Inon Z-330 ready light comes on early

I recently upgraded from a Z-240 to a Z-330 and when in full power I noticed the ready light comes on at about 2s (as advertised for the recycle time in the technical specifications) but the power is significantly less. I would say it falls short about 1-2 F-stops. It actually takes about 5-6s before my strobe is fully recycled. I am using new eneloop pro batteries.

Below is an image comparing the light output when ready light is turned on (2s recycle) and after 6s.

Is anyone else getting this result with their Z-330 ?

I am considering if the strobe is somehow faulty because the ready light comes on when it should but the power is not there. I can hear a noise in the strobe after the ready light is on meaning the capacitors are still being charged. On the other hand the recycle time specifications for the Z-240 are almost identical to the Z-330 but the Z-330 has about 1 F-stop more power. This means it should have about twice the energy of capacitors and it should take about twice as long to recycle if the current flow is the same. Because I get about 5-6s actual recycle time this could mean the specifications are misleading.

Update: Over the weekend I presented my doubts to a friend who has a bunch of UW strobes, including the Z-330 and access to a light meter from a photo studio. He was using alkaline batteries which normally take longer to recycle the strobe but since the test is about trying to find out how much power the strobe emits at the ready light this was not a problem for the test. It's even more precise trying to catch the ready light when the recycle time is longer. I was suffering with my test on the camera since 2s is very difficult to catch and the results may vary more.

Here are the differences between ready light power and full power using an Ikelite DS160, Sea&Sea YS110, Retra Strobe and Z-330:

DS160 - 0.5 F-stop

YS110 - 0.6 F-stop

Retra - 0.6 F-stop

Z-330 - 1.4 F-stop

The results can vary about 0.1 to 0.2 F-stop because the test relies on looking at the ready light and triggering the strobe as fast as possible once it turns on.

It seems all strobes turn on the ready light before they are fully recharged. Most of them do it when they are at about 75% charge (about 0.5 F-stop difference) which is disturbing because what's the point of the ready light if the strobe is not fully recharged?! Even more disturbing is that with the Z-330 the ready light turns on at about 25% charge!

It's a balancing act, If you are shooting at less than full power which is probably fairly common, you want the light to come on earlier as it has enough charge to to put out a half or quarter power flash by the time the light comes on. I know I'm shooting at 1-2 stops off full power much of the time. There will be variations in the capacitors and other components around the specs which leads to some variation in charge times but the Z-330 you have seems excessive and maybe outside tolerances.

Regarding the statement about the Z-240 vs Z-330, I recall that there was discussion on this forum around the number of full power flashes you could expect from a Z-240 vs a Z-330 on the same batteries. You would expect it to be less as the Z-240 is GN 24 and the Z-330 GN33 (just under 1 stop difference) plus the Z-330 has a wider beam requiring more power. However someone tested them and the result was that the Z-330 put out as many flashes as the specs said and about the same number of flashes as the Z-240, indicating the Z-330 was more efficient at converting battery power into light on the subject. This could mean more efficient conversion electronics for charging capacitors, more efficient flash tubes or quite likely more efficient optics to form the beam. It doesn't necessarily follow that the current flow is double and based on the tests I refer to it would mean current flow out of the batteries is about the same, it's just being used more efficiently. One of the things that INON did in the redesign was address heat buildup, with a better heat sink and it seems there might be other changes that increased overall efficiency which would result in less heat buildup as well. Or it could be a way to meet both the recycle time and number of flashes specs within the constraints of the power from 4 x AA NiMH batteries??

Regarding your flash I would suggest it's outside specifications and may be faulty, but proving that and getting something done may be a challenge?? Talk to your dealer about it. I think showing it is under performing compared to another Z-330 might help build a case.

"Ready" light on most of underwater strobes switches On rather far before stop moment. Underwater strobe continue charging after ready signal.

Regarding your flash I would suggest it's outside specifications and may be faulty, but proving that and getting something done may be a challenge?? Talk to your dealer about it. I think showing it is under performing compared to another Z-330 might help build a case.

