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chrisdarke

DIY fiber optic writeup with parts

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Posted (edited)

Another thanks for this thread, I'm going to make me own based on this info as well. 

Question, has anyone ever tried to split a cable to fire two strobes with something like this? Working on a project where I'd like to fire 3. I was going to use the recommended Asahi Kasei MCQ-1000. 

https://www.i-fiberoptics.com/couplers-detail.php?id=4

My thought is to use a heat knife to help create the best end I can to maximize the throughput (is the correct term amplitude?). 

Or is there a better way to fire a 3rd strobe? I'm using the Nauticam LED trigger and a7riv housing along with a pair of ys-d2j and an older ys-d1.

The housing hasn't arrived yet, is it THIS along with the standard connection for the housing side? I also see this one, which looks perhaps like Backscatters version of the Nauticam one I linked to.

Thanks all!

Edited by lylefk

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Has anyone found the multi-core fiber optic cable in any store in Europe or an store in Aliexpress? Buying in USA has expensive shipping costs and customs tax payment. Thanks

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Not the cable by itself but Tooke sells multi-core cables on Ali quite cheaply.

Bill

 

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There is an interesting thread in a French underwater photography forum on using large (4 mm) fiber optic cables.

These fibers are cheap, do not break easily, and transmit tons of light ... after a few trial and error, the posters managed to get them working very well. It worked so well that in some of the early trials, where they used uncoated fibers, the flashes of neighboring photographers triggered the strobes!

They have made 3D printed parts to adapt these fibers to standard connectors. Interesting of the DIY minded ...

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Posted (edited)

As Algwyn says above, the 4 mm fibers, and in my experience the 3 mm Toslink single fiber cables, transmit abundant light and trigger both Sea & Sea and Inon strobes in a highly reliable manner. 

One can use Uxcell strain relief boot protectors from Amazon, they are 7 mm diameter and work fine.  I glue the cable to the Uxcell boot with ABS glue, then trim the end with a sharp razor.  

The resulting cable is inexpensive, simple, tough and excellent, those are the words that best describe them.

Edited by Kraken de Mabini

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As for the coupler, we have used those in our lab with quite good results. BVA

 

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On 10/7/2020 at 10:30 AM, bvanant said:

As for the coupler, we have used those in our lab with quite good results. BVA

 

Thanks! I'm going to try and diy something suggested by Kraken, I'll keep that in mind if it's not reliable. Appreciate it!

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Great thread!   I've been playing with some of the 2mm endglow cable (Plastic) and have found, when you coil it (basically, around a 5/16" aluminum tube and drop it into boiling water (for, litterally, 10 seconds)), you will lose about 60% of the light output.     I took two 5 foot lengths, one I coiled 36" of the cable, the other, I just left straight.    I'm testing it with a flashlight to a set of BackScatter MiniFlashes.    The coiled cord does NOT trigger the flash from the flash light but the straight cable does.    Not exactly Lab level testing but it's pretty real world and does show, there is quite a bit of lose when coiled.    BTW, this is the same level of coil most of the "Production" cables have.    I've not tested with a "looser" coil (say, 3/4") but will in the future and will post back what I find.

I've also started "treating" the ends of the cable with just a little bit of heat.   So, the plastic inner fiber, I take a heat source (candle if nothing else) and get the very close to the flame WITHOUT catching it on fire.   When (not if) you catch it on fire, just snip off the end and start over.   No big deal.   This seems to transfer considerably more light too.   So, the combination of un-coiled and treated ends passes a lot of light for trigger.

More information in my signature links!

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That observation is how fiber optics work. If you look at the ESKA fibers for example, their 2 mm fiber has a minimum bend radius (0.5dB) of 80 mm or more than 3 inches. If you look at their 1 mm fiber the minimum bend radius is 25 mm or about an inch. If you look at the 613 core fibers (1 mm fiber diameter) the minimum bend radius is 1 mm, and for the 1.5 mm diameter fiber it is 3 mm. This means that it is easy to coil the multi-core stuff and that if you crimp a large diameter fiber it will stop transmitting. Certainly polishing of the ends (there are better ways than candles) will improve transmission. If you don't want coiled cables then large diameter fiber is fine. If you want them coiled then the multi-core stuff is easier to work with. YMMV

 

Bill

 

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I guess that the main benefit of coiled fiber optic cables is that they may be adjusted to different arms setups. I find the coiling more bothersome than convenient when installing arms.

With cheap fiber optic cables, there is no need to coil: just cut a cable length for each arm setup combination.

Regulary fiber optic cables loose a lot of light when they are bent, so coiling them is not a great idea, unless you are using these multicore fiber cables, which are not so easy to get.

