I think im still not understanding how my flash works

[dhaval]

Well I guess if up the iso and decrease the flash output you will be able to get a picture with the background exposed more than the earlier shot. :scratch:

 

[MohaimenK]

Mo. I believe you maybe confused with shutter speed vs flash power.

Changing the shutter speed from 1/200 to 1/100 has no effect on the flash exposure. But
changing the ISO value from 100 to 200 will affect the flash exposure.

I see. I wish I had kept the underexposed pictures from last night's photoshoot. I had ISO set to 100 and raised to 200 and it didn't change the subject exposure much. It finally did at ISO 800. So I know that ISO does change the subject and so does aperture.

What I was saying is that from ISO 100 to ISO 200, flash won't change much but from ISO 100 to ISO 800, flash will show the difference.

But I also say that when in outdoor with bright constant light (w/out any flash used) it will change from ISO 100 to ISO 200. Because it's constant light but soon as it starts to get dark outside, when using flash as your main light, ISO 100 to ISO 200 won't change the subject because the flash is extremely quick. However, when you raise the flash from 100 to 800 then of course it'll change.

Generally, I don't mess with the ISO much as it's much easier for me to change shutter speed. Only time I mess with ISO settings is when I'm in extremely dark situation and the shutter speed is too slow. ie. Church or reception photos

I will take a few shots later tonight to practice this. I will post results.

 

[o hey tyler]

Mo. I believe you maybe confused with shutter speed vs flash power.

Changing the shutter speed from 1/200 to 1/100 has no effect on the flash exposure. But
changing the ISO value from 100 to 200 will affect the flash exposure.

I see. I wish I had kept the underexposed pictures from last night's photoshoot. I had ISO set to 100 and raised to 200 and it didn't change the subject exposure much. It finally did at ISO 800. So I know that ISO does change the subject and so does aperture.

What I was saying is that from ISO 100 to ISO 200, flash won't change much but from ISO 100 to ISO 800, flash will show the difference.

But I also say that when in outdoor with bright constant light (w/out any flash used) it will change from ISO 100 to ISO 200. Because it's constant light but soon as it starts to get dark outside, when using flash as your main light, ISO 100 to ISO 200 won't change the subject because the flash is extremely quick. However, when you raise the flash from 100 to 800 then of course it'll change.

Generally, I don't mess with the ISO much as it's much easier for me to change shutter speed. Only time I mess with ISO settings is when I'm in extremely dark situation and the shutter speed is too slow. ie. Church or reception phototos

THE DURATION OF THE FLASH DOES NOT MATTER. REPEAT FLASH DURATION DOES NOT MATTER. Intensity matters, light reflected, and seen by the sensor matters. The flash fires when the shutter is open once the first curtain fully opens, it doesn't matter what the shutter speed is as long as it's below 1/200th (or the x-sync). There aren't any settings for "flash duration" for a reason.

"What I was saying is that from ISO 100 to ISO 200, flash won't change much but from ISO 100 to ISO 800, flash will show the difference."

No, what you were saying is that the flash duration is so short that changing the ISO doesn't matter. Which is incorrect.

 

[Village Idiot]

But I also say that when in outdoor with bright constant light (w/out any flash used) it will change from ISO 100 to ISO 200. Because it's constant light but soon as it starts to get dark outside, when using flash as your main light, ISO 100 to ISO 200 won't change the subject because the flash is extremely quick. However, when you raise the flash from 100 to 800 then of course it'll change.

You are still wrong. The speed of the flash has nothing to do with how it creates the exposure when ISO is changed. The only two times that I can think of that a flash won't be affected by changing the ISO is when your shutter speed is well about your x sync or it's pointed away from the scene you're shooting into a carboard box that's painted black and covered with a lid.

ISO is like changing the sensor's sensitivity to light. It doesn't matter how quick or how slow the flash duration is, as long as it's hitting the sensor, it's affected by the change in ISO. Some flashes have durations of 1/300 or so, so it's not about the flash's speed.

 

[Robin Usagani]

Mo, of course it affects the exposure. ISO is how sensitive your sensor is toward light. 1/128 with 200ISO will see twice as much flash as 1/128 with 100ISO. Where did you see about shooting ETTL at low power will go lower than 1/128? Your statement about full power makes sense, but at low power I feel like the flash still has plenty of juice to do preflash.

 

[MohaimenK]

Thanks VI, I'll check it out tonight. Like I said, I don't mess with ISO as much as I do with shutter speed and I wrote what I understood. When I have time to play with it I'll figure it out :thumbup:

I'm more worried about the traffic tonight cuz of this damn rain!

 

[Dao]

Mo.

Let's see it the other way.

Camera = US$200 (exposure)
Exchange rate - 100 Japanese Yen : 1 US Dollar (Make up ratio)


I gave you 10000 yen yesterday which equal to 100 USD and was not enough to buy that camera.

Due to QE2, USD value drop like a rock so now 100 Japanese Yen = 2 US Dollars. (sensitivity changed)
The same 10000 yen I gave you yesterday can buy the camera now.


You see, it doesn't matter how fast I give you (shutter speed) the money since it is not related (as long as within the time where USD value does not rise again).


make sense?

 

[MohaimenK]

LOL!!! you lost me at yen Dao

 

[Dao]

LOL!!! you lost me at yen Dao

LOL Sorry! Maybe the example is bad. Anyway, ISO value will affect the flash exposure. How's that sound?

 

[MohaimenK]

Sounds good. Take a look at this. I was doing a test for something similar to this before with different ISO and w/ flash and w/out flash. But I guess from ISO 400 to ISO 640 its not a complete full stop. These were all with flash. But I wasn't standing at the exact spot so the flash location has moved (from closer vs further from subject)

 

[Robin Usagani]

what setting on the flash Mo?

 

[MohaimenK]

As I remember you telling me when I showed you these images originally "why are you showing me these? what's the point you're trying to make here?"

and w/ your latest attitude w/ everything I say being wrong, I'm just going to let you figure it out SL. Remember, we're like water and oil. You took things too personally from debates we had about photography. Anyway I'm not going to get too personal here but read and practice with your settings you'll figure it out

 

[o hey tyler]

What power was the flash firing on?

 

[MohaimenK]

Tyler, I may have set the flash at +1/3 but don't hold me on that because I deleted the original images, they were on my desktop. But if I find it on my backup in the server then I'll let you know 100%

 

[o hey tyler]

Oh okay, so it was in ETTL mode?