I am starting to doubt it because mine and my friends are both having the same "issue". He got his early on in 2018 when they started shipping and mine was purchased recently so it's unlikely the "issue" is with a specific batch as well.

"Ready" light on most of underwater strobes switches On rather far from stop moment. Underwater strobe continue charging after ready signal.

There is no indication on any manufacturers webpage about power at ready light. Only "recycle time" which, it turns out, is not accurate at all.

It's so disappointing because we are buying a product based on specifications that are at best not accurate but at the worst completely deceptive!

.....

I was also surprised by that once, in the past. But what to do ...

Hi Everyone

It's true that UW flashguns signal the ready light at about 80% power because the capacitors take almost twice as long to charge the last 20%. It is similar to batteries in electric cars and mobile phone which advertise a fast charging time to 80% capacity because it takes so much longer to recharge the last bit.

When we started making our own flash we were surprised to find this out - as Pavel said it's not possible to recharge at such a fast rate because the charging curve is always more horizontal and not vertical! But we had to take into account everyone will compare the provided specifications and with no UW flashgun does it say the recycle time is measured to about 80% power - although in reality it is and with some flashguns it's even much lower like Jerry pointed out.

A similar problem is also with GN which we don't publish any more because there is no sense trying to compete with inflated specifications provided by some manufactures.

It's true that UW flashguns signal the ready light at about 80% power because the capacitors take almost twice as long to charge the last 20%. It is similar to batteries in electric cars and mobile phone which advertise a fast charging time to 80% capacity because it takes so much longer to recharge the last bit.

The difference being that car and phone manufacturers were transparent with their actual recharge time and power. From what I've read until now there is no indication that any UW strobe manufacturer specified their recycle time to be at 80% power let alone around 30% power as it seems to be with the Z-330. This is just fraud!

When we started making our own flash we were surprised to find this out - as Pavel said it's not possible to recharge at such a fast rate because the charging curve is always more horizontal and not vertical! But we had to take into account everyone will compare the provided specifications and with no UW flashgun does it say the recycle time is measured to about 80% power - although in reality it is and with some flashguns it's even much lower like Jerry pointed out.

Why not use a strip of LEDs to indicate the actual charging level (25/50/75/100%)? This would seem to be the best of both worlds.

The problem is not with indicator lights but the lack of a testing standard that would clearly define the flashgun specifications AND that the manufacturers would follow.

After discussing this issue among tech savvy friends on a recent dive trip it has become clear why all Z-330 indicate their ready light much before the strobe is actually recycled. The reason is that the Z-330 uses the same old electronics from the Z-240 but is fitted with higher voltage capacitors. Inon haven't bothered setting a new ready light indicator and they just used exactly the same voltage settings as for the Z-240. This means that the ready light on the Z-240 and Z-330 comes on at exactly the same time but the latter needs at least twice as long to be actually recycled! The specifications are totally misleading.

After discussing this issue among tech savvy friends on a recent dive trip it has become clear why all Z-330 indicate their ready light much before the strobe is actually recycled. The reason is that the Z-330 uses the same old electronics from the Z-240 but is fitted with higher voltage capacitors. Inon haven't bothered setting a new ready light indicator and they just used exactly the same voltage settings as for the Z-240. This means that the ready light on the Z-240 and Z-330 comes on at exactly the same time but the latter needs at least twice as long to be actually recycled! The specifications are totally misleading.

Interesting but not surprising find. However I am not sure I would want to wait for the strobe to be fully charge before firing again? The reality is that the Z330 uses 4 AA batteries and there is just as much current you can draw out of it. Looking at the Z330 my impression is that the design is the same the power of the two bulbs higher and the only novelty is the dome port. Every circuit has a time constant by which usually you have achieved 63% recharge or similar if I recall my electronics training it is easy to wire this into the strobe however the reality is that if the strobe is not fully discharged the recharge time will be much less. have never stress tested this point but I am pretty sure the green light comes at a fixed time and in some cases will be too long and others too short. I do not believe there is actually a real time measurement of how charge there is.

