[Nass]

I think I might stick to landscapes !


just to add to the freezing motion points ... The guys are right that you don't need HSS to freeze the motion ... The flash is fast enough already. If you have a lot of ambient light though you might get blurry ghosting effects around edges of your subjects (I think this is called 'dragging the shutter' when done deliberately ..). I guess its why a lot of this kind of photography has a black background, as the ambient light has been kept really low.

No - 'dragging the shutter' is another expression for rear sync. This phenomenon is called flash ghosting and can happen when ambient and flash are close to the same value.

[mcgregni]

Yes, thanks Nass, of course ...

[BrianR]

No - 'dragging the shutter' is another expression for rear sync. This phenomenon is called flash ghosting and can happen when ambient and flash are close to the same value.

I've only seen "dragging the shutter" to mean using a slower shutter than your x-sync to let the ambient contribute to the exposure (aka "slow sync" in some camera manuals), and nothing to do with your choice of rear or front sync.

Rear sync is often recommended when you're dragging the shutter since the motion blur (if any) from the ambient tends to look more natural if it happens before the flash freezes a part of your subject. My only example is a cheat using Front Sync but with the car actually moving backwards so the blur ends up behind it:

[Nass]

Looks like you're right BrianR, mcgregni - weird, I'd always associated it with rear sync. My bad

[mcgregni]

Good to know .... I'm going to have to make a new section in the guide then, covering flash with cars in reverse !

I've only seen "dragging the shutter" to mean using a slower shutter than your x-sync to let the ambient contribute to the exposure (aka "slow sync" in some camera manuals), and nothing to do with your choice of rear or front sync.

Yes. I'll typically start at 1/180 and then drop my shutter as needed to give me a better balance of ambient, typically 1/125 or 1/60. Backgrounds usually don't move.

[cali92rs]

I typically use HSS only as a fill when I am using a wide aperture outdoors with a fast shutter speed.
Of course, HSS greatly diminishes the power of your flash so it has to be real close to your subject.

[clackers]

I typically use HSS only as a fill when I am using a wide aperture outdoors with a fast shutter speed.
Of course, HSS greatly diminishes the power of your flash so it has to be real close to your subject.

But it will be, of course - a portrait or flower or whatever.

We wanted that wide aperture for a reason. :-)

Let's also mention ND filters as a possibility when freezing action isn't required.

[awaldram]

I typically use HSS only as a fill when I am using a wide aperture outdoors with a fast shutter speed.
Of course, HSS greatly diminishes the power of your flash so it has to be real close to your subject.

I use HSS when shooting moving subjects (esp panning indoors) in decent light and need fast shutter to freeze the background movement and flash to target the close subject matter.

I think a lot of people attempt to use HSS when the issue is the ambient part of the subject not flash failing to freeze the subject, Their solution should be to use a none mixed mode (X) or deliberately dial down the ambient quota.

Everyone always forgets flash golden rule - Shutter speed has no effect on flash exposures.

Ambient exposure = Aperture,Shutter Speed, ISO
Flash exposure = Aperture , Flash Power , ISO

[mcgregni]

Don't forget flash to subject distance and flash head zoom ... both add to the flash exposure equation.

Also, in practice, during HSS shooting the shutter time value WILL impact on available flash power, with progressively shorter times reducing the available flash range ... This can quite rapidly reach the power buffers and cause a loss of flash exposure. The nice thing on the dedicated flash units is the constantly adjusting flash range indicator, which in HSS mode will respond to the shutter time changes and keep showing you the exact area within which your subject will be well exposed.

[awaldram]

Don't forget flash to subject distance and flash head zoom ... both add to the flash exposure equation.
.

Well given when shooting flash ..
f-number = GN/distance

Then its already included under aperture !

And as GN alters as you Zoom or bounce that’s also included

Your point on HSS is about using the correct flash for the job and is not related to the 'flash exposure' point.

If your using HSS and don't have sufficient power then you will not be able to achieve a correct flash exposure at that shutter speed.

The Shutter speed does not effect the flash exposure even in HSS providing your flash is sufficiently powerful for the job.

All HSS does is fire the flash multiple time in sync with the slotted windows as the two shutters traverse the sensor.

The faster the shutter the smaller the slot the more flashes required the greater the power loss (your flash manual appendix will give GN's for different HSS shutter speeds.

X sync is the fastest shutter where the sensor is fully exposed before the 2nd curtain start travelling and is the only Penax mode that allows automation without ambient/flash mixing so should be heavily used in light conditions the require flash to achieve a reasonable exposure.

Its not good trying to achieve a Flash ambient mix if the ambient exposure forces you up into hi ISO's or ridiculously low shutter speeds , You better off studying correct flash use to achieve pleasing results under flash.

Only when ambient light is sufficient for a decent shot but you want flash for highlight to shadow control should you be out of X mode.

As shutter has no effect on flash exposure the fact X locks you @ 1/180 is irrelevant better than that it stops you thinking your achieving something by prating about with with the shutter speed

Control your DoF with aperture and contrast control with multiple flashes or if you only have 1 then bouncing will give you a massively larger light source leading to a more natural shot.

Again only in mixed decent light should you be off X sync and then the camera has one of the best 'fill' algorithms so can be safely switched to P-ttl and shoot away for a generally pleasing Ambient/flash mix.

In summary

Flash and Ambient is not additive (flash fall off is to rapid for that)

So if you don't have sufficient light for a decent ambient shot then get out of ambient shooting modes into flash mode ('X' Sync)
If you have sufficient light for a decent ambient shot then you may use flash to improve the image you can use any mode (but 'X') to achieve this and use exposure compensation (flash or Ambient) to control flash/ambient ratio without exceeding your flashes capability

[mcgregni]

There's a lot of good information in there! I take the point about the GN calculation, but my point was about the practical impact of making those extra changes (flash head zoom, actual distance to subject) .... I mean they would change the flash exposure if you left everything else the same. From a practical working point of view they are other factors, over and above the key ones you listed, that will give you an instant flash brightness adjustment and can be used to take more control, especially if limits have been reached already with aperture and ISO.

