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A other noob Gray Card question
I think I understand what to do with the Gray Card and how to do it. What I' like to know is the following:.

Why buy it? Why not DIY it on your printer?.

My reasoning is: If you can do the same with a white sheet of paper, or even the palm of your hand, Whats the big deal with exactly 18% and absolutely no color tint?.

Tom..

Comments (10)

Tnordahl wrote:.

I think I understand what to do with the Gray Card and how to do it.What I' like to know is the following:.

Why buy it? Why not DIY it on your printer?.

How are you going be sure it's printed entirely neutral? After all, you certainly can't tell just by *looking at it* ... !!?? If we could do that, and all of us do it under all lighting conditions.....

..we wouldn't need any kind of aids for setting WB on our cameras in the first place!.

My reasoning is: If you can do the same with a white sheet of paper,or even the palm of your hand, Whats the big deal with exactly 18%and absolutely no color tint?.

For colour balancing (WB setting) it is not necessary to have any particular or exact reflectance percentage..... although you certainly can NOT use your hand for colour!! The hand apart, it is generally helpful if the WB target is not TOO bright (full white) because channel clipping can occur in bright light..

Otherwise you are right. ANY reasonable grey tone will do as long as it is completely neutral. Current printers do not have any built-in mechanisms for printing neutral tones... least, not that I have heard of in ordinary desktop machines. However, there are some pro-level self profiling printers appearing at last.... (HP).

....... but it will be a while before they are common in people's homes, I think. .

Regards,Baz..

Comment #1

Thanks.I guess I need a better understanding of "completely neutral"..

I thought that black ink on white paper would produce a uniform gray..

Tom..

Comment #2

Tnordahl wrote:.

Thanks.I guess I need a better understanding of "completely neutral"..

I thought that black ink on white paper would produce a uniform gray..

Yeah.. sounds reasonable, but.....

If the single "black" ink is a cocktail of different pigments and/or dyes, and most of them are, then those components will have different absorption rates depending on the characteristics of the paper's coating...... in combination with the density of ink actually applied.... and not forgetting that the paper isn't "automatically" neutral as it is made...

....(many papers have fluorescent dyes as whitening brighteners built into them, like those in washing powder)..

In other words, "black" is a relative term where ink is concerned, and so is "white" where it's the paper we are talking about..

My advice?.

Buy a card, maybe one of the easy-clean plastic ones with a choice of tones, and be grateful you don't have to fart about developing production techniques of your own... (... seriously).Regards,Baz..

Comment #3

Ok,you have convinced me..

And thank you very much for the level of detail in your answers. Thanks for shaing..

Tom..

Comment #4

You've read the above.Here's a suggestion that you get one of these.A grey card that you don't use or take with you is worthless..

And remember that a grey card is not only used for white balance but exposure as well. Useful for sports shooting where you set exposure off the grey side and then use manual and avoid the delay of autoexposure..

Http://www.amazon.com/...d_t=201&pf_rd_p=250314001&pf_rd_i=B000ARHJPW.

A member of the rabble in good standing...

Comment #5

Thanks LM1.You have now opened an other can of worms:) -actually two.

Delay due to AutoFocus.

I'm asuming that the auto ex delay only impacts on sequential shooting so I pointed at a light bulb ((its dark outside) got a reading of 5.6 at 1/750. set in manual and shot the bulb at max resolution. Got 5 exposures before the buffer was full. Switched to full auto and got 5 exposures and in the same amount of time - more or less- I didn't notice any difference. I had set the camera to "release priority" to avoid any delay from the camera trying to focus on a lit lightbulb at short distance. If my Oly e-500 has an autofocus delay, it's shorter than it's "cranking time".



The Lastolite Gray and White card..

Looks practical, but if I buy a Gray card - why do I want a White card? I do understand that a card has two sides, and they have to do something with both. I guess I'm asking: Do I sometimes want to use the White card instead?.

Tom..

Comment #6

Tnordahl wrote:.

Thanks LM1.You have now opened an other can of worms:) -actually two.

Delay due to AutoFocus.

Delay due to Autoexposure, not Autofocus..

And yes you can set the camera to release the shutter even if doesn't have exposure or focus lock, but then some of your pictures may not come out..

I'm asuming that the auto ex delay only impacts on sequentialshooting so I pointed at a light bulb ((its dark outside) got areading of 5.6 at 1/750. set in manual and shot the bulb at maxresolution. Got 5 exposures before the buffer was full. Switched tofull auto and got 5 exposures and in the same amount of time - moreor less- I didn't notice any difference. I had set the camera to"release priority" to avoid any delay from the camera trying to focuson a lit lightbulb at short distance. If my Oly e-500 has anautofocus delay, it's shorter than it's "cranking time".



What you were doing is taking a picture of a simple bulb so the autoexposure has no changes to make, thus no delay. But if you had been taking pictures of a football game and various players with light and dark jerseys are moving in and out of the frame then the "exposure" as far as the camera is concerned is constantly changing. In reality since they are all lit by the same sunshine the exposure isn't changing and neither should your exposure settings. Any time you save the camera from having to make a decision you are saving time. Just some times the amount you save won't be noticable other times it will. Ditto with autofocus.

There will be almost no delay because the camera has no decision to make..

The Lastolite Gray and White card.Looks practical, but if I buy a Gray card - why do I want a Whitecard? I do understand that a card has two sides, and they have to dosomething with both. I guess I'm asking: Do I sometimes want to usethe White card instead?.

Tom.

If your shooting in raw then you can just take a shot of the grey or white and later use that for setting you white balance across a range of photos all taken under the same light. Your postprocessing doesn't care whether it's grey or white as long as it's color neutral.The grey side can also be used for exposure as previously discussed..

The white side is occasionaly useful on bright days to determine whether your going to have trouble with dynamic range, ie if the white side is clipping in the histogram or in the display of the picture. Then you might want to dial in some - EV to avoid clipping the highlights and bring up the shadows in postprocessing.A member of the rabble in good standing...

Comment #7

How about this?.

You know that your lightmeter reads your image as 18% gray: no matter what the image- whether a coal mine at midnight or an Eskimo in a blizard (and adjusts the exposure to place it in the middle of your Subject Brightness Range. "Zone" 5)..

So: all you need to do is:.

1) Decide just how "bright" you want your image to be, i.e.; just discernible highlight detail ("Zone" 7) or just discernible shadow detail ("Zone" 3) and adjust your exposure by either +2ev or -2ev (using your exposure compensation function/wheel, whatever) and.

2) Take the shot..

Of course, in some cases you may only wish to compensate +/- <2 ev..

This is all according to a simplified "Zone System", and it works!..

Comment #8

You don't really need a grey card for exposure, paticularly if you know where to point the cameras light meter or have practiced just a little and know how to read the histogram..

The vast majority of people here have no idea what you are talking about when you mention Zone5 or Zone7 so.............

One of my favorite articles addressing this issue is this one. http://www.fredparker.com/ultexp1.htmI recommend it to all.A member of the rabble in good standing...

Comment #9

Thanks guysLM1I'll try shooting a sequence that makes auto ex work overtime:)The Fred Parker link is great, but it's going to take a while to digest it!.

Mikelis, LM1 is right about not everybody knowing what the zone system is, but now that I know ther is such a thing, I'll Google it and find out..

And - Oh yes, I take back part of my initial posting:"I think I understand what to do with the Gray Card and how to do it"Boy am I glad I put the word "think" in there!.

That being said - I think the statement is kinda true now!.

Tom..

Comment #10

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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