Max Flash Sync?

Chez · 10-01-2006, 15:11

Right, I'm a bit baffled...

I understand why a camera has a maximum flash sync speed (the longest amount of time that the entire frame is exposed for).

What is the purpose of the Max Flash Sync setting though?

Why would you want to limit it at anything less than the maximum..

Surely, with it set at the max, the flash will sync at any shutter speed up to (and including) the maximum??

Let's say I'm in manual mode.

Shutter = 1/60s
Aperture = f/1.8
ISO = 200

What is the difference between having Flash Sync Speed (custom setting) on 1/60s as opposed to 1/250s?

Thanks in advance
Chez

CT · 10-01-2006, 18:02

You're thinking of this in the wrong terms Chez. If the flash is set on max sync speed it will sync with any shutter speed all the way down to long time exposures in the sense that the flash will occur while the shutter is fully open. It wouldn't be much use to you though. The idea is to be able to use the flash balanced with ambient light to provide fill flash - just enough flash to brighten the subject and lighten the shadows, allowing the ambient light to be the main source of illumination. We do that by first taking an exposure meter reading in the usual way. Say your indoor reading is 1/60th at f8. If you use Shutter Priority Mode (which I find easiest for this technique) then simply set your shutter speed to 1/60th and the flash will adjust it's output for those settings resulting in a shot nicely balanced between flash and ambient light. The other way of course is to use Manual Mode, set 1/60th at f8 and again the flash will adjust it's output to those settings.

This is often referred to as 'Slow Flash Sync' You don't know how lucky you are - prior to TTL metering, you could only achieve fill flash with a focal plane shutter(which all SLRs have) by dividing the aperture you wanted to use into the flash guide no. which gave you the distance you had to take your shot from, OR divide the distance at which you wanted to shoot into the guide number, which gave you the aperture you had to use. Modern cameras and flashguns have made what used to be a PITA into a simple process.

Another use for it is imagine it's evening and a beautiful sunset. You want to photograph your signicant other with the sunset as a backdrop. Your normal choices would be an available light shot which would be great for the sky but leave your other half as a silhoutte, OR use flash which would be great for 'er indoors, but the exposure would be far too short for the sunset and you'd end up with an under-exposed black background.

Take a normal meter reading for the sunset - say it's 1/20th at f8. Now set your camera to those settings as described. You'll have to tell her (or him ) to keep reasonably still with a shutter speed that slow, but your camera makes the correct exposure for the sunset, and during the exposure the flash fires just strongly enough to light up your foreground figure.... Voila!

What you need to do is some quick practice shots indoors under room lighting to see what a huge difference this makes to your shots,

Hope that helps Chez. Sing out if not.

Chez · 10-01-2006, 18:32

Thanks CT. That has answered a couple of questions I had about flash..

However, it doesn't fully answer this one. Perhaps I should have explained in more detail..

I am using a Nikon D200 with a Nikon SB-600 flash.

The max flash sync speed of the D200 is 1/250, with a 'pulsing' mode (called FP) above that.

I have a custom setting (e1), called 'Flash Sync Speed', which has the following options -

1/250s
1/250s (Auto FP)
1/200s
1/160s
(and so on, all the way to 1/60s)

Now, I can see why you would want to have the option of Auto FP on or off, but why would you ever set this at anything other than 1/250s or 1/250s (Auto FP)??

This has no effect on shutter or aperture speed.

So whichever mode I'm in (A,S or M), say the metering is done and the required settings are (as above) -

Shutter = 1/60s
Aperture = f/1.8
ISO = 200

What would be the difference between setting this custom setting to 1/60 or 1/250?

I hope that is a little clearer..??

MyPix · 10-01-2006, 18:32

nice description ther CT,
very usefull

on Nikons its known as ' rear curtain sync ' but exactly the same thing,
dunno about the canon, but the Nikon also does a 'slow rear curtain sync ,front curtain sync , slow sync , for lots of creative effects,
plus the usual red eye settings etc

MyPix

CT · 10-01-2006, 18:38

My Pix..... 'Rear Curtain Sync' is something else entirely! That's used to obtain blurring behind moving obects rather than in front of them for a more natural appearance.

CT · 10-01-2006, 18:52

Chez, without looking at your manual and seeing what these modes are all about it's difficult to say.The honest truth though is all these fancy modes are there to help people who don't have a basic understanding sufficient to make these settings themselves, and it really isn't that difficult.

My Canon 20D has umpteen modes I'll never use including a 'Slow Flash Sync' mode. It also has a 'Landscape' mode, but it isn't rocket science to understand that all it does is bias your exposure in favour of smaller apertures for DOF. The 'Action' programme will simply bias in favour of faster shutter speeds.

