Sync faster than 1/250?

[JustinSegura]

Sorry if this question has been asked before but i cant find an answer. I Just bought a Quantaray Qdc 900wa External Flash for my 30d and still cannot flash sync over 1/250. Is it even possible with this camera? Thanks guys

[Titus213]

Flash sync speed is a function of the shutter mechanism. Your camera max sync is 1/250.

High speed sync, a way to overcome this shutter restriction, is on the Canon EX flashes, don't know about any others. The EX flashes will sync up to max shutter speed I believe - at very reduced ranges. I've used it over 1/4000.

I would not be the least bit surprised if your flash was not capable of high speed sync. The Canon 430EX does have that function at about $60 more than the Quantaray.

[Robert_Lay]

Just out of curiousity, is it not true that high speed sync is generally not necessary unless the ambient light level is extraordinarily high?

Which then begs the question, with such high ambient light level, why does one need a flash at all?

There must be some application for which this would be important - what would that be?

[cory1848]

Just out of curiousity, is it not true that high speed sync is generally not necessary unless the ambient light level is extraordinarily high?

Which then begs the question, with such high ambient light level, why does one need a flash at all?

There must be some application for which this would be important - what would that be?

For fill in bright sunlight. Reduces the harsh shadows bright sunlight produces.

[TMc]

I use high speed sync with my 400mm f/5.6 and flash extender. I want my shutter speeds higher than 1/250 sec with this lens.

[Titus213]

Just out of curiousity, is it not true that high speed sync is generally not necessary unless the ambient light level is extraordinarily high?

Which then begs the question, with such high ambient light level, why does one need a flash at all?

There must be some application for which this would be important - what would that be?

This is also of great use if you want to use low f-stops to blur a background behind a person on a sunny day but still need flash to fill those racoon eyes.

And I've used it for cross lighting.

[JustinSegura]

Thanks for the responses. Do you guys know if there is a way to find out if it does provide high speed sync? My reason behind this is because i want to eventually get some fast moving shots. ie: Skateboarders.. etc.

[tim]

In general only EX speedlites provide high speed sync. In your case you don't need it, what you need is a better understanding of light and how to capture it.

If you're photographing skaterboarders during the day there's enough light you don't need flash. If you're shooting at night you'll be using flash or flashes, in which case flash overpowers ambient light and your shutter speed is mostly irrelevant. Set the shutter to 1/100th, ISO400, F5.6 and things will work. Heck set it to 1/30th and it'll work, possibly better as you'll get a bit more ambient.

Read up on and play with balancing ambient and flash light sources.

[SkipD]

Thanks for the responses. Do you guys know if there is a way to find out if it does provide high speed sync? My reason behind this is because i want to eventually get some fast moving shots. ie: Skateboarders.. etc.What conditions are you shooting in - daylight, nighttime under lights, etc.?

The "high speed sync" mode that some Speedlites can do is a VERY different way of functioning from the ordinary way that most flash units operate. Most flash units (including Speedlites which are NOT operating in "high speed sync" mode) emit a single main burst of light that is very fast and usually very powerful. This main burst of light is often much shorter in duration than the fastest possible shutter speed on today's cameras.

To make sure you don't misunderstand the above, Speedlites operating in ETTL mode (or variations of it) also usually emit a much weaker pre-flash burst before the main burst. The purpose of the pre-flash is for calculation of the required amount of light from the main burst to get the right exposure.

When operating in the "high speed sync" mode, Speedlites emit a series of many rather weak pulses of light. The effect is like a conventional lamp lighting for the duration of the shutter opening. The light emitted from a Speedlite in "high speed sync" mode is VERY weak compared to the main burst in normal operation mode. The only real value of the "high speed sync" mode is when using the Speedlite for fill light during the day.

[DDCSD]

Thanks for the responses. Do you guys know if there is a way to find out if it does provide high speed sync? My reason behind this is because i want to eventually get some fast moving shots. ie: Skateboarders.. etc.

The last two post really have the most important info, but to answer the question directly, the manual should state whether it is capable of HSS.

[Lotto]

HSS is a function of the flash. If you don't have a HSS button or a way to turn it on, more than likely the flash is not HSS compatible. I just look at the Ritz wedsite, it does not state that flash can do HSS.

[Titus213]

Sooner or later the real issue comes out....:lol:

[Curtis N]

There are a few aftermarket flash units that have HSS capability, including some Sigma and Metz models. If it isn't specifically mentioned in the product's specs and features then it's a pretty safe bet you don't have it.

[Robert_Lay]

What conditions are you shooting in - daylight, nighttime under lights, etc.?

The "high speed sync" mode that some Speedlites can do is a VERY different way of functioning from the ordinary way that most flash units operate. Most flash units (including Speedlites which are NOT operating in "high speed sync" mode) emit a single main burst of light that is very fast and usually very powerful. This main burst of light is often much shorter in duration than the fastest possible shutter speed on today's cameras.

To make sure you don't misunderstand the above, Speedlites operating in ETTL mode (or variations of it) also usually emit a much weaker pre-flash burst before the main burst. The purpose of the pre-flash is for calculation of the required amount of light from the main burst to get the right exposure.

When operating in the "high speed sync" mode, Speedlites emit a series of many rather weak pulses of light. The effect is like a conventional lamp lighting for the duration of the shutter opening. The light emitted from a Speedlite in "high speed sync" mode is VERY weak compared to the main burst in normal operation mode. The only real value of the "high speed sync" mode is when using the Speedlite for fill light during the day.

