18% grey and metering

gabrielh

TPF Noob!
Joined
Oct 24, 2008
Messages
62
Reaction score
0
Can others edit my Photos
Photos NOT OK to edit
Hello all,
Just wanted to be sure about this: if I point the camera (say, in spot metering mode) to a white wall, then it will be metered for 18% grey and will come out as 18% grey if I don't adjust settings. This is right, isn't it? Also, I have read that if you wanted to take some portrait, just meter the brightest part of the persons face, and then increase the exposure by two stops so the white truly comes out as white and not as grey. But that seems quit a lot for me... Anybody help please?
Thanks!
G.
 

dxqcanada

Been spending a lot of time on here!
Joined
Dec 4, 2008
Messages
7,696
Reaction score
1,585
Location
Woodbridge, Ontario, Canada
Can others edit my Photos
Photos OK to edit
Yes, it will be 18% grey.
Always handy to have a small Grey Card (I have one in my camera bag).

Not sure about the second part ... I do not do portraits.
 

tirediron

Watch the Birdy!
Staff member
Supporting Member
Joined
Jul 8, 2005
Messages
45,747
Reaction score
14,802
Location
Victoria, BC
Website
www.johnsphotography.ca
Can others edit my Photos
Photos OK to edit
All meters are designed to read a middle grey, but the actual percentage varies slightly. If you point your camera at a bright, white wall and meter it, the camera reads it as if it were a middle grey wall, and will thus over-expose the image. The resulting wall colour will be darker and muddier, but not necessarily 18% grey. With respect to your question on portraiture, I've never heard that particular piece of advice before. Two additional stops on the highlights is likely to blow out a good part of the image IMO. I would meter the scene in spot from the point which I wanted perfectly exposed (ie, if you're using a hairlight to create a "halo" you may not want to meter off of those, or if you deliberately want a good part of the face dark, don't meter from it) and use those settings to start. Take the image, review and adjust as req'd.
 

Big Mike

I am Big, I am Mike
Staff member
Supporting Member
Joined
Dec 16, 2003
Messages
33,896
Reaction score
1,853
Location
Edmonton
Website
www.mikehodson.ca
Can others edit my Photos
Photos NOT OK to edit
I think you have the basic idea correct.

If you meter off of a white wall, the camera will give you settings to expose for [18% grey]. Your wall may not come out at 18% grey in the image but it would certainly be under exposed. In this case, you would want to increase your exposure...probably between one and two stops.

Also, I have read that if you wanted to take some portrait, just meter the brightest part of the persons face, and then increase the exposure by two stops so the white truly comes out as white and not as grey. But that seems quit a lot for me
That would seem a lot to me as well...unless the brightest part of that person was pure white.

You can essentially meter off of anything...the key is knowing how reflective that surface is and what (if any) compensation you would have to add/subtract from the meter's reading.

The tone of most people's plam, is about one stop brighter than mid tone...so you could meter your palm and then increase exposure by one stop.

Green foliage (grass for example) is usually about mid tone, so you could meter off of grass and use that exposure directly.

I do think it's helpful to understand metering...but I also think that it's not nearly as important (with digital) as it was with film. Firstly, with digital you can shoot and check your exposure immediately. While it's not a great idea to use the image on the screen to accurately judge exposure, most DSLR cameras have tools to help you. Highlight tone warnings (flashing) and the histogram is great.
Rather than careful metering, I find that I prefer to shoot, test, adjust and shoot again.

Histogram

Also, with digital...the 'proper exposure' may not be the 'best' exposure.
Expose to the Right
 
OP
G

gabrielh

TPF Noob!
Joined
Oct 24, 2008
Messages
62
Reaction score
0
Can others edit my Photos
Photos NOT OK to edit
Thanks all for these fast answers! Two more questions have arrised when reading your posts:
1. How do you use a grey card to make your exposure. Do you meter that card and you're sure you've got a "good" exposure and then adjust accordingly if the subject is black (then subtrack a stop or two) or is white (then add a stop or two)?
2. Big Mike told about "what (if any) compensation you would have to add/subtract from the meter's reading". How do you know what compensation you have to add/subtract?
Thanks! :D
 

dxqcanada

Been spending a lot of time on here!
Joined
Dec 4, 2008
Messages
7,696
Reaction score
1,585
Location
Woodbridge, Ontario, Canada
Can others edit my Photos
Photos OK to edit
Place grey card in front of subject.
Meter off of grey card.
Shoot.

This is OK if the subject lighting is not extreme.

I did this a lot when shooting moving subjects on my manual exposure camera ... also I do this with my new camera in situations where I do not want the camera playing with the auto exposure (by going manual).

... I used to just use my hand-held ambient light meter, until it broke.
 