These programmes are just gimmicks. The only modes you need are Manual, Aperture Priority and Shutter Priority.... honestly.

They can be useful sometimes and convenient, but they're a real bar to you progressing and actually understanding what you're doing.

Forget the funny modes and you'll be OK.

MyPix · 10-01-2006, 19:46

MyPix, lol

Chez · 10-01-2006, 19:53

Thanks CT, but it's not an extra mode, it's a setting in the menus..

You're probably right though, it seems to work fine left on 1/250

dod · 10-01-2006, 19:58

That pulsing mode sounds a bit like high speed synch or maybe a strobe effect? What's the manual say?

Arkady · 10-01-2006, 20:37

Pulsing mode on Nikon speedlights is - believe it or not, so you can preview where any shadows will occur. Hit the pulse button and it whirrs away, emitting loads of brief pulses which are visible through the viewfinder allowing you to 'preview' the flash.

I just leave my SB-800 on program, with the camera to manual and adjust the output via the exposure compensation dial on the flash to - 1/3, 1/2 2/3 etc as required.

Flash is a black art which when done right should be seamless with the ambient light in the image. Unfortunately it's so easy to do it wrong.

Chez · 10-01-2006, 20:49

the pulsing is the high speed sync.. (FP mode)

Arkady - I know what you mean, my D200 does that when you press the DOF preview..

10-01-2006, 15:11	#1 (permalink)
Chez Been here a while Join Date: May 2005 Location: Northampton Posts: 289	Max Flash Sync? Right, I'm a bit baffled... I understand why a camera has a maximum flash sync speed (the longest amount of time that the entire frame is exposed for). What is the purpose of the Max Flash Sync setting though? Why would you want to limit it at anything less than the maximum.. Surely, with it set at the max, the flash will sync at any shutter speed up to (and including) the maximum?? Let's say I'm in manual mode. Shutter = 1/60s Aperture = f/1.8 ISO = 200 What is the difference between having Flash Sync Speed (custom setting) on 1/60s as opposed to 1/250s? Thanks in advance Chez __________________ Xbox Live = ChezUK My Photography Last edited by Chez : 10-01-2006 at 17:58.

10-01-2006, 18:02	#2 (permalink)
CT Feet under the table Join Date: Mar 2005 Location: West Mids UK Posts: 3,500	You're thinking of this in the wrong terms Chez. If the flash is set on max sync speed it will sync with any shutter speed all the way down to long time exposures in the sense that the flash will occur while the shutter is fully open. It wouldn't be much use to you though. The idea is to be able to use the flash balanced with ambient light to provide fill flash - just enough flash to brighten the subject and lighten the shadows, allowing the ambient light to be the main source of illumination. We do that by first taking an exposure meter reading in the usual way. Say your indoor reading is 1/60th at f8. If you use Shutter Priority Mode (which I find easiest for this technique) then simply set your shutter speed to 1/60th and the flash will adjust it's output for those settings resulting in a shot nicely balanced between flash and ambient light. The other way of course is to use Manual Mode, set 1/60th at f8 and again the flash will adjust it's output to those settings. This is often referred to as 'Slow Flash Sync' You don't know how lucky you are - prior to TTL metering, you could only achieve fill flash with a focal plane shutter(which all SLRs have) by dividing the aperture you wanted to use into the flash guide no. which gave you the distance you had to take your shot from, OR divide the distance at which you wanted to shoot into the guide number, which gave you the aperture you had to use. Modern cameras and flashguns have made what used to be a PITA into a simple process. Another use for it is imagine it's evening and a beautiful sunset. You want to photograph your signicant other with the sunset as a backdrop. Your normal choices would be an available light shot which would be great for the sky but leave your other half as a silhoutte, OR use flash which would be great for 'er indoors, but the exposure would be far too short for the sunset and you'd end up with an under-exposed black background. Take a normal meter reading for the sunset - say it's 1/20th at f8. Now set your camera to those settings as described. You'll have to tell her (or him ) to keep reasonably still with a shutter speed that slow, but your camera makes the correct exposure for the sunset, and during the exposure the flash fires just strongly enough to light up your foreground figure.... Voila! What you need to do is some quick practice shots indoors under room lighting to see what a huge difference this makes to your shots, Hope that helps Chez. Sing out if not. __________________ Canon 1DMk2N/ EF 50mm 1.4/ EF 17-40L/ EF180L Macro/ EF100-400L Canon 20D /17-85 EF-S 580EX Flashgun/ Gitzo Explorer

