Slow sync flash for gigs/twilight

Climate Expert

Say I want to photo at a music festival or maybe out in a city at night. In both cases there will be a small amount of mixed amibient lighting.

To photography people should I use a slow sync flash and maybe force a shutter speed of about 1/4th second so that there is a sharp person, bit of trail and a bit of ambient light 'character'.

What would the more experienced photographers here do?

Fajitas!

Pretty much as you said - I usually use shutter speed priority, set the ISO high enough, and underexpose with the flash - This way you're not going to be waiting too long for the flash's battery to recharge.

So, usually, 1/6th to 1/60th of a second shutter speed, but you can up or down that to your own preference, 800iso, underexpose both the camera and the flash by a stop, and let the camera do the aperture. I use an omnibounce on my flash too for this kind of thing.

stcstc

the other effect that works very well sometimes is where you use second curtain sync. ie the flash fires as the shutter is closing

you then get trails with a sharp subject, takes a little practice but worth if

DjDangerousDave

Fajitas! wrote: »

Pretty much as you said - I usually use shutter speed priority, set the ISO high enough, and underexpose with the flash - This way you're not going to be waiting too long for the flash's battery to recharge.

So, usually, 1/6th to 1/60th of a second shutter speed, but you can up or down that to your own preference, 800iso, underexpose both the camera and the flash by a stop, and let the camera do the aperture. I use an omnibounce on my flash too for this kind of thing.

I think I might of stumbled upon this technique by chance. I was not happy with all the results though.

This is one of the shots I took:



Can you explain what all the different aspects of the settings do for the final image? Here is what I understand them as, correct me if im wrong.

High ISO (800): This allows the lighting from the event to be captured by the camera. And allows for some "movement" between flashes?

Underexposing: Is this because the double flash will cause the subjects to be too bright in the image?

1/6 - 1/60: This is to change the amount of movement and outside lighting that will enter the final shot?

Maybe im miles off.

JMcL

DjDangerousDave wrote: »

High ISO (800): This allows the lighting from the event to be captured by the camera. And allows for some "movement" between flashes?

If you double the ISO, assuming the aperture remains constant, you can half the shutter speed. So for example 1/25 of a second at ISO 100 will become 1/50s @ISO 200, 1/100s @ISO 400 etc. Because of the increased sensitivity to light, you flash range also increases for any given power output on the flash, though it doesn't double with a doubling in ISO

Underexposing: Is this because the double flash will cause the subjects to be too bright in the image?

I'm not sure what you mean by double flash, sometimes in low light the flash will fire once so the camera can autofocus, and then a second time for the actual exposure, but it only fires once when the shutter is open (the Canon 580 II has a stroboscopic mode where the camera can fire multiple times, but I assume that's not what you're talking about

There are 2 things to take into account. Firstly the exposure for the scene using just the ambient light which would give a normally exposed image, and secondly the flash exposure, which is the amount of light the flash needs to provide to correctly expose the object for a given ISO/aperture/shutter speed. We'll assume the camera takes care of figuring out the correct flash exposure, so if you dial in some underexposure, the flash exposure will still give the correct exposure while the background lit by the ambient light will be underexposed. You can separately control the flash exposure, to brighten/darken the subject. The best way to get the hang of it is to experiment, shoot a something with flash with the sky as a background and play about with exposure compensation and flash compensation to see the effect of both

1/6 - 1/60: This is to change the amount of movement and outside lighting that will enter the final shot?

Pretty much

Fajitas!

DjDangerousDave wrote: »

I think I might of stumbled upon this technique by chance. I was not happy with all the results though.

This is one of the shots I took:



Can you explain what all the different aspects of the settings do for the final image? Here is what I understand them as, correct me if im wrong.

High ISO (800): This allows the lighting from the event to be captured by the camera. And allows for some "movement" between flashes?

Underexposing: Is this because the double flash will cause the subjects to be too bright in the image?

1/6 - 1/60: This is to change the amount of movement and outside lighting that will enter the final shot?

Maybe im miles off.

Well, I use the high ISO so that I'm not using a more powerful flash - Means faster recycling times, I'll usually shoot off 3/4 frames - Especially if it's a group of people (I can swap heads later if someone is blinking etc)

You're underexposing because the camera, set to expose perfectly, will go for 18% grey, so by underexposing, you're going to be getting blacks in your image - I know you can do that afterwards, but I want to get that right in camera, especially if someone wants to see the pic. I don't want the flash to blow things out either, nor give a glare off the subject.

Yep, that's to change the amount of movement, tbh, I bring it down lower for some situations, and much much lower for gigs - Bringing it up towards 1/60 would be more aimed towards a more formal situation where I want the ambiant light to register, aswell as the flash to illuminate the subjects in the first place - It used have the title of 'dragging the shutter' though so many people do it now, it's just known as good flashing

JMcL wrote: »

I'm not sure what you mean by double flash, sometimes in low light the flash will fire once so the camera can autofocus, and then a second time for the actual exposure, but it only fires once when the shutter is open (the Canon 580 II has a stroboscopic mode where the camera can fire multiple times, but I assume that's not what you're talking about

Actually, most flashes do fire twice! The first one is more of a metering flash, there's probably about 1/2000th of a second between the flashes during normal use - It's also how some flash units work - Some of the older flashguns or some newer strobes (Eg; MultiBlitz)

I've some examples;









I have more/better examples, but not on me

These are all at the longer side of the exposure.

Climate Expert

Thanks. I like those results.

So what mode are you shooting these in? Do you use rear flash at all?

Fajitas!

I think they're all shot in TV mode. I don't use rear flash because if I focus on someone, and it's a 1/6 second exposure, if they move in that 1/6th of a second, it's out of focus!

DjDangerousDave

Fajitas! wrote: »

I think they're all shot in TV mode. I don't use rear flash because if I focus on someone, and it's a 1/6 second exposure, if they move in that 1/6th of a second, it's out of focus!

How do focus on people in these situations, usually the light is quite low and my auto focus struggles a little bit.

Do you use manual focus?

melekalikimaka

@fajitas!

I saw the pics before user and said to myself..."al all over"

nice

Fajitas!

Cheers Mele

Dave, I use the centre AF point, which is probably the most accurate, on a 5D, and either a 2.8 or a 1.4 lens, so there's plenty of light coming in to autofocus with, but the biggest aid to focusing is with the 580ex (I'm pretty sure the 430ex is the same), it sends out a red cross pattern of light to aid focusing, works like a charm. It also means I don't have to put the camera up to my eye the whole time, I can hold out the camera, and use the beams to see where I'm shooting. Predator style

DjDangerousDave

Fajitas! wrote: »

Cheers Mele

Dave, I use the centre AF point, which is probably the most accurate, on a 5D, and either a 2.8 or a 1.4 lens, so there's plenty of light coming in to autofocus with, but the biggest aid to focusing is with the 580ex (I'm pretty sure the 430ex is the same), it sends out a red cross pattern of light to aid focusing, works like a charm. It also means I don't have to put the camera up to my eye the whole time, I can hold out the camera, and use the beams to see where I'm shooting. Predator style

I have an olympus E410 and I'm just using the pop up flash. When I try to auto focus in low light the flash pops up and aids the focusing by flashing at the subject. I find this does not work well as the subjects think that the photo has been taken when I am still focusing. So I tend to turn this off and manually focus or let the auto focus do its work withoug the flashing crap.

I have been looking at this http://www.olympus.co.uk/consumer/198_fl-36.htm. Do you think that will do the same orange "cross" that your flash can do?

Fajitas!

Yep, I'm pretty sure it will!