The HSS shutter time values are incorporated in the adjusted GN tables, yes, but again, my point was about the practical differences you would experience in that mode ....as you say, generally shutter won't impact flash exposure, but in hss it can start to limit your power available very quickly as each shorter time reduces GN. In this practical sense it affects flash exposure once the other limits have been reached in HSS mode.

[awaldram]

Agreed

[em-tx]

Hi all there – thanks for help and for the time. Sorry for delayed answers I have been traveling on last moment over 3 country and it its toll. Apologies once again and I will be very helpful if you would come back to me.

The way to freeze movement is to lower the power setting. 1/8 power is about 1/4000 of a second. Depending on what you are shooting, that will freeze movement quite effectively. To freeze hummingbird wings requires even faster such as 1/16 power.

Once you are getting into those speeds with multiple flashes, synchronizing them becomes a challenge. The latency, or delay between emitting a signal and triggering the flash using optical wireless triggering is about 1/16000 of a second, or a quarter of the 1/4000 duration at 1/8 power. That may or may not be a problem. Signal wireless using rf radio waves is much slower, you may find problems at 1/1000 speed where the synchronisation isn't effective. Others who use these systems with multiple flashes to freeze movement can comment.

Of course when you decrease the power you have less light. From a camera exposure standpoint the light from a flash is affected by the distance from the subject. Twice the distance means 1/4 of the light, roughly a square relationship as the same amount of light has to flood an area 2*2 the size. That is the basis for the exposure charts where distance, Iso and fstop are all used to calculate the exposure settings.

Depending on what you are shooting you can get into situations where everything is conspiring against your exposure, short duration, distance to subject and small aperture for depth of field. In other words, great fun and lots to learn.



The yongnuo stuff is pretty good for the price, it works OK. They are cheap.

I needed five flashes to fire simultaneously at 1/16 power or 1/6000 of a second to freeze bats in flight. Eventually I ended up using a raspberry pi board with a piface output board to trigger there bodies and five flashes. It worked quite well, the yongnuo 560iii flashes worked well.

It comes down to how fast your action is, how critical your synchronization is, how many shots.

Please did you get P-TTL with Yongnuo or HSS, so to speak? Also please do you know their triggers and support? What I am after is, that if I buy into their system, if they would have a tendency to add more brands into compatibility. I am also interested for instance – that if I get an Canon flash or Nikon one from friend, if I am able to use it in set up.

---------- Post added 3rd Sep 2015 at 16:00 ----------

I use HSS when shooting moving subjects (esp panning indoors) in decent light and need fast shutter to freeze the background movement and flash to target the close subject matter.

I think a lot of people attempt to use HSS when the issue is the ambient part of the subject not flash failing to freeze the subject, Their solution should be to use a none mixed mode (X) or deliberately dial down the ambient quota.

Everyone always forgets flash golden rule - Shutter speed has no effect on flash exposures.

Ambient exposure = Aperture,Shutter Speed, ISO
Flash exposure = Aperture , Flash Power , ISO

What I want to achieve is following:

1. Outdoor & indoor scenes
2. Backround naturally lit, if there are moving objects, create blur – this should be naturally lit (and more or less even – according to ambient light)
3. Long or relatively long exposure
4. Where I have a fast moving subject and need perfect freeze
5. Having this freeze done multiple times in 1 exposure
6. Hid flashguns into scene and let them go off in (kind of ) sequence
7. Where I am able to control strength of flashes and their order
8. Strong separation between background – kind of very dark, more or less evenly lit, color – deep, heavy, dark and brightly lighted separated subject, which might have its own light surrounding (aka falloff light from flashgun on background)

---------- Post added 3rd Sep 2015 at 16:01 ----------

Do you even need High-Speed Sync (HSS) for what you're doing? A fast shutter speed is not a requirement for using a flash to freeze motion, you just need the ambient contribution to be very low during your exposure and your flashes to have a low enough T.1 time to stop the movement (T.1 time is essentially the flash duration, for hotshoe flashes the lower the power level the shorter this is and the better the stopping power).

Can you describe in more detail what's going with your setup? Is this a long exposure you're doing with flashes going of during it? Or something else?

sorry for not answering sooner:


What I want to achieve is following:

1. Outdoor & indoor scenes
2. Backround naturally lit, if there are moving objects, create blur – this should be naturally lit (and more or less even – according to ambient light)
3. Long or relatively long exposure
4. Where I have a fast moving subject and need perfect freeze
5. Having this freeze done multiple times in 1 exposure
6. Hid flashguns into scene and let them go off in (kind of ) sequence
7. Where I am able to control strength of flashes and their order
8. Strong separation between background – kind of very dark, more or less evenly lit, color – deep, heavy, dark and brightly lighted separated subject, which might have its own light surrounding (aka falloff light from flashgun on background)

[derekkite]

The yongnuo stuff is manual; hss is going to cost lots of money and probably wont get to where you want.

Essentially you will have a flash manually set to each circumstance you are looking for. The blurry part has a long flash duration, I think 1/250 is the duration on full power. the action frozen would be at lower power with a short flash duration. you will need to aim and control the light with some kind of gizmo, and probably do something to flood the ambient. the wireless rf triggering will probably be fine unless you get into extremely high speed.

There will be quite a bit of trial and error, emphasis on the error. Read up at the strobist site, there are lots of details to get you started.