Metering - with gray card or incident meters.

<p>Hi all, quite an newbie question so I'll post it here. </p>

<p>I don't have a incident meter and been a long time since I used the gray card. Can someone confirm whether the gray card and the incident meter produce the same settings? Also can these (2) tools be used in different light condtions? For example, does it auto adjust if it was a cloudy day or if it was night time under street lights and what about if you were in the outback without street lights - therefore I think the gray card cannot be used cos it's just too dark but what about the incident meter? <br>

<br />What I am looking for is to record the scene as seen and if shadows block up or highlights blow then let that be.</p>

<p>I know that it might be easier to try it out with a dSLR and just jott some settings into a notepad with a pen but interested to hear your views on the above. </p>

<p>Reading the gray card with a reflective meter would give reading close to that of an incident meter but not the same. <br>

It would work great on cloudy day.<br>

Under street light I doubt it.<br>

In the outback without street light definitely nope. I don't know of a meter that can measure light in that condition.</p>

<p>Incident meters work best in normal light, not evenings in low light. Here's an aid for low light situations which has been around for years (because it works) - you can assemble your own (I laminated the sheets & then fit them together), or buy a commercial version for about $20 on the big auction site, or at many photo dealers - called the New Jiffy Calculator <cite>www.stacken.kth.se/~maxz/files/<strong>jiffy</strong>.ps</cite>. Kodak used to sell gray cards which have a white card on the reverse side which you can use for reflective readings in low light situations, but you have to make additional compensations if using the white card. Personally, I prefer either the New Jiffy, or a printed out version of Fred Parker's Ultimate Exposure Calculator http://www.fredparker.com/ultexp1.htm (I often use an abbreviated version which I laminated and put a copy in my camera bag, glove compartment of my car, and held on my refrigerator with a magnet.</p>

Reflective meters pointed at the subject work pretty well most of the time, especially the more sophisticated ones such as

Nikon's and Canon's current versions of matrix metering. In the old days, meters sometimes got fooled by very

anomalous situations like snow (high key) or very dark (low key) situations. With modern cameras, you see the result in

the display and you can tell if the meter is being fooled (or if it's just not taking the shot you want).

 

 

If you were taking pictures of snow you might meter a grey card and shoot on that basis since the snow would then be

rendered white in the image. But if it were electronic you'd see the image and adjust to the "grey snow" by changing the

exposure compensation. Using an incident meter would work the same way by incident metering the snow and adjusting.

 

 

Even with film, look at the scene and ask yourself if you have an unusual situation or if you want a high key or low key

effect and adjust the exposure accordingly. Then bracket if you're not sure. If you want, buy an old hand-held light meter

(like an old Gossen) with the little plastic dome you can slide over the sensor. That makes it an incident meter. Try to see

what the readings are with the incident dome taken from the subject vs. reflected readings taken from the point of the

camera. You should be able to pick up a sense of how it works.

<p> A little history will help you understand the Gray Card:</p>

<p>In the pre-historic days of film, before light meters, every film box included a data sheet to help photographers estimate exposure. The basis is the Sunny 16 rule. In bright sunlight, you set the shutter speed by affixing a 1/ to the ISO. Thus for 100 ISO film, set the shutter at 1/100 second. If 400 ISO then 1/400 of a second. Next set the aperture f/number to f/16. This works and tables in the data sheet tell you how to modify this basic setting for cloudy bright, overcast, and sunlight with indistinct shadows. Do not frown; millions of great pictures were taken by this method.</p>

<p>In the mid 1930's, Messrs Jones and Condit at the Kodak Laboratory determined that statistically, a typical sunlit scene integrated to a reflectance value of about 18%. About this time, the Western Electric Company brought to market the first light meter. Kodak Labs publish a recommendation; place a Kodak film box in the scene. Seems the box reflected 18% of the ambient light. Now measure the reflected light from the box top and use this reading to set your exposure.</p>

