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03-16-2013, 01:49 PM   #1
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Sekonic 358 Giving Me Very Underexposed Images -- Help?

Hello,

Just got my Sekonic 358 and I finally had a chance to test it out today. This is my first light meter so I'm pretty sure I'm doing something wrong. I've already headed out to YouTube and haven't really been able to find anything that addresses my issue.

I tested it out with flash and it seems to work just fine. Where it's really struggling is on Ambient Mode. I get exposures that are between 1 to 2 stops underexposed. I'm using it with a K-30 if that makes any difference.

Thank you in advance for any help.

03-16-2013, 02:07 PM   #2
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Lumisphere removed and either lumigrid or spotfinder in place?


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03-16-2013, 02:24 PM   #3
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Using it with the lumisphere on and fully extended. Just trying it out with the flash right now and I'm also getting some underexposed images. I really want to rule out user error before I send it back.
03-16-2013, 02:36 PM   #4
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Wheewwwww!!!!!!!! (supposed to be an excited sigh of relief). Just figured it out! I bought the meter used and the previous owner had the exposure compensation set to underexpose by 1.7!!! I'm not sure why anyone would do that, but they did. Thank you guys.

03-16-2013, 03:15 PM   #5
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QuoteOriginally posted by reivax Quote
Using it with the lumisphere on and fully extended. Just trying it out with the flash right now and I'm also getting some underexposed images. I really want to rule out user error before I send it back.
The lumisphere is for incident light measurements. For reflected light (Ambient mode) you use the lumigrid or spotmeter. The manual is available for download at the Sekonic Web site.


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03-16-2013, 05:59 PM   #6
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QuoteOriginally posted by stevebrot Quote
The lumisphere is for incident light measurements. For reflected light (Ambient mode) you use the lumigrid or spotmeter. The manual is available for download at the Sekonic Web site.


Steve
Reflected and ambient are not synonymous. You can take an incident reading of ambient light. You can take a reflective reading of flash light. Incident means reading the light falling on the subject. Reflective means reading the light reflecting off the subject.
03-16-2013, 07:22 PM   #7
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QuoteOriginally posted by MPrince Quote
Reflected and ambient are not synonymous. You can take an incident reading of ambient light. You can take a reflective reading of flash light. Incident means reading the light falling on the subject. Reflective means reading the light reflecting off the subject.
In what situation would want to use either/or? I don't know why I would ever want to take the lumisphere off and put the other one on...
03-16-2013, 07:57 PM   #8
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QuoteOriginally posted by MPrince Quote
Reflected and ambient are not synonymous. You can take an incident reading of ambient light. You can take a reflective reading of flash light. Incident means reading the light falling on the subject. Reflective means reading the light reflecting off the subject.
QuoteOriginally posted by reivax Quote
In what situation would want to use either/or? I don't know why I would ever want to take the lumisphere off and put the other one on...
He is correct and I was imprecise. The meter's manual is your friend. A few bullet points:
  • Your in-camera meter measures reflected light.
  • Your Sekonic can measure either reflected or incident light depending on how the meter is configured.
  • Reflective measurements are made from the camera's perspective with the meter oriented toward the subject. The lumigrid (should be included) and/or spotmeter (optional accessory) are used for reflective readings.
  • Incident light is measured at the subject position with the meter oriented toward the camera. The lumisphere is used for incident readings and serves to diffuse the full range of light sources that are illuminating the subject.
  • Incident metering is generally a little more foolproof and will virtually guaranty accurate value placement (within the limitations of film or sensor) for the full range of subject brightness. Note that accurate is not always the desired value placement.
  • Off-camera narrow angle spot metering of reflected light is a huge creative tool, particularly with B&W films. It is not just for avoiding underexposure of back-lit subjects. Matrix or multi-zone metering by the camera is an automated attempt at intelligent spot metering.
  • Averaged reflected light readings are a "blunt" tool. Thank goodness for the camera histogram. A reflected light measurement off a gray card can provide a working approximation of an incident reading.
You work with the lumisphere off (reflected measurement) when you are not in a position to measure the incident light at the subject. A good example might be the bear grotto at the zoo. You are in full sun. The bear is in full shade. No way are you going to be able to get an valid incident reading without joining him in the grotto. Not recommended.

