When did the shutter time start being called "speed"?

[xpatUSA]

... or was it always that way?

Not strictly a digital camera question ... historic info. welcome.

[xpatUSA]

... or was it always that way?

Not strictly a digital camera question ... historic info. welcome.

I like this guy:

"
Canon decided to buck the trend and label their mode dial Tv, representing Time-Value, for their shutter priority. Technically, they are correct, as you are adjusting the time between opening and closing the shutter. However, in their manuals, their description of Tv on the mode dial is “shutter-priority,” which is inconsistent.
Furthermore, they don’t follow that up by using the technically correct term, “time-value,” but the universally accepted, though slightly incorrect, shutter speed. Being pedantic, the term shutter speed is wrong because the shutter curtains always move at the same speed; it’s the time gap between one opening and the other closing that changes. Nevertheless, everyone calls it shutter speed and Canon has made an incongruous choice in their bodies' labeling."

https://fstoppers.com/gear/stupid-na...nctions-583929
.

[pschlute]

I, like many others I am sure, have always used the term "shutter speed" even though it is technically incorrect for a focal plane shutter. Were there any early shutters that utilised a single curtain and thus would move at a different speed for a different timed exposure ?

Canon are not the only one to use Tv on their mode dial. My Pentax uses the same labelling. In the manual the term "shutter speed" is used throughout, another incongruity I guess, although most folk will understand what they mean.

Anyway, Pentax cannot use the "S" on the mode dial for "shutter speed/time", because that would clash with Sv mode

[Tronhard]

Time is a continual or constant value that for us on earth is not really variable - I'm not considering the issues of time as we approach the speed of light for example or our perceptions of time - e.g. a watched pot never boils! What would be a more accurate description of something like that would be elapsed time - which suggests a slice of time relative to an event.

I think it is relevant to go back to the definition of speed, which is distance/time. The question being which is the constant, and in fact does either one have to be the constant?

We are all used to speed as being something like 30km/hour 32ft/min etc. where time is seen as a constant, but it could be given where the distance/time relationship is seen the other way round - for example, competitive performances for athletics and swimming are measured where the distance is the constant (100m for a sprint, or 50m for an Olympic pool) and is measured against a variable of time. It is certainly valid to consider that as a speed metric. Thus, shutter speed would be an expression of covering a given distance, in this case the shutter aperture transiting over the shutter space, in a variable time. e.g. the shutter transits across its range in 1/20sec.

In other words, this is not an issue specific to photography, it is a consideration applied to multiple aspects of our world. Having said all that, as a debate, it seems like a sledgehammer to crack a nut. The important thing is to realize the impact of the duration of exposure on getting a correctly exposed image and in controlling movement. Maybe instead of having the word shutter in there at all, we should call it exposure time ET= 1/10sec, etc. I shall go and change all my camera controls immediately!

[pschlute]

Time is a continual or constant value that for us on earth is not really variable - I'm not considering the issues of time as we approach the speed of light for example

For another debate, but this always fascinates me... https://www.youtube.com/watch?v=gdRmCqylsME&t=52s

[pnodrog]

Shutter speed and exposure time are two distinct values... a bit like PPI and DPI.

With leaf shutters the maximum shutter speed was of far more interest than it is now with focal plane shutters. Anyway above the normal flash sync speed FP shutters are cheating. However even now the maximum shutter speed is of great interest to salespeople and for a few applications such as sport photography.

I'm a Nikon man but I have to confess T or Tv may be better terms but I certainly won't have any sleepless nights because of it.

[MrB]

Surely the factor under discussion is the "exposure time" - the amount of time for which the light sensitive surface is exposed to the light entering the camera (or the time over which its electronic effects are recorded). The method of control - usually some form of shutter - is irrelevant to the labelling of the factor, so there is no excuse for continuing to use "shutter speed". However, it is a well-established traditional term and, as such, is not easy to change, even though it is wrong.

Philip

[Manfred M]

I was taught the term shutter speed over 50 years ago when I first started into serious photography by the commercial photographer who mentored me.

There are many terms in many fields that are not super precise, but in common use, so we live with them because everyone understands what they mean. If you look at electronic shutters (no mechanical elements), should we call this polling the sensor, rather than shutter speed???

