How does my flash work?

[Turgay]

Thank you for the reply, Geoff. I'm continuosly testing and trying to understand the exact principles that govern the flash exposures. Now, I'm thinking that I'm approaching to the point, as you said, that the manual mode is the most usable or reliable mode with a flash. I think I need to make many many more practices in order to place those principles in my mind solidly.

Thank you Colin, I'm already ordered the book you mentioned and so happied to find such a comprehensive resource about the Canon flash system.

I would like to ask more about my second question. Ceteris paribus, when I shot at the manual mode with 1/128, I got more brighter results than a shot with E-TTL II mode, as seen in my example. The second one was taken with E-TTL II and the third one was with manual mode with 1/128. So, I thought that E-TTL II mode can use less power below 1/128. I don't have any idea why I'm getting "more flash" with 1/128? (in addition, flash zoom was the same at both shots too)

[Turgay]

By the way, I've fallen in love with painting objects with a flash

[Geoff F]

Those questions are tricky for me to answer; you may need a technical person.

I understand what you ask but how to put it into words?

In full manual flash operation, when you reach 1/128 you have reached the minimum available adjustment but that is a fixed amount. Therefore adjusting the camera settings (faster shutter speed or narrower aperture) will allow less light to reach the sensor.

So the image will become darker. A bit like adjusting your camera to suit the intensity of sunshine. You don't vary the sun's output do you.

If you shoot with ETTL flash metering you have a fully auto adjustable flash output control which will set itself to suit the scene. Now, I don't know what is the absolute minimum amount of available flash, but it probably states that somewhere in the full specs.

Probably something just brighter than a glow worm as the flash attempts to adjust for the camera settings.

[Colin Southern]

when I shot at the manual mode with 1/128, I got more brighter results than a shot with E-TTL II mode, as seen in my example. The second one was taken with E-TTL II and the third one was with manual mode with 1/128. So, I thought that E-TTL II mode can use less power below 1/128. I don't have any idea why I'm getting "more flash" with 1/128? (in addition, flash zoom was the same at both shots too)

Not sure what's going on here; it looks to me like the 1/128th manual shot was about 3 stops brighter than the ETTL II exposure above. Keep in mind also, that at high ISO settings, ETTL preflash also enters the exposure - it's not an issue at higher power settings, but can be significant at minimums like 1/128th (although this is opposite to the problem you've shown above).

It would be interesting to repeat the tests and see if you got the same result. Also - at 70CM you'll probably want to set the tilt to -7 deg.

The "manual -v- ETTL" decision is an interesting one - I normally use ETTL II with FEC in conditions where the light is changing; manual gives consistent shutterspeed / aperture / flash output, but if ambient light is changing fast (as it does at dawn or dusk) then with manual exposure you'll have to keep adjusting. My advice would be to learn how metering works, and then give the automation a go - no point buying a dog and then barking yourself

[Turgay]

Geoff, Colin ... thank you so much for your very valuable helps. I think after reading more about flash photography, I will surely have some more questions for you

Thank you again ...

[PhotoByTrace]

I don't suppose there is a "ducks nuts" equivalent for Nikon (assuming from the above discussion that it perhaps meters/compensates differently for flash as Canon does). I have a newly acquired little sb-400 speedlight for the D90 and I really just wanted to use it for fill light occassionally. And while I believe I have a good handle on the exposure triangle, the lob-sided exposure square that the flash has now turned that into in my head is driving me crazy. I read the CiC tutorial and thought I had a handle on it till I tried to take a photo of a pup with my shutter at 1/500th and my camera wouldn't let me go that quick on the shutter.... arghhh. So I guess that is the effect of the above/ aforementioned "x-sync" speed. I obviously need to read more (must have skipped that bit) and then experiment some more.

[Geoff F]

Nikon users keep telling me that their cameras are much better than Canon so I would be surprised if their external flash units didn't have the same options as the Canon Speedlight.

Does your flash have a High Speed option, Trace? Or is that restricted to the larger flash units? If this is possible with your unit, beware of a few limitations with flash coverage but otherwise it should work fine.

If you don't have the high speed alternative then yes, your shutter speed is limited.

For fill flash use, I still prefer to manually set the camera options to suit the scene (after taking a few test shots and some spot meter points) then rely on the flash to adjust itself as required.