Correct Sunny 16 Technique?

[Andre Noble]

I am trying to get a correct meter calibration as a starting point for proper ASA setting to use on my Sekonic L-358 with the purpose of making more accurate transparency exposures.

I am already familiar with the "1/ISO @f16" Sunny 16 rule which applies during the time of day 2hrs after sunrise or 2hrs before sunset on a sunny, cloudless day.

However, from all the threads I've researched, none has mentioned WHERE the dome of incident meter should be properly oriented in relation to the sky. The readings one gets vary widely based just on that!

Ie, does one hold the meter perfectly vertical, with dome directly toward the sun's direction? Or does one have the meter held at an angle up slightly with dome's center directly pointed at Sun's center? Or is the meter held horizontal with dome point perfectly straight up into the sunlight sky? Or is it "none of the above"?

Expert advise appreciated!

[Tim Curry]

No expert, but I think you would point the dome at the lens itself. The meter is trying to decide how much light is falling on the subject. If you point it at the lens from the location of the subject, you are reading the light falling on the subject.

I use reflective metering, so please correct me if I am wrong about this technique.

[Michael Mutmansky]

Incident meters are deceptive tools to use. It seems like an easy thing, to simply hold the thing up, and get a reading that tells you an exposure for the subject.

However, that is truely a gross oversimplification of what it does. In most cases, the meter uses a small dome (sometimes called an integrating dome) to collect and average the light that the subject is receiving FOR A SPECIFIC ORIENTATION. This is the key to understanding how to use one well.

The orientation of the head determines a plane for which the meter is establishing an exposure. If you orient the meter with the dome pointing vertical, you are reading the exposure to correctly expose for a horizontal surface (like a table top).

If you orient the meter at the subject pointing toward the lens, you get a reading for a surface perpendicular to the camera at the point of the meter. This may not be the best orientation, depending on the subject and lighting conditions

If you point the meter directly towards the sun, you get a reading for a plane perpendicular to the sun, and will almost certainly end up underexposing the subject, except in some cases.

There's many approaches on how to meter, but I think the best way to do this is through some personal trials. When photographing a three dimensional subject, there may be several orientations of the meter that seem to make sense. Take the meter readings for the various orientations and then think about how these meter readings relate.

You could try an exposure for each meter reading and then analyze the results and see what seemed to work. What I do is consider the readings, and then do an average exposure based on the various readings that I get in the meter.

Often the lighting is such that there is little difference in the readings, as in situations where the primary light source is behind the camera (like during a sunrise/sunset). However, even in these conditions, a building surface pointing directly toward the sun will have a higher light level than one pointing 45 degrees to one side or the other. You still have to decide what surface you want 'correctly' exposed, which is where the averaging come in.

If you want both surfaces exposed well, then a true average of the two might be about right. However, you could also decide that you want one correct, and the other to either go dark or light. You might then strongly weight the exposure toward one or the other readings.

For general scenic work where there is no real orientation to the subject, I will typically take a reading towards the light source, and then away at about 90 degrees, to get a sense for the difference in exposure, and then I'll find a point in the middle, generally toward the highlight side to avoid overexposure of the highlights.

Another way to get a sense for the exposure is to orient the meter vertically towards the camera, then take a reading. Then, hold your hand over the sun, so it cases a shadow on the dome, and take another reading. These give you information on the primary light, and the light that results from the sky and reflection off the ground. Again, these can be used to determine a reasonable exposure for the subject.

Everyone is different with meters though, so you will need to develop a procedure to determine how to get accurate readings for yourself.

It goes without saying that there will be an orientation where the meter will actually give you the reading that you desire without having to average several. With some experience, you may find that you can do a good job approximating the ideal exposure by considering the various issues with the subject, and then selecting an orientation that takes them all into account.

---Michael

[steve simmons]

If you have reflected metering capability why use the incident method. It runs the risk of poor exposures in contrasty situations and does not give you an idea of the overall contrast range of the scene which you need to know regardless of the type of film you are using.

steve simmons

[Andre Noble]

Thanks Michael for taking the time to make a detailed post. But my question pertains to calibrating my Sekonic L-358 incident meter to the sun as a reference standard, and how to do that specifically.

