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What is t

Jiminee Cricketee wrote:
> What is t

Transmission. Essentially, f-stops after factoring in light loss in the
lens. Most used in cinematography.

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On 2011-11-10 19:40 , Jiminee Cricketee wrote:
> What is t


On very few lenses (for still photography) and many lenses for motion
film, "T" is the "Transmission factor" which is often slower than the
maximum aperture. This indicates that there is light loss in the lens
system.

Some specialized still camera lenses, such as the Minolta (Sony) 135
f/2.8 [T4.5] have a transmission factor (T). The "fastest" exposure
will be at f/4.5 even if the depth of field is determined by a larger
aperture (f/2.8 to f/4 ). In this case the light loss is due to the
apodization filter.

On some still cameras, usually Canon, "T" (or Tv) is the "period" or the
shutter speed. Since shutter speeds are usually expressed as a fraction
of a second, using "T" is more "correct" than "S" for speed. (eg: 1/60
is a period which in scientific convention is the letter "T").


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On Sat, 12 Nov 2011 10:34:56 -0500, Alan Browne
<(E-Mail Removed)> wrote:
: On 2011-11-10 19:40 , Jiminee Cricketee wrote:
: > What is t
:
:
: On very few lenses (for still photography) and many lenses for motion
: film, "T" is the "Transmission factor" which is often slower than the
: maximum aperture. This indicates that there is light loss in the lens
: system.
:
: Some specialized still camera lenses, such as the Minolta (Sony) 135
: f/2.8 [T4.5] have a transmission factor (T). The "fastest" exposure
: will be at f/4.5 even if the depth of field is determined by a larger
: aperture (f/2.8 to f/4 ). In this case the light loss is due to the
: apodization filter.
:
: On some still cameras, usually Canon, "T" (or Tv) is the "period" or the
: shutter speed. Since shutter speeds are usually expressed as a fraction
: of a second, using "T" is more "correct" than "S" for speed. (eg: 1/60
: is a period which in scientific convention is the letter "T").

I don't think Canon is intentionally conforming to that "scientific
convention". In their parlance, "Tv" stands for "Time value". If you choose
that mode, the shutter speed you set remains fixed, and the aperture is set
automatically.

Bob