Steve


Last edited by stevebrot; 03-16-2013 at 08:08 PM.
03-16-2013, 08:20 PM   #9
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QuoteOriginally posted by reivax Quote
In what situation would want to use either/or? I don't know why I would ever want to take the lumisphere off and put the other one on...
A teacher of mine has a very simple and extremely effective method for lighting and exposure. He taught us to use reflected (spot) readings to determine the actual contrast between objects in a scene. Next, he uses an average incident reading with the sphere pointed towards the camera to determine exposure (or as the basis for his own determination of exposure). The thing about reflected readings is that they are more accurate in the sense that they mimic what you actuay see in an image; i.e. an incident reading of the light falling on a zebra tells you nothing about its white stripes or its black stripes. spot readings of both would tell you more about what the contrast will look like in your image.

I like to think of incident readings this way: IF you put a grey card in your scene, and IF you take an incident reading towards camera and set your f-stop (or t-stop, to be more accurate) accordingly, the grey card should appear to be middle grey in your final image. If you want any other result, you will have to put on your thinking cap.
03-17-2013, 07:13 AM   #10
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Generally, incident metering is more accurate than reflected metering because, in most (but not all) cases, an incident reading will record a medium tone as a medium tone, whereas a reflected reading will record whatever is metered as a medium tone. An incident meter is not fooled by how much light the subject reflects and so will give an accurate reading regardless of how close the scene being photographed is to middle gray (assuming the incident reading is taken under the same light the subject is in). A reflective meter, on the other hand, can give inaccurate readings if the scene being metered averages out to brighter or darker than middle gray. It is then up to the photographer to know the scene being metered is not middle gray, and to compensate accordingly.

I always use an incident meter when doing off-camera flash work. Otherwise, I use my camera's reflective meter, knowing I may have to compensate for what the meter reads. I generally don't take my incident meter (a Polaris SSP-100, which meters both flash and ambient) when I'm shooting in natural light simply because it's one more piece of equipment to carry around.
03-18-2013, 08:14 AM - 1 Like   #11
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QuoteOriginally posted by reivax Quote
Wheewwwww!!!!!!!! (supposed to be an excited sigh of relief). Just figured it out! I bought the meter used and the previous owner had the exposure compensation set to underexpose by 1.7!!! I'm not sure why anyone would do that, but they did. Thank you guys.
Glad you figured it out, I was about to suggest that you check the exposure compensation, but there are a few other things that fall under the "user error" category that you'll want to be aware of as you begin to use your meter.

As several folks have mentioned, you always want to take incident readings from the subject's position, and for most subjects you will want to point the meter with the dome up straight back at the camera, right down the axis of the lens. Dome-up mode takes a 3 dimensional average of the lighting in your scene. If you're in the studio for instance, the meter will measure you key and fill lights from your subject's position, but ignore the background lights (because they're not in the 180 field of view of the dome). Edge lights it may or may not pick up, depending on how far behind your subject they are placed.

Furthermore, when you're using studio lighting or speedlights, the flash-to-subject distance is many times smaller than when you're outdoors using the ambient light of the sun. That means that the inverse square law will play a much larger role in the fall off of your lights, particularly if you like to get your lights in close as I do. What that means is you have to be very precise in your placement of your meter. If you're lighting people, that's usually under their chin so that the meter is the same distance as the person's face. There's a video on Youtube from a very knowledgeable photographer that I won't link here, but he claims that you don't need a light meter. In this video he goes about to try to prove that light meters give false readings. He has his octobox maybe 6 feet from his model, and then proceeds to take the reading from about a foot and a half in front of her face and points the dome directly at the light, not the camera. Not surprisingly the shot is a stop and a half underexposed. This his horrible metering technique, and yet he has probably managed to convince a few people. I will reiterate, when the lights are close to the subject, the meter has to be positioned and oriented very precisely.

Now as for dome up or dome down? Dome up as I've said is for metering three dimensional subjects, dome down then meters for two dimensional subjects. For most studio photographers it's useful for checking the evenness of illumination on the background. You might also use it when photographing a piece of art, or a document. But, there is also another use, and that is in determining lighting ratios. Again I'll use the example of a person as your subject, but it would be equally true of a product shot or a still life. To check the relative strengths of different lights in your scene, you would put the dome down, and point the sensor not at the camera, but at the lights from your subject's position. There is even a button on sekonic meter that will tell you the difference in strength between two lights. On the 758 (and I believe it's the same for the 358) you meter one light put it in memory, and then hit the ΔEV button, and meter the second light, but you have to hold the meter button the second time. The meter will display the difference in the two lights in f-stops. This allows you to calculate your lighting ratio.

I haven't used the spot meter attachment of the 358, so I won't try to speak authoritatively on it's proper uses, but generally speaking, if you're taking a reflected reading with a hand held spot meter, you want to be as close to the lens as possible and pointing out into your scene.

Last edited by maxfield_photo; 03-19-2013 at 06:53 AM.
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