Some help with strobe terminology

[jwlast]

Looking at strobes in conjunction with a possible digital camera purchase. Some of the terms have me a bit confused....for example the Ikelite 50 description says "The 50 is a TTL version and the 50s is a slave only strobe" What does that mean....how does that effect how the flash integrates with the camera and/or housing?

Looking specifically at the Olympus C5050 and PT-015 housing. Any suggestions on a versitale strobe for this set up the can handle both macro and zoom applications? Marine Camera is advertising "PT-015, Epoque ES150DS Strobe, Fiber optic sync, Epoque Tray and ESA-FASF-10cm arm $644.35" Any thoughts on the ES150DS strobe?

Thanks
JW

 

[pdoege]

TTL means "Through The Lens". A TTL strobe takes its firing cue from the camera.

A slave strobe goes off whenever the cameras flash fires.

So a TTL strobe can theoretically be more automated and do a better job than a slave strobe.

I have no knowledge of the ES150DS. I imagine that it is a slave strobe because it uses a fiber optic sync.

Peter Doege

 

[Dee]

pdoege once bubbled...
....So a TTL strobe can theoretically be more automated and do a better job than a slave strobe.

Theoretically this statement is mostly correct. With TTL, the camera 'reads' the scene Through The Lens, sets the exposure using your choices in the menus, and starts and stops (quenching) the strobe when it thinks the picture will look like it should. That's alot of decisions being made by the camera. But TTL does not guarantee the perfect exposure every time. In fact, I've been disappointed more times than not with the results of TTL. I like being in total control of my photos...good or bad, it's my fault!

That's why I much prefer the manual slave strobes. And you can't get much simpler, IMHO, than the S&S YS90DX. The fiber optic cable isn't mechanical so it can't flood, there's no sensor to aim, and with my PT-10 I've never had a problem with the connections. I have 12 power settings. With a digital camera, I can see what the photo I just took looks like. So I use that feature to my advantage. If it looks too dark or too light, I change the strobe setting, with a simple turn of one knob and take another one. It sounds like I change strobe setting with every shot but I don't. I find that I'll change 2-3 times, at the most, during a dive.

I wasn't impressed with the Epoch when I was doing my strobe research. But that may have been because I have used Sea & Sea strobes for years and had no reason to give serious thought to others. The Epoch had nothing that tempted me to change.

 

[vicky]

(Oly 5050) you need a strobe that can work with your camera. I don't know your specific model, but you have to check if your camera supports an external TTL strobe... Just read in the manual what type of external strobes can be used and what type of connection.
Moreover, the housing that you intend to use needs to support the external strobe too- a special connection between the camera's connector and the external strobe. Various strobe and cameras manufacturers have different connection types.
Many digital camera do not support TTL strobes at all (they have an external flash exposure sensor), others support only manual strobes. In some, it is possible to use only a strobe in "slave" mode: the camera's original (crappy) flash shoots, a sensor on the external strobe detects it and then shoots practically simultaneously. However- some slave strobes can be triggered by other diver's cameras

 

[TedJ]

My recommendation is the Sea & Sea YS90DX. it's ideal for the 5050 and PT-015. The PT-015 will not support TTL flash, therefore you need a flash that can be fired as a slave. The YS90DX has a lot of manual settings so by trial and error you can dial in an appropriate exposure. I don't know anyone who has used the Epoque, sorry.

 

[clive francis]

TedJ once bubbled...
I don't know anyone who has used the Epoque, sorry.

i do a guy was using it with a sony.

it is real close to the camera so you get back scatter

and it flooded, the o ring slipped off the groove.

if it can come off then it is no use to man or beast, some one else on here had a new one flood due to manufacturing errors, so i would say it is best to leave well alone

 

[ReyeR]

When you use a strobe in TTL it's the camera that dictates when to fire the strobe and, more importantly, when to quench it. It's the camera that determins when the correct exposure has been reached and shuts the strobe down. Like Dee mentions, TTL will not work in every situation - for instance if the subject is particularly light reflective or absorbant the camera tends to get 'fooled' and under or over expose the photo respectively. I personally use TTL and find it works well for me. It's upto your judgement to determin when to use TTL and when not to. Ofcourse you've always got the instant feedback in digital.

In a situation where TTL will fails I then use the strobe manually ie select the amount of light (power setting) according to the distance and aperture.

Now how a strobe is 'connected' or controlled, whether TTL or manual, depends on your camera, housing and strobe. It can either be via an electrical wire (popularly called sync cord) or light sensor.

When using a sync cord your camera must have an external flash connector, the housing must have a sync cord connector (called bulkhead) and the strobe must have a sync cord connector too. The camera sends an electrical signal via the sync cord to control the strobe. If the strobe is a TTL strobe and can understand the TTL 'language' of the camera then it will fire and quench as dictated by the camera. If it is manual strobe only and/or cannot understand the camera's TTL language then it will only fire the strobe. When the strobe quenches depends on the 'power setting' you've selected on the strobe. As of today there's no underwater strobe that can work in TTL with an Olympus camera using a sync cord.

When using a light sensor to control a strobe it 'watches' the camera's built-in flash and syncs the strobe accordingly. Some strobes can work in TTL by watching the camera's flash and firing when it fires and quenches when it quenches. Some strobes can only work in manual and fires when the camera's flash fires. When it quenches depends on the 'power setting' you've selected on the strobe.

The Ikelite DS50 and DS125 with a TTL slave sensor will work in TTL with the C5050 and PT-015. The TTL slave sensor has the light sensor that watches the camera's built-in flash. It is what controls the DS50 and DS125 by telling it when to fire and quench. Additionally the DS125 has 4 manual output settings or increments. By selecting these settings you control the amount of light. In this case the TTL slave sensor only fires the strobe and doesn't tell it when to quench. Note: the 50 and 50s you mentioned is different to the DS50.

The Ikelite DS50 and DS125 can also be used as a manual strobe by using a manual slave sensor. The manual slave sensor has 10 power settings which allows you to select the amount of light in 10 increments. This system works in a similar fashion to the Sea and Sea YS90DX that Dee mentions. Other similar setups are the Epoque you mentioned and the Inon D180 and Z220.

I don't know much about the Epoque but I suspect you'll be disappointed with it's power and angle of coverage.