Wetpixel strobe review

I have just posted the Wetpixel review of the Inon Z330, Retra Flash and Symbiosis SS2 strobes on the front page:

http://wetpixel.com/articles/strobe-tests-inon-z330-retra-flash-and-symbiosis-ss2

If you are just coming to this, please check out the extensive threads on the Z330 and Retra Flashes too:

Z330: http://wetpixel.com/forums/index.php?showtopic=61091

Retra Flash: http://wetpixel.com/forums/index.php?showtopic=59574

Perhaps we can amalgamate the threads and add personal experiences to this thread?

Adam

Thanks for the extensive review Adam!

On the methodology can you confirm how you’ve done the extensive battery test in water bucket? Shooting lots of continuous full power flashes wouldn’t have been possible (well, depending on the frequency) on the Z240 due to heating, so it looks like Inon did address well the heating issue on Z330?

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I can confirm that I did the battery testing by cycling the strobes at full power with them being triggered as soon as the ready lights illuminate.

The strobes were in bucket of water at room temperature.

Adam

The z330 now has a warning sticker in the box that tells you. That if u fire (more then) 10 flashes... U have to wait 5 min before firing again

Adam!

1 Joule is correctly equal to 1 Ws and not 1W / s

Bumbi

and more:

The guide number has a unit of measurement: for distance. Feet or meter. Manufacturers do not even say it, but it's a mistake because it's not 33 feet or 33 meter. The guide numbers of the flashes in the article are given in feet.

Bumbi

and more:

The guide number has a unit of measurement: for distance. Feet or meter. Manufacturers do not even say it, but it's a mistake because it's not 33 feet or 33 meter. The guide numbers of the flashes in the article are given in feet.

 

Bumbi

Let me say this a little differently and in more detail, because I'm sure many people are confused about it.

The Guide Number (GN) is what you divide by the distance-to-subject to get an f-stop. The distance to subject can be in feet or meters. So, if you are 10 ft away with a GN of 33, you should use f/3.3. But, if you are a meters person, like most of the world (!), the GN should be given as 10, so when you divide by 3m (i.e, 10 ft) you still get an f-stop of 3.3.

Because f-stops are a ratio of lens focal length to lens opening, the f-stop has no units, it is a pure ratio of two lengths. So when you multiply distance x f-stop = GN, you still have units of distance, be they ft or meters. This means the GN MUST HAVE ITS UNITS ATTACHED -- feet or meters -- or it is incorrect and potentially will give you greatly underexposed pictures. .

Using the example of GN33 and assuming it works for meters, and you are 3m away, you will use f/11. But the correct f-stop is 3.3, because the GN is in feet. So you are underexposing by a factor of over eleven (11/3.3 squared).....good luck.

 

 

The z330 now has a warning sticker in the box that tells you. That if u fire (more then) 10 flashes... U have to wait 5 min before firing again

This is very interesting and there was certainly no such notice with the strobes supplied for this review. Could you take a picture of it?

I can state that I have seriously violated this guideline repeatedly and there has been no obvious negative effect on the Z330s or their performance! I did 4 back to back battery tests of the strobes, cycling at full power soon as the ready light appeared... that's around 1000 flashes with no break in between!

In terms of guide numbers, I think we should, in this instance, perhaps simply look at them as a non specific and hence fairly generic way of comparing strobe output. As mentioned, I was quoting manufacturers specifications, which (I think) did not list units.

I note that the unit is Ws rather then W/s and thank you for this correction.

Adam

 

 

In terms of guide numbers, I think we should, in this instance, perhaps simply look at them as a non specific and hence fairly generic way of comparing strobe output. As mentioned, I was quoting manufacturers specifications, which (I think) did not list units.

 

 

What's worse is when the manufacturers themselves get confused. From the Sea and Sea website, http://www.seaandsea.com/

"Maximum guide number is a powerful 32 (ISO 100, meter)."

From the Retra website, where they ignore the GN units and get the Energy rating wrong

• 100W/s
• GN30 in comparison with two strobes - see comparison here
• GN18 (absolute measurement on land)

And so on.

Adam,

thanks a lot for the very helpful anaysis work.. You helped me a lot to make my decisison....

Sascha

Because f-stops are a ratio of lens focal length to lens opening, the f-stop has no units, it is a pure ratio of two lengths.

From a purist point of view, f-stop does have units. As an example, mm focal length/mm effective aperture diameter. Since the 2 lengths are referring to different parameters, they do not cancel. While I realize that ignoring the units greatly simplifies communications, as a chemist, I find that many professionals can't solve problems by simple unit conversions because they think things like vapor/liquid distribution constants (concentration vapor/concentration liquid) also have no units.

 

From a purist point of view, f-stop does have units. As an example, mm focal length/mm effective aperture diameter. Since the 2 lengths are referring to different parameters, they do not cancel. While I realize that ignoring the units greatly simplifies communications, as a chemist, I find that many professionals can't solve problems by simple unit conversions because they think things like vapor/liquid distribution constants (concentration vapor/concentration liquid) also have no units.

LOL. I guess this is the difference between mathematics and chemistry.

