Little trouble with TTL

Josh66 · Apr 23, 2013

I'm assuming that an "increment of exposure" = Exposure Compensation (nothing else would make sense).

Designer said:
Maybe your TTL is not working correctly.

If he is dialing in "+1 unit" exposure compensation, and the photo is coming out "+1" overexposed, and vise versa, I'd say the flash is working properly.

TTL does (normally) produce a good exposure, but if you tell it to over expose one stop, that's what it's going to do...

Derrel · Apr 23, 2013

O|||||||O said:
I'm assuming that an "increment of exposure" = Exposure Compensation (nothing else would make sense).

Designer said:

Maybe your TTL is not working correctly.

Click to expand...

If he is dialing in "+1 unit" exposure compensation, and the photo is coming out "+1" overexposed, and vise versa, I'd say the flash is working properly.

TTL does (normally) produce a good exposure, but if you tell it to over expose one stop, that's what it's going to do...

EXCEPT, when as I mentioned above, that there is "no more excess flash power available". What happens when the user adds +1.0 EV of flash...and the flash is already at maximum output????

Cough,cough...the same exposure results, over and over...

as Designer said, re-set everything. Some TTL flash systems are, frankly, not all that reliable. Canon's was not that hot until the 580-EX II hit the streets; the EX-II protocol flashes were really a LOT better. Also...sometimes there is something so basic, so Homer Simpson "Do'ah!!!" that one can be doing incorrectly, so...Read The Fine Manual, take a few notes, and see what the issue is.

Again, the MANUAL tells you stuff that we as individual users might not be aware of; For example: "some cameras", like most earlier Canon's and the earlier Nikons, are extremely sensitive to the AF point used...and they base their FEC (canon's term) off of the AF point used...and THAT can regally,royally,resplendently screw things up....like...do a focus and recompose with focus lock, and have the FEC tied to a now-off-center AF point...boy howdy!!! Talk about a shot to the foot! Not to sound like a broken record, but...comb thru the manual.

tecboy · Apr 25, 2013

I resettled everything, and the TTF is working fine. Thx guys. According to the manual if I use 20 continous flashes, speedlite can gets damage from overheating. Does the speedlite gets hot when I touch it? What it mean by 20 continous flashes?

Designer · Apr 25, 2013

tecboy said:
I resettled everything, and the TTF is working fine. Thx guys. According to the manual if I use 20 continous flashes, speedlite can gets damage from overheating. Does the speedlite gets hot when I touch it? What it mean by 20 continous flashes?

Not knowing what flash you have, I can't read the manual, so I will attempt a guess. After 20 flashes in rapid succession, there may be overheating. The elements that overheat are the flash tube, the capacitors, the solid-state control chips, and the batteries. None of these will tolerate "overheating", although you may notice some "heating" while using the flash. Try not to overheat the sensitive electronics.

tecboy · Apr 25, 2013

I have 430EXII. It is on page 7 of the manual. Canon U.S.A. : Support & Drivers : Speedlite 430EX II
The batteries get hot, and I assume the hot batteries make the speedlight slightly warm.

tecboy · Apr 26, 2013

I will take pictures with people in cosplays. I may have to rotate the camera in vertical position. What about the speedlite? Will the light changes direction? Will I get the same of quality of lights as a horizontal position of my camera?

Josh66 · Apr 26, 2013

It you're bouncing off the ceiling, it probably won't make much difference.

If you're aiming the flash right at the subject, you might want to look into a flash bracket:
Vello QuickDraw Rotating Flash Bracket CB-100 B&H Photo Video

You will also need something like this:
Canon OC-E3 Off Camera Shoe Cord 3 1950B001 B&H Photo Video

Really, you could just use the cord and hold the flash in your hand - but then you would have to hold the camera with one hand, not sure if that would be a problem or not...

You could also use a wireless trigger instead of that cord with the bracket.

TCampbell · Apr 26, 2013

The 430EX II will let you adjust flash exposure compensation in 1/3rd stop increments and there's really no reason to go finer than that.

If you shoot manual, you control the exposure based on (a) power level on the flash (e.g. full 1/1, 1/2, 1/4, 1/8, etc.) AND (b) the f-stop on the lens AND (c) distance from the subject.

You can shoot very quickly (event photography where you're on the move and don't have time to set up the shot) IF you learn the relationship between f-stop and distance for YOUR particular flash. This is how we did weddings on full-manual. We KNEW the f-stops which corresponded to the camera-to-subject shooting distance for our particular flash. It's very consistent once you learn it.

Make a table and memorize it.

Set your ISO to 100. Set your flash to... say... half power. Set your aperture to an arbitrary (but consistent) f-stop.... say f/5.6.

Take photos of a subject at exactly 5, 7, 10, 14, and 20' away (all those distances vary by 1.4 ... the "rounded off" square root of 2).