I have only seen one strobe that tells you what power it discharged and therefore measured the output and it is more expensive than an Inon

Have to agree you cannot get blood out of a stone. The test reports that came out when first released: http://wetpixel.com/forums/index.php?showtopic=61091&hl=z330&page=1 report the same number of full power flashes out of the same batteries as used in a Z-240, but the Z-330 is a stop brighter with a wider beam. If the tests are accurate it means the Z-330 is more efficient and this may be in the reflectors or quite likely in the charging circuit, Seems like quite a reasonable improvement if these figures are in any way accurate!

Not to mention, if you shoot a Z240 repeatedly on full power in tropical water then you will melt the capacitors pretty quickly or the tubes themselves if the capacitors keep up.

The Z330 is meant to have overheating protection. Or is it just misleading you into thinking you're shooting repeatedly on full power when in fact it's only 25%? Given the use of high voltage capacitors then maybe this will be less of an issue. I'd be interested to see the internals of a Z330 to see what the heat sink looks like, if any.

I think there is a bit of overexcitement on the topic

Typically recycle time is when a flashlight has reached 80% of the charge this is because a tube has a working voltage for small linear ones 280-360V (280 is around 80% of 360) below this voltage the tube will not discharge so surely the capacitor is sufficiently charged in all cases

However the conversion from tube discharge to optical guide number is not linear so depending on the design it could be that 80% of charge is more or less of 80% of the guide number. The Inon strobes are the only one with two flash tubes so it is possible that the design is very different from the other strobes that have only one element.

So the strobe is ready to fire because it can discharge and potentially is at 80% recharge but this does not mean you get 80% of power. I would also avoid assumption on how large are the capacitors because flash bulbs tend to have operating voltage that are quite similar depending on shape with circular ones with higher voltage and therefore requiring larger battery packs

The ops says that it takes up to 5 seconds to have full power and 2 seconds to get ready if we oversimplify things say that the time constant is 1 second the strobe is ready to fire in 2 seconds and fully charges in 4 seconds (or maybe more) and that the charge % is not linear to the emitting light for this design

So I think it is a case of expectations not being met and design being more complicated than what you would think

If the tests are accurate it means the Z-330 is more efficient and this may be in the reflectors or quite likely in the charging circuit, Seems like quite a reasonable improvement if these figures are in any way accurate!

The test you mention was made by firing the strobe when the indicator light is on. This means the result is completely false!

Basically the strobe indicated it was "ready" when capacitors were charged to about 30-40% which means that half the energy was used from the batteries.

Not to mention, if you shoot a Z240 repeatedly on full power in tropical water then you will melt the capacitors pretty quickly or the tubes themselves if the capacitors keep up.

 

The Z330 is meant to have overheating protection. Or is it just misleading you into thinking you're shooting repeatedly on full power when in fact it's only 25%? Given the use of high voltage capacitors then maybe this will be less of an issue. I'd be interested to see the internals of a Z330 to see what the heat sink looks like, if any.

Yes, on the Z-330 the specifications of recycle time is false and misleading. Tested on several units and result is always the same. See above posts for more precise explanation.

I think there is a bit of overexcitement on the topic

 

Typically recycle time is when a flashlight has reached 80% of the charge this is because a tube has a working voltage for small linear ones 280-360V (280 is around 80% of 360) below this voltage the tube will not discharge so surely the capacitor is sufficiently charged in all cases

 

However the conversion from tube discharge to optical guide number is not linear so depending on the design it could be that 80% of charge is more or less of 80% of the guide number. The Inon strobes are the only one with two flash tubes so it is possible that the design is very different from the other strobes that have only one element.

