newbie strobe question

Hi all,

I was wondering if somebody could explain the following newbie questions.

When reading forums and manufacturers sites (eg Ikelite) I hear everybody about the difference between manual or the TTL remote system.

I suppose that the TTL remote system is a system where a cell catches the build-in flashlight from the camera and generates a flashlight of its own as a response. Is this correct?

What I really do not undestand is a manual flash. Are you supposed to press a button on the flash at the same time you take the picture? How does this work.

I myself use a canon S45 with a WP DC300 underwaterhousing. Can anybody recommend any of the two systems for this config?

thanx a lot

Danny

The "manual" part just refers to setting the strobe power. The manual trigger just tells the flash "hey, it's time to fire!"

You set the power on the strobe or using a manual controller.

HTH

James Wiseman

Dan,

Here are some answers to your questions:

1) I suppose that the TTL remote system is a system where a cell catches the build-in flashlight from the camera and generates a flashlight of its own as a response. Is this correct?

>>>>>NO!

TTL can be remote or not and if we are talking about TTL flash here is how it works. The camera tells the flash to flash, the flash turns on, the light reflects back to the camera from the subject, the camera makes the measurements (f stop and time) takes the picture and then tells teh flash to turn off.

2) What I really do not undestand is a manual flash. Are you supposed to press a button on the flash at the same time you take the picture? How does this work

>>>>>As James said. No, you just set the power of the flash on the strobe and when the flash of your camera fires the strobe will fire too.

I have also an S50 with a strobe and I am very happy with it.

The confusion you make is between let's say reflective strobes (that's how I call it) and cabled strobes.

The reflective strobes have an light path from your camera's flash to their light sensor

The cabled strobes have a cable from the camera to the strobe.

Let me know if you want more explanation

Vlad

James and Vlad.

I understand now. Thanks a lot.

Ok nuther bunch of newbie questions?

I recently got back from a great dive vacation in Grand Cayman! I had some videos done by the dive operator and all the while I am thinking 'darn I wish I had a housing for my Digital camera!"

The challenge is seems digital cameras are advancing so rapidly that with the high costs of housings one could be stuck with a housing that costs nearly/or more $1000 and an obsolete camera, or at least one that could not be serviced?

I recently purchased a Nikon 5700 and love it, however I just put my hands on a new "Canon A70" and was wowed by the quality of the photos and not to mention it would take video for 3 minutes at 15 fps without any chatter!

I see now that Canon makes a 100ft housing for $150 to go along with the camera $300 Now this sounds pretty reasonable?

What about light? is the internal strobe enough? Can you use an external strobe or light? if so how do you fire the strobe??

Thanks folks!

Thawmeout (here in the Pacific NW (50 degree water)

Hi Dan,

If I read your question right, then I reckon Vlad has got slightly "the wrong end of the stick" about TTL. What he says is perfectly correct about how film cameras do TTL. However I think you are asking about how Ikelite's digital TTL sensor works.

With the DS50 and DS125, they can be made to flash multiple times to "echo" the output of the internal strobe. The Remote TTL sensor picks up this internal flash, which is often masked to cut out backscatter. The first flashes from that strobe are used for focus and/or metering. The Ikelite strobes using the remote TTL sensor provide the light for this, by firing when the internal fires, and quenching when the internal strobe quenches. When the main flash goes off for the exposure (usually for longer than the metering flash) the strobe again echo this.

Now if I have got this wrong, then please correct me, but I beleive this holds true for setups where the strobes are optically coupled to the internal strobe on the camera.

I also believe that the Sea & Sea DX strobes, when used optically only allow you to ignore the metering flash and fire only on the main flash, rather than providing any intelligence like the Ikelite system, which allows the camera's TTL system to work properly.

As ever TTL is opnly of any real help for exposure in a macro environment, and for wide angle you are best running on manual strobe, manual exposure on the camera.

Sorry this has been sucha rambling post, but I'm trying to get much of this straight in my head also, so corrections are gratefully received.

Cheers

Martyn