Sony A6000 + Sea&Sea YS01 + Seafrog case

[Pyndle]

Hi everyone,

I am fairly new to underwater photography and there's a few things I don't understand. I've been using this gear for the past 8 months on over 100 dives now, and I'm pretty happy with some of the shots I get but I feel like it could be better if I understood how things work

I use the camera in Aperture Priority more (which doesn't seem to matter as it's always on 1/60) and the strobe on TTL mode. I don't do real wide angle shots, because my YS01 is not powerful enough and I don't have a dome. Most of my shots are overexposed though (especially the subject), and I'm wondering why this happens.

Isn't the TTL mode supposed to adjust the lighting automatically? how does it calculates how much light is needed? Taking an average on the whole picture or a random point in the middle?
I don't have a pre-flash when I shoot in TTL, is that normal? Is there a specific mode I need to select on the camera beforehead?
Why is the shutter speed only 1/60? I thought I could go up to 1/160 or even push it to 1/250 with this camera? I'm syncing using fiber optic cable and internal flash.
There's a lot of wireless transmitters for strobes outside the water (that can sync really fast), why are there none fore underwater? Signal doesn't travel as fast underwater? Is there really no way to get 1/4000 sync speed underwater?

But then I'm also wondering, is it really a problem if the subject is overexposed? I don't seem to lose details when I reduce the exposure on lightroom (while I do if I shoot a landscape and it's overexposed). Are underwater shots meant to be overexposed?

I tried to look on the internet but couldn't find much. Any answer, tip or link would be greatly appreciated

Thank you!

 

[Chris Ross]

TTL tends to be a bit hit and miss underwater, as the camera is not designed to deal with it and that's the reason many people will shoot manual flash underwater. If you don't mind the extra processing there's no reason you can't keep doing it that way. Sometimes though it my be beyond the range available to process, you can get closer by dialling in -ve exposure compensation on the flash in the camera, which would be a practical option if it were reasonably consistent.

I think the reason all the wireless stuff does not work or has not been developed is that it is a relatively small specialised market and manual flash tends to work better anyway.

 

[Tbar]

Why is the shutter speed only 1/60? I thought I could go up to 1/160 or even push it to 1/250 with this camera? I'm syncing using fiber optic cable and internal flash.

Hi
I have an older Sony Nex5N and find that if I use on Aperture priority I only have shutter speed set to 1/60 when using the flash. If I go in full manual I can set the the shutter speed up to 1/160 (fastest for my camera on flash) and then set the aperture.

I play with the aperture to get good exposures, the strobes are quite powerful so there is a limit to the camera/strobe being able to compensate.

 

[Chris Ross]

The reason you are at 1/60 is because this is the minimum shutter speed programmed in for taking flash photos at night. In Av the shutter speed would otherwise drop way down to try to get the background properly exposed. and yes going to full manual is the way around it. The flash is auto-TTL only so it will still attempt to expose your subject correctly.

 

[Pyndle]

Thanks for the answers!
I'm gonna try to go manual for the next dives and see if that's better. I guess I will always leave Iso 100 and SS at 160 so it's only a question of playing with aperture (depending on how much blur I want in my background) and the flash power. Is that a good approach?

Chris when you say the flash is auto ttl, what does that mean exactly? The A6000 "looks" at the scene and evaluates how much light is required then adapts the power output of the internal strobe? And then my YS01 can detect how much power that was through the fiber optic cable and fire the same kind of power? And if that's the case, how does the A6000 evaluate the lighting required? One spot in the center? Average of the whole scene?

Thanks again for the help!

 

[Barmaglot]

Chris when you say the flash is auto ttl, what does that mean exactly? The A6000 "looks" at the scene and evaluates how much light is required then adapts the power output of the internal strobe? And then my YS01 can detect how much power that was through the fiber optic cable and fire the same kind of power? And if that's the case, how does the A6000 evaluate the lighting required? One spot in the center? Average of the whole scene?

