Fibre optics and TTL

[TimG 62]

Folks

 

I'd welcome your views and advice on an aspect of TTL and fibre optics.

 

I use my Nikon D800 built-in flash to fire my Inon Z240 strobes via fibre optic cables. It works well.

 

What are the advantages of using a different form of strobe initiator, for example the recently advertised Turtle TTL or Subal's TTL V1 system? I understand that recycling will be faster (although that bothers me that I'd burn out my Inons!). But are there other advantages?

 

I read somewhere that the strobe output of the Inons is limited by the guide number (thus power) of the built-in camera flash. A different initiator would avoid this. Is this true?

 

To upgrade what I have would likely cost between 500-800. Quite a chunk of cash. Is it worth it? What would I gain?

 

Thanks!

[nortoda1 13]

Hi Tim
I have the same setup (D800 with Z240s). I originally used the on-board flash to trigger, but found it too slow. About 4 years ago I invested in Hedwigs "little micro strobe" (search this forum you'll find the details). I have never looked back, it costs 90euro. Had to modify it slightly to fit in my S&S housing but nothing too technical. It will trigger the flashes with sync speeds up to 1/400, brilliant. I like it so much I recently invested in a backup. I personally would not pay 500-800 euro.

 

cheers

 

Darragh

[TimG 62]

Hey Darragh

 

Many thanks. A really helpful response.

 

Do you get TTL out of Hedwig's gizmo? I PMd him a short while ago and from his reply I thought there was no TTL.

[nortoda1 13]

Sorry, yes it's trigger only.

 

 

Sent from my iPhone using Tapatalk

[trimix125 73]

Hi,
very interesting theme.
Buit i cannot find the thread or article...
Could you please mark it?
Thanks a lot,
Wolfgang

[nortoda1 13]

Thread is labeled "Little micro strobe batch!"

 

http://wetpixel.com/forums/index.php?showtopic=44632

 

 

 

Sent from my iPhone using Tapatalk

[TimG 62]

.... and the Turtle TTL is in the Wetpixel News and also at:

 

http://trt-electronics.com

 

Has anyone "invested" in a Turtle yet?

 

Sorry, yes it's trigger only.


Sent from my iPhone using Tapatalk

 

Thanks nortoda1.

 

Hmmm, don't want to lose my TTL!

[eyu 27]

I switched from electronic TTL when my Sea & Sea TTL and my backup Sea & Sea flooded in Komodo.

I liked the quick recycle time of the electronic Sea & Sea, I could get off 2-3 shots before the Inon Z 240's had to fully recycle.

I do not like the longer recycle time on the pop up flash and I have ordered the Subal TTL V1.

Nauticam is rumored to be coming out with a TTL version of their flash trigger in both Nikon and Canon protocols.

At DEMA I learned that the original Subal TTL V1 had some issues and Subal has come out with a second version.

I am current waiting to receive the second version of the Subal TTL V1.

I figure that the flash recycle time with be quick like the electronic Sea & Sea TTL.

I will have the convenience of fiber optic and my camera battery will now go a few days before requiring a change.

 

Elmer

[TimG 62]

Thanks Elmer

 

I'm assuming in addition to the Subal V1 you also have the hot shoe connector and cable that leads to the V1? And then I understand Subal needs a small board that runs from the V1 to the housing fibre optic ports - and has the LED initiators? So two extra bits to the V1.

 

Any chance of a pic of the setup if it's not too much of a nuisance?

 

As I said in my initial post, I'm using the in-camera flash as the initiator - and that works fine. In practice I usually take about 250 pics a day over, say, 3 dives. I've not had problems so far with the Nikon D800 battery coping with that and change it each evening. But when I got my Subal D800 system and switched to fibre optic (much better!) about 3/4 years ago, I was advised then that strobe activation using the in-camera strobe would limit the u/w strobe output because of the difference in Guide Numbers - the lower GN of the in-camera flash being the determining factor.

 

I'm no electronics techie and have no idea if this is true or not. But I was mulling whether switching to an external initiator (the V1 or maybe the Turtle TTL) would give me more Inon strobe power for w/a pics. It'd be nice to achieve but I'm not sure it's worth it at the cost of the Subal V1 plus the extra bits.

 

Thanks - and best wishes

[Pavel Kolpakov 74]

What are the advantages of using a different form of strobe initiator

Hi Tim,

Usually uw photographers see 7 reasons for going from pop-up flash to LED control:

 

1) Reflections, blinks through the port hole.

