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Pavel Kolpakov

Member Since 27 Nov 2015
Offline Last Active Yesterday, 04:42 PM
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#390398 Professional on dry land - Strobe insights

Posted by Pavel Kolpakov on 19 December 2017 - 04:35 AM

TTL accuracy mainly depends on TTL Converter and right cable. I know a lot of people who shoot now with modern TTL converters and fiber optic or electric cables, getting 95% successful shots. Of course automatics simplifies the work of underwater photographer.

But if you use a camera built-in flash for optical TTL synchronization, in some cases it works good enough, but in many cases it gives very different results for TTL, because of technical reasons.  Better use TTL-converter.

 

You can use TTL with Ikelite strobes on other housings too, because many TTL-Converters officially support Ikelite strobes. Such TTL circuits are available for Nauticam, Sea&Sea, Aquatica, Seacam, Subal, Sealux, Hugyfot, Isotta, and some other housings. 




#389897 New Inon Z330

Posted by Pavel Kolpakov on 30 November 2017 - 07:16 AM

Pavel-do you mean the tubes? I assume so.

For what it is worth, the focus/aiming light is more powerful.

Adam

Adam, thank you.

I mean xenon tubes of course. They must be bigger size, because strobe power is doubled comparing with Z240.




#389892 New Inon Z330

Posted by Pavel Kolpakov on 30 November 2017 - 01:52 AM

It is difficult to recognize from the picture .... do the Z330 lamps look bigger than Z240 lamps?




#389707 Subal ND500 housing and V2 TTL system

Posted by Pavel Kolpakov on 25 November 2017 - 02:55 AM

I can help with information.

Switch settings:

-        OFF, OFF  = Z-240, YS-D1

-        OFF, ON    = YS-D2

-        ON, ON      = YS-250

-        ON, OFF    = DS-161, DS-160 

 

Connectors:

Attached Images

  • V2-connectors-web.jpg



#388385 ​​Is there a Smart Underwater LED Strobe in our future?

Posted by Pavel Kolpakov on 14 October 2017 - 04:09 AM

Xenon tube works at high voltage, usually 330v...450 V.  Such high voltage together with current 100...200A leads to huge flash energy 100...250 joules in pulse, - this is the key feature (together with super fast xenon discharge 1...5ms for getting sharp pictures) of xenon tube. Only this way we can get Guid Number (GN) =24...32 for wide-angle underwater strobes today.

By the way, xenon tube is very cheap, it costs 3 $. 

 

LED flash energy is hundred times less than xenon at the same pulse duration, because of low voltage and small current through the LED. This is the key feature here.

Working voltage for most powerful COB LEDs is 40...50v, at current 10....20A.  Using 800w COB LED, it is possible to build photo flash with GN=8 (at ISO 100). Very weak flash.

By the way, such powerful COB LED costs several hundred USD.

 

But people (including me) build LED strobes from time to time ...., - for interest, as experimental, for research etc.

As a fact, LED usage for underwater strobes is not effective for today, - very low power in flash, big size body, very expensive in manufacturing. They cannot compete with xenon strobes yet. 

But LED technology is developing rapidly, maybe after few years we can see any good news at this field, who knows. Let's be optimists.




#387336 Problem mounting flash trigger in D810 Nauticam housing

Posted by Pavel Kolpakov on 05 September 2017 - 02:51 PM

Prism is glued very slightly on the black plastic podium. It is like a sticker, easy to delete it. Pick up the prism by a sharp knife. After deleting the prism you will see 2 bolts of podium mount. Unscrew bolts and delete the podium.

If you mean UWTechnics TTL converter, it must be mounted directly to metal, to the same screw holes.




#386908 Flash duration?

Posted by Pavel Kolpakov on 22 August 2017 - 11:22 PM

Thank you, Pavel.
From your test, which strobe brand and model delivers the most energy in the shortest period of time?

If you mean powerful wide-angle strobes, the shortest duration in that class has Z-240. There are 2 pcs small size linear tubes in that strobe. That is why full duration is rather short - 3.2 ms. You can get full power from Z240 at camera shutter speeds up to 1/320.  But 80-90% energy available even at 1/500, approximately.

 

If you want to use 1/320...1/500 for shooting with uw strobes, pay attention that modern DSLR cameras with mechanical shutter have normal sync speeds up to 1/250 in menu, not faster. Usually the next speed 1/320 is marked as "1/320 Auto FP" (FP or HSS, - High Speed Synchronization, 40khz blinking). At FP speeds the window does not open full, but curtains make only open strip going through the window. For example, If you try to use "1/500 Auto FP" on modern DSLR with Z-240 flash, you will see only a lighted strip on the shot.