Since Adam was asking for personal experience i’ll shared mine with a pair of Retras which i borrowed for about 1700 shots over 6 dives (some dives 2h40 long with action, i am not shooting that crazy )

My current strobes being Inon z240 x2, here is my subjective take on the Retras:

Pros for retras:

-maintenance: much quicker to swap batteries as i am leaving the oring in and grease it every 10 openings only

-simplicity of usage

-no acc button/magnet that can get stuck/corroded and mess-up my photos

-fiber optics routing (rear mounting ball easier i find)

-battery indicator... though i like in principle the idea, in reality it didn’t turn too reliable, and after exchanges with Retra it appeared it was due to me using very old batteries (1st gen eneloop). I bought some new eneloop pros but couldn’t try them as i had to return the strobes before.

-ease to mount various diffusers

-resistance to overheating - though i haven’t tested it that much but trust that aluminium housing helps cooling strobes down

Cons:

-batteries drain if left in strobe turned off! Again this may not happen with my fresh eneloop pros, but with my inons i had the habit to leave batteries in between dives (usually i dive once a week on weekend only) and that wasn’t a problem with inons

-strobe angle: probably just subjective, but i was shooting with shark diffusers (didn’t get the wide angle diffusers) which are supposed to preserve the retra’s original 110deg, but i felt like the coverage was lower than with my Z240s and diffuser (although 110 degrees).

Now i am left to choose between Retra and Inons and still not sure what to do :-)

The over-heating issue of the Inons was big concern for me but Adam’s review indicates this is solved... although i wish Inon didn’t keep that statement on letting strobe cool down if the problem really got addressed!

Also, not sure how useful the rotating Inon shade is.

Thinking... thinking...

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The batteries left the retra appear to drain quite fast while off, even with brand new eneloops. It's annoying because I normally load batteries into strobes for travel to reduce the number of spare batteries I'm carrying. With the retras I then take them out and put fresh ones in on arrival. Then again, Z240s could have been doing the same thing and with no battery indicator I wouldn't know. I rarely run the Z240s flat with changing the batteries before every dive and have never had a problem with them going flat after only a few shots.

With the help of the review, I decided now to give the Inons a chance.....and wait for the colour diffusors to come, too. What I still haven't understood is, why the battery compartment needs an inner and outer cap....others have it in one piece....

Sascha

With the help of the review, I decided now to give the Inons a chance.....and wait for the colour diffusors to come, too. What I still haven't understood is, why the battery compartment needs an inner and outer cap....others have it in one piece....

 

Sascha

It is the system Inon has used for years. From a technical standpoint, the inner piece is not really a cap as much as it is the contacts for the batteries. It isn't waterproof. It appears that Inon has not changed the battery compartment at all. I think they should have re-designed it so that a flooded compartment could not flood the strobe. I think that is the one real weakness of these, although I have used Inon strobes for a long time with no problem and would not let it deter me from buying these. I think the color diffusers may be out already. Backscatter lists them on their site.

If you are using the battery indicator to judge what is going on be careful as it could just be self discharge, The capacity voltage curve of the NiMH type battery is very flat so difficult to judge% charge based on voltage, which I am assuming what is being used with the charge indicator. The best way to judge would be to take two sets of known good eneloops or your battery of choice of about the same age. Charge them up put one set in the flash, the other out, wait your week then recharge them both together and see if the set in the flash takes longer to recharge indicating more drain.

If you are using the battery indicator to judge what is going on be careful as it could just be self discharge, The capacity voltage curve of the NiMH type battery is very flat so difficult to judge% charge based on voltage, which I am assuming what is being used with the charge indicator. The best way to judge would be to take two sets of known good eneloops or your battery of choice of about the same age. Charge them up put one set in the flash, the other out, wait your week then recharge them both together and see if the set in the flash takes longer to recharge indicating more drain.

I have no idea about this. just asking. If what you say above is true, then would that suggest the charge indicator lights are unreliable in general?

In general yes, if it is based purely on voltage, the cells typically experience a small drop and then voltage remains pretty much flat till it is is all but empty then drops rapidly. The indicator will give some representation but due to the small voltage changes involved is only an approximation.

If you are storing for a period of time it is possible that the drop you see from is the initial rapid drop from about 1.4V to about 1.22. From this point on the voltage drops very slowly from maybe 1.22 to maybe 1.18 then drops rapidly. This may be enough to cause the power signal to drop from 4 to 3 lights on. but in reality only represents something like 5% of the battery capacity. Before concluding this is a problem I suggest you need to compare to batteries charged at the same time, but not stored in the flash.

 

This is very interesting and there was certainly no such notice with the strobes supplied for this review. Could you take a picture of it?

 

I can state that I have seriously violated this guideline repeatedly and there has been no obvious negative effect on the Z330s or their performance! I did 4 back to back battery tests of the strobes, cycling at full power soon as the ready light appeared... that's around 1000 flashes with no break in between!

 

In terms of guide numbers, I think we should, in this instance, perhaps simply look at them as a non specific and hence fairly generic way of comparing strobe output. As mentioned, I was quoting manufacturers specifications, which (I think) did not list units.

 

I note that the unit is Ws rather then W/s and thank you for this correction.

 

Adam