TTL flash works by having the camera flash fire an initial brief pulse ("pre-flash") and using it to evaluate the scene lighting using the metering mode that you have selected, then the flash fires again, this time with the power deemed necessary by the camera and taking the actual exposure. With slave strobes in TTL mode, they mimic both the pre-flash and the main flash - xenon tube 'power' is not actually brightness output but duration, so the slave strobes turn on while the camera flash shines and immediately turn off when it quenches, precisely mirroring its duration and therefore power. If you use the slave strobes in manual mode, and the camera does not have the ability to turn off TTL (as is the case with Sony; it always fires the pre-flash), the external strobes have to be set to ignore the pre-flash and fire only on the main pulse.

 

[Chris Ross]

As per Barmaglot, Auto TTL is the auto exposure flash system used. Some cameras have the option of firing manual flash, the Sony does not. You can set your S&S to TTL or to manual. In TTL it will apply what ever flash exposure compensation you apply in camera. Manual flash is more consistent and reliable underwater in most cases.

I don't know what the sony uses to evaluate the scene, it may well be an average of the whole frame and because it can't get the water brighter it over exposes. But whatever it does you can apply flash exposure compensation to dial down the flash exposure.

If you want to try manual set your S&S to manual with pre flash option and dial the power up and down to get the right exposure, if you are close like you should be the flash exposure required is surprisingly consistent. If you try this turn flash exposure compensation to maximum -ve in camera to conserve battery power. In manual pre flash the camera ignore the first flash and the second flash is purely a trigger to fire the manual burst.

 

[Pyndle]

If you use the slave strobes in manual mode, and the camera does not have the ability to turn off TTL (as is the case with Sony; it always fires the pre-flash), the external strobes have to be set to ignore the pre-flash and fire only on the main pulse.

Maybe my camera has a defect but I've never seen that pre-flash, whether it's on the camera or on the S&S strobe itself. And I also don't think there's a way to set the S&S to ignore the preflash? There's basically only one wheel which can be set on TTL or a different power outputs for the manual mode, that's it.

If you want to try manual set your S&S to manual with pre flash option and dial the power up and down to get the right exposure, if you are close like you should be the flash exposure required is surprisingly consistent. If you try this turn flash exposure compensation to maximum -ve in camera to conserve battery power. In manual pre flash the camera ignore the first flash and the second flash is purely a trigger to fire the manual burst.

I'm not sure I understand the last sentence (sorry I'm not really an expert on the flash settings of the A6000 as you can probably tell ). And I also don't get a pre-flash, ever, is that normal?
What I was about to try is change the flash exp compensation to save battery, and set the strobe on manual. No pre-flash is required for that since I'm manually setting the strobe, right? Pre-flash is only here to evaluate the exposure required when the strobe is not set manually.

Thanks again for the help by the way (both of you )!

 

[Barmaglot]

The interval between pre-flash and main flash is very brief, far shorter than the naked eye can see. See this post for an example: a6000 Internal Flash and TTL Flash Metering - Lights, Strobes, and Lighting Technique

On your YS-01, the mode switch has four positions - off, twin lightning bolts, single lightning bolt, and TTL. When you put it in the twin lightning bolts position, you tell the strobe to expect a pre-flash, ignore it, and fire on the second flash, using the power setting set by the light level dial - this is the setting that you want to use with cameras that always fire their internal flash in TTL mode. Conversely, in the single lightning bolt position, it fires on the first flash that it detects - this is the setting that you use when your camera doesn't have a TTL mode, or has it turned off. If you use this setting with a camera set to TTL, the YS-01 will fire on pre-flash and won't be ready on the main flash, resulting in an underexposed image. In TTL mode, it will fire on both pre-flash and main flash.

If you set the camera flash compensation to minimum, then yes, you will save some battery power (and increase the flash recycle speed) and so long as put the mode switch in twin lightning bolts position, the strobe will ignore the camera pre-flashes and fire with the power that you set manually.

 

[Chris Ross]

yes try that, I'd suggest getting flash exposure right on a subject about 300-500mm away from the lens on land and use that flash power setting setting(on your external strobe) on your next dive. It should be quite close to where you need to be on flash exposure and you can fine tune from there. You need to be quite close to your subject underwater! Also put the camera in manual exposure mode somewhere between 1/125 and max sync speed and maybe f5.6 or 8 to start with and low ISO maybe 100 or 200. Stop down more for close ups