Question about double sync cord for Nikonos

[KevinB]

Hi all,
I am going to try double strobes to see if I can reduce backscatter in turbid water. I am using a Nikonos V with 2 Sb-105 strobes. I hooked up my new double syc cord and when I perform the mechanical test: where you cover the lens, take photo on Automatic, shutter should open but not close, then turn strobe on to any setting and the shutter should close. (These mechanical tests are on Bob Warkentines website at http://www.southern-nikonos.com/) This test works fine with the black sync cord but the test does not work (shutter does not close when I turn the strobe on) with the gray sync cord.

Is this a problem with the double sync cord?

Thanks!

 

[donnyb]

Aloha Kevin:

Some dual cord setups (Ikelite) have one cord dedicated as the master & the other as the slave. This might be the case there. If so, the master must always be on & the slave can be added or turned off as needed. Try switching on & off one strobe or the other to see about that. Also try switching the strobes cords around from one to the other & see if the problem follows one strobe.

Sorry I am not that familiar with the V. Are you just trying to see if both strobes will fire? Or are you trying to check for TTL function? Here is my test for dual strobe function & TTL ( I use housed Nikon F100's). With everything connected & turned on, I set the camera on manual, f stop at small aperture like f 16-22, shutter within sync speed, like 1/60th. Strobes are set on TTL. Cover the lens and press the shutter. Both strobes should fire (connectivity test), and they should fire at MAX power. (TTL test, since lens is covered, camera is asking for max from strobes).

Next, open the aperture to say f 4 or 2.8, and uncover the lens. Turn the strobes around so they are pointing at an angle back towards the lens. Press the shutter.
The strobes should both fire, but very lightly on output. This confirms your TTL is working, by quenching the strobes when less light is needed.

Finally, you will not reduce backscatter by adding a second strobe. The best technique is to move your strobes wider and/or tilt them wider so you minimize light in the area of water between the lens and the subject. Also known as "edge lighting" the inside edge of your light beam is all that lights up your subject. It takes practise but stick with it. Dual strobes is still good, but its for lighting up a wider area or larger target, and reducing hard shadows. FYI I never use my strobes on TTL for wide angle, I refer to the distance/aperture chart and set them manually.

Good luck, Donny

 

[KevinB]

Aloha Kevin:
Are you just trying to see if both strobes will fire? Or are you trying to check for TTL function?

Thanks for the reply Donny!
The test that I was performing was just a simple test that I frequently run when using a single strobe. It just verifies that the strobe is communicating with the camera when the shutter closes after turning the strobe on. I suspect that the test does not work properly because one cable is primary and the other is secondary and that everything is probably fine. Both strobes do fire by the way.

I also run the same TTL test that you mentioned but I never got that far because I got too hung up on the first test failing :11doh:

I read in a book somewhere that double strobes can help backscatter by aiming each strobe staight ahead (instead of aiming a single strobe just in front of the lens at the subject) causing the beams to intersect while minimizing the illuminated water between the subject and lens.

Can anyone comment on this method? Does this really work or would I be better off holding a single strobe by hand (instead of keeping it mounted on the strobe bracket). Double strobes seem very bulky but I will go that route if it can truly help to minimize backscatter.

 

[donnyb]

You use the same technique in both cases. The strobe illuminates the subject and the remaining light falls behind the subject, as little as possible in front.

The "straight ahead method" you are referring to requires you to reposition the strobe's lighting by moving the strobe(s) towards or away from the camera, basically parallel to the lens, facing straight forward. Kind of like spreading or contracting the distance between headlights on a car.

Another method is to have the strobes already fairly far away from the camera and you simply tilt the strobe in or out to try to avoid the lighting of the area in front of the lens.

So many divers try to avoid repositioning the strobe, they think "set it & forget it" but the problem is you'll end up lighting the foreground if you move away from your subject. You pretty much have to be willing to set up & position your strobes for each shot. Thats why the strobe arms with the rubber o-rings in the ball joints are so popular (ultralight control systems, etc.). You can tighten them fairly tight, but still move them as needed for repositioning.

I use two strobes and will often use one to light the closer foreground (manually setting the strobe power based on the f stop & the distance) and the second strobe up & away aimed farther back in the scene (with a higher power setting for the greater distance to subject) to illuminate a larger area.

Edge lighting with either one or two strobes will reduce backscatter.

Hand holding a strobe is not necessarily bad in itself, but I hate having both hands full in case I really need one hand.

 

[Sharky1948]

Aloha Kevin:

Some dual cord setups (Ikelite) have one cord dedicated as the master & the other as the slave. This might be the case there. If so, the master must always be on & the slave can be added or turned off as needed. Try switching on & off one strobe or the other to see about that. Also try switching the strobes cords around from one to the other & see if the problem follows one strobe.

I think there is a misconception about dual sync cords and slave strobes. Slaves are typically triggered optically, i.e., by sensing the master when it fires.

The Ikelite dual sync cord definitely works the same on both ends. I have a D70, Ikelite housing, with a DS125 and DS50. It doesn't matter which end of the cord I attach.

With respect to the Nikonas V, try screwing the sync cord in only a few threads in the camera and then pushing it as far as it will go into the camera before tightening. I had a problem with the new Delrin sync cords on my Nikonas V. Both the single and the double gave me fits, even though I had the camera re-threaded.

Good luck.

 

[donnyb]

Mike:
Slave strobes that work optically do not have dual cords. Some of the newer dual cords may be switchable with no primary-secondary, But the older ones, for example Ikelite's, had a red marker on one cord and nothing on the other. The instructions stated something like: the red marker cord is the secondary (slave) and gets its quench info from the primary.

I had trouble with mine (Ikelite housing) and tech support said the primary strobe had to be turned on for the second strobe to get TTL info, and I believe firing info. Its been a while. But pretty sure thats what I remember.

A poor seating contact on the Nikonos V would result in neither strobe firing, correct? Kevin B has both strobes firing but was doing some feed back test for connectivity using a dual cord. I would agree with him that some test shots for TTL are in order.

Donny

 

[Sharky1948]

Donny,
Learn something new every day! Thanks. I guess I never ran into that since I always had both strobes TTL compatible.

And, you're correct about the seating. I had misread Kevin's problem.

Oh well...I tried to be helpful!

See you in the Solo forum!
Mike

 

[donnyb]

Donny,
Learn something new every day! Thanks. I guess I never ran into that since I always had both strobes TTL compatible.

And, you're correct about the seating. I had misread Kevin's problem.

Oh well...I tried to be helpful!

See you in the Solo forum!
Mike

Yeah, I switched to Sea & Sea pro housings when the Nikon F-100's came out. Dual bulkheads and fully TTL any way you set them up using Ikelite cords & strobes.
Really saves on the headaches. I am actually waiting to switch to digital... when they sort out these strobe to camera communication bugs...