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Author Topic: ETTL Flash in Av Mode (YN460)  (Read 174 times)

Offline Ctwo

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ETTL Flash in Av Mode (YN460)
« on: February 22, 2012, 05:50:40 PM »
I was wondering, I do not see my exposure meter responding on half press with ETTL flash in Av mode...

So if I set my aperture too small, I'm underexposed and won't know it until I see the result. I'm underexposed because the flash shutter range is set to 1/60 - 1/200, auto.

I think I read something about the canon flashes will have some info on the LCD, but mine just gives focal length and shutter speed - not any flash output level or exposure reading...

In Manual, it seems the exposure meter works.

Is that normal and how to work with it?
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Offline rpavich

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Re: ETTL Flash in Av Mode (YN460)
« Reply #1 on: February 22, 2012, 07:01:27 PM »
Wouldn't you only get the output level in manual since the very definition of ETTL is "I adjust based on a preflash and no two flashes are the same"....?
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Offline Ctwo

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Re: ETTL Flash in Av Mode (YN460)
« Reply #2 on: February 22, 2012, 09:10:22 PM »
Who is adjusting what?

I just adjust the aperture, so I can spin that aperture wheel all the way in both directions, but I have no feedback whatsoever, except the F number is F1.8 or F22.

F1.8 looks great. F8 looks great too...but somewhere, I max out the flash output and get a dark image.

OK, so "I, Mr. Flash" will adjust to your aperture automagically, but when you exceed my capabilities, mums the word?
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Offline rpavich

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Re: ETTL Flash in Av Mode (YN460)
« Reply #3 on: February 23, 2012, 01:51:58 AM »
Quote from: Ctwo on February 22, 2012, 09:10:22 PM
Who is adjusting what?



The flash.

The flash is doing all the "on the fly" adjusting...therefore...no power settings needed.

When doing manual output, you need to tell it how much juice to use...1/8, 1/32 etc...but ETTL is different...it makes the decision every time you pull the trigger with a "pre-flash"...there are no settings set in stone...it's all dependent on what it decides so it's natural that you wouldn't see any power level settings...there aren't any.
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Offline Ctwo

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Re: ETTL Flash in Av Mode (YN460)
« Reply #4 on: February 23, 2012, 05:22:45 AM »
The question is still, how do I know when I've gone beyond the capabilities of my flash? When I get a black photo, it is kind of obvious, but what about in between?

In Manual, the camera's metering will tell me if I'm a couple stops either way...but there is no pre-flash...?

So, here is an example - I'm in a dimly lit room set full manual, 1/10, f/1.8, ISO400. My metering says proper exposure, around 0 and the photo comes out fine. I set ISO100 and the meter still says around 0, and the photo comes out fine, maybe a bit different in lighting/color.

So, I presume the flash has adjusted its output level via the wonders of ETTL technology...

Now I go to Av mode, still set at f/1.8, ISO100. My exposure meter is locked at 0 no matter what, and the photo comes out dark.

The reason why? Well, my camera is set for auto shutter range of 1/60 to 1/200 (the default is locked at 1/200). So now I presume that there is not enough flash power to take a photo in these conditions at 1/60, the max the camera will go. I verified this by going full manual with same settings and setting flash to full output - same dark exposure.

It is even more interesting though, because if I set my camera shutter range to full auto (this is a custom menu for shutter range with flash), still in Av mode, f/1.8, ISO100, the shutter goes to like 15 seconds! Now why would that be when 1/10 is sufficient? I presume that the flash goes to minimum output and the shutter is set accordingly.

Now, it just might be as Larry Potterfield says, "That's the way it is!" but I wonder why?
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Offline rpavich

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Re: ETTL Flash in Av Mode (YN460)
« Reply #5 on: February 23, 2012, 06:05:19 AM »
Ahhh....

I think I see what's going on.

The shutter speed controls the "ambient room light" independent of the flash. That is to say within reason, no shutter speed will change how much flash you have.

It WILL have the effect however of darkening the ambient light..that's how you control your "subject/background" light ratio.


Here is the accepted way to "chimp" a flash photo into acceptability:

1.) Meter for the ambient. Let's say it's ISO 800, Aperture f/8, SS 1/30.

Now depending on the mix of room light to flash, you decide what to do with that. If you want to have a "two stop difference" then move the shutter speed two stops higher; to 1/125.

Then set the flash (I use manual) for a setting and pop a photo...decide how the mix looks based on your histo and LCD and adjust accordingly.



OR (my preferred method)


Meter for the room USING A HAND HELD LIGHT METER (we'll use the same numbers as above)

Set the camera for that. ISO 800 / f/8 / ss 1/30.

