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12-17-2016, 04:04 AM - 1 Like   #1
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For curiosity, I have R930, V6II, X1N all for review.

I collect these triggers and I expect a reasonable, fair, and scientifical test for all of them.
And they arrived.

I am not to intentionally specify which is best but I would like to have many chapters and make marks. As so many debate here about this topic. I think this might help people to make clear understanding rather than by heard on the road method.

CHAPTER 1 TRIGGER BASIC

OK, first things first. Triggers, or radio triggers. No matter how complex they can be, basically, they are used the fire the flash as quick as possible as the camera tells it to do. for normal sync speed. for example, Pentax 1/200 second max. and Nikon 1/320 second.

At the right beginning, the front curtain of the shutter open, the CCD is exposed to light. the flash fire, have the light reflected to the CCD. this last 1/320 = 3125 uS for Nikon and shutter speed 1/320. and CCD exposed last for this long time. the rear curtain close the exposure.

So it is clear, if the flash fire after 3125 uS from the first curtain open. I would not give light to CCD.

The radio delay, Should come from the electronic circuit. circuit processing need time to be done. I call this as speed of radio trigger.or trigger delay and this figure show the delay data for each of these 3 triggers.



From the above, We learn that, third party RADIO trig isn't an ideal tech. for it simply have the delay. while a wire or ottical would make no delay.
this make effect when shotting moving object, it is impossible to mimic a wire or optical trigger.

Though, How it matter the camera processing isn't known.


The delay should be as short as possible. I give 4 star for R930, 3 for X1N, and 2 for V6II.

CHAPTER 2 Manual Fire

All 3 triggers are able to set manual flash output. The use similar tech. first, set the flash to TTL-Hss mode., they mimc the TTL to set a power level.
The question arise: is this manual power the REAL manual ? If you exmaine the photo taken, yes the power have been set.

But, further examination make me so suprised, and I classify them in to 2 kinds.

1) Real Manual. this make exatly the same power like setting the flash to manual mode.

2) Fake Manual, this introduce some other preflash, this waste power and most worse. impossible to use light meter.

figure 2-1 for fake Manual trigger, firgure 2-2 for real Manual. Set the camera as the parameters suggested by the light meter.

another one: http://i1.piimg.com/4851/903a437a3f09a26e.jpg
2-1
another one : http://i1.piimg.com/4851/cca67f84bb5df78f.jpg
2-2

The V6II make fake Manual and R930 make Real.
CHAPTER 3 PTTL
Here is the picture taken
https://www.pentaxforums.com/forums/125-flashes-lighting-studio/336313-pttl-v...ml#post3862307
CHAPTER 4 Multi Brand

Multi Brand makes it possible for cross brand usage, Both R930 and V6II claim supporting M.B. But actrually, due to this tech complexity, It seems easily introduce problem. I don't have all models for test, but accoding to the SB600 I have, which supposed to be supported well, It is.
[B][I][U]CHAPTER 5 Support studio flash
Some studio flash use the 3.5mm port to let triggerring. So the all 3 seems to have such function.

UI

Radio Optical Mix



Last edited by andy888; 12-31-2016 at 03:37 AM.
12-17-2016, 04:21 AM   #2
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Be interesting to see how the Acon triggers work, they were the ones I was looking at before I got the V6II
12-17-2016, 02:18 PM   #3
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I'm keen to understand how you're measuring the delay between camera firing and the Rx trigger firing the flash. Looking at the delay numbers you've published, none of these triggers would appear to support a shutter speed of 1/4000 (250uS) or 1/8000 (125uS), as they'd fire the flash after the curtain has closed. Since people are happily using the Godox and Cactus (and I believe the Acon, although I'm less familiar with it) for HSS up to these speeds, this seems a little off.
12-17-2016, 07:07 PM   #4
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QuoteOriginally posted by paulster Quote
I'm keen to understand how you're measuring the delay between camera firing and the Rx trigger firing the flash. Looking at the delay numbers you've published, none of these triggers would appear to support a shutter speed of 1/4000 (250uS) or 1/8000 (125uS), as they'd fire the flash after the curtain has closed. Since people are happily using the Godox and Cactus (and I believe the Acon, although I'm less familiar with it) for HSS up to these speeds, this seems a little off.
These was measured by simple oscilosicope, an electronic tool.

