![]() ![]() Putting in the shutter speed and aperture and ISO will give you that lightings LV value. In the reverse, if you have already taken a picture, you can back calculate out LV with your formula. In taking a picture you normal go from the light meter's LV then add ISO and get EV and then choose which pair you wish of aperture and shutter, ( for reasons of coma(spherical aberration, distortion/sharpness diffraction, bokeh, depth of field frozen motion etc ) Light meter + ISO, give you an EV to work with on your lens. You derive your EV from a light meter reading and then using the ISO you desire. You can just imagine these all give equal exposure. Think of it as a set of equal pairs, for shutter speed and aperture openingįor instance EV = 12, has the following pairs f/22 and 1/8s, f/16 and 1/15s,į/11 and 1/30s, f/5.6 and 1/125s, f/4 and 1/250s, f/2.8 and 1/500s. LV is the lighting for the scene, it doesn't change.ĮV is adapting LV by incorporating ISO, and thus gives you a set of pairs to choose fromįor 'that' particular LV reading and that chosen ISO.ĮV is a number, usually on a lens it will scale from 2 to 18 Perhaps it is affected by the rounding in shutter speed selection or is a characteristic of matrix metering. I don't know why there's a difference in the calculated and "Effective" LV recorded in the EXIF as there was no EV comp. The camera's EXIF has a embedded Effective LV of 3.1. A blowing-out-the-birthday-candle-in-the-dark shot from a K100D Super:į/5.6, 1/6s, ISO1600 = LV 3.6. LV = log2 (f-number^2 / shutter speed / ISO/100)Ĭhanging just ISO100 to ISO200 = LV 12, meaning there was less light because, at the the same exposure, we had to use a larger ISO (more gain) than in the previous example to make the captured scene brighter.Ĭhanging just aperture from f/8 to f/5.6 = LV 12 (approx.) meaning less light was available and we had to open the aperture more.Ĭhanging just shutter speed from 1/125s to 1/250s = LV 14, means there was more light, so we were able to use a faster shutter speed. The formula used in the LV Calculator is: This was critical for this program as I wanted to cover 1EV, 1/2EV, 1/3EV ISO & aperture steps, and 1/2EV & 1/3EV shutter speed steps.ĭaily Dose of Excel Blog Archive Conditional Data Validation I mainly used the indirect addressing & conditional formatting methods mentioned in a link heliphoto provided in response to varying items in a drop-down pick list based on another selection. Here's my LV calculator for Excel 2003 (extended version) EV is the same as LV, except that EV is only for one ISO value, typically EV 100, whereas LV considers the effect of varying the ISO as well. Of particular importance is Table 2: Exposure values (ISO 100 speed) for various lighting conditions. You can use the embedded EXIF to calculate the LV (Light Value) required for that exposure setting.ĮV (Exposure Value) is covered here. ![]() I'm interested in the light level that a shot was taken in so I can plan in future shoots what exposure combinations will work. ![]()
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