Pop-up flash produce strong light widely inside the housing. In many cases user can see some reflections on the image, because some light from flash goes to the dome port from inside. Usually it takes place in case the objective diameter is significantly smaller than port mount diameter. User even can see objective digital scale on the picture sometimes. I also have such defected shots in my stock. Manufacturers improve housings from year to year, but the issue is still not solved completely yet.

But the LED device solves the issue. It has narrow 8-15 degrees beam angle and it lights directly to the optical bulkhead.

 

2) Camera battery life

Pop-up flash consumes the battery rather fast. User have to change camera battery rather often. But impossible to change battery underwater during the dive. Also, in some dive trips can be difficult to recharge camera batteries. This is important for those people who make a lot of shots.

The LED device has battery life for 5-7 years, user need not think about the battery at all. LED devices save camera battery.

 

3) Pop-up flash overheating

After many continuose flashes inside the housing the pop-up flash sometimes switches off, because of overheating. There are thermo sensor inside the pop-up flash, which save it from overheating. When we have thermo shutdown, we cannot shoot, must wait for flash cooling.

But the LED does not heat, there is no temperature issue with LED devices.

 

4) Pop-up flash significant recharge time

Pop-up flash as classic xenon tube has a capacitor which requires significant time for recharging. User cannot shoot fast, he has to wait flash charging, some important shots can be lost. Continuose shooting (CL, CH) is impossible.

But the LED devices allow very fast shooting, cause LED has not any recharge time. Continuose shooting modes CL/CH are available with LED. I tested CH camera mode at 12 shots per second with Z-240 (at min power), it works perfect.

 

5) Pop-up flash max duration is not enough for uw strobe full range TTL control

Camera pop-up flash has a smaller xenon tube, than uw strobes have. Pop-up flash max fire duration is about 2 ms. But the full TTL range for Z-240 is 3.5 ms. So, pop-up flash cannot control underwater strobe in full required TTL range.

LED device have max fire time 4ms for Z-240, so the full Z-240 power is available for TTL control.

 

6) TTL accuracy by pop-up flash control sometimes is not very good

Camera flash xenon tube and Z-240 xenon tubes have different discharge curves, timings are little bit different for the concrete power values, that is why TTL accuracy sometimes is not very good under pop-up flash control. In some cases we almost don't see it, but sometimes we see it significant.

LED device does not have such issue. TTL LED Converter firmware is made for concrete Z-240 strobe type curve, that is why TTL accuracy is better this case.

 

7) Optical TTL control, Wire TTL control

Pop-up camera flash gives only optical TTL.

Some TTL Converters have complex TTL output: Optical TTL + Wire TTL. So, photographer can use fiber optic cable, or electric 5-pin cable. He also can use both at the same dive. These are extended capabilities for uw strobe TTL control.

Edited December 22, 2016 by Pavel Kolpakov

[TimG 62]

Pavel, that is REALLY helpful - many thanks indeed; points 1 and 5 I found especially interesting.

 

Thanks!

[eyu 27]

Pavel,

Thank you for the analysis of pop up vs LED TTL. It was educational for me.

 

Tim,

I am waiting for the Subal TTL V1 to arrive, will have to see how accurate it is with exposures.

One of the features I liked with the Sea & Sea TTL was that it had the options to go manual, TTL and the TTL was adjustable underwater

The Subal TTL is adjustable, but not underwater.

 

Elmer

[TimG 62]

Ok, understood Elmer

 

One of the neat things about the Turtle is it's switchable underwater - according to their video.

Pavel,

Thank you for the analysis of pop up vs LED TTL. It was educational for me.

 

Tim,

I am waiting for the Subal TTL V1 to arrive, will have to see how accurate it is with exposures.

One of the features I liked with the Sea & Sea TTL was that it had the options to go manual, TTL and the TTL was adjustable underwater

The Subal TTL is adjustable, but not underwater.

 

Elmer

[Pavel Kolpakov 74]

One of the features I liked with the Sea & Sea TTL was that it had the options to go manual, TTL and the TTL was adjustable underwater

The Subal TTL is adjustable, but not underwater.

 

Elmer

Hi Elmer,

Do you have Subal housing? I heard, that at the end of January 2017 there will be Subal V2 (version-2) available on the market. Using a case, I already have tested the sample of that new board. It is adjustable underwater and switchable TTL/ M underwater.

 

Other brands of housings also have TTL Converters adjustable and switchable underwater.

Nauticam has #26307, Aquatica has also its own TTL board, Sea&Sea also.

 

Trt-electronics have the same option in TTL board.

