# Thread: super noob question. is f2.8 = f/2.8??

1. Originally Posted by Noir
And apart from F-stop, there is something called T-stop too. Know what it is ?
is that something found on a video camera?

2. Originally Posted by Astin
Ok, now you go and find out what does the letter "f" stand for?
(Give you something to do on a boring Thursday afternoon )
Hey Astin,
If I recall correctly, the 'f' in f/stop stands for foot-candles right?

Please correct me if I am wrong.

Cheers,
-Michelle-

3. Originally Posted by mich_2103
Hey Astin,
If I recall correctly, the 'f' in f/stop stands for foot-candles right?

Please correct me if I am wrong.

Cheers,
-Michelle-
Not really lah Michelle.
According to the legend, (I copied this out)
"...Willard (Van Dyke) remembered that he proposed "U.S.256," the old system name for f/64. He said that Ansel responded, "U.S. 256 is not good, it sounds like a highway." Willard continued, "He then took a pencil and made a a curving 'f' followed by the dot and 64. The graphics were beautiful and that was that." At first, it was written "Group f.64" in the style of the old aperture notation, but that was soon updated to the new notation with its slash, "Group f/64." To those familiar with Ansel's handwriting, the f in the Group f/64 exhibition invitation appears nearly identical to his own typical, very musical looking f."

But I think it more or less is a mathematical notation, f stands for "function of" eg f(1/diameter)

4. Quoting from a site

" F-stops vs. T-stops
When you are calculating exposure, you need to know how much light passes through the lens to the film. The f-stop is a geometric relationship between focal length and aperture and does not take into account how much light is lost within a lens. Each air-to-glass surface within a lens reflects some light. A zoom lens (like the one on the Bolex you will use) can have more than 15 elements and lose a significant amount of light to internal reflections.

A perfect lens, a lens of 100% transmission, transmits all the light that it gathers with no internal losses. The T-STOP is defined as the equivalent to an f-stop of a perfect lens.

Thus on a perfect lens, the f-stop and the t-stop are identical. On a lens that lost a full stop in transmission (that is, a 50-percent loss), f/8 would result in the same exposure as T11.
"

T-stops are usually found on motion picture lenses to compensate for the loss of light within. However I do have a question, and hope someone is able to shed some light? So are the stop markings found on stills photography lenses already compensated for this light loss, no matter how slight? Thanx!

5. the t stop is transimssion stop if i recall correct..they say its a more accurate form of f stop

6. wah, a super noob question turns into a super deep question now, pangz.

7. Originally Posted by Astin
wah, a super noob question turns into a super deep question now, pangz.
Ha Ha! Yes Astin. Need to be technically apt to be creatively sound in photography. Let's learn from one another here.

8. Originally Posted by Noir
Quoting from a site

" F-stops vs. T-stops
When you are calculating exposure, you need to know how much light passes through the lens to the film. The f-stop is a geometric relationship between focal length and aperture and does not take into account how much light is lost within a lens. Each air-to-glass surface within a lens reflects some light. A zoom lens (like the one on the Bolex you will use) can have more than 15 elements and lose a significant amount of light to internal reflections.

A perfect lens, a lens of 100% transmission, transmits all the light that it gathers with no internal losses. The T-STOP is defined as the equivalent to an f-stop of a perfect lens.

Thus on a perfect lens, the f-stop and the t-stop are identical. On a lens that lost a full stop in transmission (that is, a 50-percent loss), f/8 would result in the same exposure as T11.
"

T-stops are usually found on motion picture lenses to compensate for the loss of light within. However I do have a question, and hope someone is able to shed some light? So are the stop markings found on stills photography lenses already compensated for this light loss, no matter how slight? Thanx!
Nope, the F stop for still cameras is the F stop. If it's compensated already, then it would be called the T stop and not the F stop. But as I said earlier, the difference is very slight in todays lenses, with their multicoating, aspherical design, etc. You will loss more light tranmission by slapping a filter over the lens. Anyway, since the camera is situated behind the lens, any light loss will be factored into the metering.

9. Originally Posted by Astin
wah, a super noob question turns into a super deep question now, pangz.
i was JUST about to say that!

10. but it's been a great learning experience for me. do continue the conversation. i'll just sit back and read the info..

all this is really way outta my league.

11. No problem. When you become oldbie, you would then explain to the newbie and not scold or laugh at them ok?

12. Originally Posted by Astin
No problem. When you become oldbie, you would then explain to the newbie and not scold or laugh at them ok?
sure thing. and i'll always remember to ask them their physics and maths score..

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