The shutter speed for 1/320 to 1/8000 is HSS, this isn't the same as what happend in Chapter 1. I would mention in other Chapter.

12-17-2016, 08:19 PM   #5
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QuoteOriginally posted by paulster Quote
Looking at the delay numbers you've published, none of these triggers would appear to support a shutter speed of 1/4000 (250uS) or 1/8000 (125uS), as they'd fire the flash after the curtain has closed.
There are two different ways of firing a flash:
  1. standard sync timing: shutter speed must not exceed the sync speed of the camera.
  2. high-speed timing: any shutter speed is supported as the flash gets an advance warning that it will need to create output. Often people refer to a "pre-sync" signal.
The delay introduced by a trigger is most relevant for case 1., as any delay inevitably pushes the flash output "later into the frame", potentially moving parts of the output outside the frame (the more, the faster the shutter speed becomes). The worst effect occurs when the closing curtain already started to move before the flash output occurred, in which case you'll see a black bar (at the bottom of the frame, unless a camera uses an upside-down shutter, like the K-1, for instance). Some triggers, like the RF-620 are so slow on a Pentax camera that this actually happens at shutter speeds of 1/180s or even 1/160s.

For case 2. the trigger delay does not translate to an actual delay of the main flash because the trigger and flash gets such an advance warning that they have time to produce the output on time.
12-17-2016, 09:45 PM   #6
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QuoteOriginally posted by andy888 Quote
for normal sync speed. for example, Pentax 1/200 second max. and Nikon 1/320s second.
Are you aware of any cameras with a focal plane sync speed higher than 1/320s?

In the past, there were some models that used an electronic shutter to achieve higher sync-speeds but I understand the combination of electronic shutter and flash is not a good idea.

So that seems us to leave with physical shutter speeds and I wonder if there are no shutter assemblies that support a higher sync-speed than 1/320 then why are you looking in detail at delays that are already small enough to comfortably meet 1/320s?

I have a couple of questions about your diagram and measurements.

Question 1:

The first camera side signal slope shows when the shutter has been fully opened, correct?
At least the definition of X-sync is that the "the timing of the contacts coincides exactly with the full opening of the shutter".
Or does the sync signal occur slightly before the first curtain fully opens?

The sync-speed defines the shortest exposure time that still exposes the full frame at once. However, does that mean that the second curtain starts moving immediately after the first curtain has reached its destination? In terms of exposure time for ambient light, that would be fine, but it would represent a problem for flash photography, because the part of the frame that gets covered by the second-curtain sync first would not receive most of the flash output unless the flash output is instantaneous.

However, we know that flash output is not instantaneous. In your example, the output appears to require 1/800s, and the Metz 58 AF-2 manual states at full power, the flash duration T0.1 time is 1/125s (8000μs). I actually confirmed that at 1/180s, I'm not getting all of the light that the Metz 58 AF-2 emanates at full power.

So do you know more about the curtain timing? Is there perhaps a small pause between the first curtain arriving and the second curtain closing even at sync-speed for allowing a flash to discharge? Or is the sync signal occurring slightly before the first curtain arrives? All this would have some impact of how bad radio trigger delays are.


Question 2: The signal form shown for the flash output is just a schematic, right? I don't know the D-lite RX 4, they don't seem to be IGBT-based. Speedlights (and increasingly more strobes) have a very different discharge characteristic. A very quick rise and discharge of most of the power is followed by a long tail of exponentially decreasing output. As a result in practice most flashes are a lot quicker than 1/800s to produce the majority of their output. For instance, the Metz 58 AF-2 already is at 1/1500s for 1/4 output and in the much more common T0.5 currency that is 1/4500s. This means that radio trigger delays are not that critical as they may first appear in your diagram as there is typically more than 3125-1250μs = 1875μs time to get a useful amount of the flash's output on the sensor.