 

So the strobe is ready to fire because it can discharge and potentially is at 80% recharge but this does not mean you get 80% of power. I would also avoid assumption on how large are the capacitors because flash bulbs tend to have operating voltage that are quite similar depending on shape with circular ones with higher voltage and therefore requiring larger battery packs

 

The ops says that it takes up to 5 seconds to have full power and 2 seconds to get ready if we oversimplify things say that the time constant is 1 second the strobe is ready to fire in 2 seconds and fully charges in 4 seconds (or maybe more) and that the charge % is not linear to the emitting light for this design

 

So I think it is a case of expectations not being met and design being more complicated than what you would think

Unfortunately your calculation is wrong. Energy of capacitors is calculated like this: E= 0.5 * capacitance * voltage ^2

This means that if capacitors are rated for 360V when they will be charged to 280V the strobe will have about 60% charge which is almost 1 F-stop less power. The voltage numbers are of course fictitious.

Also your assumption that strobes do not fire below a certain voltage is not true in the case of Inon Z-330. The Z-330 will fire almost immediately after they start recycling and therefore their trigger voltage is very low.

After speaking with one of my dive buddies who is engineer for a hair removal product (they use strobe design) he noted that power of the strobe is directly connected with the voltage with the formula above and the higher the voltage the longer it takes the batteries to charge the capacitor.

I will contact Inon in hopes of getting some clarification... Probably not but anyhow...

The test you mention was made by firing the strobe when the indicator light is on. This means the result is completely false!

Basically the strobe indicated it was "ready" when capacitors were charged to about 30-40% which means that half the energy was used from the batteries.

 

Yes, on the Z-330 the specifications of recycle time is false and misleading. Tested on several units and result is always the same. See above posts for more precise explanation.

 

Unfortunately your calculation is wrong. Energy of capacitors is calculated like this: E= 0.5 * capacitance * voltage ^2

This means that if capacitors are rated for 360V when they will be charged to 280V the strobe will have about 60% charge which is almost 1 F-stop less power. The voltage numbers are of course fictitious.

Also your assumption that strobes do not fire below a certain voltage is not true in the case of Inon Z-330. The Z-330 will fire almost immediately after they start recycling and therefore their trigger voltage is very low.

 

After speaking with one of my dive buddies who is engineer for a hair removal product (they use strobe design) he noted that power of the strobe is directly connected with the voltage with the formula above and the higher the voltage the longer it takes the batteries to charge the capacitor.

 

I will contact Inon in hopes of getting some clarification... Probably not but anyhow...

I think you keep missing the point here the relationship between fstop and light intensity is not necessarily linear so the fact you get 60% of charge does not mean you get 60% of light as the tube itself is not linear.

And the way the light is delivered is not to partially charge the capacitor, the way it works is that the the capacitor circuit is interrupted sooner so the duration is shorter. In fact if the capacitor was only charged 40% the tube would not even fire

Finally the recharge time is not related at all to the power of the tubes it depends entirely from the size of the capacitor (and don't assume the Inon has double capacity as all photo capacitors are 2000-3000 microfarads) and the resistance of the charging circuits. As the battery pacs of most (but not all the strobes) in question is 4 AA cells it is likely that the other strobes charge faster because of lower resistance (you would say better design) of the charging circuit

I am strongly suspecting that the behaviour you see with the Z330 is not unique to this model and it may have been there in the Z240 D2000 and in any strobe with dual tube but I will run some tests myself. Generally I do not look at the ready lamp behind the strobe to see if I can press the shutter or not but it is important to understand how long it takes a strobe to have the full power as I would then count that in my head if it makes sense

 

I think you keep missing the point here the relationship between fstop and light intensity is not necessarily linear so the fact you get 60% of charge does not mean you get 60% of light as the tube itself is not linear.

