ACCURATE EXPOSURES
Sekonic L758D
IAN BARBER PHOTOGRAPHY
C HAPTER 1
Sekonic L-758
The Sekonic L-758D DigitalMaster can be calibrated to read light the way your particular camera system reads light.
Introduction Like most things in the digital age, this light meter is no exception, it has more bells and whistles than I can count. Putting all these to one side, it is one of the most accurate and versatile light meters I have used to date. This document is not intended to explain all the functions, dials and menu options, I will leave all that tucked away in the 57 page manual. What I do want to explain though is how this light meter can be setup with a great deal of ease to help you with your exposures whilst out in the landscape. I want to talk about two things in particular, calculating the dynamic range of a given scene and also how to let the light meter do the maths for us when we want to take full advantage of the digital capture by exposing to the right also known as ETTR.
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C HAPTER 2
Calculating Dynamic Range
Dynamic Range Unlike our eyes, digital cameras have a much smaller dynamic range. The dynamic range is how much detail the sensor can capture from the darkest darks to the brightest whites. All DSLR cameras will have a different dynamic range which will also vary depending on which ISO setting and lens you use. Knowing the dynamic range of your camera and lens combination can be useful and the Sekonic L758 allows you to create custom profiles which will then synchronize your camera to your light meter. You can store up to three separate profiles in the light meter by using the Sekonic Data Transfer Software which can be downloaded directly from the Sekonic website.
On the previous page, we mentioned that the light meter can be synchronized with your camera by the way of custom profiles. Although calibrating your camera to the light meter is good practice, in most cases you will probably find that the light meter by default is relatively accurate. How to calculate the scene dynamic range. Calculating the dynamic range of the scene is probably best accomplished by using the spot meter function. 1.
Set your desired ISO and Aperture in the light meter
2.
Point the spot meter at an area that represents middle grey and take a reading.
3.
Press the Mid Tone button to place this value into memory.
4.
Point the spot meter at the brightest area in the scene, take a reading and press the memory button to place this value into memory.
5.
Point the spot meter at the darkest part of the scene where you want to retain detail in the shadows, take a reading and press the memory button to put that value into memory.
Once you have stored the profiles into the meter, you can select which one you want to use by doing the following. 1.
Turn on the light meter
2.
Press and hold the ISO 1 button
3.
Tap the Mid Tone button and you will be able to cycle through the profiles which are displayed just above the Aperture values.
Now you have all three measurements placed into memory, the middle grey reading, the brightest highlight and the darkest shadows, look at the light meters lcd display and you
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will be able to see the full dynamic range of the scene as shown in the following image. (4 stops)
If on the other hand you feel that the shadows are falling a little low on the scale, what you can do is move the middle value up which in turn will move the shadows and highlights up the scale. Moving the middle value. 1.
Press and hold the Mode button and at the same time press the Mid Tone button.
2.
Release the Mode button and press the Mid Tone button and move the jog wheel. As you move the jog wheel, you will see all the values starting to move. Keep moving then until the shadow area is with the range that you want.
Remember, if you end up moving the tones so that the middle value is now on +1 for example in order to lift the shadows, what ever you first metered for Zone V (middle grey) will now be represented as 1 stop brighter (Zone VI) In this example we can see that the shadows are falling just over 2 stops under middle grey which would place them between zones 2 and 3 when we are talking about zones.
In the next Chapter, we will look at how we can use the meter to quickly work out the exposure for when we want to expose to the right (ETTR)
The highlights are falling just under 2 stops above middle grey placing them just under Zone 7. If you feel that your camera can capture detail within this range, use the readings displayed in the light meter for your exposure 1/250th sec @ f/4 at ISO 800 in this case. 5
C HAPTER 3
Exposing To The Right (ETTR)
With Digital capture, it is always best to expose as far to the right of the histogram as we possibly can without actually clipping any data on the right hand side. By exposing to the right, we are capturing as much information as we possibly can.
As our light meter is calibrated to give us a base reading which is equivalent to middle grey (18% grey) or Zone V, when exposing to the right we will need to open up our exposure reading by 2 1/2 stops. Lets break this down... Say we have determined that we want to use an aperture value of f/16 for a deep depth of field and use an ISO value of 200. We set our light meter to Aperture Value and dial in f/16 and then we set the ISO to 200. In spot metering mode, we point the spot meter at say the brightest part of the scene (the bright white clouds for example). The meter tells us that we need to set our shutter speed to 1/500th of a second. If we use 1/500th then it is going to render these big white fluffy clouds as middle grey because the meter is always going to return the base reading as middle grey but we know they do not look grey to our eyes.
Most high end DSLR cameras can capture somewhere in the region of around 5 full stops, which is made up of: 2 1/2 stops above middle grey
We now have to open up the exposure by 2 1/2 stops which would now make our shutter speed 1/80th of a second thus placing the white clouds between zones 7 and 8 just where we want them.
2 1/2 stops below middle grey 7
I find that calculating the 2 1/2 stop difference in your head can be a little challenging especially before the caffeine starts to take hold.
the meter will automatically do the calculations and display what shutter speed you need to be using. It is really that simple.
This is where we can use the computing power of the Sekonic L758 light meter to do all the heavy lifting for us.
The Sekonic L758 is a wonderful tool and is in my opinion it is a great asset to any landscape photographers camera bag.
First you have to go into the custom settings of the meter which you do by pressing and holding the Mode button and then turn on the light meter.
Should you have any questions regarding the contents of this document, please feel free to contact me via the contact form on either of the websites below.
To confirm you are in the Custom Settings mode, you will see CS in the upper right hand corder where the ISO value is usually displayed.
Ian Barber
By default, the LCD read out may display 01 where the shutter value is and 0 where the Aperture value is. Tap the Mode button until 1 is displayed where the Aperture value is. The readout should now read 01 1 Turn off the light meter and turn it back on again. Now, press and keep pressed the ISO 2 button and move the jog wheel so that 2.5 is showing in the upper right hand corner. This has now set the compensation to +2.5 stops. The next time you take a base exposure reading, to calculate the 2 1/2 stops difference, simply press the ISO 2 button and
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