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Author Topic: Grey Card Question?  (Read 10717 times)

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« on: February 15, 2014, 18:09 »
0
So I have been using the same grey card for a year but its just a cheap cardboard one and I had to buy a new one. The Grey on the old one is a very light grey and the new one is a very dark grey, does that matter or will the result be the same for the 18% grey?

Thanks!


« Reply #1 on: February 15, 2014, 18:32 »
+1
If they are different, the result will be different.
Not colourwise, but exposure wise.

I never use a grey card. I use auto WB, and when sometimes wb is wrong, I correct it in photoshop.

« Reply #2 on: February 15, 2014, 18:36 »
0
Regarding white balance, I've used white, grey, and black to set white balance in the past and they have all worked. As JPSDK said, the only difference would be if you are using histogram of grey card photo for exposure purposes.

« Reply #3 on: February 15, 2014, 19:29 »
+1
Are you using the gray card for white balance or for exposure readings? For white balance it likely won't matter. For exposure readings it will make a big difference.

In my estimation the gray card for 18% gray exposure readings is a little darker than medium gray. In Photoshop or other photo editor the RGB colors are 127,127,127. If your PC screen is calibrated you should be able to match the card and the screen.

« Reply #4 on: February 15, 2014, 19:32 »
0
that is:
7f7f7f

and if the printer is calibrated ;-), you can also print one out.
« Last Edit: February 15, 2014, 19:35 by JPSDK »

« Reply #5 on: February 15, 2014, 19:39 »
+2
Here we are:

« Last Edit: February 15, 2014, 19:42 by JPSDK »

Uncle Pete

« Reply #6 on: February 15, 2014, 23:34 »
0
All these years of buying and using Grey cards for white balance, and it's for exposure readings? Sorry but I must disagree.

http://www.digitalartsphotography.com/instructions.htm

And for the OP, yes there are different grey cards, different levels. Only one I know is the 18% grey card, but that doesn't stop someone from making one that's lighter or darker as long as it's ONLY grey.

The idea is to eliminate color tones and have a base white level for your starting point.

And yes, most of the time, I just use auto white balance and fix it later. But I carry an 18% grey card in case I run into a tricky situation.

There's no way to correct mixed light temperature.



Are you using the gray card for white balance or for exposure readings? For white balance it likely won't matter. For exposure readings it will make a big difference.

In my estimation the gray card for 18% gray exposure readings is a little darker than medium gray. In Photoshop or other photo editor the RGB colors are 127,127,127. If your PC screen is calibrated you should be able to match the card and the screen.

« Reply #7 on: February 16, 2014, 00:31 »
0
All these years of buying and using Grey cards for white balance, and it's for exposure readings? Sorry but I must disagree.

I believe that people are saying that it's not only for white balance. When filming, I use my collapsible 18% grey card to set both white balance and exposure. Of course, I may need to fine-tune the exposure, but it gives me a very close starting point.

All of the data in your histogram should be bunched right up in the middle with 18% grey filling the frame completely.

« Reply #8 on: February 16, 2014, 01:14 »
0
Yes I am using it for the White Balance, I was told that no matter if its a light color grey or dark color grey its still a 18% grey and that it does not matter if its light or dark grey. I bought it from a local camera store but I was not sure if they guy knew what he was talking about so I thought I would check here.

I dont understand how you would use it to set exposure can someone explain that also?

Beppe Grillo

« Reply #9 on: February 16, 2014, 02:57 »
0
All these years of buying and using Grey cards for white balance, and it's for exposure readings? Sorry but I must disagree.



The 18% gray card has been used decades before the invention of digital photography and the idea of white balance.
It has been invented to measure exposure.
After if you can use it for white balance too it is another story

____


There's no way to correct mixed light temperature.


In digital photography it is not easy but not impossible, shooting different images with different WB and assembling them then in Photoshop.

With film photos it was another story.
Here for example I have done 10 or 11 different expositions (on the same sheet film) with different combinations of filters to correct lights with different color temperatures


(Sorry for the quality, it is an old XX century photo and the scan is not so good)
« Last Edit: February 16, 2014, 10:26 by Beppe Grillo »

« Reply #10 on: February 16, 2014, 07:33 »
0
Tharts a good photo, but maybe it would have been even better with mixed white balances?