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I don't mind the coiling for setup; for me straight FO cables always seem to somehow get in front of the lens or are too short to get the arms out straight (something I rarely do). Certainly they are much cheaper and if you get a large enough diameter fiber you can use the LED triggers and TTL at least on Inon strobes. I have not had good success with straight fibers (although at 1.5 mm diameter) getting reliable TTl from my OMD-EM1 -II and some S&S strobes. The other disadvantages are that if you are at all klutzy (guilty) you can end up getting them crimped and you get a lot less light through and they are hard to fit into the 90 degree fittings.

 

Bill

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As Algwyn observes, coiling the fiber optic cables is not useful, as the coil floats about, is in the way, and can get caught; in fact, the coils waste cable as they are not necessary at all. 

All I do is thread the cable thru the holes in my strobe arms, and wind any excess around the clamps and arms.  That way the cable is secure, out of harms way and well organized. 

(I had described this approach in this thread, on Sept 21, 2017).

Edited by Kraken de Mabini
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I am pretty sure that most FO cable sinks. PMMA has a density of 1.2 or so. 

If the cable is secure in a given strobe configuration then moving the strobes out will either require unwinding or it will pull the fiber out of the camera or the strobe. I suspect that there is a reason that all of the commercial FO cables are coiled, both for strain relief and for ease of changing lighting configurations.

 

Bill

 

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Fiber Optic Cables do not need coils except to make it easy for cable makers to sell a single model of cable that can be stretched to fit the needs of different photographers. 

Otherwise, Cables with Coils can get caught on outside objects and pulled off, they flop around and are a nuisance. I learned this the hard way while diving when one of my coiled cables was inadvertently kicked off, and lost, by the dive guide. 

Another important drawback to coils is that they double or more the length of the cable, thereby significantly cutting down the amount of light that reaches the strobe. 
Coiling requires heating the cable, as in hot water, and heating is well known to "cook" the optic fiber, making it opaque and markedly reducing the light transmitted.  Both the added cable length and the reduced light may explain why some strobes such as the Sea&Sea are said not to fire consistently with coiled fiber optic cables.

Coiling requires a thin cable, and thin cables break easily, two or three of mine have broken, like brittle spaghetti, during daily use.

In contrast, thicker cables with no coils, ie, Toslink,  in my experience have always triggered Inon and Sea&Sea strobes of several models, have not gotten caught on external objects nor interfered with the taking of photos.  

To ensure one has a cable sufficiently long for other, longer strobe arms, it is easy to make it long enough so one can thread or wind the cable around the arms being used, and to add one or more wraps for the spare length.

It is important to use Toslink of 3 or 4 mm o.d. as it is much tougher than the 1 or 1.5 mm cable, and transmits much more light, at almost no additional cost. These thicker cables do not break, in my experience. 

In brief, to fire a strobe from an underwater housings, a short, thick, un-coiled straight fiber optic cable is much tougher, and carries much more light than a long, thin, coiled cable.  It  always fires the strobe, is inexpensive, dependable and easy to make, with few if any problems.

==
 

 

Edited by Kraken de Mabini

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Well I am not sure about the much more light argument, the 3 mm cable has a loss of 0.24 dB per meter and the 613 fiber optic has a loss of 0.4 dB which is the difference between 94 and 91 % transmission if the NA of the two cables is the same. So you get 3% more light from a 3x larger cable. In any case, if it works it works. As for "coiling requires heating the cable, as in hot water, and heating is well known to "cook" the optic fiber, making it opaque and markedly reducing the light transmitted.  Both the added cable length and the reduced light may explain why some strobes such as the Sea&Sea are said not to fire consistently with coiled fiber optic cables." this is simply not true at least for the 613 cable fibers. I have tried to measure (with an integrating sphere) the loss of transmission upon cabling and it is hard to see the difference; it is only a few percent. I have never broken even the 1 mm single fiber cables (they are PMMA and if you try to break one by pulling or bending good luck). The biggest advantage to me is that the multi-core fibers can be bent over a 1mm bend radius and still transmit 95% of the light, if you bend a thicker fiber it will stop working. 

Again if it works for you then don't worry.

Bill

 

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My comments were only about single fiber cables, as I have no experience with multi fiber cables, and my comment above did not mention or refer to them. I use of 3 or 4 mm Toslink cables, have no need for the more complicated variety.

As  I have seen single fiber cables lose light transmission when put in hot water to coil them, my point is there is no need to coil the cables as when kept straight they transmit more light; they readily available from Amazon or eBay for a low price; plus they are tough, simple to use, and always fire the strobe.  

Edited by Kraken de Mabini

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If it works for you then great. I prefer the 90 degree cable connectors and they are hard to use with thicker cables. In terms of cost they are about $6 each in small quantities. Toslink cables I think are about $6.50 on Amazon for a meter and you can make straight connections for very little 4 using heat shrink tubing. A meter of 613 fiber cable is $7.50 (you can of course use them straight not coiled) so the total cable is $20. Not a large difference, basically a single nitrox fill here in LA. 

Bill

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