Underwater strobes can not blink for FP (HSS) mode, they produce only a continuos flash, this case shutter window must be fully open at the flash moment. This means that 1/250 is the fastest sync speed for us in most cases. 

 

Nikon in the past produced DSLR cameras with electronic-mechanical shutter, which had normal sync speeds up to 1/500 without FP.  

Previous year i tested Nikon D50 at sync speeds 1/320 and 1/500, with UWTechnics TTL-Converter, - i got perfect TTL lighting with my Z-240 strobes. I was impressed with that camera.

So, if you need something very fast for uw strobes (for any special task), you can buy Nikon D50 or other DSLR cameras with electronic-mechanical shutter.

 

NikonD50.jpg




#386885 Flash duration?

Posted by Pavel Kolpakov on 22 August 2017 - 07:27 AM

Hi Pavel,
Thank you for the explanation and testing.
Am I understanding the explanation correctly in saying that when using the YS-250 at full flash energy at a shutter speed faster than 1/50, I will not benefit from all the light energy as the shutter will open and close before all the light energy from the strobe could be "absorbed" by the camera sensor?

Yes, it is truth.

But 80-90% energy of YS-250 flash is concentrated in significantly shorter period, you can get it at faster speeds, for example 1/125. 

Typical discharge curve of xenon tube:

Flash curve.gif




#386693 Flash duration?

Posted by Pavel Kolpakov on 13 August 2017 - 04:05 PM

YS-D2 full flash duration - 4.2 ms. You can use full energy at shutter speed slower than 1/250.

YS-D250 full flash duration - 23 ms. You can use full flash energy at shutter speed slower than 1/50.  

But how often do you need full energy? - very rare. In many cases we use only a small part of it, and there is no problem to set more fast shutter speeds (up to Nikon's max synch speed 1/250).

Sorry, I don't know Seaflash-60 flash duration. There is a round tube inside, but tube's diameter and thickness are small. I can suppose duration about 5...8 ms. 

 

Underwater objects move rather slowly because of the water, flash freezes them fine, independently of strobe type and duration. There is no need to specifically take care of this.




#386683 Flash duration?

Posted by Pavel Kolpakov on 13 August 2017 - 11:01 AM

Xenon tube in uw strobe works at the constant voltage, control is only in flash duration. More duration, - more energy in flash.  User controls duration manually or by TTL.

Linear shape tubes max flash duration - 1...4 ms (full energy), round shape tubes max flash duration - 8...25 ms, depending on the size. For example, Inon Z-240 full flash duration is 3.2 ms,  Sea&Sea YS-250 full flash duration is 23 ms.




#384786 Nauticam TTL Converter

Posted by Pavel Kolpakov on 07 June 2017 - 03:06 AM

Helo John,

 

I can help you to solve any problems with TTL lighting.

Also, i can tell you that previous month I tested 2 housings NA-D500 in my place, with Z-240 strobes. TTL system works perfect there.  

If your Z240 fires only from time to time, gives wrong lighting and etc., i understand that something is wrong in your setup or usage. Maybe the reason is defected core FO cable, or defected strobe, or wrong LED installation, wrong modes, and etc.

 

First of all, please show a photo of installed TTL Converter, to look how are LEDs installed in optical bulkheads. And the photo of your FO cable. What is Nauticam product number for that cable type?, how old is the cable?

 

To make your system clear test, do step by step:

1) Install LEDs maximum deep inside optical bulkheads. Push the LED by any tool, maximum deep. LED must be max close to optical cable end.

2) Use only new and undamaged Nauticam FO cable. For NA-D500 housing and Z-240 you must use only #26211 cable. TTL Converter #26308 is calibrated for it. Change the cable to new, maybe the fibre core inside it is defected.

3) Install new batteries CR2032 to TTL Converter.

4) Install fresh charged ENELOOP batteries to Z240.

5) Set both switches (1, 2) of TTL-Converter board to OFF position (for Z240 profile usage).

4) Make initial test now using only 1 strobe Z240, on the land, in medium conditions. Better take another Z240 than yours, from any friend, just for test. And you have to exclude all other components from the lighting system, to clear the test.

Set Z240 initial mode: left switch - "S-TTL", right switch - "12 o'clock" (zero correction).

Camera initial settings: Exposure compensation - 0 ev, Flash Exposure compensation - 0 ev. Max sync speed (by menu): 1/200 without Auto FP.  Shutter speed - 1/200. If you test macro, better set aperture F16-F22, for wide angle set aperture F11.  

TTL-Converter confirms "TTL Mode" by green light of status LED after each flash. Check it also.