« Reply #11 on: February 16, 2014, 07:39 »
+1
I dont understand how you would use it to set exposure can someone explain that also?


With a true 18% gray card you hold the card in the same plane as your subject and with the same light source. For a portrait hold vertical in front of the face with the card flat gray side oriented towards the camera normal shooting position. For a landscape maybe top tilted back a bit and standing in the same sun. With the camera close to the gray card, view only the card - don't cast your shadow on the card. Set your camera for manual control and exposure to 0ev for a non-strobe scene. With a DSLR in a strobe/studio scene, you can take a picture of just the gray card, as situated, and there should be a narrow spike in the histogram at dead center of the histogram representing the middle (18%) gray of the card. In manual mode again, adjust shutter, aperture, ISO to get the spike in the dead center. For studio strobes your shutter likely has to be 1/200 or slower for proper sync. If the gray card is not really 18% between black and white then all bets are off for correct exposure. The correct gray level on the card is required for this to work.

In my few studio occasions I do the gray card and histogram reading since I don't own a light meter that can capture studio strobes blinking. With the studio lights I also do the gray card for white balance since I'm a bit color blind to skin tones. With these two presets I can trust my output that otherwise I would personally have problems adjusting later with confidence.

Note that some very old 18% Gray cards were only made for exposure and may not be truly gray. A color cast will result if these are used for white balance. I'd think newer cards are OK.

When doing the real subject shooting, take an image with the gray card in it. The later you can also adjust that image to be the correct gray and then use those adjustments on the imagess without the card visible. This is my "fail-safe" backup for my color blindness problems. In Photoshop, adjust gray by numbers. If I got more serious I would invest in the color swatch panels and color adjust software to do this task.

A few references:
http://digital-photography-school.com/get-your-white-balance-right-in-seconds-using-grey-card
http://lifehacker.com/5659324/use-an-18-gray-card-for-better-color-balance-in-your-photos
http://www.lastoliteschoolofphotography.com/using-calibration-greycards
http://www.bhphotovideo.com/c/product/740518-REG/Datacolor_DC_SCK100_SpyderCheckr_Color_Calibration_Tool.html
« Last Edit: February 16, 2014, 07:59 by StanRohrer »

« Reply #12 on: February 16, 2014, 07:51 »
+1
Yes I am using it for the White Balance, I was told that no matter if its a light color grey or dark color grey its still a 18% grey and that it does not matter if its light or dark grey. I bought it from a local camera store but I was not sure if they guy knew what he was talking about so I thought I would check here.

I dont understand how you would use it to set exposure can someone explain that also?

There is black and white and grey in a picture.
It is sometimes scewed. But if it is not, you have a good oppertunity if you can set the WB on grey via photoshops levels.
Easy enough.. You have a photo. Look around and see if you can set the white, the grey or the black point.
I usually go for the white.

Uncle Pete

« Reply #13 on: February 16, 2014, 09:44 »
0
Funny, I usually start with black first, a tire or grill or inside a wheel well. But as usual, it's kind of specific to what I like to shoot.  :)

Yes I am using it for the White Balance, I was told that no matter if its a light color grey or dark color grey its still a 18% grey and that it does not matter if its light or dark grey. I bought it from a local camera store but I was not sure if they guy knew what he was talking about so I thought I would check here.

I dont understand how you would use it to set exposure can someone explain that also?

There is black and white and grey in a picture.
It is sometimes scewed. But if it is not, you have a good oppertunity if you can set the WB on grey via photoshops levels.
Easy enough.. You have a photo. Look around and see if you can set the white, the grey or the black point.
I usually go for the white.

Yes it is a nice photo and besides good lighting it does have an attractive color balance.

Tharts a good photo, but maybe it would have been even better with mixed white balances?

Beppe Grillo

« Reply #14 on: February 16, 2014, 10:12 »
0
Tharts a good photo, but maybe it would have been even better with mixed white balances?

Yes today absolutely yes!