As it stands now, my meter consistently underexposes different transparency emulsions, despite good metering technique. This is in line with it's reputation as expressed by other photographers on photonet, etc.

But perhaps I should just take a film that's known to be rated accurately (such as the Kodak 100S transparency film) and calibrate my meter to proper exposure of that, instead of calibrating to the sun - although some swear by calibrating to the sun using the Sunny 16 rule.

[Andre Noble]

Steve, you're right. I use the incident meter for LF portraiture and (dare I say it) a lot with 35mm and MF handheld - and just wanted to see what info I might get from this LF group.

[Nick_3536]

Sunny 16 is a way of estimating exposure for an object lit by the sun. So the meter must be lit by the sun. If you hold it up then won't the bottom of the dome be in the shadow of the top of the dome? Tilting will help some. But if you hold it out flat in the palm of your hand the sun will hit the whole dome. Makes sense? Maybe just to me. Basically you don't want the light casting any shadows. I don't have any sun or I'd check for you.

[Ralph Barker]

To paraphrase dear old Obiwan, "Meter the light, Luke. Meter the light." ;-)

In other words, pointing the axis of the incident dome at the light source will give you an exposure reading that will render the "true tonality" of that portion of the subject exposed to that light. Whether that is the optimal exposure for the subject is a separate question, of course. But, for the stated meter calibration purposes, that may be the best method. An alternative method would be to take a reflective reading off a new (unfaded) 18% gray card held perpendicular to the light source (the sun in this case) under the appropriate conditions. Then, validate that base calibration with equipment and film tests.

It seems, however, that "proper metering technique" is highly subjective. Asking that question to six different photographers usually produces at least eight different answers. ;-)

[Steve J Murray]

I think the incident meter is great for metering portraits, where its much like taking a spot meter reading off a gray card in front of the subject's face. It will accomodate multiple light sources or other complex lighting situations. Metering a landscape is much different, and to me the incident meter is not as useful. After all, the subject is infinitely broad, and you have to take into consideration shadows and highlights that are all over the place. At any rate, if I were going to test an incident meter, I would use a human subject and go for accurate skin tone, or maybe meter and shoot a gray card. That would at least tell you if your meter is over or under exposing for a known and predictable subject.

[tim atherton]

And of course the sunny f16 "rule" depends/varies on latitude and time of year.

I remember reading once the (probably apocryphal) anecdote that Kodak calibrated it's film speeds by taking a grey card reading on a sunny day at mid day in mid summer in the Kodak staff car park at Rochester - and that was the standard/baseline....

[Steve Rowell]

Don't know if you had the manual or not. If not you should be able to get one here.

http://www.sekonic.com/InstrManuals/L-358.pdf

Also contains proper info for meter orientation for each type of metering.

Steve

[Ken Lee]

But perhaps I should just take a film that's known to be rated accurately (such as the Kodak 100S transparency film) and calibrate my meter to proper exposure of that, instead of calibrating to the sun - although some swear by calibrating to the sun using the Sunny 16 rule.



If you want to calibrate your meter against something of known luminosity, don't rely on the sun, since its brightness varies with altitude, time of day, and atmospheric conditions. Why not just drop into a store where they sell new high-end meters, and compare yours to 2 or 3 of them. My guess is that they will all be close to one another - and you will soon find out it yours disagrees with them, and by how much.



Make sure to compare it at different levels of brightness.

[Henry Ambrose]

Andre,

Testing is how to find your speed for more accurate exposures, and its very easy. The following assumes that you have a well proven method or technique that you use to meter. If you don't have this down pat you need to develop this first before you do anything else. For a portrait in controlled lighting conditions I "meter to the camera" placing the meter in front of the subject and pointing the dome directly at the lens. For really tight exposure control you need Polaroid and you need to know how that Polaroid and the film you choose compare to each other in their response to light. And it never hurts to have tested because then you know how your lab runs the film and how much to ask for in push or pull for the real fine tuning.

