Posted 29 June 2005 - 09:55 AM
Posted 29 June 2005 - 10:31 AM
If you're using T stops marked on your lens, then you're effectively measuring T stops with your meter.
i.e. actual amount of light transmitted by the lens.
Posted 29 June 2005 - 06:35 PM
Your lens is calibrated for exposure in T-stops: it's the actual amount of light that usefully passes through the lens. So you simply set the exposure meter reading on the T-stop scale of the lens.
F-stops are precise for depth of field calculations as they relate to the diameter of the aperture: but they ignore light losses, so aren't so precise for exposure.
The difference between the two (f & T) is a property of the particular lens, and may only be a fraction of a stop, or a little more. But if your lens has - say - one third of a stop difference between f-stop and t-stop, that is more or less a constant over the range.
Posted 01 July 2005 - 09:49 AM
Posted 01 July 2005 - 10:00 AM
As noted, T-Stops take the lens transmission into account. The correlation of the two depends on the particular lens.