[LensBeginner]

HSS isn't really compatible with the manual flash mode. Even on an expensive flashgun, if I set my Metz 58 to a manual power setting like 1/64, M mode, then the camera refuses to shoot at higher than 1/180. Only if I set the flash to PTTL-HSS mode will it let me shoot faster, at 1/640 for example.

If I'm wrong with the following explanation then someone correct me, but I think it's because M mode on a flash is a 'whole sensor illumination flash mode', and there's a hard coded limit in Pentax cameras (except K1?) of 1/180 on every 'whole sensor illumination flash mode'. Only HSS, a PTTL function, gets round this by being special, having 'multiple flashes over the travelling curtain partially exposing parts of the sensor'. But only HSS lets you go above 1/180.

Bottom line, it's not exactly a Tumax thing, although labelling it TTL rather than PTTL isn't correct.

That's correct, it's an entirely different ball game.
In "normal" use the shutter's first curtain opens, leaving the sensor completely exposed to light, then the flash fires, then the exposure time passes, then the second curtain closes.

In HSS the second curtain starts moving before the first one has completed its travel, so only a slit of the sensor is exposed at any given time.
If the flash was to fire once, you'd only get a slit of the picture illuminated and the rest would be dark(er), you'll need the flash to fire repeatedly and precisely instead, which makes "dumb" manual triggering impossible.

[DafTekno]

Thanks y'all for the replies.

When I say "TTL" clearly I mean Pentax's "P-TTL", just abbreviated to "TTL".
We're all Pentaxians here, so why need I specify the "P" in front of "TTL"..? ;-)

I was trying to use HSS to take shots in our garden.
I was trying to fade the background into darkness (also using 4-stop ND filter) and re-illuminate the foreground subject with HSS flash.
Garden had very bright natural exposure requiring 1/6000 ISO 100.
I always shoot iris wide open to get maximum 'depth of field effect' / minimum actual depth of field.

I found the subject was 4 times out of 5 totally dark / underexposed, 1 time correctly illuminated. Camera framed virtually identically each time.
I can see why every camera shop I talk to says forget about TTL flash units, just go manual and buy some inexpensive units like the Yungnuo!
(I've already bought one, very good unit! Non-HSS but built-in radio transceiver).

My question regarding 'normal' flash mode in relation to HSS is that, clearly, the camera and flash need to communicate to synchronise the pulse timing, but why can't I then still have manual control over the flash power / brightness? Use the TTL com-link to sync the pulses but NOT for exposure info! Let ME dial in manually the flash power, keeping it consistent with every shot. Shame these 2 aspects can't be addressed separately.

And how exactly does the camera meter flash exposures?
If altering the spot / centre / matrix setting makes no difference, then this suggests that flash exposure is metered differently to ambient light metering.
Maybe the exposure of hot-shoe flash guns is done via the flash gun's own sensor..?

I love my Pentaxs. Over here in Canada, you rarely see Pentax DSLR's, making me even more drawn to them.
My Mother-in-law has a Canon DSLR. I picked it up the other day. It felt hollow, plasticy, rather unpleasant and the controls made no sense.
The K-50 and Kx feel like silky smooth, crafted precision instruments in comparison!

- D

[maxfield_photo]

When I say "TTL" clearly I mean Pentax's "P-TTL", just abbreviated to "TTL". We're all Pentaxians here, so why need I specify the "P" in front of "TTL"..? ;-)

Not many people are aware of this, but there actually is a difference in (Pentax) TTL and pTTL. The former is the old analog film flash system, and it works on a completely different principle. There was a sensor in the mirror box of TTL film cameras which pointed back at the film which was shiny. During a flash exposure this sensor would monitor the amount of light being contributed by the flash. Once it saw that the correct amount of light for the particular ISO and aperture had reached the film, the camera sent a quench command to the thyristor circuit in the flash and it would quench the flash. This all happens in a fraction of a second in real time, as the exposure was happening.

pTTL on the other hand, uses a low powered pre-flash to gauge the correct exposure, but it happens just prior to the main flash. If you watch closely, you can actually see it.

