How to calculate light loss in higher shutter speeds?

[Joel Arvidsson]

Say you start with 1/50 and take it to 1\125, 250 and 500. How do I calculate the light loss from 1/50?

 

[Siva Kollipara]

1/50 to 1/100, you are reducing exposure time to half and
hence you need double your iso
OR open your aperture by one f-stop
OR increase amount of light(1KW to 2KW) by one stop.

 

[Nick Gardner]

Seriously? Why do you own a professional camera if you don't know basic high school level photography? I don't mean to be a dick, but for fucks sake read a book. Forums are great for discussion, but if you don't have a grasp of the absolutely basic fundamentals, I highly recommend you read every book you can find on photography and cinematography. Start with the American Cinematographers Manual and google anything you don't understand. example -

http://en.wikipedia.org/wiki/Shutter_speed

Nick

 

[Joel Arvidsson]

I come from the post side and videographer where you most time stay at 1/48 and 1/50. This does not mean I know jack ass about the art of film making. Sorry Nick if I stepped on your toe, did not mean to spit in your church.
You know you dont have to be rude

So its a stop betwen each of 1/25, 1/250, 1/500.


Need to wipe of spit from Nick

Joel

 

[PatrickFaith]

Every Divide by 2 is half the light ( 1/24, 1/24/2=1/48, 1/24/2/2 = 1/96 ... etc)

 

[ericyoung]

A stop up is a doubling of exposure. A stop down is halving of exposure.

If you switch the shutter to Relative Mode and Display to Angle rather than Secs it's easy to double the Shutter Angle for double the exposure (one stop up) or halve the Shutter Angle (one stop down). Eg Stepping up from 45deg, to 90deg, to 180deg, to 360deg each step represents a stop increase in exposure (with increasing motion blur).

If you prefer Shutter Speed in seconds, then 180deg shutter = 1/50sec when framespeed is 25fps. Stepping from 1/50, to 1/100, to 1/200, to 1/400 each step is a stop decrease in exposure (with decreasing motion blur, but potentially increased perceived motion stutter).

 

[Joel Arvidsson]

I se the "pattern". Thanks for answers.

 

[Björn Benckert]

Seriously? Why do you own a professional camera if you don't know basic high school level photography? I don't mean to be a dick, but for fucks sake read a book. Forums are great for discussion, but if you don't have a grasp of the absolutely basic fundamentals, I highly recommend you read every book you can find on photography and cinematography. Start with the American Cinematographers Manual and google anything you don't understand. example -

http://en.wikipedia.org/wiki/Shutter_speed

Nick

Or do as the professionals.. ask you camera assistant... thats what I see all the time when working around serious high paid DP's all over the world that has a struggle with simple math and do not know how to calculate for a 30 degree shutter or such. Normally if I comment this then I get the reply that they did not get to work with pictures because they where so good at math. Still I find it amazing to see how low the math / technical knowledge is out in the field.

Questions like: You shoot 24fps 180 shutter.then you want to do a pass in 3fps with half the shutter.... Then how much ND should you ad to get the same exposure?

Now I come from post so my reply to that would not be instant but to me it's odd that A DP even thinks before he answers...

 

[Joel Arvidsson]

A stop up is a doubling of exposure. A stop down is halving of exposure.

If you switch the shutter to Relative Mode and Display to Angle rather than Secs it's easy to double the Shutter Angle for double the exposure (one stop up) or halve the Shutter Angle (one stop down). Eg Stepping up from 45deg, to 90deg, to 180deg, to 360deg each step represents a stop increase in exposure (with increasing motion blur).

If you prefer Shutter Speed in seconds, then 180deg shutter = 1/50sec when framespeed is 25fps. Stepping from 1/50, to 1/100, to 1/200, to 1/400 each step is a stop decrease in exposure (with decreasing motion blur, but potentially increased perceived motion stutter).

Thanks. I know what a stop is. Just werent sure if it were a stop for each jump or if i had to calculate it. I thouht were all friends here so I post a question here.

 

[David Mullen ASC]

The rough math just says that a jump from 1/50 to 1/100 means you've cut the exposure in half, i.e. by one stop, and 1/200 would be another stop loss from 1/100 (it's all halves or doubles), so from 1/50 to 1/125 would be about a stop and a third loss, if that's close enough for you. If you want to get more precise, you'd have to do more math... but in most cases, getting the correct exposure within a 1/3-stop is close enough.

 

[PatrickFaith]

The rough math just says that a jump from 1/50 to 1/100 means you've cut the exposure in half, i.e. by one stop, and 1/200 would be another stop loss from 1/100 (it's all halves or doubles), so from 1/50 to 1/125 would be about a stop and a third loss, if that's close enough for you. If you want to get more precise, you'd have to do more math... but in most cases, getting the correct exposure within a 1/3-stop is close enough.

Does anyone ever change the "shutter speed" in a show or movie (shutter speed is constant for the entire show/movie), thus you only change the stop via ND filters or iris (i.e. t-stop) ?

 

[William Albertini]

Seriously? Why do you own a professional camera if you don't know basic high school level photography? I don't mean to be a dick, but for fucks sake read a book. Forums are great for discussion, but if you don't have a grasp of the absolutely basic fundamentals, I highly recommend you read every book you can find on photography and cinematography. Start with the American Cinematographers Manual and google anything you don't understand. example -

http://en.wikipedia.org/wiki/Shutter_speed

Nick

Calm down...

Any one want to weigh in on shutter angle v shutter speed. I am beginning to find shutter angle to be a more intuitive approach to motion, even though I come from a still photography background...

 

[Shane Kelly]

Does anyone ever change the "shutter speed" in a show or movie (shutter speed is constant for the entire show/movie), thus you only change the stop via ND filters or iris (i.e. t-stop) ?