[xpatUSA]

I was also interested in the historical aspect.

Back in 1888, Hurter & Driffield simply talked about "Exposure" with units of seconds ** it seems:



** as opposed to the modern-day 'secs-to-the-minus-one'.

[xpatUSA]

I, like many others I am sure, have always used the term "shutter speed" even though it is technically incorrect for a focal plane shutter. Were there any early shutters that utilised a single curtain and thus would move at a different speed for a different timed exposure ?

A bit of searching found the 'flap' type shutter wherein a "pneumatic delay" gets mentioned:

http://www.earlyphotography.co.uk/si...tern.html#Flap

Whether that slowed the actual speed of the flap, I have no idea ...

[xpatUSA]

A bit of searching found the 'flap' type shutter wherein a "pneumatic delay" gets mentioned:

http://www.earlyphotography.co.uk/si...tern.html#Flap

Whether that slowed the actual speed of the flap, I have no idea ...

Historically speaking, it could be actual speed !!

"Until the 1880s, shutter timing was very crude, depending on the tension of a spring or rubber band or the retarding effect of a leather brake." (my bold).

And:

"The first major advance in shutter timing occurred in 1886, when Arthur S. Newman developed a shutter with a pneumatic cylinder retarding mechanism" (my bold).

https://randcollins.wordpress.com/category/shutters/

So, it could be that the term "shutter speed' was used ab initio and only later obfuscated by advances in shutter design.

[pschlute]

A bit of searching found the 'flap' type shutter wherein a "pneumatic delay" gets mentioned

no idea what that is.... but i want one !

[Tronhard]

Darn it Paul, now I have to go back and reset all my Canon controls from ET to Tv again! This is seriously stressful.

Shutter speed and exposure time are two distinct values... a bit like PPI and DPI.

With leaf shutters the maximum shutter speed was of far more interest than it is now with focal plane shutters. Anyway above the normal flash sync speed FP shutters are cheating. However even now the maximum shutter speed is of great interest to salespeople and for a few applications such as sport photography.

I'm a Nikon man but I have to confess T or Tv may be better terms but I certainly won't have any sleepless nights because of it.

[pnodrog]

Darn it Paul, now I have to go back and reset all my Canon controls from ET to Tv again! This is seriously stressful.

Have you anything better to do? I sincerely hope the answer is yes.

[DanK]

Hmm. “The speed of the second shutter curtain relative to the speed of the first” or some such.

Since everyone know that it means the length of time he stutter is open, I think I’ll just consider it an example of polysemy and go back to worrying about how little I’ve produced lately at any ET.


Sent from my iPad using Tapatalk

[xpatUSA]

Hmm. “The speed of the second shutter curtain relative to the speed of the first” or some such.

Hmm ... could use different speeds for those really bright days outside ... ... allowing the second curtain to catch up with the first or fall behind or summat ... LOL.

[DanK]

If the speed is the same for the two curtains, then the use of "speed" in "shutter speed" is correct: exposure is proportional to the speed at which the opening moves across the focal plane

[xpatUSA]

If the speed is the same for the two curtains, then the use of "speed" in "shutter speed" is correct: exposure is proportional to the speed at which the opening moves across the focal plane

Not sure whether I believe Wrotniak or your good self:

Quote ... the slot width. That width is used to adjust the exposure time (referred to as shutter speed), while the actual velocity with which the curtains are moving remains unchanged ... endquote.

Quote ... Note that the speed with which both curtains travel down the frame is the same for all shutter speeds; what changes is the delay with which the second curtain starts after the first one ... endquote

https://www.wrotniak.net/photo/tech/fp-shutter.html

Exposure being proportional to slit width makes more sense to me.

[pschlute]

If the speed is the same for the two curtains, then the use of "speed" in "shutter speed" is correct: exposure is proportional to the speed at which the opening moves across the focal plane

But how does that statement equate to any exposure below sync speed ? Below sync speed there is no slit. Exposure is determined by the time between the first curtain starting to open, and the second curtain starting to close ?

[pnodrog]

Will the speed of an electronic shutter end up being measured in nanoseconds?....