OP
G

gabrielh

TPF Noob!
Joined
Oct 24, 2008
Messages
62
Reaction score
0
Can others edit my Photos
Photos NOT OK to edit
So... No adjusting for more bright or dark when using grey cards? Why nog? Why yes?
Just wanting to learn and understand!;)
 

dxqcanada

Been spending a lot of time on here!
Joined
Dec 4, 2008
Messages
7,696
Reaction score
1,585
Location
Woodbridge, Ontario, Canada
Can others edit my Photos
Photos OK to edit
You meter a 18% grey card with a light meter that is balanced for 18% grey ... and you will capture grey.

As long as the exposure latitude does not go beyond the latitude of the film/sensor ... there is no need for adjustments.

In some extreme exposure cases you may need to shift the exposure up or down to move the highs/lows up or down to retain detail in one of those areas (and sacrificing the other).

Ansel Adam's Zone System is a great tool to understanding exposure.
 
OP
G

gabrielh

TPF Noob!
Joined
Oct 24, 2008
Messages
62
Reaction score
0
Can others edit my Photos
Photos NOT OK to edit
Ok! Thanks dxqcanada! It sure helps!
 

Jon_Are

TPF Noob!
Joined
May 12, 2007
Messages
655
Reaction score
13
Can others edit my Photos
Photos NOT OK to edit
Rather than careful metering, I find that I prefer to shoot, test, adjust and shoot again.

(jumping in here)

So if I'm checking my histogram and 'flashing highlights' screen, and all is OK, I don't have to bother with a grey card?

Here's where my ignorance will show: I thought the grey card metering was used to obtain correct white balance (only).

Is it also used to obtain proper exposure?

If I have attained proper exposure, is it a given that my white balance then is correct? Or not necessarily?

Thanks,

Jon
 
OP
G

gabrielh

TPF Noob!
Joined
Oct 24, 2008
Messages
62
Reaction score
0
Can others edit my Photos
Photos NOT OK to edit
Thanks Jon, for jumping in! I also knew that the grey card (I prefer a white card) was used for white balance. But I don't think the white balance is correct if the exposure is good (and vice versa). If incorrect, please correct me...
Thanks!
 

Turnerea

TPF Noob!
Joined
Aug 28, 2008
Messages
212
Reaction score
0
Location
SoCal
Can others edit my Photos
Photos OK to edit
I'm pretty sure the typical use is a white card for WB, and a grey card for exposure. Though to be fair I don't use either.... If I need to do manual WB, I'll just shoot something around me (usually I'm outside) that appears white in the lighting I'm using (basically a 'white card') and just using that to adjust WB.
 

Big Mike

I am Big, I am Mike
Staff member
Supporting Member
Joined
Dec 16, 2003
Messages
33,896
Reaction score
1,853
Location
Edmonton
Website
www.mikehodson.ca
Can others edit my Photos
Photos NOT OK to edit
So if I'm checking my histogram and 'flashing highlights' screen, and all is OK, I don't have to bother with a grey card?

Here's where my ignorance will show: I thought the grey card metering was used to obtain correct white balance (only).

Is it also used to obtain proper exposure?

If I have attained proper exposure, is it a given that my white balance then is correct? Or not necessarily?
Grey cards are primarily used for exposure...and have been used for decades. Using them for White Balance is rather new because digital cameras have a variable WB. I've used a white card (or white anything) for setting the WB...but never a grey card.

So since you can use your histogram for exposure, you don't really need a grey card at all. It still might not hurt to have one, as it can help you understand.

White balance and exposure are separate entities. One can be accurate while the other may be way off.

Personally, I shoot in RAW, which gives me the ability to adjust the WB after the shoot, when I have the images on the computer...so I usually leave the WB on auto and don't worry about it.
 

Mike_E

No longer a newbie, moving up!
Joined
Jan 26, 2007
Messages
5,327
Reaction score
266
Location
The Upper West Side of Mississippi (you have no i
Can others edit my Photos
Photos OK to edit
Have whomever you are shooting hold up their hand plam forward and meter off their palm. All races's palms are about the same. :)

Go ahead and shoot RAW so that you can fine tune later as little in life is constant.
 

Jon_Are

TPF Noob!
Joined
May 12, 2007
Messages
655
Reaction score
13
Can others edit my Photos
Photos NOT OK to edit
Have whomever you are shooting hold up their hand plam forward and meter off their palm.

This is to meter for exposure, correct?

So, in terms a simpleton would understand:

1. Arrange the subject (human) in the pose/composition you want.
2. Have them show you their palm.
3. Set the shutter speed and aperture in a way that indicates a correct exposure.
4. Step back and fire away, using these same settings.

I assume this method is only for taking shots of people?

Thanks for the help,

Jon
 

Most reactions

Top