X Rite Gray Card too light????...not using properly

I fill my screen with the Gray Card exposing to get the histogram spike in the middle or just below; in the embient light of the subject. When I recompose, or set manually on the aforementioned exposure...well the subject is way too dark by about 2.5 - 3 stops.

The gray card looks very much lighter than other grey cards I have.

Am I using it incorrectly??

Please some help...I've got a wedding coming up with sunny cloudy showery day comiing up ie very changeable light. I want that grey peak to correspond with an overall correct exposure each time I measure against the gray card; of course I'll be measuring as the light changes each time.

Thanks in advance, Dave S

That card is for setting white balance, not exposure.

dik said:

That card is for setting white balance, not exposure.

Click to expand...

yeah, what you want is an incident reading light meter.
such as a Sekonic L308s, a nice little multi-mode meter for less than 300$
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if I mock you, it may be well deserved.

What is the exact name of the particular card you are using?

B&H lists several models, with some differences.

That said, there's specific mention that the cards are designed for color balancing, not exposure control.

And with that said, can you tell us camera model and exposure measuring mode (matrix, evaluative, partial, etc).

And semi-finally, does your card have three stripes on it, of varying shades of grey?

And finally, what other grey cards do you have, and do they work OK?

BAK

Hi BAK

I use Kodak Grey cards, and others which vary a little in lightness. But the X Rite is the one I am questioning. I now gather it is a colour balance card, unfortunate not to have got an 18% Grey Card for exposure. But there you are...Color Checker by X Rite is a bit of a clunker. Terrible design, nasty hinges and a pointless declaration taking up a whole page???Eh! And so much processing turning RAW into DNG, etc etc, I only use CS4 so not as easy as the recommended Lightroom.

Answering your question further, I know how to meter etc with spot evaluative on a card, or Gry tone...often grass lawn is a good metering subject.

I am really looking for exact exposure reference point for my Canon 60D.

cheers Dave S

Hi drh

Yes, I might go back to my Gossen Lunasix 3; takes incident and reflected light readings.

Thanks for your advice, Dave S

If you have CS4, Bridge will generate DNG files from RAW. It's a check box in the import dialog.
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Member of The Pet Rock Owners and Breeders Association
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if I mock you, it may be well deserved.

Regarding > I am really looking for exact exposure reference point for my Canon 60D.

I don't think there's any such thing.

Or if there is, it doesn't really matter.

A while ago I went to see an exhibit of the works of Yousuf Karsh.

Lots of his photographs are here:

http://www.google.ca/search?q=Karsh&hl=en&rlz=1T4ADFA_enCA445&prmd=imvns&tbm=isch&tbo=u&source=univ&sa=X&ei=HFYCT5OQDMLW0QH3p9zLBw&ved=0CEMQsAQ&biw=1090&bih=716&sei=KFYCT6G_D-bh0QH22-CDAg

One of the exhibits was original Life magazines, witgh the Churchill and Hemingway covers, And in the prints hung ont eh wall were original prints, made by Karsh's own darkroom staff, of the same shots.

And the real prints were much darker than the nice bright magazine covers.

If, between Karsh and Life's editors, photo editors and production editors there were prints from the same neg, with such diffferences, it certainly works out that no exposure is precisely right.

And yes, we can all find books that specify viewing lights, by color temp and by brightness at difference distances, and we can find the actual lights if we go to0 a good printing house, but in the real world, looking good under the conditions we have is certainly good enough.

Which brings us to establishing a starting point.

When I'm paying particular attention to exposure, I do one of two things, more often than not, outdoors.

First is to use a Sekonic L-358 incident light meter pointed at the light source, and then transfer the settings to the camera.

That seems to work.

The alternative, when I have a grey card, is to place it in front of the lens, with the samel ight hitting it as hitting the subject, and setting the camera manually.

The fact that camera have three or four exposure meteringmodes -- evaluative, centerweighted, etc., really meanthat you need to look at the subject, examine how much is light or dark, and select a metering pattern that works, based on what it sees.

BAK

BAK

David Strachan said:

Hi BAK

I use Kodak Grey cards, and others which vary a little in lightness. But the X Rite is the one I am questioning. I now gather it is a colour balance card, unfortunate not to have got an 18% Grey Card for exposure. But there you are...Color Checker by X Rite is a bit of a clunker. Terrible design, nasty hinges and a pointless declaration taking up a whole page???Eh! And so much processing turning RAW into DNG, etc etc, I only use CS4 so not as easy as the recommended Lightroom.

Answering your question further, I know how to meter etc with spot evaluative on a card, or Gry tone...often grass lawn is a good metering subject.

