HSS Shooting Strategy

[Big Stan]

I am hoping to shoot slow moving wild life (not BIF) with a 5D2 (BIGMA) and a 600EX-RT with a Better Beamer (Fill Flash). I am getting totally lost with regard the strategy of using HSS. Depending on which web site I visit, I see “don't use HSS, just shoot at standard sync speed” or “use, HSS at higher speeds but it comes at a cost of performance” but nobody seems to quantify the expected loss in performance. Since distance, camera to subject, is important for my shooting scenarios I am trying to understand what HSS loss in performance actually means, e.g., what happens to the GN, as a function of shutter speed, when using HSS while trying to use higher ISO values to increase "reach".

[Manfred M]

I am hoping to shoot slow moving wild life (not BIF) with a 5D2 (BIGMA) and a 600EX-RT with a Better Beamer (Fill Flash). I am getting totally lost with regard the strategy of using HSS. Depending on which web site I visit, I see “don't use HSS, just shoot at standard sync speed” or “use, HSS at higher speeds but it comes at a cost of performance” but nobody seems to quantify the expected loss in performance. Since distance, camera to subject, is important for my shooting scenarios I am trying to understand what HSS loss in performance actually means, e.g., what happens to the GN, as a function of shutter speed, when using HSS while trying to use higher ISO values to increase "reach".

Stan - the way that HSS works is that the flash cycles very quickly to give you the approximation of continuous light. This comes at a "cost" as the amount of light output will drop by a good stop or so when shooting that way. As you are likely to use this at a shutter speed above your camera's synch speed, you are going to take a double hit here; the light output is lower than with a normal flash on top of using a higher shutter speed, which means you will need more light to get a correct exposure.

The second part of the issue is trying to shoot with flash with a long lens (yes we own the Sigma 150-500); the inverse square law is going to really hit you hard if you are trying to light something at the far end of the lens range unless you are off-camera and have the flash units near where the wildlife is going to appear and use the RF trigger.

[inkista]

The loss can be characterized as 2 stops.

One of the best articles I've seen on HSS is Neil van Niekerk's.

http://neilvn.com/tangents/high-speed-flash-sync/

If you scroll down to where he shows a progression of shutter speeds with HSS and the 5DMkII, you'll note the shots at f/9 and 1/200s differ between having HSS off and having HSS on.

Given that you're going to be using flash over long distances with a Better Beamer--I say stay away from HSS and keep your shutter speed at your max sync speed and use a tripod/monopod. You can't take the power hit.

[Big Stan]

Inkista, You wrote that the loss can be characterized as 2 stops. I have one more (I hope) question, does that mean each time I double the speed, the effective GN goes down by SQRT 2 (1.414)?. I have seen several references to a "HSS performance chart", which is supposed to describe the impact on GN as a function of shutter speed, for example, at 1/500 sec the sync speed GN is reduced to xx. Several blogs have suggested that the "HSS chart" is included in the Speedlite user manual but I cannot find it in the manual or in on-line searches.

[NorthernFocus]

What kind of wildlife are you planning on shooting that you feel the flash is needed?

[Big Stan]

Primarily birds shadowed by trees or in the open

[Manfred M]

Stan - I don't think that the light fall off impact is quite linear.

Two factors impact the light loss with HSS. The first is that the light pulses, so the capacitor that fires the flash cannot not store the same amount of power as for a single flash.

The other impact is that with the shutter only being a narrow slit moving across the sensor, you get the impact of both having less light hitting the sensor due to the size of the slit (which will be variable) and the speed of the curtain moving (which will be constant).

Bottom line is you are starting with less light output from the flash and complicating the issue by being inefficient with the light; at very high shutter speeds more light will be bouncing off the shutter curtains than hitting the sensor. I have yet to see any specific tables for this, but do suspect that onboard electronics may vary light intensity depending on the actual shutter speed.

[Colin Southern]

Hi Stan,

For the most part, it's a moot point because the flash will either have the capability or it won't; if it does then great, but if it doesn't then there's nothing you can do about it anyway.

Ditto for normal sync -v- HSS; if you're not going to use HSS then you're going to have to find a way to get your shutterspeed into X-Sync range - and the only way you'll be able to do that is to stop-down the aperture -- which will of course attenuate light from the flash anyway, so it becomes somewhat of a self-defeating strategy.

Personally, my rigs are setup to use HSS 100% of the time because at X-Sync speed or below they'll revert to normal sync automatically anyway.

Just remember that when using HSS the normal rules of flash freezing motion don't apply because you're effectively working with a continuous light source.

