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06-29-2015, 10:05 PM   #46
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QuoteOriginally posted by stevebrot Quote
Or shoot with available light and call the blur "art".


BTW...the dancer and everyone else on stage will thank you for not using flash during the performance.


Steve
It occurred to me that the comment above might be read as being flippant, but that was not the intent. As with most tasks, the intent (use case) determines best practice in terms of tools and techniques. From my perspective, on-camera flash automation (P-TTL, TTL, and auto-thyristor) has its best use for documentary photography where little is predictable and the photographer cannot completely control the staging of the subject. On the other side of the spectrum you have the strobist approach where the photographer has almost complete creative control over light and how it plays on the subject. In between is the realm of multi-flash automation using P-TTL, TTL, and auto-thryristor where the intent is to control as much of the light as possible, but the real-time settings are not predictable.

In both the first and third cases, automation in real time is preferable and allows for flash discharge as soon after the shutter-press as possible. Of the three types, only true TTL and auto-thyristor adjust flash duration in real time. P-TTL will always result in a lag between shutter press and the main flash. The duration of that lag may vary by subject, ambient light, and system vendor, but it will always be there. In this thread, we have discussed the latency of the Pentax P-TTL implementation on the K-3. Total latency (AF, shutter actuation, etc) may or may not be better/worse than other Pentax models or P-TTL systems from other manufacturers. For some subjects, a few milliseconds make little difference. For others, say the dancers referenced above, the lag may result in a total loss of the shot.

Oh...and there is always the option of available light. A question might be, why am I using flash? A good example might be stage lighting. In many cases the light striking your subject on stage is at least as bright as full daylight. So, put the camera in M-mode at ISO 1600, 1/2000s, and f/8 and shoot at will.


Steve

06-30-2015, 05:15 AM   #47
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QuoteOriginally posted by enoeske Quote
When the pre-flash goes off matters. Imaging you are trying to snap a shot of a dancer jumping in the air. You fire a shot mid jump. But due to the pre-flash delay, the dancer is already on the ground and onto the next move when your flash finally goes off. You'd have to try and memorize the exact amount of delay and shoot before the move is performed.
Tanks, of course it matters... but above was stated the preflash delay was fixed but the final flash exposure still came 'late',
that's why I don't value the 'faster pre-flash' : what counts is the time it takes 'the whole system' to do what it needs doing

---------- Post added 06-30-15 at 05:33 AM ----------

QuoteOriginally posted by stevebrot Quote
Or shoot with available light and call the blur "art".


BTW...the dancer and everyone else on stage will thank you for not using flash during the performance.


Steve
The K3 cought my attention by its high ISO capabilities, thus being able to avoid flash for (mostly well lit) stage performances
At parties where lighting is constantly changing and flickering I like subject-motion blur, frozen at the end by some extra flash in 2nd ctn

With the K3 I would try to play with ISO/flash ratio to find a ratio where flash output is minimised without losing the effect,
an extra bonus would be faster flash recycle times

btw, I won't be going with 'fast primes', at indoor parties I like to have zoom range and will stop it down anyway to get reasonable dof

---------- Post added 06-30-15 at 06:00 AM ----------

QuoteOriginally posted by stevebrot Quote
It occurred to me that the comment above might be read as being flippant, but that was not the intent. As with most tasks, the intent (use case) determines best practice in terms of tools and techniques. From my perspective, on-camera flash automation (P-TTL, TTL, and auto-thyristor) has its best use for documentary photography where little is predictable and the photographer cannot completely control the staging of the subject. On the other side of the spectrum you have the strobist approach where the photographer has almost complete creative control over light and how it plays on the subject. In between is the realm of multi-flash automation using P-TTL, TTL, and auto-thryristor where the intent is to control as much of the light as possible, but the real-time settings are not predictable.

In both the first and third cases, automation in real time is preferable and allows for flash discharge as soon after the shutter-press as possible. Of the three types, only true TTL and auto-thyristor adjust flash duration in real time. P-TTL will always result in a lag between shutter press and the main flash. The duration of that lag may vary by subject, ambient light, and system vendor, but it will always be there. In this thread, we have discussed the latency of the Pentax P-TTL implementation on the K-3. Total latency (AF, shutter actuation, etc) may or may not be better/worse than other Pentax models or P-TTL systems from other manufacturers. For some subjects, a few milliseconds make little difference. For others, say the dancers referenced above, the lag may result in a total loss of the shot.

Oh...and there is always the option of available light. A question might be, why am I using flash? A good example might be stage lighting. In many cases the light striking your subject on stage is at least as bright as full daylight. So, put the camera in M-mode at ISO 1600, 1/2000s, and f/8 and shoot at will.


Steve
oops...
got to read this after replying to your your previous post ...
but we seem to think +- alike

I got pretty wel used to dealing with shutter lag (calling it that because what counts is when the pic is taken)

got a bit scared when I read all these 'delay reportings',
guess pre-visualisation will always be necessary for what I want to obtain

so all that matters is : is the delay consistent...
(my present m.o. for fast spinning salsa-girls is depressing shutter when I see theyr back...
that usually gets me a pic of their face with the hair whizzing around )

Last edited by pavare; 06-30-2015 at 06:05 AM.
07-01-2015, 07:36 AM - 1 Like   #48
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Based on Imaging Resources tests, and my own somewhat unscientific tests, the additional delay due to pre-flash roughly doubles the timing between shutter press and image capture. Whether it adds 1.8x or 2.2x is not easily nailed down, but it is tangible. We tend to assign very short latency to "instantaneous" because we aren't noticing it. On my very old, very original LX - the TTL is a somewhat slow process. On the *istD - which performed far better in TTL in all respects than any of the pTTL-only units since among the four later models I have owned - it was very quick but still not as fast as auto-thyristor.

Every operation in a flash system - even any electrical pulse involved in triggering - takes some amount of time. People have complained even that the Metz AF-58 maximum flash duration is 1/500 (not hss related) - and that's valid because in specialized situations you'll get blur with such long duration. What makes auto-thyristor and ratio superior is that absolutely nothing the camera is doing adds into the flash operation. The camera sends its pulse to the PC connection and hot shoe on every shot whether or not a flash is connected; the flash is on its own from there. Even on real TTL, because you have the in-body sensor, electronic operations are carried out (Steve is correct that it is real time), and you can have some added delay. It was somewhat noticeable in the early film days, but relatively quick.

It was a sad day when Pentax brought out the new line of flashes. Yes, WR and metal feet (for clumsy folks), but they were cheapened where it really counts - taking away Auto and no longer capable of real sensor-based TTL. If Pentax wanted to make greater inroads into the pro community with FF and MF, they should have considered returning to real TTL for their best cameras. I'm happy, though, that the K-3 has ratio down to 1/128 on-board - which works great for very soft fill coupled with an external bounced flash.
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