Urgent question about Inon S-220 + Canon G7X II

[edwinov]

Thanks again. My understanding is growing but still not 100%. I have my camera's flash set to 'On', not 'Auto' because without the flash the photo is wasted pretty much anyway as the ambient light here makes for a dull green photo. I would imagine there is no difference between the output of the strobe with the camera on 'On' vs 'Auto' (provided the camera on Auto would decide a flash is needed). Right?

Or wait... Are you saying the Auto (flash 'Auto') setting not only determines if the internal flash should fire but also how much light to emit and that in 'On' it will just flash with a fixed output of light (depending on FEC)?

The moment you think you understand it you realize maybe you don't at all. *sigh*

 

[edwinov]

Also, I still don't understand S-TTL. To me TTL is Through The Lens. That means camera. A strobe now having a feature called S-TTL confuses me.

With Inon'sd S-TTL who decides when enough light has been received? The camera or the strobe?

I would think the camera would close it's shutter the moment the amount of received light was sufficient. But I get the impression it's actually the strobe, does it have some ambient light sensor (obscured in my case by the diffuser)? How would the camera know if I'm taking a macro photo (requiring spot metering) or a wide angle photo?

I'm surprised I actually go a whole number of decent shots because I seem to have not much of an idea of what's actually going on.

 

[Barmaglot]

Also, I still don't understand S-TTL. To me TTL is Through The Lens. That means camera. A strobe now having a feature called S-TTL confuses me.

With Inon'sd S-TTL who decides when enough light has been received? The camera or the strobe?

Many years ago, there were some underwater strobes with an "auto" feature that relied on a sensor on the front of the strobe that quenched the bulb when it got enough light, with a dial on the strobe that you were supposed to set to match your camera's aperture. This worked quite poorly and has long since been abandoned.

The way it works in modern strobes is that the camera fires a brief pre-flash, evaluates the resulting exposure, decides how much flash power it needs to properly expose the shot, then fires the flash again and takes the actual picture. Remember that flash power is modulated by duration, not intensity, so that when you're using external strobes such as your S-220, they simply mimic both the pre-flash and the main pulse, amplifying both, turning on when triggering light is detected, and quenching when it's cut off. The TTL power compensation dial on the strobes adjusts the power of the pre-flash "copy" - when you turn it up, it causes the strobe to quench the pre-flash early, reducing the light output on the evaluation exposure, and biasing the camera towards a stronger (=longer) flash pulse on the actual image.

 

[David Haas]

Edwinov,

On your camera under the Menu choices the RED tab 5 at the bottom determines what I meant by AUTO. You'll see choices how your pop up flash will work.

Included are:

AUTO or MANUAL

Flash Exposure Compensation

Shutter Synch (if it close the shutter 1st curtain or 2nd curtain, basically when it fires the flash) and 1st is used mostly.

Red Eye Lamp (which I have to OFF.)

To get to this Flash Settings Menu choice quickly I save it to one of 5 parameters max you can choose in the far right GREEN My Menu tab.

Barmaglot very well described how S-TTL (SLAVE TTL) works.

Basically it's a start / stop of the flash which via the fiber optic cord to your Inon S220 strobe duplicates.

When your camera based on settings thinks enough light has been received it will "quench" or stop the duration which then transmitted up the cord stops the Inon S220 output.

With camera flash popped up and camera in M mode (yes, AUTO FLASH works even if you're shooting in M shooting mode) the 3 o'clock button around your 4 way rear control has a flash icon.

Tap it and you'll see only ON and OFF choice in M and Tv shooting modes.

In Av and P shooting modes those choices have a LIGHTNING Bolt icon plus A meaning the flash may or may not fire depending if the camera "thinks' it needs to fire the flash.

You basically want the SOLID Lightning Bolt icon choice meaning "fire my flash each time".

With the SOLID LIGHTNING BOLT choice on when you push the 3 o'clock push a little icon on the bottom right will pop up for a second or so.
It shows the icon for your FRONT COMMAND RING allowing you to quickly adjust the FEC (Flash Exposure Compensation) from -2 to +2 output.

I use this quick method from the back of my camera way more often than adjusting the Inon S220 rear dial but that's just my choice.

Finally, don't fret over all this mumbo jumbo........

Go shoot underwater pics and have fun!

David Haas

Some friends I met on Bonaire! LOL......