Sigma EF500DG Super
Posted 15/02/2008 - 02:29
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At what focal length are you shooting?
If your at a wide angle like 18mm, the flash will likely not cover the entire area. The center may be somewhat brighter and the camera will adjust by underexposing.
With the wide angle diffuser dropped down, the light is more evenly distributed and you won't get the hot spot. The camera's metering doesn't have to work to compensate for uneven lighting.
If your at a wide angle like 18mm, the flash will likely not cover the entire area. The center may be somewhat brighter and the camera will adjust by underexposing.
With the wide angle diffuser dropped down, the light is more evenly distributed and you won't get the hot spot. The camera's metering doesn't have to work to compensate for uneven lighting.
Posted 15/02/2008 - 11:47
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Quote:
At what focal length are you shooting?
If your at a wide angle like 18mm, the flash will likely not cover the entire area. The center may be somewhat brighter and the camera will adjust by underexposing.
With the wide angle diffuser dropped down, the light is more evenly distributed and you won't get the hot spot. The camera's metering doesn't have to work to compensate for uneven lighting.
I'm not talking about coverage, I'm talking about exposure. It happens at longer settings where the wide panel would'nt normally be used. And I don't have flash vignetting. It is just that the camera meters the exposure differently if the wide panel is used or not.
At what focal length are you shooting?
If your at a wide angle like 18mm, the flash will likely not cover the entire area. The center may be somewhat brighter and the camera will adjust by underexposing.
With the wide angle diffuser dropped down, the light is more evenly distributed and you won't get the hot spot. The camera's metering doesn't have to work to compensate for uneven lighting.
Posted 15/02/2008 - 12:04
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If the flash is like the Pentax flashes, when the wide angle panel is down, the head inside the flash focuses for widest angle regardless of your lens's focal length. The diffuser plate just adds to the effect.
The camera is going to adjust exposure Dependant on the amount and coverage of light. With PTTL, the entire frame is used for metering the amount of flash used, so flash coverage plays a role.
I personally have found most of my images are slightly underexposed (K10D with Pentax 360 or 540 flashes). I often jack up the flash by .7 or 1 stop.
It could be that the camera gets less light from the flash and compensates more. PTTL isn't perfect and I have not found it to be very consistent...
Take the same scene with camera on a tripod. Adjusting ONLY the aperture, the flash and camera should adjust to get very similar exposures. Yet you will likely find that for each stop or two of aperture each frame may be off by half a stop or more.
If you're not using a controlled scene with a tripod, it will be difficult to tell if your exposure is caused by the flash or by environment.
Even the slightest movement of the camera can cause radically different exposures depending on the scene. A bright reflection, or someone standing and shifting/leaning by half an inch could greatly affect your exposure.
The camera is going to adjust exposure Dependant on the amount and coverage of light. With PTTL, the entire frame is used for metering the amount of flash used, so flash coverage plays a role.
I personally have found most of my images are slightly underexposed (K10D with Pentax 360 or 540 flashes). I often jack up the flash by .7 or 1 stop.
It could be that the camera gets less light from the flash and compensates more. PTTL isn't perfect and I have not found it to be very consistent...
Take the same scene with camera on a tripod. Adjusting ONLY the aperture, the flash and camera should adjust to get very similar exposures. Yet you will likely find that for each stop or two of aperture each frame may be off by half a stop or more.
If you're not using a controlled scene with a tripod, it will be difficult to tell if your exposure is caused by the flash or by environment.
Even the slightest movement of the camera can cause radically different exposures depending on the scene. A bright reflection, or someone standing and shifting/leaning by half an inch could greatly affect your exposure.
Posted 15/02/2008 - 21:00
Link
If you're not using a controlled scene with a tripod, it will be difficult to tell if your exposure is caused by the flash or by environment.
Even the slightest movement of the camera can cause radically different exposures depending on the scene. A bright reflection, or someone standing and shifting/leaning by half an inch could greatly affect your exposure.[/quote
I tried on a tripod, same scene same lighting, just dropped the wide panel of the Sigma flash and exposure was completely different. Then tried with different suject, and got the same result.
Even the slightest movement of the camera can cause radically different exposures depending on the scene. A bright reflection, or someone standing and shifting/leaning by half an inch could greatly affect your exposure.[/quote
I tried on a tripod, same scene same lighting, just dropped the wide panel of the Sigma flash and exposure was completely different. Then tried with different suject, and got the same result.
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1603 posts
18 years
North of Montreal,Quebec,
Canada