Incident vs. Spot metering in Landscape work?greenspun.com : LUSENET : Large format photography : One Thread
I shoot Velvia for landscape shots. I am sometimnes confused which is best when I have the option of taking an incident reading and a spot reading. For example, on a bright sunny day, when the sun is illuminating the subject the same as it is illuminating the camera, shouldn't both the incident reading at the camera and spot reading from the camera looking at the subject be the same? (assuming the subject is 18% reflective) I rarely find this the case. It seems that since the incident reading is reading direct light from above, it does not have any losses in the process of being reflected in all different directions, thereby allowing only some of the reflected light to enter the spot meter. So should they be the same readings? When you have the option of using both, which would be considered more accurate? Thanks in advance for your help.
-- Bill Glickman (Bglick@pclv.com), May 05, 1999
Hi Bill. In theory, a spot meter reading off a gray card (angled as recommended by Kodak) should give the same result as an incident meter reading. But a better approach is to use the spot meter to see what the range of the scene is, allowing you to be sure that the highlights won't be blown out. The spot meter gives you more control, but takes a little more thought.
-- Stewart Ethier (firstname.lastname@example.org), May 05, 1999.
I find that an incident reading is usually right on the mark. A spot meter is good if you are using the zone system, but for most shooting, I find I get more keepers with an incident reading, with average reflective readings coming in second.
-- Ron Shaw (email@example.com), May 05, 1999.
Yes it should be the same...you are not that much nearer or farther from the sun from camera position to infinity or the horizon. Check your meters and methods! Are you compensating for middle gray with your spot? How many stops different? If I'm in the same sunlight as the subject I use my incident meter. If not spot.
-- Trib (firstname.lastname@example.org), May 05, 1999.
Bill, I've done this, and as Trib says, the results are very similar. The "lumisphere" should be pointed at the camera and not up directly at the sun - are you doing this?
-- Carlos Co (email@example.com), May 05, 1999.
I have found it best to use my spot meter to determine the contrast range of the subject. read the brightest highlight you want detail in, read the deepest shadow you want detail in, and average. If your images are intended for reproduction try to make sure the range is no more than 4 stops. If you have to lose one end or the other, my advice is to tend to slightly bias in favor of retaining highlight info, but this is really something that you have to decide on an individual basis. As somebody else pointed out, If I am in the same light, I'll use my incident meter. From your note it sounds as if you might be pointing the dome directly at the sky above you. If this is the case, point more directly at the lightsource creating the light.
-- Ellis Vener (firstname.lastname@example.org), May 05, 1999.
Ellis and others... do you mean point the dome at the subject from the camera position? I was holding the dome to the sky, that is why I got different readings. Plus, I found out, not all 18% grey cards are the same, this accounts for more error when directing a spot meter at it. Thanks again...
-- Bill Glickman (Bglick@pclv.com), May 05, 1999.
Bill, right idea with the incident, but backwards. Incident meters are designed to be used at the subject with the sphere pointed at the camera. The idea being that the 3-dimensional sphere duplicates a human head, and collects the light from both sides, top and bottom.
Sooo, in a landscape situation, hold the meter in the light the subject (i.e. the landscape, or maybe that really big rock there, or the barn, or whatever your subject is) is in. Imagine if your landscape included your best friend and the sphere was their face. Hold the sphere as if they were standing in the frame, looking back at the camera. This supposses of course that you are in the same light the subject is in and not under a tree or cloud or whatever. If not, move into the subjects light.
-- Sean yates (email@example.com), May 05, 1999.
Sean -- absolutely correct. As mentioned, the incident meter measures the light falling on the subject, not reflected from it. If shooting a person, the globe is pointed directly back at the camera from a point just in front of the model's face. If shooting a landscape scene, which is in the same light as your camera position, just hold the meter up at the camera position and point the BACK of the meter globe toward the subject. (Think about it.) The hemisphere collects the light and registers it in the proper proportion as the angle of the light striking it -- thus a side-light reading in front of a face is proportionally less than a front-lighted face.
Studio photographers DO point incident meters directly at light sources when they are checking light ratios in multi-light setups.
My meter features a retractable globe for metering flat work (copying, etc.) For a multi-dimensional face or piece of sculpture, etc., the globe is not retracted.
To repeat a comment above, the incident meter provides you with a "grey card" reading. It does not help you, as such, with information about brightness extremes. However, if you suspect the possibility of blown highlights, knowing the median brightness level, you can fudge it a bit, stopping down and bracketing a bit.
While all this is really very simple, discussions can go on ...and on...and on. To see for yourself, just go to photo.net and search under the words "incident metering."
-- Henry Stanley (HTStanley@prodigy.net), May 06, 1999.
Henri, Amazing, we must have been seperated at birth!
After posting the short answer version, I began to consider whether or not I should come back and detail the other more complicated factors of incident meter use/interpretation. Then I got to thinking, that's a lotta typing - go to the photo.net page and look at the "metering" thread.....
What is this, synchronicity?
-- Sean yates (firstname.lastname@example.org), May 06, 1999.
Bill, point the dome in the general direction of the lightsource 9the sun. Some people like to point the dome at an angle some where between the position of the sun and the camera's position (both relative to the geral subject. If you want to read the general intensity of the open area shadow light, point the dome about 90 to 120 degrees away from the sun so little or no direct light is falling on the dome. Pointing the dome towards the subject from the camera position will tell you how much light is falling on you on the front of the camera. or on the side of your subject that the camera doesn't see. Not very very useful information. Want to learn more quickly, shoot some polaroids.
-- Ellis Vener (email@example.com), May 06, 1999.
This is something that I learned from Pat O'Hara.
First, you should make at least two, and preferably 3 images having the same amount of light falling on the film. If the light is constant, you use the same exposure. If the light is changing, spot meter the same place or use your incident meter in the identical way. Take the meter reading and expose accordingly.
Next, process only one sheet of film for a given composition. Put it on the light table and decide whether and how much you need to push or pull the remaining sheets for that composition. You will double or triple your film expenses, but you will be guaranteed at least one correct exposure and a lot less worry while you're making the composition. That will put some of the fun back into your photography.
I don't think that this is as useful for people using negative film, in which the final product is the print. But for positive films like Velvia, where the transparency is the final product, this is a way to insure that you get the results that you want.
Best wishes, Bruce
-- Bruce M. Herman (firstname.lastname@example.org), May 08, 1999.