[rpcrowe]

I totally agree with Colin when he states, "Personally, my rigs are setup to use HSS 100% of the time because at X-Sync speed or below they'll revert to normal sync automatically anyway." That is the way I always have my cameras set up.

With respect to Neil's "Tangents" piece on HSS, I think that he is muddying the water when talking about HSS and posting images shot in a studio using the same f/stop at various shutter speeds. That is just not the way one uses HSS.

For the most part, HSS is used outdoors when you need to do one of two things:

Shoot at a higher shutter speed to stop motion or use a wider f/stop to allow selective focus.

You take an intial one-stop hit in flash power when going from standard sync to HSS. After that you will be increasing your f/stop every time you increase your shutter speed.

Additionally, since I usually have my fill flash about 1/stop below the ambient light, that initial hit in flash power is not impactful.

Finally, at extreme ranges, even when adding a Flash Xtender, you are not expecting to use flash as your primary light source. You use it to fill in a bit of shadow (thus the term fill-flash) but, when shooting wildlife at ranges far beyond the capability of the flash to provide light on your subject, the flash will still add those important catch lights in the animals eyes. Of course, you can fake catch lights using an editing program but, I far prefer to get the best in camera image possible.

[RustBeltRaw]

HSS is somewhat counterintuitive. Basically, at shutter speeds faster than the camera's sync speed, the flash duration will always be equal to the sync speed. So a 1/8000th shutter speed might have a 1/250th flash duration, which seems impossible until you realize that a focal plane shutter is only partially open for shutter speeds above its sync speed (see image below from Kathy's article).



Weirdly, this makes high-speed sync best suited to outdoor portraits, rather than the action one would expect. The flash lasts longer during HSS, so the subject is more likely to blur. Flash durations below the sync speed may be in the 1/500th-1/15,000th range (depends on the flash). So if flash if your main light, a 1/200th action photo may appear sharper than (for example) a 1/2000th action photo, since the firing flash, with its extremely shot duration, becomes the action-stopping mechanism instead of the shutter.

[Colin Southern]

HSS is somewhat counterintuitive. Basically, at shutter speeds faster than the camera's sync speed, the flash duration will always be equal to the sync speed. So a 1/8000th shutter speed might have a 1/250th flash duration, which seems impossible until you realize that a focal plane shutter is only partially open for shutter speeds above its sync speed (see image below from Kathy's article).



Weirdly, this makes high-speed sync best suited to outdoor portraits, rather than the action one would expect. The flash lasts longer during HSS, so the subject is more likely to blur. Flash durations below the sync speed may be in the 1/500th-1/15,000th range (depends on the flash). So if flash if your main light, a 1/200th action photo may appear sharper than (for example) a 1/2000th action photo, since the firing flash, with its extremely shot duration, becomes the action-stopping mechanism instead of the shutter.

For anyone who's interested, here's a site with some measured duration values ...

http://www.gock.net/2012/01/flash-du...small-strobes/

[RustBeltRaw]

For anyone who's interested, here's a site with some measured duration values ...

First round's on me, Colin. I spent about forty minutes looking for that info yesterday. Interesting that the 580EX II's full-power t.1 time is almost exactly equal to most Canon SLR sync speeds (1/250th). Canon really pushed that thing to the edge. Also interesting that some full-power durations are slower than that same sync speed. Buyer beware, it seems.

[Colin Southern]

First round's on me, Colin. I spent about forty minutes looking for that info yesterday. Interesting that the 580EX II's full-power t.1 time is almost exactly equal to most Canon SLR sync speeds (1/250th). Canon really pushed that thing to the edge. Also interesting that some full-power durations are slower than that same sync speed. Buyer beware, it seems.

No worries Lex,

Personally, I just mount the darn things and start shooting! Not much I can do about the rest.

[RustBeltRaw]

...just mount the darn things and start shooting! Not much I can do about the rest.

Good advice in general.

In other news, you were absolutely right about the 600EX-RT's addictiveness. I just ordered my third after going through some of my old work which used a three-light setup (two 580EX IIs and my first 600EX-RT), bemoaning the fact that I couldn't do that anymore. My total investment in hot-shoe flashes now exceeds the cost of both my camera bodies, even though each flash is used or refurbished.

[Colin Southern]

Good advice in general.

In other news, you were absolutely right about the 600EX-RT's addictiveness. I just ordered my third after going through some of my old work which used a three-light setup (two 580EX IIs and my first 600EX-RT), bemoaning the fact that I couldn't do that anymore. My total investment in hot-shoe flashes now exceeds the cost of both my camera bodies, even though each flash is used or refurbished.

