shutter drag

blinkerz

blinkerz

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Tristan
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Does anyone know the flash to ambient percentage/ratio to freeze a model holding a pose when dragging the shutter, instead of relying on the back of lcds which is hard to tell if its worked.

Sekonic light meters give a flash percent, so you can tell how much this is contributing to the included amibent lighting of a scene. Would be useful if there was a percentage that anyone knows works.

If anyone knows a ratio, ie meter the model with correct fstop/iso value with flash and then adjust shutter speed for the correct ambient exposure, by lowering the ambient with shutter x amount of stops to let the flash freeze the subject.
 
I guess it largely depends on how much ambient you want in the shot?

Personally I would hazard a rough guess that you want the ambient about 2-3 stops below, so just meter for ambient, dial down 2-3 stops, then switch on the flash. I'd guess that'll give you a fairly typical looking drag.
 
Righty,,,,,, ermmm are you wanting the background to be relativly still and the model within it?

if so the old trick is:

Drag the shutter as long as required (meter for ambient light) so could be 1/10th or 20 seconds!
Then set the flash via camera to trigger or be delayed so it fires on the back of the shutter curtain.

This gets ambient light in and just before the shot finishes exposing gets the model pin sharp in the frame with realistically no motion blur.

Which you would get if you had it fire at the beggining of the exposure.

What kit you got? some one may be able to advise you better.
 
There is not really any set ratio for flash-to-ambient ratios. It depends a lot on the situation and also on personal preference.

If you set the camera to auto-TTL flash, it will do it's best to balance the two exposures, aiming for a roughly 1:1 ratio, but it's usually best to chimp that on the LCD and tweak it one way or the other with the +/- compensation controls to taste. You can do that very easily, usually by shooting on aperture priority.

Rear curtain sync is only useful if the particular direction of any ambient movement blur is significant, ie do you want the flash image at the beginning of the ambient movement, or at the end?

Or does it matter? Usually it doesn't and front curtain sync makes the timing of the flash easier with longer exposures. Either way it makes no difference to the relative exposure levels or any ghosting see-through effects.
 
blinkerz said:
so its basically how ive been doing stuff already, which is chimping.. but thats not too easy to see if the flash has frozen the image in on the back of the lcd with the 5d mark 1
Click to expand...

Why is that not easy? If you can't see it on the LCD image, then you probably won't see it in the final output. Make it brighter, increase exposure for ambient or flash, or both, until you can.

There is no other way, apart from making some test exposures in identical conditions, in full manual so you can note the settings and being careful to measure the flash distance exactly, then replicate.
 
it really depends on how much ambient light youre working with.
ambient light at noon, is a lot different than ambient light at 7pm. much like the light during summer months will be different than winter months.
i dont think there is going to be any sort of defining ratio because of the varying light.
 
im talking about dragging the shuttter to get some ambient at the evening... when i say i cant see the image on the back to see if its frozen, i mean i cant see if theres any blurring, in the same way its difficult to see if focus is achieved with f/1.2 -f/2 easily..
 
Surely you can see if it's blurred by zooming in on the LCD:shrug:
 
The flash image is unlikely to be blurred by movement, due to the short flash duration. At full power it will be around 1/1000sec, and at lower power outputs a lot less - likely 1/5000sec or even 1/10000sec.
 
you mean the ambient light falling on the subject blurring it?

I've had issues with that and my only real solution is to underexpose the ambient/keep subject really still
 
I think I understand your question; you want to light the subject with flash, but let the bg burn in (lit by ambient). Correct?

If so, the amount of blurring will depend on the particular scene you are shooting. It's not the ratio of flash to ambient that you want to be concerned about, it's the ratio of 'ambient hitting the subject' to 'ambient hitting the bg'.

If your subject is brighter than your background when lit only by the ambient, you will always blur the subject, so the key to it is framing your shot so that they are darker than the bg (without the flash)

You might be able to do this with careful composition, or you might need to gobo the ambient, especially if your bg is very dark. Provided the ambient light on the subject is about 3 stops (maybe even 2 if your pushing it) below the ambient light on the bg, then the blurring should not be noticeable.
 
starabo said:
I think I understand your question; you want to light the subject with flash, but let the bg burn in (lit by ambient). Correct?

If so, the amount of blurring will depend on the particular scene you are shooting. It's not the ratio of flash to ambient that you want to be concerned about, it's the ratio of 'ambient hitting the subject' to 'ambient hitting the bg'.

If your subject is brighter than your background when lit only by the ambient, you will always blur the subject, so the key to it is framing your shot so that they are darker than the bg (without the flash)

You might be able to do this with careful composition, or you might need to gobo the ambient, especially if your bg is very dark. Provided the ambient light on the subject is about 3 stops (maybe even 2 if your pushing it) below the ambient light on the bg, then the blurring should not be noticeable.
Click to expand...

Sure enough. Basically the problem with bluring is movement. If there's no movement, either of the camera or the subject, then there's no bluring.
 
HoppyUK said:
Sure enough. Basically the problem with bluring is movement. If there's no movement, either of the camera or the subject, then there's no bluring.
Click to expand...

True, but if (as I suspect) the op has fairly long shutter speed to burn in the ambient (say, during an evening shoot) then movement of the subject is pretty much unavoidable. Better to kill the ambient on them and get the lighting right.

Either that or dope with with a sedative to stop them moving.
 
yeah thats basically it, you cant avoid movement if your doing slow shutter speeds to get some ambient background exposure. Alot of the time the background ambient exposure is equal to position of the model, so this is why i was asking for the minimum ratio of underexposure of the background to flash,to bring out the model to avoid blur.
 
Some cameras (top end Nikon I think) can do double exps in the camera itself. Otherwise it'd be a photoshop job; which is much more time consuming than just killing the ambient that's hitting the subject in the first place! (at least it is with my PS skills!)
 
I think you need to clarify whether you're talking about movement/blur of trees/people/cars/water, or blur caused by shaky hands and a slow shutter.
 
ust had a wonder, never tried this myself but one to throw in to the mix,,
How about a double exposure? one for drag the other shorter with flash???
Click to expand...

balancing flash with ambient is a double exposure. it's an exposure within an exposure.

I don't really understand the question OP, since there are so many variables i'm not sure if such a set ratio did exist how you might use it even. It depends how far your flash is from the subject too. I've thought about long exposures with rear curtain sync to get light trails in the back of a night portrait and i've seen it done, albeit not very well.

as starabo says, you need as little ambient hitting the subject as possible otherwise any movement will come out as motion blur. but surely you can just zoom in on the LCD to check for sharpness? I reckon composition is really important.
 
bomberman said:
balancing flash with ambient is a double exposure. it's an exposure within an exposure.
Click to expand...

Double exposure is also know as exposing the same frame twice in olde world film talk...

Its an option still on digital slr's,,, like I said, never tried it (well not with digital!) might be worth a try.
Exposure 1 with something like a 2 second exposure
Exposure 2 40th second with flash?

For what its worth, it costs nothing to try and think I am going to try it this weekend...
 
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