To find your personal speed for your film do this test: Set up a typical scene (ask someone to sit for you) with a small label that has the speed you have rated the film for that scene, adjust your meter to the box label film speed, meter as you usually do (toward the camera, toward the light source, whatever is your standard method), and shoot a frame. Next frame adjust your speed or aperture for 1/3 stop more light, put a label in the scene that indicates that number, adjust the camera, shoot and so on. If you are using 100 speed film the first shot is at 100, next at 80, then 64, then 50. One of those will work for you. Four sheets or one roll of film you're done. It does not matter what number you set your meter to get the exposure you want, you just set it the same every time you use that film. So if you like the way it looks rated at 64 on the meter then just set your meter to 64 when you use that film.

If you want to calibrate your meter you should send it to the manufacturer or a reliable repair service to have it calibrated via instruments. As others have pointed out the sun and its position vary too much for this purpose. All meters vary a little and I think unless yours is defective you are wasting your time. Just test your film and then you know how to set your meter.

[Graeme Hird]

Andre,



You mention problems with exposure control across various emulsions. Does this mean that your problems occur with different formats also? I'm asking because the variations you are seeing could be due to inconsistencies with your lens/shutter combinations. They are often not "correct" and each one should be calibrated via testing. I remember reading somewhere film tests should be carried out for each shutter.



Regards,
Graeme

[Andre Noble]

Various transparencies were underexposed by appx 1 stop or less on 35mm w/various lenses & MF w/various lenses when relying on the Sekonic L-358 to set exposure manually.

[Wayne Crider]

Your opening sentence has two disparging points. One, a meter is calibrated by the factory according to their own idea of a true reflectence value which can range from 13% to 18%. Two, a personal E.I. comes as a result of a testing of the film being used, and in b&w, the development of that film and the printing of that film. Since you shoot transparencies you need to do a simple film test and bracket your exposures to tell you what E.I. you should shoot the film at.

When using an incident meter you stand in front of the subject and meter the light hitting it with the dome oriented towards the lens. If the sun is over your shoulder, (subject in front), hold the meter up as if pointing towards a camera behind you. A incident meter will essentially tell you what a zone 5 exposure is for the light oriented towards the dome, or, towards the subject in this case, not what it is for the reflected light from the subject, since light is reflected differently per subject. You want to place the value of the reflected light on the zone that you need it on, and not necessairly on the middle zone. For portraits an incident meter generally works fine; For color landscapes you have to figure out the contrast range and in extreme contrast situations lean towards the most important feature such as the highlights or shadows. In b&w we expose for the shadows and develop for the highlights.

[Ellis Vener]

The "sunny 16" rule is not a way to calibrate a meter. It is a way of guessing at an okay exposure when you don't have a meter.

To actually calibrate a meter you need a light source of an established intensity at a fixed distance from source to meter or target, and a target of a known reflectivity.

[Ellis Vener]

After you have calibrated your meter, you need to test your specifc combination of film(s), camera(s), lenses, and processing to find what should be the "normal" E.I. setting for you , as opposed to the official ISO rating for the film you are using.. ISO ratings are establishjed in avery controlled testing enviroment and processing conditions and only refer to how a gray scale is rendered. Since you are combining all of the above set of mechanical variables and color , you have to look at your imaging system frm metering to exposure to processing.

[Andre Noble]

Lots of good, back-to-basics advice here. Now that it's the weekend, I have time to do a test along the lines of what Steve M. suggests and clear this up.

[Øyvind Dahle]

So if everybody could please test their meters in incident metering mode against the sun when the sun is more than 30° above the horizon (just barely possible in Norway midday), and you can tell absolutely that there is no haze or clouds blocking or filtering the sun, post the EV here! Also test your meter against a OK grey card and post it the EV here.

Then we could tell whether the sunny f:16 rule still holds water

Øyvind:D

[Gary Meader]

I can get pretty close to seeing if my camera meter is OK by filling the frame with clear north sky. That should read a pretty good Sunny 16. Is that the answer you're looking for?

[Andre Noble]

Good info. While that pertains to calibrating reflective type (not incident) meters, it has the advantage of being easily checked for validity with a quick test.

[Øyvind Dahle]

So I get Sunny 16 Incident. 2/3 more on a Kodak grey card

Øyvind:D

[Andre Noble]

Perfectly Clear Sky, Noon, Los Angles. I get F16.3, @ 1/60th ASA 64 on Sekonic L-358 with factory calibration(ie, no recalibration on my part).