<p>In 1941, Ansel Adams, a prominent landscape photographer and his friend, Fred Archer, a photo magazine editor, jointly published the Zone System which provided photographers with a method to precisely fine-tune exposure. Their zone system revolves around the use of an 18% placard (battleship gray). This card replaces the Kodak box top. The 18% gray target became the de facto standard. Today film and paper speed as well as the digital chip are calibrated and film and digital ISO is established using the 18% gray card.</p>

<p>Because of the pitfalls associated with reflected metering, a second measuring method evolved called the incident-light reading method. This method places a transparent sphere placed over the entrance of the light meter. The meter is positioned close to the subject and pointed backwards towards the camera. Thus, the meter measures the light just prior to striking the subject (incident old French word for about to happen).</p>

<p>The incident method yields the same reading as a reflected meter taken from a gray card however, it eliminates most of the pitfalls revolving where to hold and place the meter. In sunlit vistas the photographer can merely turn about and point the meter backwards at an imaginary camera. This method is highly accurate and was adopted by Hollywood camera operators because they are filming a scene and maybe a hundred thousand dollars rides on a correct exposure.</p>

<p>Technical stuff:<br>

When negative film is correctly exposed and processed, an image of the gray card on the film will be rendered to a specific shade of gray. This shade of gay is equivalent to a neutral density filter with a factor or 5.5, it cuts light transmission 2 ½ stops. When written as percentage this value is 18%.</p>

<p>When the image of this gray card on the negative is printed, and if the print paper is exposed and developed to specification, the resulting image of the gray placard on the print paper will have the same 18% reflectivity as the original gray card.</p>

<p>The 18% placard is the only tone that:</p>

<ol start="1">

<li>In actuality it has 18% reflectivity.</li>

<li>The resulting image of gray card on the negative has a transmission of 18% .</li>

<li>On the print the image of the gray card matches the original gray card reflecting 18%.</li>

</ol>

<p>This 18% value is the key tone or axis of the photographic system - film – digital – and lithography. This is science -- not guess work.</p>

<p>More gobbledygook from Alan Marcus</p>

<blockquote>

<p>Can someone confirm whether the gray card and the incident meter produce the same settings?</p>

</blockquote>

<p>Short answer: not necessarily. When you use an 18% gray card, you are still using reflective metering (metering the light reflected by a surface) rather than light falling on the subject.</p>

<p>This may get tomatoes thrown at me, but I don't think an incident light meter should be high on the list for most beginners. I don't think I have used an incident meter since I discovered spot metering with my Canon FTb in 1972. If the image has complex lighting, you can use spot metering to gain control, e.g., you can decide which regions you want to be recorded as mid-tones. You can use spot metering with an 18% card, but in a pinch, you can also spot meter off your palm (as long as the light hitting your palm is the same as the part of the image you want to be mid-tone) and then open up the aperture a bit, depending on your skin tone. I find one stop works for me. So I use only reflective metering. I tend to use evaluative metering in relatively straightforward lighting conditions and spot metering when I want more control. I have not found myself wanting an incident meter for a long, long time. I don't own one, and I can't remember the last time anyone with whom I was shooting pulled one out. However, YMMV, and if you find it helps you, go for it.</p>

<p>In the 1970s, for slide film I wanted incident metering but didn't have an incident meter. I took readings off the palm of a hand with the meter in my Canon FTbN and opened up one stop. The same can be done with white paper or card: except that one must open up two and a half stops to let in five times as much light: 18 is close to 20, and five times 20 is 100. I now use a Leica M6 with a meter (reflective) built in, but I still sometimes bring out one of my incident light meters. Never owned a grey card.</p>

<blockquote>

<p>Can someone confirm whether the gray card and the incident meter produce the same settings?</p>

</blockquote>

<p>I can confirm that they don't. The only situation where they do is when one use a flat diffuser on the incident meter instead of the sphere one and this diffuser is on the same plane as the gray card. If light is coming from purely in one direction then the normal spherical diffuser would produce a lower reading than reading from the gray card. In most situations, light don't come purely from 1 direction so the 2 readings are close. </p>

