Jump to content
Sign in to follow this  
Interceptor121

Single core vs Multi Core Fibre? Scam or reality

Recommended Posts

I have been testing my Sea and Sea YS-D2 strobes with DS-TTL using single and multi-core fiber optic cables.

Sea and Sea specifically says new cables are required for the strobes to work in DS-TTL however during my test both single core and multi core managed to get DS-TTL II acknowledgement green light after shot. This did not make the exposure correct or anything however it left me wonder about this multi core story

I understand Multi Core cables have less attenuation when you bend them however fiber optic cables have always been coiled historically the signal being transmitted is a dumb light why exactly would I need multi core cables for optical TTL?

Share this post


Link to post
Share on other sites

Hi,
as i have tried a lot, the Sea & Sea YS-D2 need a lot light to ignite.....
So i think the only reason is that the multicore are newer and will transfer more light ;-))

The Inon type 4 take nearly everything....

Regards,
Wolfgang

Share this post


Link to post
Share on other sites

With my A6300, SeaFrogs housing and SeaFrogs strobes, the fiber optic ports are a little offset to the left from the camera flash, which fires through a polished metal reflector. This results in the left port getting less light than the right port, which sits in front of the flash rather than offset, and with single core cables that shipped with the strobes, I was having trouble triggering one of the strobes - frequently it would miss the TTL pre-flash and only fire the main flash, which would produce overexposure. I got a pair of multicore cables from Nitescuba and haven't had a single flash sync issue since, so they definitely transmit more light.

Share this post


Link to post
Share on other sites

In my hands at least, if you are shooting with an onboard flash then single core might be OK. If you are shooting with an LED trigger though, and using S&S strobes, multi-core is the way to go, my single core fibers will not trigger my YSd1 with the Nauticam LED trigger.

It is easy and quite cheap to build your own multi-core fibers. If you look at the specs for 1 mm single core fiber its bend radius to get a 0.5 dB loss is like 20 mm while the multi-core stuff Is 1 mm. So a sharp.bend might leave your single core fiber in not so good shape.

Bill

Share this post


Link to post
Share on other sites

I got a multicore to go with a recently purchased flash trigger with no success on the D2s, so I'm going to take the DIY route now (have months before next deadline).   I got by on this last trip by running the cable to a D1 which I then routed to a D2.  Slightly awkward/confining, but let me stop using the camera flash.  

 BTW, I had not read that the D1s had any issues with the trigger.   I used the MC cable between the two strobes.  

Share this post


Link to post
Share on other sites

I shoot with a mini flash
I am somehow perplexed by the whole topic fiber optic cables are usually coiled and the radius is at most 1 cm
Based on this theory there would be zero transmission of light with old cables
So either the old cables were already multicore but maybe not 613 just 10 cores or similar or I am missing something
I have home made single cores straight used for remote strobes maybe I will do a bens test later


Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites
Posted (edited)

Hi:  For the past 3-4 years I have used DIY, Toslink single core cables and they work just fine withseveral housings, including a Nauticam NA500 housing, Nauticam LED trigger and two S&S YS-D2 strobes. 

The boiling water to coil the cable damages the fiber and reduces the light transmission, so I do not coil my cables.  

DIY single core cables:  great performance, minimal cost.  

Edited by Kraken de Mabini
edit

Share this post


Link to post
Share on other sites

The minimum bend radius is for something like the Asahi 1 mm fiber is 30 mm which is quite large. For the ESKA single 1 mm fiber it is 5 mm (for a 0.5 dB loss). It is relatively easy to show that the ESKA materials have about a 9% loss on coiling, while the 613 core fibers show less than 1 % (on my homemade coils). I think the point is that if you get a kink in a fiber, the multi-core will survive while the single core won't. A 0.5dB loss means you only get 94.something percent transmission, not that it goes to zero.

 

Bill

Share this post


Link to post
Share on other sites
15 minutes ago, bvanant said:

The minimum bend radius is for something like the Asahi 1 mm fiber is 30 mm which is quite large. For the ESKA single 1 mm fiber it is 5 mm (for a 0.5 dB loss). It is relatively easy to show that the ESKA materials have about a 9% loss on coiling, while the 613 core fibers show less than 1 % (on my homemade coils). I think the point is that if you get a kink in a fiber, the multi-core will survive while the single core won't. A 0.5dB loss means you only get 94.something percent transmission, not that it goes to zero.

 

Bill

What I don't understand is if there is loss for each bend once you coil it the loss will continue?

9% loss is not enough to justify all this fuss and the issue with transmitter. If something stops working out of 9% loss this is unacceptable for rugged equipment like underwater photo should be

I manage even to trigger DS-TTL with my cables just fine and it makes not difference if I use the 613 to the quality of it

I think we are making some confusion between transmitting signal for which loss can be important and needs to be rectified and transmitting a pulse of light which is rather basic

Share this post


Link to post
Share on other sites
Posted (edited)

IF each bend is bigger than the minimum bend radius you will not keep getting losses, the overall transmission is what is important. Clearly there is no "information" in the pulse from a flash other than intensity. BUT that being said, if your cable is not optimal it just won't trigger your strobe. I have some single core cables that will trigger a Z240 with ease but will not trigger a YSD1 at all if I am using an LED trigger on the camera. Nothing happens, the strobe just doesn't fire. If I use the same system but with a multi-core fiber then the strobe fires. A lot depends on the sensitivity of the optical probe on the strobe and also on what you are using on the camera. If I use the Olympus flash, then things are good with all types of FO cables, but not so much with the Nauticam LED trigger.  I would like to believe that 9% loss is not important for most things, but of course there are all kinds of tolerance stack ups that you need to think about, and in some cases 9% or 10% loss is enough to make things not work.

Bill

 

Edited by bvanant
  • Like 1

Share this post


Link to post
Share on other sites
IF each bend is bigger than the minimum bend radius you will not keep getting losses, the overall transmission is what is important. Clearly there is no "information" in the pulse from a flash other than intensity. BUT that being said, if your cable is not optimal it just won't trigger your strobe. I have some single core cables that will trigger a Z240 with ease but will not trigger a YSD1 at all if I am using an LED trigger on the camera. Nothing happens, the strobe just doesn't fire. If I use the same system but with a multi-core fiber then the strobe fires. A lot depends on the sensitivity of the optical probe on the strobe and also on what you are using on the camera. If I use the Olympus flash, then things are good with all types of FO cables, but not so much with the Nauticam LED trigger.  I would like to believe that 9% loss is not important for most things, but of course there are all kinds of tolerance stack ups that you need to think about, and in some cases 9% or 10% loss is enough to make things not work.
Bill
 

Conclusion the nauticam LED trigger is not a robust solution albeit in some cases is the only solution


Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

Certainly the Nauticam LED trigger is not robust in the sense that you can use it with most flashes but only if you use a multi-core fiber. With multi-core it works with Inon, S&S (D1 and D2J), Kraken, and the new Backscatter mini.

Bill

Share this post


Link to post
Share on other sites
Sign in to follow this  

Sponsors

Advertisements



×
×
  • Create New...