Here is an interesting read about flash control methods.
FlashZebra.com: Flash Exposure Control Methods

[mcgregni]

Your power demands sound potentially unrealistic ....a very bright garden, 4-stop ND and 1/6000th sec! The flash had to 'power through' and overpower all of that. 1/6000th at ISO 100 will already have caused a serious guide number drop (HSS loses power at progressively shorter exposure times), plus you're taking away 4 more stops with the filter.

I would try and get used to HSS working with a more realistic situation, say a nice backlit portrait with sun in behind giving rim light and the flash providing front fill. You should be able to get a better feel for your flashes capabilities and how it responds than when pushing things to such an extent.

[clackers]

My question regarding 'normal' flash mode in relation to HSS is that, clearly, the camera and flash need to communicate to synchronise the pulse timing, but why can't I then still have manual control over the flash power / brightness? Use the TTL com-link to sync the pulses but NOT for exposure info! Let ME dial in manually the flash power, keeping it consistent with every shot.

Well, just remember P-TTL does allow for Flash Exposure Compensation. You can manually boost by up to a stop, and go down by up to two.

You're never going to overpower sunlight except by being fairly close and perhaps using a snoot, because most of each pulse is hitting the backs of the two curtains as they swing through.

You can get very, very close and take two shots so you can Photoshop the strobe out.

Or you can use a reflector. I've always thought it more useful for macro than for portraits, where they make people squint in sunshine.

[LensBeginner]

Well, just remember P-TTL does allow for Flash Exposure Compensation. You can manually boost by up to a stop, and go down by up to two.

You're never going to overpower sunlight except by being fairly close and perhaps using a snoot, because most of each pulse is hitting the backs of the two curtains as they swing through.

You can get very, very close and take two shots so you can Photoshop the strobe out.

Or you can use a reflector. I've always thought it more useful for macro than for portraits, where they make people squint in sunshine.

I believe he was asking for manual as a way to achieve consistency, which can't be achieved with flash exposure compensation if pttl is acting up.

@OP: can't you lock down everything once you've found a setting you're happy with?
I believe pttl should allow that...

[UncleVanya]

Well, just remember P-TTL does allow for Flash Exposure Compensation. You can manually boost by up to a stop, and go down by up to two.

You're never going to overpower sunlight except by being fairly close and perhaps using a snoot, because most of each pulse is hitting the backs of the two curtains as they swing through.

You can get very, very close and take two shots so you can Photoshop the strobe out.

Or you can use a reflector. I've always thought it more useful for macro than for portraits, where they make people squint in sunshine.

Will multiple flashes help? I can't recall if P-TTL HSS permits that...

[mcgregni]

Any number of HSS capable flashes can be triggered as slaves, so long as the line of sight remains.


There's no 'lock down' of a P-TTL automatic exposure....a new reading is taken for each shot. However, if nothing changes then in my experience I have found the exposures to remain completely consistent.


... Strangely, HSS is often derided and questioned as unnecessary and alternative techniques promoted as better, even in some commercial publications (eg Neil van Niekerk). I'd suggest that in many situations it is the more practical option, assuming that the distances can remain realistic (we have the flash range indicator to help with this). Honestly, unless you've got plenty of time the extra faffing with a filter, especially in changing light when the exposure time may need to fluctuate around x-sync, is too much for me!

The modern Pentax flashes very conveniently flick into and out of HS mode automatically (once the mode is selected) when your time value switches to above or below the max sync. No need to keep resetting the mode. This advantage does not exist on any manual radio system alternative as these would involve going to the flash each time to adjust the mode and reset any delay setting.

[CarlJF]

I was trying to use HSS to take shots in our garden.
I was trying to fade the background into darkness (also using 4-stop ND filter) and re-illuminate the foreground subject with HSS flash.
Garden had very bright natural exposure requiring 1/6000 ISO 100.
I always shoot iris wide open to get maximum 'depth of field effect' / minimum actual depth of field.

You will have a hard time to overpower the sun with a speedlite! Usually, people who want to achieve this use some high power studio strobes...