I am really looking for exact exposure reference point for my Canon 60D.

cheers Dave S

Click to expand...

You have me totally confused. X-Rite makes both the excellent ColorChecker Passport and an 18% gray card.

Which are you using?

All those squares on the ColorChecker Passport serve a good purpose. They allow the Datacolor software to color calibrate the response of your camera & lens combinations to colors under the lighting conditions present when you take the photos. The bottom chart is a standard Classic Color chart. The lower row is a row of squares of various % gray, including 95% gray, 18% gray , and 5% gray (95% white).

The upper chart is the Creative Enhancement Target. For instance there are two gray scales. One is blue tinted, the other red tented. Selecting one of these for white balance will allow you to cool or warm your images in that set.

The white balance chart on the flip side of the Classic Chart is NOT 18% gray so don't expect it to give you a peak centered in the camera histogram. It is lighter than 18% gray so it can be used by either cameras who tell you to use a white target or a gray one. Actually the only difference between a gray target and a white one is exposure so you can set a custom white balance with either regardless of what the camera maker says.

If you use the Passport and then apply the color correction it provides to all of the images taken in the same lighting conditions then they will all be white balanced and color corrected to a standard. If you aren't happy with the "standard" color values you can then put together an action in Photoshop or a Preset in ACR to change the images to what you prefer. The advantage is that you will always be starting at that standard condition so the same action or preset will always work.

I suggest you go back and study your Passport manual and check out some of the tutorials Datacolor has on using it.

By the way, 18% gray doesn't fall in the exact center of your histogram in Photoshop. The actual value should be 219, not 227 (half way between 0 and 255 is 227, not 228).

the standard grey is 12,5% and both Nikon and Canon use that. 18% was the old standard, it's long gone. Pentax uses 14,5% if I remember correctly. Sekonic uses 12,5%.

The problem is how you should angle the grey card. The material used is painted with grey color reflecting 12,5% of the light, but a good card lasts only a few minutes in real life, so some coating is needed, making shifts in reflectivity impossible to avoid. So, take great care when using a grey card.

The histogram in camera is affected by all jpg settings, even if you shoot raw. So make sure white balance is perfect and that contrast, colorspace etc is set in a way that the histogram is useful to you. Don't trust the values.

Photoshop histogram is an approximation of the rgb values of the working space. the actual data remains in LAB at all times during it's stay in photoshop. Trust the values, but remember what they are...
--
Anders

'It is nice to be important but it is more important to be nice'

Just to clarify a bit... I think using a histogram to set aperture and shutter speed is a less than wise approach.

?Use the meter scale, then look at the image. And different images yield different histograms, even when properly exposed.

David Strachan said:

Yes, I might go back to my Gossen Lunasix 3; takes incident and reflected light readings.

Click to expand...

I like my Lunasix 3.

If you are measuring "correctly", the reflected measurement of the 18% grey card should be equal (within 1/3 of an f/stop) to the incident reading.

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The Business of Being a Photographer -- Lightroom Q&A

Hi ellfrogio

Last evening I measured the reflected light off a grey card, and then used the incident method with sliding diffuser for the incident light. Both methods showed exactly the same reading.

So I reckon I'll work with my Lunasix 3.

Looks like it might be heavy to medium overcast...yahoo...no shadows.

cheers Dave S

Hi Sailor Blue

I've been using the colorchecker passport. Now I understand it is about colour correction and accuracy. The grey card is useless to me, I'm thinking.

It's more important to me to set the exposure accurately...I don't usually have problems with color shifts too much with the Canon 60D digic4 processor.

I'll make sure to keep a look out for the light color though...for the wedding on saturday, looks like overcast, perhaps stormy weather...blue light!

Thanks for your help I'll watch some videos when I get the chance, and will be usuing the Colorchecker anyway as insurance

cheers Dave S

There is no magic way to always get the "right" exposure with a meter. The meter will only give you a starting place. You then need to engage the 14# computer between your ears.

When you use any meter reading you are trusting that the subject has an average reflectance of 12.5% . If you read off of an 18% gray card you exposure will automatically underexpose by 0.5 stop. Some think of it as a safety factor to keep the highlights from blowing out. I think of it as not understanding what you are doing.

All we can do is use a meter, or some other method as a guide. It is almost always necessary to make some change in the meter reading to get the best possible exposure.

I try to Expose To The Right (ETTR) as much as possible so that any highlight I deem must have texture is not overexposed and I have as much shadow details as possible. In most cases some highlight I have decided is not critical or is a specular highlight will be overexposed and some shadows will lose all details. That is inevitable with a digital camera unless you do HDR photography.