And the way the light is delivered is not to partially charge the capacitor, the way it works is that the the capacitor circuit is interrupted sooner so the duration is shorter. In fact if the capacitor was only charged 40% the tube would not even fire

Finally the recharge time is not related at all to the power of the tubes it depends entirely from the size of the capacitor (and don't assume the Inon has double capacity as all photo capacitors are 2000-3000 microfarads) and the resistance of the charging circuits. As the battery pacs of most (but not all the strobes) in question is 4 AA cells it is likely that the other strobes charge faster because of lower resistance (you would say better design) of the charging circuit

 

I am strongly suspecting that the behaviour you see with the Z330 is not unique to this model and it may have been there in the Z240 D2000 and in any strobe with dual tube but I will run some tests myself. Generally I do not look at the ready lamp behind the strobe to see if I can press the shutter or not but it is important to understand how long it takes a strobe to have the full power as I would then count that in my head if it makes sense

On the contrary, it is very clear what the connection between strobe power and F-stop number is:

100% = full

50% = -1 F-stop

25% = -2F-stop

12% = -3F-stop

etc.

It is also clear that the Inon will fire when the capacitors are at about 20% (before the ready light is turned on). Read the first two posts where the measurements are presented. After this I have confirmed on four different Z-330 the same result.

Now let me ask you: If you knew the Z-330 indicates the ready light (full charge) when it is charged to about 30-40% (-1.4 F-stop less power), would you buy it?

I know a lot of photographers who would think about it twice if they knew the actual recycle time was about 4-5 seconds.

My Z-330's aren't going away for this reason but I want to point out that it is very unfair to photographers who are making choices on their purchase based on completely false and misleading specifications.

On the contrary, it is very clear what the connection between strobe power and F-stop number is:

100% = full

50% = -1 F-stop

25% = -2F-stop

12% = -3F-stop

etc.

 

It is also clear that the Inon will fire when the capacitors are at about 20% (before the ready light is turned on). Read the first two posts where the measurements are presented. After this I have confirmed on four different Z-330 the same result.

 

Now let me ask you: If you knew the Z-330 indicates the ready light (full charge) when it is charged to about 30-40% (-1.4 F-stop less power), would you buy it?

I know a lot of photographers who would think about it twice if they knew the actual recycle time was about 4-5 seconds.

 

My Z-330's aren't going away for this reason but I want to point out that it is very unfair to photographers who are making choices on their purchase based on completely false and misleading specifications.

I think you have some expectations of what certain specifications are that are not what manufacturers mean

When I read Inon Z330 specifications it says recycle time Approx. 1.8 seconds minimum ["eneloop" batteries]

Reading Sea and Sea specifications the language is different [Recycle time (full)*2] A: 2.5 sec. Ni-MH: 1.9 sec.

On Ikelite DS-160 it mentions 1.5 second recycle time at full power

My interpretation of those specifications is that once you output a full power flash this is the minimum amount of time you need to wait to fire again but there is no specifications anywhere to say that it will do so at full power.

So what is happening here is that you are expecting the strobe to give a ready signal when full charge is reached but this is not what is happening the ready lamp in all cases comes as soon as the strobe can fire and output whatever it can.

If you look at some example xenon tubes you see how much variation there is between tubes and you can also see that some will fire at over 50% some can fire at 18% of full power.

Example circular 100J tube trigger between 250-500 Volts min power 25% (-2 stops)

circular 200J tube trigger between 300-700 Volts min power 18% (more than -2)

linear 50J tube trigger between 280-360 Volts min power 60% (less than 1 stop)

linear 100J tube trigger between 300-450 Volts min power 44% (more than 1 stop)

linear 200J tune trigger between 330-450 Volts min power 53% (less than 1 stop)

So what I believe is happening here is that a combination of different design and different bulbs is producing more difference between the ready light and full power

Technically all strobes are 'ready' but the power they can produce varies maybe what would be useful would be not just to have a ready light but also an (almost) full light but frankly I won't be looking at the strobe to fire nor I want the strobe to only fire when it reaches 98% so what is key is to know how long does it take to cycle between full to full without this becoming the ready signal

I think that Interceptor121 has identified the real problem here. The OP seems to think that the ready light means "full charge" whereas, in fact, it simply means that the flash is able (ready) to fire again.