[WONTFIX] Request: display T/stop equivalent

[skymouse]

It'd be really cool if we could see a display of the T/stop equivalent for the current aperture setting.

This, of course, varies from lens to lens, so could be accomplished by having a lookup table with a light transmission factor for each lens for which this factor is known (or user settable values, for lenses not listed and for situations when a filter is used).

[ItsMeLenny]

The t-stop is what you do see, as it is a digital camera. It doesn't show the f-stop.

[Walter Schulz]

You got this one wrong.
http://en.wikipedia.org/wiki/F-number#T-stop

[ansius]

I'm wondering what would be the point for T stops in digital camera? For film cameras without internal light metering that made a lot of scene because you used T stops to account for light loss in lens, but you needed that, because you never really knew what you have until seeing developed film. In digital cameras that does not make seance, because you use Trough The Lens metering, thus you can have adequate estimates of exposure of the sensor or light mattering circuity. Especially if you learn how to use zebras, histograms and waveform monitor, there really is no need for T stops.

[jimmyD30]

I would say that the f number is an objective value without regard to the lens' light transmission efficiency, while T stop value is subject to the 'quality' of the lens.

Also, I have to disagree with you regarding film cameras not having 'through the lens metering', see here: http://en.m.wikipedia.org/wiki/Through-the-lens_metering

T-stop values are typically used when relying upon external light meters for either digital or film cameras. Also, T value for a lens informs you to the real amount of light passing through it, valuable for comparing lenses when low light conditions call for faster/fastest lens as two different lenses with the same maximum aperture may in reality pass through different amounts of light.

[dubzeebass]

So OP wants the camera to calculate light loss for lenses? Impossible. Maybe it can hash my Bitcoins at the same time.

[jimmyD30]

...hash my Bitcoins at the same time.

Now that's a feature I can get behind

[Walter Schulz]

So OP wants the camera to calculate light loss for lenses?

No, he doesn't want that at all. Read the part about lookup table.

[jimmyD30]

Difficult and impractical, yes, impossible, no, worthwhile, maybe (depends on individual).

The initial compilation of current lens t-values look up table, though arduous, is achievable. The active adding of new lenses in a timely manner, improbable

My question is, what would you do with such a value on a through-the-lens metering device (camera)? Use it for reference/research? Or are you planning on using external light meter?