Question 3:
Did you perhaps make an error for the PocketWizard Plus III?
PocketWizard state for the Plus III:
"Up to 1/250 for focal plane shutters
Up to 1/500 for leaf shutters
"
According to your measurement (3125μs delay), the PocketWizard Plus III does not support 1/320s at all and at 1/250s (4000μs) it would only support fully capturing a flash duration of 1/1142s, i.e., it would cut off most of the output produced by a speed light at full power (taking 1/125s to discharge to a level of 90%).

That cannot be right, can it?

I don't hear PocketWizard users complaining about not being able to properly use their speedlights at 1/250s.

Is your 3125μs figure for the PocketWizard Plus III an error? It is exactly 1/320s, so perhaps did you mix it up with the sync-speed?
Is there any other reason why it would be exactly 1/320s, the highest physical sync-speed of a Nikon camera?

Last edited by Class A; 12-17-2016 at 10:31 PM.
12-17-2016, 09:46 PM   #7
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QuoteOriginally posted by andy888 Quote
These was measured by simple oscilosicope, an electronic tool.
Do you own an oscilloscope?
These aren't exactly cheap, are they?

What else do you use it for?

BTW, how do you measure when the shutter is fully open?

Or do you rather measure the point in time when the trigger receives the sync-signal from the camera?
As I discussed earlier, the latter point in time may not be exactly the time when the shutter has fully opened.

As a matter of fact, I think it is unlikely, that sync-signal occurs exactly when the shutter has fully opened because even optical triggering induces some delay. There is at the very least the processing time of the optical receiver that has to be taken into account. I could also imagine that some kind of information is transmitted even during the trigger flash and that would induce a further delay, but I have no knowledge about when information is transmitted to off-camera flashes. After the initial pre-flash phase, the camera has to inform the off-camera flash what actual flash power to use, but I don't know whether that occurs during the trigger flash or an advance control flash.


Last edited by Class A; 12-17-2016 at 10:39 PM.
12-17-2016, 10:16 PM - 1 Like   #8
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How does your rating system work?

QuoteOriginally posted by andy888 Quote
I give 4 star for R930, 3 for X1N, and 2 for V6II.
How does your star rating system work?

In terms of a ranking from fastest to slowest, your ordering is correct (but misses the PocketWizard trigger for some reason).

This is not how star systems typically work, though.
Often a five star system is used with roughly the following meaning
5 star = excellent
4 star = very good
3 star = OKish
2 star = has significant problems
1 star = has serious problems to the point of being unusable

Let's say no radio trigger deserves five stars as there is always some small delay and this delay can (but need not always) impact on how much of the flash's output is actually captured.

We should then reserve one or two stars for triggers that are so slow that they actually cause black bars at the sync-speed or even slower.

That leaves four and three stars for triggers that do not introduce black bars but may cause some of the flash output (at long flash durations) to be cut off.

Noticing that the V6II has 97.5% of the speed of the X1N (whereas both only have 43.75%) of the speed of the R930, it does not seem warranted to separate the X1N and V6II with a different star rating.

Looking closer, let's look at what the latency differences mean:

We already know they mean nothing with respect to black bars. The highest Pentax sync-speed is 1/200s and even the 1/320s of some Nikon camera are comfortably supported.

Let's look at what the latency means for cutting of flash output at the end:
Assuming a 1/125s discharge time for a flash (Metz 58 AF-2 T0.1 time at full power) then the R930 allows using a maximum shutter speed of 1/119s (350+8000μs) to capture 90% (we are dealing with a T0.1 time) of the output. Faster than that and more of the flash's output will be cut off.

What is the fastest shutter speed supported by the slowest of the triggers you looked at that still supports 1/320s (V6II)?
It is 820+8000μs = 1/113s.

So, we have a difference between 1/119s and 1/113s. That's a 0.07stop difference. That's nothing. The difference is irrelevant in practical terms.

So I'd say all R930, X1N, and V6II deserve four stars while the PocketWizard Plus III only should receive three or two (depending on whether your measurements are correct).

P.S.: Even the PocketWizard Plus III (assuming your measurement is correct) still supports 1/90s as the maximum shutter speed to capture 90% of the output of a Metz 58 AF-2 at full power. Again, that is not a huge difference compared to the 1/119s of the R930.