 

After the test, please inform us about results.




#384278 YS-D1, Manuel with Nauticam TTL converter

Posted by Pavel Kolpakov on 21 May 2017 - 04:14 AM

Using that TTL-Converter (Nauticam #26308), you can set YS-D1 dial switch to both positions: "with pre-flashes", or "without pre-flashes", as you like it.  Of course, you also have to set Converter to appropriate mode, via your camera menu. This is easy available to do underwater, when you need it.

Yes, that Converter has manual mode without pre-flashes. It names "Controlled Manual Mode". It is popular for strobe battery saving, because pre-flash is excluded. Also it is popular for manual power control using camera wheel, such functionality is available in this mode. 

All manual modes are described in "User's Manual":

 

 

Shooting in Controlled Manual Mode of TTL-Converter

§  Switching to Controlled Manual mode during the diving (underwater) is useful feature. It gives possibility to set strobe power manually by the camera  controls. User need not set power manually on underwater strobe body, he can keep hands on the housing.

§  Underwater strobes must be set in “S-TTL” (“DS-TTL II”) mode. Strobe’s dial (+/-Ev) corrector set to “0” position.

§  Switch TTL-Converter to Controlled Manual Mode using the camera menu: Bracketing/flash >> Flash sync speed >> 1/200 (Auto FP).  Sync speeds marked as “Auto FP”, points TTL-Converter to Controlled Manual Mode without pre-flashes.  Then, underwater strobe light power can be adjusted by camera controls, using “flash exposure compensation” function.

§  Available adjustment range for underwater strobe: from Minimum strobe’s power (displays as “-3ev” on camera screen) to Maximum strobe’s power (displays as “+1ev” on camera screen). Possible to set step 0.3ev or 0.5ev, by menu.

§  TTL-Converter does not make pre-flashes in this mode.

§  Pay attention, that “Auto FP” function also makes available to set very fast shutter speeds on the camera. To avoid mistakes for lighting using underwater strobes, set shutter speeds not faster than speed of synchronization for your camera.  Most Nikon cameras with mechanical shutter have maximum sync speed 1/200 or 1/250 (without Auto FP). Some old Nikon cameras have electronic shutter and maximum synchronization speed up to 1/500 (without Auto FP).

 

Shooting in Manual Modes of underwater strobe

§  Photographer can also switch system to Manual mode by the main dial switch on the strobe body.

§  If TTL-Converter is in TTL mode, then set “Manual mode with pre-flashes” by the the strobe dial switch.

§  If TTL-Converter is in Controlled Manual mode, then set “Manual mode without pre-flashes” by the strobe dial switch.

§  Adjust strobe’s light power by the second dial switch on the strobe body.

 

Shooting without batteries (Manual mode only)

§  TTL Converter can work without batteries (by electric wire cables) in simple Manual Mode.

§  Underwater strobe must be set to "Manual mode without pre-flashes", by it’s dial switch.

§  Communication protocol between camera and TTL Converter is totally switched off. The “flash” sign disappears on the camera service screen. Camera does not recognize the TTL device on its hot shoe. Only manual flash control is available.

§  Power of underwater strobe light can be adjusted only by the strobe’s dial switch.

 

Indication

§  Onboard 3-color status LED shows system information after each flash: 

o    GREEN – “TTL is OK”

o    BLUE – “Manual Mode”

o    RED – “Low Battery”




#384245 DX to FX and back again

Posted by Pavel Kolpakov on 20 May 2017 - 10:37 AM

Hi Tim,

 

I use underwater FX and DX Nikons all my life, compare them from time to time. 10 years ago i would say that FX was better for me, because of dynamic range. But the time is going, DX cameras become much better in that parameter and now there is no great difference. Personally for me currently Nikon DX gives some more advantages: 

1) Quality of DX Fisheye 10.5mm is still the best among all fisheyes,

2) more easy to shoot macro (60mm lens on DX, instead of 105mm on FX),

3) DOF is much better, DX forgives small mistakes in focusing. I like sharp underwater pictures.




#383738 Troubleshooting YS-D1 Sea and Sea strobe

Posted by Pavel Kolpakov on 02 May 2017 - 04:29 AM

Connect X and GND pins.

nikonos-pinout.jpg

This way you check if the strobe still can give normal power flash, triggering by electric input.

Then, the next steps wiill be more clear.




#383330 Fibre optics and TTL

Posted by Pavel Kolpakov on 19 April 2017 - 07:18 AM

Please advise which product works with Canon cameras, and where can one buy it? Where can one read more about it?

Hello Brandon,

For today that product is not announced yet. Press release will be soon.