[a little off topic]
But this was shot in the eighties.
And Probably you don't know well the world of furniture catalogs as it was at this time.
For bars it was not too much hard, but for kitchens it was so difficult because the customers wanted to see the furniture exactly the same color everywhere, so it was a heavy job to balance the color of all lights.
We had Fatif softboxes (banks), Ianiro lamps and Kremer spots, and some other lamps from different brands of course all with different color temperatures (theorically all 3200 K but in fact from 2600 K to 3800K with green or magenta color cast).
In 1983 when I begun to work with this studio one of the first thing that I asked was new strobes but I did not get them because of the high cost.
So I asked for a Minolta Color Meter II, and I got it.
And of course we (me) had to play a lot with it :)
[/a little off topic]



(These old memories make me think I'm starting to be part of the history of photography  ::) )
« Last Edit: February 16, 2014, 10:15 by Beppe Grillo »

ShadySue

  • There is a crack in everything
« Reply #15 on: February 16, 2014, 10:48 »
+1
There is black and white and grey in a picture.
Correction: there is black, white and grey in 'some' pictures, by no means all - many nature photos (for example) have none of these present.

NB: When reviewing images it's virtually impossible to remember if 'something grey' in a photo was 'warm' or 'cool', so setting your colour balance by a 'random something grey' in a photo can result in the rest of the photo going way off-kilter. It's really unlikely that any random grey object will be 127, 127, 127 or any other balance of RGB tones.

« Reply #16 on: February 16, 2014, 11:45 »
0
I dont understand how you would use it to set exposure can someone explain that also?


  • Purchase a grey card similar to this one on eBay
  • Take a photo with it filling your frame in manual mode under the same light that you will be shooting in
  • View the histogram of your photo. All data on bottom histogram should fall in the center. (see attached photo of 5DII histogram)
  • Adjust exposure as necessary


Batman

« Reply #17 on: February 16, 2014, 11:58 »
0
Funny, I usually start with black first, a tire or grill or inside a wheel well. But as usual, it's kind of specific to what I like to shoot.  :)

Yes I am using it for the White Balance, I was told that no matter if its a light color grey or dark color grey its still a 18% grey and that it does not matter if its light or dark grey. I bought it from a local camera store but I was not sure if they guy knew what he was talking about so I thought I would check here.

I dont understand how you would use it to set exposure can someone explain that also?

There is black and white and grey in a picture.
It is sometimes scewed. But if it is not, you have a good oppertunity if you can set the WB on grey via photoshops levels.
Easy enough.. You have a photo. Look around and see if you can set the white, the grey or the black point.
I usually go for the white.

Yes it is a nice photo and besides good lighting it does have an attractive color balance.

Tharts a good photo, but maybe it would have been even better with mixed white balances?

I'd bet in the old days you used an incident light meter and it had a crank on the side for winding it up. That's old.

We didn't use color balance with film because the film had it built in. You got what you bought, and same for ISO.

Beppe Grillo

« Reply #18 on: February 16, 2014, 12:14 »
0
^
I used a Sinar Booster (spot measure) with a Minolta Flashmeter IV, so with a gray card, or even on a white one (Exposure +2 + 2,5 max.) because keeping the whites "printable" in offset was very important.

And the Minolta Flashmeter IV in incident light too
« Last Edit: February 16, 2014, 12:16 by Beppe Grillo »

« Reply #19 on: February 16, 2014, 12:18 »
0
I'd bet in the old days you used an incident light meter and it had a crank on the side for winding it up. That's old.

Using an incident light meter is more or less like using a light meter with a built in grey card. Or maybe that's what you're saying.

My dad taught me to meter off the grass, normally.

I contemplated having my study painted 18% grey. I like it.

We didn't use color balance with film because the film had it built in. You got what you bought, and same for ISO.

But you would often still have to gel the lights if they were different temperatures.
« Last Edit: February 16, 2014, 13:15 by bunhill »

Goofy

« Reply #20 on: February 16, 2014, 12:41 »
+1
I have a grey card but never use but it does make you look cool when you carry it along with you- people actually think that I must know what I am doing  ;)


« Reply #21 on: February 16, 2014, 13:06 »
0
With sheet film (4x5 & 8x10) in studio we would buy a case of film, shoot tests, run them through the lab and fine tune the color balance with wratten gel filters behind the lens. Depending how reliable the lab was you would be good for that case. Sometimes their chemistry would be off a bit and you would have adjust the filters to retain the same balance.
And every lab had their own color balance so it was best to stick with one pro lab and develop a good relationship with them.