Many thanks for the very lucid explanation of a very complicated and often misunderstood topic.

[JeffreyG]

Thanks for the responses. Do you guys know if there is a way to find out if it does provide high speed sync? My reason behind this is because i want to eventually get some fast moving shots. ie: Skateboarders.. etc.


In general HSS isn't useful for sports, including skateboarding.

If you are shooting skaters from below in sunlight, HSS could be helpful to brighten their undersides which will be shaded.

Any other skating shots where you want the flash to illuminate a skater in low light (indoors, dusk, night) should not be shot with HSS. You will almost certainly get more blur and ghosting that way. I'd shoot low light skaters at the synch speed usings settings that underexpose ambient by at least 3 stops. The flash will light and freeze the skater.

[Curtis N]

The light emitted from a Speedlite in "high speed sync" mode is VERY weak compared to the main burst in normal operation mode.I'm not entirely sure that the maximum total light output from the flash is less in HSS mode. It could be that more energy is wasted when the flash operates this way, but I doubt that's the main reason for the reduced effective range.

It's important to understand that in HSS mode, the high frequency bursts of light begin when the first shutter curtain starts to open, and continues until the second curtain is completely closed. So there is an inherent loss of efficiency because part of the light is always being blocked by the partially open shutter curtains.

Compare that to normal flash, where all of the light is released while the shutter is completely open. This alone would explain the loss of effective range.

[JeffreyG]

I'm not entirely sure that the maximum total light output from the flash is less in HSS mode. It could be that more energy is wasted when the flash operates this way, but I doubt that's the main reason for the reduced effective range.

It's important to understand that in HSS mode, the high frequency bursts of light begin when the first shutter curtain starts to open, and continues until the second curtain is completely closed. So there is an inherent loss of efficiency because part of the light is always being blocked by the partially open shutter curtains.

Compare that to normal flash, where all of the light is released while the shutter is completely open. This alone would explain the loss of effective range.

I think I will have to disagree Curtis. Imagine firing the flash normally above the synch speed. The part of the sensor exposed to the flash light will appear normal and the part covered by the shutter will be dark. Just because some of the sensor is covered we would not expect the flash exposed part to be darker.

So if the flash could fire maximum power repeatedly at high speed the flash would be able to provide the same range as when used normally. Each successive slit would see full flash power.

Instead we can easily assume that the flash simply cannot deliver several full power bursts within 1/1000th of a second or so. This makes sense of course. How could a capacitor sized to deliver one good burst of power for normal use also be able to deliver a dozen equal bursts in rapid fire?

If the capacitor was large enough, the next problem would be that the flash would probably overheat and fail.

[Curtis N]

So if the flash could fire maximum power repeatedly at high speed the flash would be able to provide the same range as when used normally. Each successive slit would see full flash power.But that's not what I'm assuming.

The capacitor's energy is spread out for the entire duration of shutter curtain movement, in a high frequency series of very low-power flashes. Efficiency is lost because it's firing at a partially closed shutter.

[PacAce]

I'm not entirely sure that the maximum total light output from the flash is less in HSS mode. It could be that more energy is wasted when the flash operates this way, but I doubt that's the main reason for the reduced effective range.

It's important to understand that in HSS mode, the high frequency bursts of light begin when the first shutter curtain starts to open, and continues until the second curtain is completely closed. So there is an inherent loss of efficiency because part of the light is always being blocked by the partially open shutter curtains.

Compare that to normal flash, where all of the light is released while the shutter is completely open. This alone would explain the loss of effective range.

I wouldn't necessarily call it "wasting" energy although I do agree with Curtis in that only a portion of the image sensor is exposed to the flash light emitted at any given point in time. Since the total light energy put out by the flash is the same whether the flash is in normal mode or HSS mode, the difference then is the fact that not all the light is captured by all parts of the image sensor in HSS mode. So, maybe in that sense, you could call it wasteful usage of the flash. But then, in that case, so would using f/8 instead of f/2.8. ;)

[DDCSD]

But that's not what I'm assuming.

The capacitor's energy is spread out for the entire duration of shutter curtain movement, in a high frequency series of very low-power flashes. Efficiency is lost because it's firing at a partially closed shutter.

So are you saying that the cumulative effect of the flashes is what is giving you the same maximum total light output? Makes sense thinking of it that way.

[PacAce]

I think I will have to disagree Curtis. Imagine firing the flash normally above the synch speed. The part of the sensor exposed to the flash light will appear normal and the part covered by the shutter will be dark. Just because some of the sensor is covered we would not expect the flash exposed part to be darker.

So if the flash could fire maximum power repeatedly at high speed the flash would be able to provide the same range as when used normally. Each successive slit would see full flash power.

Instead we can easily assume that the flash simply cannot deliver several full power bursts within 1/1000th of a second or so. This makes sense of course. How could a capacitor sized to deliver one good burst of power for normal use also be able to deliver a dozen equal bursts in rapid fire?

If the capacitor was large enough, the next problem would be that the flash would probably overheat and fail.


But that's not what I'm assuming.

The capacitor's energy is spread out for the entire duration of shutter curtain movement, in a high frequency series of very low-power flashes. Efficiency is lost because it's firing at a partially closed shutter.

Yes, what Curtis said.

[Curtis N]

So, maybe in that sense, you could call it wasteful usage of the flash. But then, in that case, so would using f/8 instead of f/2.8. ;)This is true, which is why your range in HSS mode doesn't decrease as you speed up the shutter and open the aperture by the same number of stops.

You'll get the same range with 1/500 f/8 as you will with 1/2000 f/4.