Pop the flash and measure it's output USING THE HAND HELD METER. Once you know it's value; you set it for whatever ratio you want; in this case we'll say it's a fill light at a 2:1 ratio. so we set it to "1 stop less" or something (f/11 at the same ss and aperture)

Then set the camera to what the ambient read and viola! You have a perfectly exposed shot with perfect (amount) of fill light.


I hope that helps. It's the SS that controls the ambient light. Aperture controls ambient AND flash.
« Last Edit: February 23, 2012, 06:18:27 AM by rpavich »
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Offline Ctwo

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Re: ETTL Flash in Av Mode (YN460)
« Reply #6 on: February 23, 2012, 10:57:58 AM »
rpavich,

Thanks for helping me along here. Everything you say makes sense, I'm just not using manual modes for either the camera or flash.

In Av mode with E-TTL flash, I just cannot get a proper exposure unless I up the ISO. I think the way to control what you suggested (2 stop difference between subject and ambient lighting) is to use flash exposure compensation.

In Tv mode, it sounds like you are saying the flash level does not change with changing shutter speeds (again in E-TTL)?

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Offline rpavich

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Re: ETTL Flash in Av Mode (YN460)
« Reply #7 on: February 23, 2012, 11:00:03 AM »
Ahh....yes...in AV it's FEC...you are correct.

And in TV the shutter speed (in any mode) will not affect the flash...its' just too fast 1/10000 of a second or something like that.
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Offline Ctwo

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Re: ETTL Flash in Av Mode (YN460)
« Reply #8 on: February 23, 2012, 01:41:24 PM »
This flash goes about 1/30,000 when set to 1/128 power and about 1/1,000 when set to full power.

I'll check later tonight, but the flash must adjust its output in Tv mode too.

I need to find something to read about it...the camera's manual does not say much, the flash manual covers the basic buttons. Does the Canon flash manual explain what is going on any more...?
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Offline rpavich

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Re: ETTL Flash in Av Mode (YN460)
« Reply #9 on: February 23, 2012, 01:50:17 PM »
Quote from: Ctwo on February 23, 2012, 01:41:24 PM
This flash goes about 1/30,000 when set to 1/128 power and about 1/1,000 when set to full power.

I'll check later tonight, but the flash must adjust its output in Tv mode too.



It does but my point is that the AMOUNT OF LIGHT...the OUTPUT doesn't actually change.....only the DURATION....and the DURATION is WELL ABOVE the shutter speed so the shutter speed has NO AFFECT on amount of flash....


So when you want to raise ambient...you lower shutter speed...the flash STAYS THE SAME

When you want to raise BOTH the flash and ambient level you open the aperture.

And of course just the opposite for lowering the ambient level or flash level.
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Offline Ctwo

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Re: ETTL Flash in Av Mode (YN460)
« Reply #10 on: February 23, 2012, 02:37:30 PM »
OK, now it is starting to make a bit more sense...at least that is one fewer wrinkle...

so the flash duration is fixed based on the ambient lighting conditions? Seems that would be true in Tv...

But in Av changes based on aperture, sets longest available shutter, and adjusts flash duration for proper exposure?

I'll look at the flash again - it was showing me a shutter speed, but maybe that was the flash duration.
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Offline rpavich

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Re: ETTL Flash in Av Mode (YN460)
« Reply #11 on: February 23, 2012, 04:22:11 PM »
Well...since I don't use TV or AV mode I can't comment on how the camera sets them...I can just say this.


At the sync speed 1/200 the ambient is contributing some light...at 1/125...it gets more at 1/30 it's more and so on.

At lower apertures both the flash and the ambient are brightest...and as you close down...they both go darker...

Thats' all I know. I don't shoot in anything but manual and manual flash (except for those times I'm bouncing on camera flash which I shoot ETTL).

If you set your camera on high speed sync and really crank the shutter speed up....say 1/1000 you can turn day into night...you won't see the sun at all...you can shoot dark pictures with what looks like a flash ONLY but during full sun....
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Offline Ctwo

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Re: ETTL Flash in Av Mode (YN460)
« Reply #12 on: February 23, 2012, 07:36:39 PM »
OK, some info...I am shooting ETTL and bouncing - the YN does not support HSS...

Also, I had this confusing experience again.

I shot a moderately lit scene in ETTL, Av, F2.8, ISO800, Shutter came up 1/60 and the exposure was very dark (like darker than a moonlit night). I shot it again and same result. Then I switched the flash to manual, full output, same camera settings, and the exposure was blown out. Then I switched back to ETTL, same camera settings, and the exposure was right on...so the YN flash is, well, not good, or not reliable, at least in ETTL. I tried to "break" it again, but it was working as expected...
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