I think of it as a film camera and sometimes change the shutter angle for an effect or when I shoot hi-speed but I never change the speed/angle for exposure reasons. Ok, almost never, if I need another stop on a lock off e.g interior with no movement, then I may go to 1/24, but not for when there is too much light which I believe is your question. For stills photographers this is not usually an issue as they are not dealing with strobing in motion. I'd advise staying at 180 degrees or 1/48 but that's just me.

 

[ericyoung]

The biggest effect of changing Shutter Speed apart from exposure is motion blur rendering - so for shows/movies it'd often be for artistic reasons. Eg Saving Private Ryan beach landing scene, dream sequences, flashbacks.

But I've seen it used for exposure control in things like tabletop food advert shots where motion is minimal, and the DOP dislikes using filters and wants Depth of Field to stay the same.

 

[ericyoung]

Calm down...

Any one want to weigh in on shutter angle v shutter speed. I am beginning to find shutter angle to be a more intuitive approach to motion, even though I come from a still photography background...

I find relative shutter angle more intuitive most of the time. But had to use absolute shutter speed in seconds when varispeed ramping on Red One so that exposure stayed the same throughout, and we had no way of iris ramping.

 

[Shane Kelly]

Calm down...

Any one want to weigh in on shutter angle v shutter speed. I am beginning to find shutter angle to be a more intuitive approach to motion, even though I come from a still photography background...

I use both, having come from a movie background and using shutter degrees all of my life, I recently started to also think in shutter speeds. This came into play recently shooting hi-speed and needing to verify that the shutter speed was correct for the shot if I wanted it to appear with "normal motion blur" at 24fps. Basically, if 24fps is 1/48th, then 48fps is 1/96th, 120fps is 1/240th, just double the fps number and you will get the "correct" shutter speed. In degrees, this would be 24fps is 180 degrees, 48 is 90, 96 is 45 and so on. I didn't have the epic reading degrees and couldn't find the menu item to change it in the heat of the moment and so had to think in shutter speeds. It's elementary math but very necessary.

 

[Nick Gardner]

Perhaps the language barrier made it sound like I was calling you an asshole. I was merely shocked that you lack an understanding of the basic fundamentals of photography. Rather than ask here piece by piece, I was suggesting that if you read a book, you would get a better grasp on how the basics all work together. If you don't have an understanding of shutter speed and exposure, nothing else is going to make sense.

Cheers,

Nick

 

[Nick Morrison]

I use both, having come from a movie background and using shutter degrees all of my life, I recently started to also think in shutter speeds. This came into play recently shooting hi-speed and needing to verify that the shutter speed was correct for the shot if I wanted it to appear with "normal motion blur" at 24fps. Basically, if 24fps is 1/48th, then 48fps is 1/96th, 120fps is 1/240th, just double the fps number and you will get the "correct" shutter speed. In degrees, this would be 24fps is 180 degrees, 48 is 90, 96 is 45 and so on. I didn't have the epic reading degrees and couldn't find the menu item to change it in the heat of the moment and so had to think in shutter speeds. It's elementary math but very necessary.

Shane is there a way to MANUALLY dial in the shutter speed and shutter angle independently of each other? Or are they always tied together like this?

EX: lets say I'm shooting at 24fps at 1/48th (STANDARD), but I want a 90degree shutter angle instead of 180. Is that possible, or am I being crazy?

Beause the shuttle ANGLE is how much of the 360degree shutter is OPEN or CLOSED. And the SPEED is how many times said shutter rotates per sec right? Surely they can be seperated? Or am I missing something clutch and looking like a total idiot?

Thanks in advance.

 

[ericyoung]

Shane is there a way to MANUALLY dial in the shutter speed and shutter angle independently of each other? Or are they always tied together like this?

EX: lets say I'm shooting at 24fps at 1/48th (STANDARD), but I want a 90degree shutter angle instead of 180. Is that possible, or am I being crazy?

Beause the shuttle ANGLE is how much of the 360degree shutter is OPEN or CLOSED. And the SPEED is how many times said shutter rotates per sec right? Surely they can be seperated? Or am I missing something clutch and looking like a total idiot?

Thanks in advance.

"Shutter Speed" and "Shutter Angle" are different ways of describing the same thing - ie how long the camera is sampling light WITHIN each frame interval. So those specific terms are tied together.

With an electronic shutter, Shutter Speed can theoretically be any time value from zero (albeit pretty useless as that's just black!) to a maximum length of the frame interval, and Shutter Angle can be any angle from zero to 360degrees.

However, FRAME Speed and Shutter Angle are indeed independent, so you can be at 24fps and in theory have any Shutter Speed from zero to 1/24th sec, or any Shutter Angle from zero to 360degrees.

 

[Shane Kelly]

Shane is there a way to MANUALLY dial in the shutter speed and shutter angle independently of each other? Or are they always tied together like this?

EX: lets say I'm shooting at 24fps at 1/48th (STANDARD), but I want a 90degree shutter angle instead of 180. Is that possible, or am I being crazy?

Beause the shuttle ANGLE is how much of the 360degree shutter is OPEN or CLOSED. And the SPEED is how many times said shutter rotates per sec right? Surely they can be seperated? Or am I missing something clutch and looking like a total idiot?

Thanks in advance.

Nick, what Eric said. They are essentially the same thing, just different ways of expressing it. You are correct on the shutter angle but speed has traditionally referred to the amount of time that a stills camera opened its shutter- a different mechanism to the movie camera's rotating shutter. What it comes down to is the amount of time that light is reaching the film/sensor and the characteristic motion blur that results from this value.
As per your example, if you are shooting 24fps and want a 90 degrees shutter angle, then you dial in 90 degrees or switch to 1/96th sec, they are the same thing. No you cannot separate them.