That said, you should still be able to underexpose the background a bit, although not fade it in darkness. First thing to do is to set your camera in manual mode and set the time at 1/180 (the highest flash sync you can achieve), ISO100. The reason for this is that at flash sync, or slower speed, your flash can give you its max power. Then, close down the aperture to get a correct exposure. This will be your starting point and the largest aperture you can use without using ND filters. Now, if you want to underexpose the background, you close down the aperture for the # of stops you want to underexpose. Obviously, your flash have to be powerful enough to provide enough light to get a correct subject exposure. And there will be a point where it will not be possible to close more without getting the whole frame underexposed, the flash not being powerful enough. Outside in daylight, you may not be able to get more than half or 1 stop underexposure without hitting the flash power limit...

Now, if you don't want the close the aperture, you could add ND filter instead of closing down. But since the ND filter also cut the light from the flash, you will have the same limitations as above, the difference in exposure between the background and subject staying the same. For example, you will not be able to get more than half stop difference, but at F5.6 instead of F11...

But, in these situations, it's usually easier to make do with the bright ambient light and just use the flash to fill shadows by dialing negative flash compensation... You can use large aperture if you wish to and a speedlite usually have enough power to do this instead of having to over power the sun. And this is were HSS is really useful: to get a fill flash using large aperture at fast shutter speed.

[LensBeginner]

Any number of HSS capable flashes can be triggered as slaves, so long as the line of sight remains.


There's no 'lock down' of a P-TTL automatic exposure....a new reading is taking for each shot. However, if nothing changes then in my experience I have found the exposures to remain completely consistent.


... Strangely, HSS is often derided and questioned as unnecessary and alternative techniques promoted as better, even in some commercial publications (eg Neil van Niekerk). I'd suggest that in many situations it is the more practical option, assuming that the distances can remain realistic (we have the flash range indicator to help with this). Honestly, unless you've got plenty of time the extra faffing with a filter, especially in changing light when the exposure time may need to fluctuate around x-sync, is too much for me!

The modern Pentax flashes very conveniently flick into and out of HS mode automatically (once the mode is selected) when your time value switches to above or below the max sync. No need to keep resetting the mode. This advantage does not exist on any manual radio system alternative as these would involve going to the flash each time to adjust the mode and reset any delay setting.

I've heard that in a Joe McNally video... maybe it's just a Nikon thing. As I said I only shoot manual only.

[clackers]

Will multiple flashes help? I can't recall if P-TTL HSS permits that...

Yep, I've got a triple holder for a light stand. They can all live inside your softbox or behind your umbrella.

And the Priolite is an HSS strobe.

[maxfield_photo]

I like to lash two flashguns together by the heads, one upside down on top of the other. I haven't broken down yet and bought a triple or quad flash bracket but it's on my list of gear to acquire. I use that when my subject is stationary, and I can take the time to get the exposure right, like outdoor fashion shoots.

I also made a long TTL cord out of a short coiled cord, and a 25 foot CAT5 ethernet cable. I can even sub out the 25 foot cable for a 50 footer if I need to, but so far I haven't. That allows me to use my Metz 58 hardwired and off-camera as if it were sitting on the hotshoe. It's a good setup for moving subjects when there isn't time to take an incident reading and adjust the exposure manually, like dancers on a ballroom floor.

[clackers]

I believe he was asking for manual as a way to achieve consistency, which can't be achieved with flash exposure compensation if pttl is acting up.

Sure, P-TTL metering is heavily influenced by anything reflective in the scene. Glass indoors can be a nightmare.


I do shoot manual flash quite a bit with the Yongnuo and Cactus v5 wireless systems with a Sekonic light meter, so consistency is great, but of course, there's no HSS.

[stevebrot]

Not many people are aware of this, but there actually is a difference in (Pentax) TTL and pTTL. The former is the old analog film flash system, and it works on a completely different principle. There was a sensor in the mirror box of TTL film cameras which pointed back at the film which was shiny. During a flash exposure this sensor would monitor the amount of light being contributed by the flash. Once it saw that the correct amount of light for the particular ISO and aperture had reached the film, the camera sent a quench command to the thyristor circuit in the flash and it would quench the flash. This all happens in a fraction of a second in real time, as the exposure was happening.

Yep...I own and use both body and flash that support that protocol. It works very well.


Steve

[UncleVanya]

Maybe I was unclear. Does Pentax HSS P-TTL take multiple units into account or does each provide the light output it thinks is needed without respect to the other flash or something else?