<p>You may be interested in this article on Thom Hogan's site:</p>

<p><a href="http://www.bythom.com/graycards.htm">http://www.bythom.com/graycards.htm</a></p>

<p>Briefly, his research indicates many camera manufacturers calibrate their meters to 12% gray, not 18%.</p>

<p>A gray card will still give you a consistent reference for those situations where you need one. For most practical situations, once you have some experience with your camera's light meter you'll know how much exposure compensation to dial in.</p>

<p>It doesn't matter how you meter with what gear so long as you get the right exposure which comes from experience in using which ever method you choose. At one time I had a Weston Incident 'Invercone' ... which illustrates how long ago that was :-) Never had a grey card or a spot meter but that didn't stop me reading specific areas with my ordinary meter the way a spot would. I also frequently used the back of my hand :-)</p>

<p>Your comment ...<em>What I am looking for is to record the scene as seen and if shadows block up or highlights blow then let that be ....</em> disturbs me because the biggest no-no with digital is to blow the highlights and unless there is extreme contrast there is no need for that to happen. * </p>

<p>Early on I read the Luminous Landscape page "Exposing to the right" of the histogram if you have one. I didn't then but I got the message and I also had the 'blinkies' option in my camera.<br>

Blinkies are the white flashing when you review the shot of the highlights which are blown. I then decide if all or some of them I don't want to be blown and adjust the exposure to give less exposure. This can be as simple and quick as taking half trigger with the camera pointed to include more highlight in frame, holding HT, and dropping camera to the frasming I want.</p>

<p>This often results in under exposed darker areas and these I lift in editing. I will be told that that is dreadful for the noise that this treatment produces in the darker areas, but frankly I rarely see that happening ... I do admit as a film user in the past that noise is not the bugbear it appears to be to some, I am used to and accept grain as a part of life unless shooting with MF/ LF cameras. There is a shot on the Olympus and 4/3 forum POTW taken at 6400 ISO which probably is noisey but is perfectly acceptable at that size ...I looked at it at 100% and it was drack and only just acceptable at 50%, but that is from a 16Mp file.</p>

<p>So PLWEASE :-) watch your highlights and attend to the shadows in editing and use those two essential tools, camera and editor, the way they are designed to be used.</p>

<p>*Even when there is extreme contrast there are often ways to cope with it without making it like an over compensated HDR image. </p>

<p>I also quite a bit of film still ... :-)</p>

<p>With digital yes, there is the LCD, you can just shoot as many diff exposures until the LCD looks happy. I asked the question before I have been shooting slides which I just project them in a slide projector. But I would probably get a light meter later anyway, because I have bought some 120 film but not the camera yet and intend to get into 4x5 as well.</p>

<p>Ray! The incident light meter (or metering with a gray card) isn't very good when you have a scene with extreme dynamic range. It won't tell you which parts of the scene will be lost in the shadow and which parts would burn out. A spotmeter would be a better choice for this situation.<br>

When you asked if it would work in cloudy days, I said it works great because in cloudy days the light is very even and the brightness differences are due solely to the reflectance of the subject.</p>

<p>My $.02 worth: I have 2 old Gossen Luna Pro meters that have the white dome used for incident metering. They were essential for starting points when I shot film for architectural interiors and exteriors, and outdoor portraits. I still use them for the large format apsect of my professional work. Most of my work is digital now. To assist me, I use an Ed Pierce Target. It will give me 2 things: perfect color and exposure, using at most 1 or 2 shots to get a custom white balance and exposure. The target features 3 strips; grey, white, and black. I'm not shilling for it but will tell you that it is ideal for my purposes. In the field or the studio, I can nail perfect color and exposure using it as a starting point in just one or two shots. For exposure, I just shoot the target, look at the histogram, and adjust settings until the highlight spike is just to the left of the right edge of the frame. The handheld gray card of long ago, made by Kodak, I found not to be perfectly neutral grey. I might also suggest the use of a Color Checker to assist as well. By including either the CC or Target in one frame you shoot under the same light source you are using, modifying colors and exposure in post is a snap.</p>