The main problem with the high latency of the PocketWizard Plus III is therefore not how much it impacts on shutter speed to avoid cutting off flash power; the main problem is that (according to your measurement) it does not support a 1/320s sync-speed (which would not be a problem for use on Pentax cameras, BTW). None of the other three triggers have an issue with supporting 1/320s (and well beyond) so I really don't see why one would separate them in a rating.

Last edited by Class A; 12-17-2016 at 10:27 PM.
12-17-2016, 10:22 PM   #9
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QuoteOriginally posted by Class A Quote
Are you aware of any cameras with a focal plane sync speed higher than 1/320s?

In the past, there were some models that used an electronic shutter to achieve higher sync-speeds but I understand the combination of electronic shutter and flash is not a good idea.

So that seems us to leave with physical shutter speeds and I wonder if there are no shutter assemblies that support a higher sync-speed than 1/320 then why are you looking in detail at delays that are already small enough to comfortably meet 1/320s?

I have a couple of questions about your diagram and measurements.

Question 1:

The first camera side signal slope shows when the shutter has been fully opened, correct?
At least the definition of X-sync is that the "the timing of the contacts coincides exactly with the full opening of the shutter".
Or does the sync signal occur slightly before the first curtain fully opens?

The sync-speed defines the shortest exposure time that still exposes the full frame at once. However, does that mean that the second curtain starts moving immediately after the first curtain has reached its destination? In terms of exposure time for ambient light, that would be fine, but it would represent a problem for flash photography, because the part of the frame that gets covered by the second-curtain sync would not receive most of the flash output unless the flash output is instantaneous.

However, we know that flash output is not instantaneous. In your example, the output appears to require 1/800s, and the Metz 58 AF-2 manual states at full power, the flash duration T0.1 time is 1/125s (8000μs). I actually confirmed that at 1/180s, I'm not getting all of the light that the Metz 58 AF-2 emanates at full power.

So do you know more about the curtain timing? Is there perhaps a small pause between the first curtain arriving and the second curtain closing even at sync-speed for allowing a flash to discharge? Or is the sync signal occurring slightly before the first curtain arrives? All this would have some impact of how bad radio trigger delays are.


Question 2: The signal form shown for the flash output is just a schematic, right? I don't know the D-lite RX 4, they don't seem to be IGBT-based. Speedlights (and increasingly more strobes) have a very different discharge characteristic. A very quick rise and discharge of most of the power is followed by a long tail of exponentially decreasing output. As a result in practice most flashes are a lot quicker than 1/800s to produce the majority of their output. For instance, the Metz 58 AF-2 already is at 1/1500s for 1/4 output and in the much more common T0.5 currency that is 1/4500s. This means that radio trigger delays are not that critical as they may first appear in your diagram as there is typically more than 3125-1250μs = 1875μs time to get a useful amount of the flash's output on the sensor.


Question 3:
Did you perhaps make an error for the PocketWizard Plus III?
PocketWizard state for the Plus III:
"Up to 1/250 for focal plane shutters
Up to 1/500 for leaf shutters
"
According to your measurement (3125μs delay), the PocketWizard Plus III does not support 1/320s at all and at 1/250s (4000μs) it would only support fully capturing a flash duration of 1/1142s, i.e., it would cut off most of the output produced by a speed light at full power (taking 1/125s to discharge to a level of 90%).

That cannot be right, can it?

I don't hear PocketWizard users complaining about not being able to properly use their speedlights at 1/250s.

Is your 3125μs figure for the PocketWizard Plus III an error? It is exactly 1/320s, so perhaps did you mix it up with the sync-speed?
Is there any other reason why it would be exactly 1/320s, the highest physical sync-speed of a Nikon camera?
I used Plus III as rough demo, actrualy no measuement for it provided for me. so I refined it to other,
12-17-2016, 10:44 PM   #10
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QuoteOriginally posted by andy888 Quote
I used Plus III as rough demo, actrualy no measuement for it provided for me. so I refined it to other,
Oh, I see.

I hope you will answer my other questions as well.
12-17-2016, 11:12 PM   #11
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QuoteOriginally posted by andy888 Quote
2) Fake Manual, this introduce some other preflash, this waste power and most worse. impossible to use light meter.
I agree that during manual control there should ideally be no pre-flash.

