.

If the grey still looks different to the actual card, then your monitor needs to be calibrated.

Going back to Alfred's comments (Morning sir, I've just made some strong coffee ;) would you like some?), I know the differences between the two grey card functions but they are more similar than you think. To set your colour balance/profile with any accuracy the exposure needs to be bang on. Hence modern grey cards still need to be 18% as well as RGB balanced.

Also, there really are no more tools to control exposure on a digi camera than a film one. I have a film eos that uses all the same methods as the digi ones. It's also not really correct to think that you can adjust exposure on the pc. I know some software has a little slider that "says" exposure but it doesn't really mean it. It's no different from making a lighter or darker print from a neg. You can change the appearance of the finished image but the negs exposure is set and sealed the instant the shutter closes. Same with digi.

Now, milk and sugar?? :D
 
Nice to see such a civilised argument :)

Only thing I'd add is to agree that getting the exposure right is equally important in digital and exposure sliders in RAW processing are for rescue not standard editing.
 
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