I have little sympathy for you Lex ... I'm up to 6 now!

Do you have the ST-E3-RT also?

[RustBeltRaw]

I have little sympathy for you Lex ... I'm up to 6 now!

That'll take me a while. My skills can't juggle 6 lights yet. However, the lights are so damn good I no longer think you went overboard.

Do you have the ST-E3-RT also?

I don't. So far, my applications haven't absolutely required it. Most of my portrait work is two-light stuff, where I'll use the third light as a master to manually control the others. In derby, I pair two TTL lights with FlexTT5 radios, and trigger a third manually as a rim light. Considering the cost of the ST-E3, I'll probably make the plunge eventually. But for now, I think I'm in danger of my gear exceeding my skill.

[Colin Southern]

I don't. So far, my applications haven't absolutely required it. Most of my portrait work is two-light stuff, where I'll use the third light as a master to manually control the others. In derby, I pair two TTL lights with FlexTT5 radios, and trigger a third manually as a rim light. Considering the cost of the ST-E3, I'll probably make the plunge eventually. But for now, I think I'm in danger of my gear exceeding my skill.

Interesting; When I upgraded from the 580EX IIs I sold-off the TT5s. They worked OK, but the built-in RT is considerably better. I'd really encourage you to get the St-E3-RT; I think that a lot of people are still sniggering about the ST-E2, but about the only thing the ST-E3-RT has in common with it is that they both mount on the camera hot shoe. Highly recommended, and as you say, not very expensive. For portraits you could use one light for key, one for fill, and one for hair; a hair light is one of the key areas that lifts a portrait from amateur into professional quality.

[rpcrowe]

Funny thing happened on the way to the forum I was at a seminar on flash photography given by an "expert " from Canon...

I asked why one couldn't have the camera with HSS selected all the time (as Colin and I do) and then just have the shutter speed select whether you would be using HSS or standard sync. IMO, since the camera/flash revert to standard sync whenever the speed is at or slower than the maximum camera sync speed, there is no real reason to have a separate setting for HSS sync.

Our Canon "expert " didn't know that the sync would revert to standard sync when speeds at or below the maximum camera sync speed were selected and told me I was wrong. Luckily, I had the manuals with me and showed that to him in black and white. He saved face by saying that he was going to "look into the matter" and have the manual corrected

This reminds me of when in the second grade of grammar school (age seven or so), I mentioned (when we were all telling what happened over the summer) that I had received a gift of stamps from Monaco. The teacher said, you mean Morocco, there is no such place as Monaco (this was before Grace Kelly married Prince Ranier which made the name Monaco commonplace in America)! I realize that the general knowledge of geography held by many Americans ends at their city limits or state borders but, this gal was just plain dumb!

As was the Canon presenter about his product. He probably couldn't find Monaco on a map either

[Colin Southern]

Funny thing happened on the way to the forum I was at a seminar on flash photography given by an "expert " from Canon...

I asked why one couldn't have the camera with HSS selected all the time (as Colin and I do) and then just have the shutter speed select whether you would be using HSS or standard sync. IMO, since the camera/flash revert to standard sync whenever the speed is at or slower than the maximum camera sync speed, there is no real reason to have a separate setting for HSS sync.

Our Canon "expert " didn't know that the sync would revert to standard sync when speeds at or below the maximum camera sync speed were selected and told me I was wrong. Luckily, I had the manuals with me and showed that to him in black and white. He saved face by saying that he was going to "look into the matter" and have the manual corrected

This reminds me of when in the second grade of grammar school (age seven or so), I mentioned (when we were all telling what happened over the summer) that I had received a gift of stamps from Monaco. The teacher said, you mean Morocco, there is no such place as Monaco (this was before Grace Kelly married Prince Ranier which made the name Monaco commonplace in America)! I realize that the general knowledge of geography held by many Americans ends at their city limits or state borders but, this gal was just plain dumb!

As was the Canon presenter about his product. He probably couldn't find Monaco on a map either

Hmm - if Canon's technical guru Chuck Westfall made the statement then I'd believe him -- but few others! Oh and good luck to your man getting the manuals changed - in an eMail exchange with Chuck a few years ago he tells me that he's still trying to get them to change the manuals to clarify IS performance when tripod mounted; no success so far!

By the way -- I know Monaco very well - it's a few minutes drive from where I live ... lets see how long it takes folks to work THAT one out

[revi]

Well, you ex-europeans have taken to re-using a lot of names from here, so...