We would do the same for roll film 120 mostly but you could do it with 35mm too, though usually the filters went in front of the lens on those cameras.
You could also do snip tests on a roll of film and adjust the development for either push or pull exposure.

All these would affect color balance.

Uncle Pete

« Reply #22 on: February 17, 2014, 16:01 »
0
PhotoBomb you didn't send it off to Sundance or Cook photo in IA? I mean back then we had those little yellow Fotomat booths all over the place?  ;)

And since it was the "good old days" I'll explain for some of the younger members. If you took your film to the corner store, someone from one of these commercial processing places would come around every afternoon and pick up.

Some would go by truck and Cook was Mid-West would fly the film to Iowa. Depending on the process, and what they were running, you could get next day service or a few days. Eventually, B&W would take longer than color, because they didn't run it as often.

This pretty much ended with 1 Hour Photo in store processing. (Wolf, Black, Fox, whatever else, there were hundreds of them) But some of those places would bag the slides or two day stuff, and run what they needed at home.

If you wanted to know that you had fresh chemicals and good consistent quality control, you would take your film downtown or someplace that did professional processing. Something else that less and less important in the digital age with most places running computer controlled Fuji or Kodak machines now.

Definitely less problems and chance of losing everything, after you wait days to see the negatives. Now we can look at the image, exposure, highlights, and histogram, on the back of the camera. Nice!

So no, I do not long for the "bad old days".  :)


« Reply #23 on: February 17, 2014, 16:57 »
0
PhotoBomb you didn't send it off to Sundance or Cook photo in IA? I mean back then we had those little yellow Fotomat booths all over the place?  ;)

And since it was the "good old days" I'll explain for some of the younger members. If you took your film to the corner store, someone from one of these commercial processing places would come around every afternoon and pick up.

Some would go by truck and Cook was Mid-West would fly the film to Iowa. Depending on the process, and what they were running, you could get next day service or a few days. Eventually, B&W would take longer than color, because they didn't run it as often.

This pretty much ended with 1 Hour Photo in store processing. (Wolf, Black, Fox, whatever else, there were hundreds of them) But some of those places would bag the slides or two day stuff, and run what they needed at home.

If you wanted to know that you had fresh chemicals and good consistent quality control, you would take your film downtown or someplace that did professional processing. Something else that less and less important in the digital age with most places running computer controlled Fuji or Kodak machines now.

Definitely less problems and chance of losing everything, after you wait days to see the negatives. Now we can look at the image, exposure, highlights, and histogram, on the back of the camera. Nice!

So no, I do not long for the "bad old days".  :)

No I had to drive it up to A&I in Hollywood from Orange County. That sucked.

jbarber873

« Reply #24 on: February 17, 2014, 21:34 »
+1
With sheet film (4x5 & 8x10) in studio we would buy a case of film, shoot tests, run them through the lab and fine tune the color balance with wratten gel filters behind the lens. Depending how reliable the lab was you would be good for that case. Sometimes their chemistry would be off a bit and you would have adjust the filters to retain the same balance.
And every lab had their own color balance so it was best to stick with one pro lab and develop a good relationship with them.

We would do the same for roll film 120 mostly but you could do it with 35mm too, though usually the filters went in front of the lens on those cameras.
You could also do snip tests on a roll of film and adjust the development for either push or pull exposure.

All these would affect color balance.

   Clip tests! I had mercifully forgotten all about them! Push and it goes red, pull and it goes green. Monday's color was always off, and you were guaranteed to have a scratch on the best sheet. Dust on the film, wasting sheets on color tests and buying cases of film to get a good batch. I don't miss film at all!
   On the original subject, I have always found that if I have a perfect grey card the whole shot is off in some way. I used to always put one of those kodak process chip charts with all the colors and grey scale. But that was just to put on a show for the client, and throw the blame over to the printer when the color was off. ( "But you had a chip chart in a test shot! It must be bad printing")  ;D


 

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