This is the best technique I have found for ETTR. This technique involves using the Highlight Alert, which I have found to be very consistent in its operation and much easier to interpret than a camera histogram.

I found a 14" square of 1/8" thick white plastic at a local art supply store. Sanding the shiny surface gave it a nice dull surface. After careful testing vs the Passport gray scale in the Classic Target I determined that it was almost exactly 95% white and very close to neutral in color. I scored the sheet with a box cutter and snapped off two 4"x7" squares to carry with me, leaving me a 10"x14" sheet for studio use. The total cost was less than $2.

When shooting a scene I first LOOK at the scene and FIND the brightest highlight that must retain details, i.e. not be completely overexposed. I start at the meter reading and increase or decrease the camera exposure until that HA just stops blinking for that important highlight.

With my Canon 7D this is the best possible ETTR JPG exposure. Because RAW files have more dynamic range the best possible ETTR RAW exposure is when the highlight just starts to blink.

If there isn't an important highlight in the scene, which is very common, I place one of my plastic 95% white cards in the scene and find the ETTR exposure as above.

With the Passport you can use the bottom right square, which is also 95% white. The advantage of my plastic cards are that they are larger than the Passport squares and if they get dirty they can be cleaned with soap and water or even sanded down again to get rid of the dirt.

Hi Sailor Blue

Thanks for the work flow you use. I will be trying to incorporate some of your methods into my photography.

Yes, I use the blinking highlights too...a really beaut part of digital photography.

All the best and thanks for your input to this post.

Cheers Dave S

David Strachan said:

I fill my screen with the Gray Card exposing to get the histogram spike in the middle or just below; in the embient light of the subject. When I recompose, or set manually on the aforementioned exposure...well the subject is way too dark by about 2.5 - 3 stops.

The gray card looks very much lighter than other grey cards I have.

Am I using it incorrectly??

Please some help...I've got a wedding coming up with sunny cloudy showery day comiing up ie very changeable light. I want that grey peak to correspond with an overall correct exposure each time I measure against the gray card; of course I'll be measuring as the light changes each time.

Thanks in advance, Dave S

Click to expand...

Dave,

A true 18% gray card will produce a 0.74 (+ - 0.03) density reading on a calibrated densitometer. An 18% gray card that can be used for color balance must produce that 0.74 reading for each primary (R/G/B) color.

There are various color balance references that can have other density readings for R/G/B as long as all three are the same, but to be an 18% gray, they must be 0.74 + - 0.03.

Not all gray cards are 18% or neutral. Some that appear neutral can throw you off by being printed on a cardboard with optical brighteners, which fluoresce when tested under a UV black light. The ideal 18% gray card should have a non-optically brightened substrate. Original Kodak 18% gray cards fit this requirement, but the current version (produced under license by another manufacturer) is printed on an optically brightened card stock with very high UV reflection.

There is a manufacturer in the UK producing a gray (“grey” in the UK) that is made from a washable, non-optically brightened 18% gray plastic base which in my tests, gave a perfect 0.74 density for R/G/B.

Sekonic Exposure Profile Targets I & II provide an extremely accurate 18% neutral gray reference on the back of the meter calibration targets. These are more expensive, but they also provide precision reference patches for meter calibration on the front side.

The Zone System developed by Ansel Adams and Fred Archer was based on the 18% gray card as the standard for their calibrations of meters and film processing. The ideas and techniques of the Zone System are still successfully applied to digital photography with a few modifications.

This response could go for several pages, but the short version is you will not get an accurate exposure of an 18% gray card using a factory calibrated reflected meter (TTL, spot, averaging, etc.). Since incident meters are calibrated to 18%, a gray card exposed by an incident reading will produce an accurate 18% exposure of the card.

Reflected meters are set at the factory to a 12.5-14.5% gray depending on the manufacturer, so they will always try to turn an 18% gray into a 12.5-14.5% gray (13% gray has a 0.89 density). I always calibrate my reflected meters to read 18% -- that way, when I read an 18% gray card with my spot meter, it will match the reading I get with my incident meter reading made in front of the gray card.

My apologies for a long response...

same in LR - Copy as DNG in the import dialog

drh681 said:

If you have CS4, Bridge will generate DNG files from RAW. It's a check box in the import dialog.
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Photons by the bag.
Gravitons no longer shipped outside US or Canada
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if I mock you, it may be well deserved.

Click to expand...

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Hi Pro DigitalTalk

Sorry for late response...slipped under the radar.

Yes, I like the old Koday Grey Cards too. Having a dark room for many years, I followed a lot of Adams teaching and others on the Zone System. A very important principal of photography.

Thanks for your considered input.

cheers Dave S