10-01-2006, 20:37	#10 (permalink)
Arkady Forum Regular Join Date: Feb 2005 Location: Aldershot, Hampshire Posts: 1,198	Pulsing mode on Nikon speedlights is - believe it or not, so you can preview where any shadows will occur. Hit the pulse button and it whirrs away, emitting loads of brief pulses which are visible through the viewfinder allowing you to 'preview' the flash. I just leave my SB-800 on program, with the camera to manual and adjust the output via the exposure compensation dial on the flash to - 1/3, 1/2 2/3 etc as required. Flash is a black art which when done right should be seamless with the ambient light in the image. Unfortunately it's so easy to do it wrong. __________________ "When I hold a camera, I Know no fear..." Alfred Eisenstadt Nikon D2x Bodies x2 14mm f/2.8 Sigma; 17-24mm f/2.8 Nikkor; 28-80mm f/2.8 Nikkor; 24-85mm f/2.8-4 Nikkor; 80-200mm f/2.8 Nikkor; 300mm f/2.8 Nikkor; 600mm f/4 Nikkor SB-800 Flash x2

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10-01-2006, 18:32	#3 (permalink)
Chez Been here a while Join Date: May 2005 Location: Northampton Posts: 289	Thanks CT. That has answered a couple of questions I had about flash.. However, it doesn't fully answer this one. Perhaps I should have explained in more detail.. I am using a Nikon D200 with a Nikon SB-600 flash. The max flash sync speed of the D200 is 1/250, with a 'pulsing' mode (called FP) above that. I have a custom setting (e1), called 'Flash Sync Speed', which has the following options - 1/250s 1/250s (Auto FP) 1/200s 1/160s (and so on, all the way to 1/60s) Now, I can see why you would want to have the option of Auto FP on or off, but why would you ever set this at anything other than 1/250s or 1/250s (Auto FP)?? This has no effect on shutter or aperture speed. So whichever mode I'm in (A,S or M), say the metering is done and the required settings are (as above) - Shutter = 1/60s Aperture = f/1.8 ISO = 200 What would be the difference between setting this custom setting to 1/60 or 1/250? I hope that is a little clearer..??

10-01-2006, 18:32	#4 (permalink)
MyPix Forum Regular Join Date: Jan 2005 Location: Gloucester UK Posts: 745	nice description ther CT, very usefull on Nikons its known as ' rear curtain sync ' but exactly the same thing, dunno about the canon, but the Nikon also does a 'slow rear curtain sync ,front curtain sync , slow sync , for lots of creative effects, plus the usual red eye settings etc MyPix

10-01-2006, 18:38	#5 (permalink)
CT Feet under the table Join Date: Mar 2005 Location: West Mids UK Posts: 3,500	My Pix..... 'Rear Curtain Sync' is something else entirely! That's used to obtain blurring behind moving obects rather than in front of them for a more natural appearance.

10-01-2006, 18:52	#6 (permalink)
CT Feet under the table Join Date: Mar 2005 Location: West Mids UK Posts: 3,500	Chez, without looking at your manual and seeing what these modes are all about it's difficult to say.The honest truth though is all these fancy modes are there to help people who don't have a basic understanding sufficient to make these settings themselves, and it really isn't that difficult. My Canon 20D has umpteen modes I'll never use including a 'Slow Flash Sync' mode. It also has a 'Landscape' mode, but it isn't rocket science to understand that all it does is bias your exposure in favour of smaller apertures for DOF. The 'Action' programme will simply bias in favour of faster shutter speeds. These programmes are just gimmicks. The only modes you need are Manual, Aperture Priority and Shutter Priority.... honestly. They can be useful sometimes and convenient, but they're a real bar to you progressing and actually understanding what you're doing. Forget the funny modes and you'll be OK.

10-01-2006, 19:46	#7 (permalink)
MyPix Forum Regular Join Date: Jan 2005 Location: Gloucester UK Posts: 745	MyPix, lol

10-01-2006, 19:53	#8 (permalink)
Chez Been here a while Join Date: May 2005 Location: Northampton Posts: 289	Thanks CT, but it's not an extra mode, it's a setting in the menus.. You're probably right though, it seems to work fine left on 1/250

10-01-2006, 19:58	#9 (permalink)
dod Feet under the table Join Date: Feb 2005 Location: Nairn Posts: 1,911	That pulsing mode sounds a bit like high speed synch or maybe a strobe effect? What's the manual say?

10-01-2006, 20:49	#11 (permalink)
Chez Been here a while Join Date: May 2005 Location: Northampton Posts: 289	the pulsing is the high speed sync.. (FP mode) Arkady - I know what you mean, my D200 does that when you press the DOF preview..