Hello I use 758Dr ( newly purchased ). I am stuck with the reading jargon. The aperture is shown always with a fraction and another number. It is stops and the extra number. Light meter is on 1/10 or full stops, and camera can handle only 1/3 or 1/2 stops. So how can I fully use the power of handheld meters? I tried to custom set function in Sekonic, but still fractions are shown.
There is a chart of Tenth stops at http://www.scantips.com/lights/fstop.html (down low on page)
But a third stop is 0.333 stops. Two thirds is 0.667 stops. A half stop is 0.5 stops.
So if your meter shows f/8 plus 0.7 stop, that is approximately 2/3, or virtually the same as 0.667 stops. So merely open 2/3 clicks above f/8, or 1/3 click below f/11. Either way, this is about f/10.
Tenth stops are not particularly useful outdoors in ambient light, since we cannot set the camera directly in tenth stops. We would just set it as close as possible, the difference is minor, and your only choice.
But tenth stops are extremely useful for metering multiple studio flash. We can set their differences more closely. But the overwhelming advantage of tenth stops is when pondering fill level for that lighting ratio - how much is one and a third stop less than f/10? It is about f/6.3, but who knows that? But if we read these two values as f/5.6 plus 3/10 stop vs. f/8 plus 6/10 stop, then in our heads we easily know 1.3 stops difference, immediately (in use, that is really a big deal for lighting ratio).
Most Sekonics have switches to set it to read Full stops (which is tenths) or third or half stops. Check the manual for your switches.
There is a great demo of setting the Sekonic 758DR light meter Custom Setting function #3 to display full or 1/10 (default: 0), 1/3 f-stop (value: 1) and 1/2 f-stop (value: 2) aperture values: https://youtu.be/3Yuw00sCFvY?t=2m30s
With the light meter turned off:
- Hold the "MODE + POWER" button to turn on the meter in Custom Function setting mode
- Turn the jog wheel counter-clockwise until setting number 3 is selected
- Press the "MODE" button to cycle through the values to select either 1 (for 1/3 stop) or 2 (for 1/2 stop) increments.
- Hold the "POWER" button to power off then again to power back on
The Custom Setting instructions can also be found in the L-758 user manual, with Advanced Functions on page 44-45. http://www.sekonic.com/downloads/l-758_english.pdf
The aperture reading is indeed in 1/10 stop increments. I deem it impossible, except under laboratory conditions, to use the 1/10 f-number setting. Say a 50mm lens is mounted and set to f/8. The working diameter of the iris is approximately 50 ÷ 8 = 6.25mm. Opening up 1/3 f-stop, the revised f-stop is 7.1. Now the approximate working diameter of the iris increases to approximately 50 ÷ 7.1 = 7.0mm. Such slight changes are mechanically achievable. However, changes to the iris diameter finer than 1/3 f-stop will be challenging. To achieve, the price of the lens will escalate beyond the reach of the average photo enthusiast.
I found a really useful post on http://www.photographymad.com/pages/view/what-is-a-stop-of-exposure-in-photography
From this i understood that on most cameras ( set to 1/3 stops ), 3 clicks means 1 stop. 2/3 clicks means 2 clicks ( of dial ). To alter 1/10 system reading, eg= 0.7 (7/10) multiply 0.7*3 which will give 2.10 ie 2 ( cut fraction here ) and make 2 clicks ahead. You will get the 1/3 steps value of f
To get 1 step ahead in 1/3 steps, multiply original f with 1.41
f5.6.3 its exactly 1/3, so plus one click from 5.6 = f6.3
f5.6.4 or .5 you are in the middle, same distance from all so it can be plus 1 or 2 clicks from 5.6 = f6.3 or f7.1
f5.6.7 is exactly 2/3 so its plus 2 clicks from 5.6 = 7.1
f5.6.8 or.9 its closer to f8 so its 3 clicks from 5.6 witch is a full stop = f8