You will find that ONE of those photos is quite nicely exposed... lets just pick one as an example... we'll pick 10'. That means that if you shoot at 7 fit, the inverse square law states that the light will be twice as bright, but that means you just have to stop down once (e.g. switch to f/8) and you'll be fine. Move the subject to 5 feet and you'll stop down an addition stop (f/11) and you'll be fine again. If you go in the opposite direction (from 10' increase it to 14') you'll need to open up from f/5.6 to f/4. At 20' you'd need to go to f/2.8.

The relationship will hold. But what YOU need to do is find that base distance and power level. Also note that if you increase or decrease the power level on the manual flash, the distances will change. Manual flash power levels typically are reduced by halves... e.g. 1/1, 1/2, 1/4, 1/8, 1/16, etc. (I think your 430EX II goes down to 1/32nd... it might go to 1/64th).

Once you know the relationship between the flash power level, camera ISO, aperture, and distance (notice that shutter speed is missing... that is NOT an oversight), it's easy to shoot with a flash on manual.

The shutter speed simply needs to be at or below the flash sync speed (which for most cameras these days is 1/200th... a few can handle 1/250th... and sometimes if you introduce radio relays like pocket wizards it slows things down fractionally and you have to cut back to 1/160th).

When I did weddings, we used a medium format camera & prime lens... and since the lens cannot 'zoom', that means the "framing" of the subject (how much of their body fits in the frame) is a reliable indicator of distance from the subject. So we knew that with OUR flashes, we needed to use f/16 if we framed the subject for a 1/2 shot (meaning we only see half of their body -- e.g. from the waist up.) If we did a 3/4 shot (knees up) that'd be f/11. A "full" shot was f/8. A group shot (small group - a few people) was f/5.6 and so on...

If we knew we were going to take a half-shot of someone, we'd just dial in f/16 on the aperture and walk up to them to frame half their body and take the shot... and you'd nail that exposure every time (no guessing involved... it becomes a reflex after you've done it enough.)

If you want to shoot with the flash on manual, you'll want to test your camera, make a table of the relationship between distance and aperture required (at some given ISO and power-level on the flash) and then use it enough that you basically memorize the table.

tecboy · Apr 29, 2013

Thx for explaining.

tecboy · May 2, 2013

Is there a way to disable built-in flash and run speedlite unattached while shooting my camera?

pgriz · May 3, 2013

tecboy said:
Is there a way to disable built-in flash and run speedlite unattached while shooting my camera?

That will depend on how far away from the camera the flash will be. If it's 2ft. or less, then a connector cable like this: (Amazon.com: Canon OC-E3 Off Camera Shoe Cord 3: Camera & Photo) or (Amazon.com: Pixel 3.6M /10 FEET E-TTL Off-Camera Shoe Cord for Canon DSLR Flash 580EX II 550EX Canon 430EX II Canon 420EX 380EX replaces OC-E3b: Camera & Photo, which goes to 10 ft). If you want simple, cord-free triggering, then a simple radio sync trigger will work, with a trasmitter on the hotshoe of the camera, and a receiver for the flash - but then you're 100% manual. If you want E-TTL wireless, then you either use the build-in commander mode (I think the T3i has that feature), or you use the canon's "wireless" trigger (ST-E2) or the more expensive radio triggers from Radio-popper or Pocket-wizard.

tecboy · May 3, 2013

I don't understand, why you need additional cord or transceiver to use wireless external flash only?

IByte · May 3, 2013

tecboy said:
I don't understand, why you need additional cord or transceiver to use wireless external flash only?

Because commander mode infared is not as reliable than radio wireless, tethered triggers. That's even if your camera has commander mode.

pgriz · May 3, 2013

tecboy said:
I don't understand, why you need additional cord or transceiver to use wireless external flash only?

You can use the flash in two ways: Manual or E-TTL. Manual needs only a sync signal, and this can be done with a simple trigger (radio or physical cord). In this case, the settings on the flash are set manually by the operator, and the sync signal only functions to trigger the flash at the right moment (ie, when the shutter is open). The flash has no knowledge of the camera settings, and fires at whatever power level it has been set to.

E-TTL needs the camera to communicate to the flash a series of instructions, and coordinate the pre-flash and real flash. The camera has two ways to communicate this information - either by energizing the pins in the hotshoe, or by encoding the commands in a series of flashes from the commander unit. If the flash unit is physically not connected to the camera, then the only way it can get E-TTL information from the camera is from the encoded flashes from the commander unit. The commander unit can be either the camera's own flash (on some Rebel units) or the infrared emitter (ST-E2) or a flash that can act as a commander (580EX II for example). Another way of communicating the E-TTL commands is to use a synch cable which in essence extends the "physical" connection between the camera and the flash. Still another way is to use a wireless transceiver that knows E-TTL commands (like the Flex units from Pocket-wizard), or one that transmits the E-TTL signals (Radio-popper).

But the real question is - what do you mean by "wireless external flash only"?