 

UW Technics TTL boards version of 2017 year also are adjustable +/- underwater and switchable TTL/M underwater. Company produces TTL boards for previous housings Nauticam, Sealux, Sea&Sea, and customizations. In January 2017 there will be also available version for additional strobes: Ikelite DS-161, Sea&Sea YS-250.

 

So, at the beginning of 2017 almost all TTL devices on the market have adjustment+/- underwater and switching TTL/M underwater. There is no any difference in that option. The difference is in other parameters.

Edited December 23, 2016 by Pavel Kolpakov

[eyu 27]

Hi Pavel,

 

At DEMA I was informed that the Subal TTL V1 had been modified and a second version was on the way.

I am currently waiting to receive the second version for my Subal ND800 housing.

Thank you for information that this version will allow switching from manual/TTL and adjust TTL underwater.

Being able to switch between manual and TTL, fine tune TTL underwater are a great features

I will also pick up a second Subal TTL V2 for my wife's Subal ND7200

Have a Merry Christmas and a Happy New Year,

Elmer

Edited December 23, 2016 by eyu

[Pavel Kolpakov 74]

At DEMA I was informed that the Subal TTL V1 had been modified and a second version was on the way.

I am currently waiting to receive the second version for my Subal ND800 housing.

Hi Elmer,

Subal V2 is really nice TTL board. There are many new features and improved parameters. Also, it supports more strobes: DS-161, YS-250, Z-240, YS-D1, YS-D2.

I heard that V2 may be available after Dusseldorf "Boat Show" (21-29 January).

Edited December 23, 2016 by Pavel Kolpakov

[eyu 27]

Hi Elmer,

Subal V2 is really nice TTL board. It also includes more strobes support: DS-161, YS-250, Z-240, YS-D1, YS-D2.

Try to order V2 at the end of January. People hope that it will be available after Dusseldorf "Boat Show" (21-29 January).

Hi Pavel,

I have the Subal V2 on order with Reef Photo

One of the features I liked with the V1 is that the board also works with electronic flash activation.

This would allow me to either use the 5 pin electronic or the fiber optic flash connections and I assume V2 is the same.

Thanks again, your knowledge and explanations have been very, very helpful

Elmer

Edited December 23, 2016 by eyu

[TimG 62]

Good stuff, guys. Many thanks indeed.

 

I'll take a look at the V2 when it is available.

 

I would be interested though of any experience anyone has of the Turtle TLL unit. It looks a very neat package, seems to do what the V2 will do - and the price is good.

[Pavel Kolpakov 74]

One of the features I liked with the V1 is that the board also works with electronic flash activation.

This would allow me to either use the 5 pin electronic or the fiber optic flash connections and I assume V2 is the same.

Yes, Subal V2 has the same connectors as V1. You can use fiber optic cables or electric 5-pin cables, or both simultaneously.

Edited December 23, 2016 by Pavel Kolpakov

[eyu 27]

Yes, Subal V2 has the same connectors as V1. You can use fiber optic cables or electric 5-pin cables, or both simultaneously.

Very Cool, thanks

 

Elmer

[Pavel Kolpakov 74]

Very Cool, thanks

 

Elmer

Hi Elmer,

Today i was informed that previous TTL prototype V2 is cancelled by Subal now. Subal is preparing another V2 board today.

I don't know anything about it's TTL accuracy or construction. This is absolutely another board. Sorry.

Hope it will be also nice. The future will show.

Edited December 24, 2016 by Pavel Kolpakov

[eyu 27]

Pavel,

 

Thank you for the update. I have one on order, will have to wait and see what the Subal V2 will be.

 

Elmer

[adamhanlon 0]

We have the the TRTL here and waiting to test.

 

One idiosyncrasy of TTL is that you cannot get full strobe power with it. Even though the pre flash output is small, it still stop the strobe providing a full power dump on the main flash.

 

All the best

 

Adam

[TimG 62]

I'll be really interested to read the TRTL test, Adam. Thanks for doing that.

 

That power limitation is a bummer. No way around it?

[KeithG 21]

I'll be really interested to read the TRTL test, Adam. Thanks for doing that.

That power limitation is a bummer. No way around it?

Not if you are using the onboard camera flash as your control signal. See Pavels item #5 in post 10.

 

Different strobes have different power discharge curves which really means they take different lengths of time to fully fire. Your onboard flash is fast and weak. Your external strobe is much more powerful but slower. So the fast weak flash tells your strobe to stop firing too soon.

 

For proper full power fumction you need a controller that speaks digitally to the camera and has been calibrated for your strobe.