Jerry Nemeth wrote:

Not everyone reads the whole thread on MM.   

Not everyone reads even the whole OP.  Sigh.

Seattle Photo wrote:
sure it does.  it's just that the front of your softbox is the source of the light now for that equation and the light head is the origin

Actually, the position of the light head is irrelevant.  What counts is the position of the front surface of the softbox.

Again, I didn't believe that until I actually tested it, and it's correct.

TXPhotog wrote:

Seattle Photo wrote:
it does work that way to a degree.  if you are dealing with ambient light, changing your shutter sped like that will increase your ambient by a stop.

TXPhotog wrote:
No, actually, it won't, unless the contribution to total exposure from the flash is very small.  Please go back and read ALL of the original post.


See above.  There are a VERY SMALL number of equipment cases - a trivially small number, for this purpose - where there is a relationship between shots at max sync speed and exposure, but even for those, it is NOT TRUE that shutter speed can be used to control exposure, yielding a one stop difference in exposure for a one-stop change in shutter speed.

Of course it "will affect" ambient exposure.  What it will NOT  do is make a one stop change in exposure based on changing the shutter speed one stop, unless the contribution to the exposure from the flash is very small.

i think you must be talking about a shot where there is no ambient light.

with mixed lighting you will have two or more 'exposures' to be thinking about and so YES changing the shutter speed will affect the ambient exposure

TXPhotog wrote:
Not everyone reads even the whole OP.  Sigh.

After some of the threads I've seen in the past 24 hours, I'm beginning to believe that some people here CAN'T read...

Seattle Photo wrote:
i think you must be talking about a shot where there is no ambient light.

with mixed lighting you will have two or more 'exposures' to be thinking about and so YES changing the shutter speed will affect the ambient exposure

Please go back and read all of the OP.  And all of the subsequent comments about ambient light.

J. Stakeman wrote:
Its amazing to be how much photography wants to stay "magic"

There is all the resistance to things that make it simple... small ambiguities that get pried open in order to make things seem more complicated than they are.

There is probably a blog essay or two in there somewhere

TXPhotog wrote:

Actually, the position of the light head is irrelevant.  What counts is the position of the front surface of the softbox.

Again, I didn't believe that until I actually tested it, and it's correct.

that is exactly what i said.....if you understand the principle of origin vs source

.l think fresnels and parabolics do not adhere to this though

TXPhotog wrote:
There is probably a blog essay or two in there somewhere

Most definitely... thank you for that thing on "published" I would have never thought of defining it before.

... and now I'm done with the thread hijacking...

Seattle Photo wrote:

that is exactly what i said.....if you understand the principle of origin vs source

.l think fresnels and parabolics do not adhere to this though

They do.

Seattle Photo wrote:
that is exactly what i said.....if you understand the principle of origin vs source

.l think fresnels and parabolics do not adhere to this though

They do, if you understand the principle of origin vs. source.

J. Stakeman wrote:

They do.

not is the same way though.  you would not measure the fresnel from the position of the head. since it acts more like a lens. 


i am not sure who really uses the inverse square law in settign lights except someone doing a big, elaborate setup....like a vegas show

heck, i rarely use a meter anymoe

TXPhotog wrote:
Let's not forget "72 dpi".  But I digress . . . .

TXPhotog wrote:

They do, if you understand the principle of origin vs. source.

exactly

Seattle Photo wrote:
i am not sure who really uses the inverse square law in settign lights except someone doing a big, elaborate setup....like a vegas show

A theatrical lighting designer, or a cinematographer, or.... an assistant who's run out of room to dial down a power pack and just moves the light further away?

Dobias Fine Art Photo wrote:
Try this one.  Ask the guy what his sync speed is for a leaf shutter.  ;-)

ha. the guy @ a local photostore told me leaf shutters synced @ 500. needless to say, i laughed. inside, but i laughed none the less.

TXPhotog wrote:
Not everyone reads even the whole OP.  Sigh.

On MM, sometimes not even the OP reads the whole OP.