I don't care about the impact on light meters because I don't use them (professionals like David Hobby don't use light meters either), but I care about the delay introduced by the pre-flash and the battery life that it impacts on.

During beta testing the V6II, I provided feedback to Cactus stating that there should be a mode in which one can manually control a flash that does not involve a pre-flash, even if it only works for shutter speeds that do not exceed the sync-speed. I was told that due to technical reasons this would not be possible. Cactus told me that many modern flashes make the pre-flash non-optional.

So how does the R930 do it?

The R930 is first and foremost a P-TTL trigger, right?
So normally, there is a pre-flash, correct?

Now the R930 also supports manual remote control, but how can it prevent the pre-flash from occurring in this case?

Does the R930 still imply a delay, but just manages to not issue a pre-flash?
Does this work for all flash models (e.g., Pentax AF 540 FGZ II)?

Are we talking about the same situation, that is remotely controlling the power level via the camera-mounted transmitter?

Of course, if one puts a flash into manual mode than even a V6II can trigger it without causing a pre-flash. But that would mean no remote power-level control.

Based on Cactus' reply, I was under the assumption that it is technically not possible to remotely control the power level of a modern flash and avoid the pre-flash at the same time. Were Cactus wrong in their response?

QuoteOriginally posted by andy888 Quote
figure 2-1 for fake Manual trigger, firgure 2-2 for real Manual.
Well, all you are showing here is that your light meter got confused by the pre-flash.

Your use of "Fake Manual" makes it sound as if the power levels are not right and your images appear to provide support for that. However, you clearly did use different manual flash power settings for those different images, so you are not showing any difference in "fake" vs "real" output, you are just showing that light meters cannot cope with pre-flashes.
12-18-2016, 12:37 AM - 1 Like   #12
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QuoteOriginally posted by Class A Quote
So how does the R930 do it?
All these detailed technical questions.
Sounds like it may be time for you to invest in a R930 pair [for science].
12-18-2016, 01:37 AM   #13
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I suggest if he got a pair, that ClassA should be tasked with carrying out a series of extreme body casing stress tests, to assess the performance of the Acons in staying complete and intact. ... For example in conditions such as being hurled violently against a brick wall, being attacked with a baseball bat or stamped on with large tramping boots.
12-18-2016, 01:41 AM   #14
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QuoteOriginally posted by rawr Quote
All these detailed technical questions.
I don't view asking how the R930 manages to not use a pre-flash as a technical question (and I have difficulty thinking of other technical questions).

I'm mainly looking for confirmation that Andy888 indeed uses the R930 in a remote power control situation and still avoids the pre-flash. If he is not, then he is not doing a fair comparison. If he is, I'll get back to Cactus and tell them, "Look, there is a way. You should try harder.". I like the V6II in many, many ways, but I don't think it is optimal that flashes other than the RF60(x) always use a pre-flash.

QuoteOriginally posted by rawr Quote
Sounds like it may be time for you to invest in a R930 pair [for science].
I'm accepting donations.

Seriously, I won't spend my money on triggers I don't want, just to play with them. Maybe the newer model with a display could be interesting, if it supports efficient manual control, but the R930 as it is, I'm not keen on. I'm not a P-TTL user at all and the R930's usability for manual control is heavily compromised by the lack of supporting hardware.

Anyhow, I don't have an oscilloscope so I wouldn't be able to do detailed technical measurements. I wouldn't have the interest nor the time to reverse engineer the R930 and even if I did, what would I do with the results?

Last edited by Class A; 12-18-2016 at 06:41 AM.
12-18-2016, 01:46 AM   #15
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QuoteOriginally posted by mcgregni Quote
I suggest if he got a pair, that ClassA should be tasked with carrying out a series of extreme body casing stress tests, to assess the performance of the Acons in staying complete and intact.
I had to laugh about the phrasing you used in your post, but seriously what makes you think I harbour any aggression towards the Acon triggers?

I won't deny certain frustration levels when it comes to communicating with certain proponents of said triggers, but the source of the former are unrelated to the trigger hardware.
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