430ex ii wont read sigma 30mm

[wwwcjx]

Hi.

I got a canon 450D, 430exii and sigma 30 f1.4. put them together, but the 430ex ii doesn't read the lens corretly. it shows Zoom 28mm in the top right hand corner?:rolleyes:

another question is, when the 430ex going to flash, does it read all relevant parameters like ISO, f, focal lenghth,sensor size,even distance; and adjusts the power and shape of flash beam accordingly?:confused:

thanks

[quientus]

There are only a few zoom modes, and 28mm is the closest.

Yes.

[tim]

There are only a few zoom modes, and 28mm is the closest.

Yep, it goes to zoom setting that will cover the focal length selected, which is usually a little wider than the lens or zoom length the lens is set to.

[wwwcjx]

thanks for your replys. :)

[egordon99]

My little E-TTL "recipe"

Basically, with flash, the FLASH exposure is solely determined by flash power (actually duration, how long the bulb is actually firing for), aperture and ISO. Ambient exposure is determined by ISO, shutter speed, and aperture (just like without any flash), so the trick is balancing the two. If I'm indoors in a smallish room (such as in someone's house), I usually just forget about ambient since the flash is powerful enough to light up the entire room (hence the 1/250s below, if the flash didn't fire, I'd have a more or less black picture) Now although you're shooting MANUAL Mode, that's only for the ambient exposure (the exposure needle in the viewfinder will blink warning you about underexposure, but ignore that). The camera's E-TTL metering will determine the needed flash output for a proper exposure.

Here's something I wrote on another forum -
"Easy" recipe for great E-TTL flash shots -
1)Point flash at ceiling
2)Put camera in MANUAL mode on the mode dial
3)Set FEC to +1 on the flash head


4)Shoot RAW (this allows you to recover some highlights that might get "blown" as a result of #3 above)

5)Set ISO to 200 (to start)
6)Set shutter speed to 1/250s
7)Set f-stop to whatever DOF you want



Now if the flash runs out of "power" because of high ceilings, you can raise the ISO or open up the f-stop to compensate. Or you can slow down the shutter to bring more ambient light into the exposure (in addition to adjusting ISO/f-stop) If the ceiling is REALLY high (like in a church), you may need a reflector to throw some of the light forward (I use the Joe Demb Flip-it).

Quick and dirty outdoor fill flash tutorial -

Basically, if your subject is in shade and the background is bright (ie under a tree) or majorly backlit, fill flash is your friend. Think of those times when you got a properly exposed background, but the subject was almost pitch black.

Put camera into Av mode, metering will set the shutter speed to expose the overall shot (which in the situations that call for fill-flash will generally be the background) based on your selected aperture/ISO.

Make sure flash is set to HSS (in case your shutter speed go faster than 1/250s) and E-TTL. Fire away! The shutter speed/f-stop/ISO will expose the background, and the flash should output enough power to light up the foreground.

Now to control the background exposure, you use exposure compensation on the camera body (which would adjust the shutter speed), to adjust how much fill for the flash exposure, you use Flash exposure compensation. The trick is balancing the two (as it is with indoor work), and that comes with experience/experimentation.

[wwwcjx]

thank you "egordon99", this is very helpful for a beginner.

after reading some documents/experience/threads, my curiosity is when the camera's E-TTL metering determines the needed flash output for a proper exposure, which area the camera's E-ttl metering is looking at? is it the set AF point or all AF points (say all 9 AF points for most of Canon SLRs)? does the exposure valuation mode affect flash output?

[Curtis N]

when the camera's E-TTL metering determines the needed flash output for a proper exposure, which area the camera's E-ttl metering is looking at?The E-TTL II flash metering system used by your camera ignores AF points.

You basically have three options:
1) Evaluative E-TTL (default) evaluates the pre-flash from dozens of metering zones, attempts to identify your subject and adjusts exposure accordingly. This mode seems to be susceptible to white or highly reflective areas and will often underexpose in such conditions. However, it is generally the best mode to use outdoors or whenever the background is distant.

2) Average E-TTL (selectable via custom function on your camera) averages the pre-flash reflected throughout the field of view. In my opinion, this mode is more predictable and usually my preferred mode indoors.

3) Flash Exposure Lock (FEL), activated with the * button, is akin to spot metering. It evaluates the pre-flash reflected within the partial metering circle (the center of the frame). It is sometimes useful for difficult situations.

Keep in mind that your camera's ambient metering mode (Evaluative, Center-Weighted Average or Partial) has no effect on the flash exposure.

[wwwcjx]

thanks Curtis N for the great information.