J. Stakeman wrote:

A theatrical lighting designer, or a cinematographer, or.... an assistant who's run out of room to dial down a power pack and just moves the light further away?

that is also going to change the quality of the light....making it harder

but um, they are not using the rule, per se, just obeying it.

moonshots wrote:

ha. the guy @ a local photostore told me leaf shutters synced @ 500. needless to say, i laughed. inside, but i laughed none the less.

that is often the fastest shutter speed on many leaf shutter lenses

215 Studios wrote:
Been one of those weeks, TX?

TX switch to decaf its ok the world is lucky to use studio stuff

Duane  Allen wrote:

TX switch to decaf its ok the world is lucky to use studio stuff

if you switch to decaf you can then use a slower shutter speed

Michael Alan wrote:
So the most obvious thing should jump right at all you GWC. Exposure by shutter is controlled by strobes and ambient light is controlled by shutter speed. It is therefore possible to have two different exposures in one shot.

Color me confused . . . .

TXPhotog wrote:

Color me confused . . . .

LOL.. give me a break.. I'm sipping my coffee... But you got me..

Warren Leimbach wrote:
I don't get it.

I keep turning up the shutter speed and the pictures still come out dark!   

LOL.. GO THE OTHER WAY///200/100/60/30/15...

TXPhotog wrote:

Color me confused . . . .

So the most obvious thing should jump right at all you GWC. Exposure by aperture is controlled by the strobe and ambient light is controlled by shutter speed. It is therefore possible to have two different exposures in one shot.

Michael Alan wrote:

So the most obvious thing should jump right at all you GWC. Exposure by aperture is controlled by the strobe and ambient light is controlled by shutter speed. It is therefore possible to have two different exposures in one shot.

Except that... ambient light is also affected by aperture... and they were talking about in studio... with no ambient light......

If you want it to be more confusing... you can talk about the model light in the strobe head too.. but that doesn't bring anyone closer to the point.

Studio 925 wrote:
...trying to figure out if I'm supposed to be somewhat aloof in this thread...

Don't worry.  You're fitting right in.

Studio 925 wrote:
I think what those photographers were trying to tell Tex is that they are using the shutter dial to reduce the amount of light coming into the lens.

Actually, the reverse, but it doesn't matter, since it's wrong anyway.

Studio 925 wrote:
We all pretty much have a basic understanding of shutter (light) and aperture (depth of field).

Actually, my point is that many people, including working professionals, seem NOT to have that basic understanding.

Studio 925 wrote:
What some may not understand at first when shooting with strobes, is the effective use of the strobe's power level settings, and its effect on image exposure when paired with the camera's various iso, aperture and shutter speed settings (edit: combinations).

...trying to figure out if I'm supposed to be somewhat aloof in this thread...

Again, assuming only a small-to-negligible contribution from ambient light, (which is usually true at reasonable shutter speeds in the studio), shutter speed IS NOT a way to control exposure.  That is the whole point of the OP.

J. Stakeman wrote:

Except that... ambient light is also affected by aperture... and they were talking about in studio... with no ambient light......

If you want it to be more confusing... you can talk about the model light in the strobe head too.. but that doesn't bring anyone closer to the point.

you are correct.

Ambient light is controlled by both, speed and aperture/over film rating set for a neutral (18%) gray rating. Strobe only affects the aperture and should stay within the rating for the equipment you are using (1/250 or slower on most 35mm cameras). The way to expose for studio lighting (done commercial phototography in all formats with a top notch pro) is to determine what stop you need to get the job done, and then set the lights to meet your expectations of exposing the subject. If you’re using modeling lights on your strobes, make sure that your aperture and shutter speed will be set to either have no effect on your subject by taking a reading of your ambient light using the stop that you’re exposing the flash to and determined the strength and shutter speed of your exposure. Usually the higher the aperture and faster the shutter will reduce any ambient light falling onto the subject. If you want more ambient light to fall in your picture then go the other way with shutter speed.

Monad Studios wrote:
TX, could we state it this way?

Shutter speed doesn't affect the amount of strobe light getting into the exposure (except if the shutter speed is faster than the camera's sync speed).

We could, and perhaps it's a better way to say it. 

However, somehow people seem not to understand that "the amount of strobe light" and "the amount of light" are, in the studio, with typical levels of ambient illumination, essentially the same thing. 

As so many people have, for some reason, felt the need to point out, it is possible to make exposures where ambient light is, usually deliberately, a significant contributor to total exposure.  However, that misses the basic point.

Warren Leimbach wrote:
I don't get it.

I keep turning up the shutter speed and the pictures still come out dark!   

Thats got me puzzled too!  Shouldn't a faster shutter speed capture more light?

I mean the light has less time to get away!