If we change ISO, it changes the metered EV and the settings we would select. ![]() The one EV chart is for ANY AND EVERY ISO value, meaning specifically whichever chosen one is in use. EV is technically computed from only the camera settings (only shutter speed and f/stop are computed), but those choices course depend on the ISO value. It is how the EV Chart would be used, we would use the settings on that indicated EV chart row, for the proper metered exposure at that ISO (example next page). That settings EV is that Exposure Value that a light meter would read when set to that ISO. However in practice, the EV number alone is not meaningful without specifying the corresponding ISO number. An equivalent is also 1/125 second at f/16 (EV 15) at ISO 100 (is EV 15 100), or other Equivalents, like 1/250 at f/11 at ISO 100 (also is EV 15 100). The way the exposure is said is 1/2000 second at f/11 (EV 18) at ISO 800 (is EV 15 100). The calculator default numbers represent full bright direct sunlight. The camera settings are not necessarily a correct exposure unless ISO does match them to the scene. So maybe the formula to calculate EV does not include the ISO number, but the choice of the proper camera settings used depends on ISO. The settings combination of f/16 at 1/125 second is numerically EV 15 for any ISO, but those settings are chosen and only applicable for the one specific ISO currently being used. This ISO number was identified to the camera, so the metering knew it and could compute how much the camera settings needed to change to match exposure to this film speed. Then film speed (called ASA then, ISO today) was a temporary constant determined by the roll of film in the camera. Numerical EV was developed when light meters were to be added into film cameras (late 1950s) to aid computing exposure. This Settings EV is seemingly independent of ISO, except the EV number is computed from the camera settings already chosen for whatever appropriate ISO is in use, which makes ISO in fact be all important. The camera settings EV term might be misunderstood, because it is computed from only the shutter speed and f/stop values (a calculator is on next page). If that change is still not in the range you prefer, a bit of trial and error with other manual adjustments can help to choose settings more optimized to your preference. In contrast to Option 1 which updates at any click (but does not itself change any field). Options 2 & 3 will not change any setting until you are ready and click Compute (to avoid any unwanted changes). You must specify that one value which will be changed at B. Options 2 and 3 will only change the one setting specified (shutter speed, f/stop or ISO).Another calculator will show both precise and nearest nominal values in that case. The result will be shown as the nearest nominal third or half stop, like the camera (so adding 0.1 EV won't actually show any nominal change). Option 3 adds a plus or minus EV value to the value at B.Comparing a third stop and a half stop can never be closer than 0.17 EV. If the settings are already an equivalent exposure (0 EV difference), then no visible change will occur. Option 2 changes a value in B be Equivalent Exposure of A.If the exposure difference is positive EV, then B is greater exposure, so the B Light Value EV 100 is lower numerically (a lower light value needing the greater exposure). ![]() ISO 100 is NOT special in any way, it's just a number, one among many, and only the popularity might make it seem special. We could have used any number, but ISO 100 is simply familiar and comfortable for us. ![]() ISO 100 is Not magic nor unique nor special in any way in the EV system. This arbitrary conversion to ISO 100 is called Light Value (next page). The set of the corresponding Equivalent Exposures are those on the row in the EV chart for that EV number.Įxposure Difference makes comparison of two exposures possible by first converting both EV results to ISO 100 (as if metered at the same ISO value). The exposure EV uses these settings AT THAT ISO. So ISO is definitely an EV factor, but like if a film camera, settings EV applies to whatever film speed is in the camera that caused selection of these settings. Meaning, if assuming it is a proper correct exposure for the situation, it is the exposure that a light meter would read for that ISO. This computed EV is the exposure performed for whatever ISO that has caused the choice of these settings. The Settings EV is the computed EV for the two settings (shutter speed and f/stop). The wide range prevents some equivalents of unsuitable settings from simply going out of range. Shutter speed range is 2048 seconds (34 minutes) to 1/32000 second (26 EV range). The f/stop range is f/0.5 to f/512 (20 EV range). The calculator range of Nominals is large, but not quite infinite. The selections above provide the possible camera settings.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |