Shadow question

TB68 · Feb 5, 2021

I am having an issue I've never had before and I'm not sure what to do about it. I am getting a shadow along the top line on a horizontal photograph. It also does it when I hold my camera vertically and the shadow goes to the left. Is it my flash, a setting, or my camera in general? I am including examples. Thanks for any advice/help.

stk · Feb 5, 2021

Looks like your shutter speed is faster than your cameras maximum flash sync speed.

Space Face · Feb 5, 2021

I'm no expert in flash photography but that were my first thaughts as well. It’s something I've suffered too.

Strodav · Feb 5, 2021

The meta data with the first image says your shutter speed was 1/400 sec, ISO 400, f/5, but it also says the flash did not fire. There is no metadata on the 2nd image. Most flash units with HSS (High Speed Sync) work up to about 1/200 sec then you'll start to see part of the frame blacked out. The flash did not fire value is confusing. What type of flash did you use?

I'm surprised they let you use a flash during a game as it distracts the players. I had an on camera flash fire at a game and they nearly threw me out.

TB68 · Feb 5, 2021

Strodav said:
The meta data with the first image says your shutter speed was 1/400 sec, ISO 400, f/5, but it also says the flash did not fire. There is no metadata on the 2nd image. Most flash units with HSS (High Speed Sync) work up to about 1/200 sec then you'll start to see part of the frame blacked out. The flash did not fire value is confusing. What type of flash did you use?

I'm surprised they let you use a flash during a game as it distracts the players. I had an on camera flash fire at a game and they nearly threw me out.

Thanks for the response. I used a Godox TT600 flash. It all depends on the situation as far as using flashes at games. When it comes to basketball, I don't use a flash when they are shooting free throws. They don't allow them at state basketball or wrestling tournaments, but other than that, I've never had a problem.

Original katomi · Feb 5, 2021

Without knowing your camera I can say but 125th to 120th is sync speed for flash
If you can look up your camera and find the sync speed or post the detail of your camera here and someone will tell you what the sync speed is
Edit looking close at your two images
In both there are signs of flash
The second image the man back left has a hard shadow
The brightness of the white kit and the white line reflections on the steps In the first images to me are all signs of flash

480sparky · Feb 5, 2021

You're shooting at 1/400 sec, which won't synch with the speedlight. Lower the shutter speed to the camera's stated synch speed and you're golden.

Make Canon
Model Canon EOS Rebel T6
Orientation Normal
Creator
Copyright
Exposure Time 0.0025s (1/400)
Aperture ƒ/5.0
Exposure shutter priority (semi-auto)
ISO equivalent 400
Exposure Bias none
Metering Mode Matrix
Flash Fired No (enforced)
Focal Length 45.0mm
CameraInfo ªª}.}-X
ModelID -2147482620
Lens EF-S18-55mm f/3.5-5.6 IS II
User Comment
Color Space sRGB
FocalPlaneXRes 2864.0883977900553
FocalPlaneUnits 25.4
White Balance Auto
LensModel EF-S18-55mm f/3.5-5.6 IS II
Date 2021-01-29 09:18:09 (no TZ)

Original katomi · Feb 5, 2021

Now I know your camera the sync speed is 1/200 of second

John Fantastic · Feb 5, 2021

as mentioned above you are using a shutter speed higher than you flash sync speed which is 1/200 second.

wfooshee · Feb 5, 2021

Explanation, if you don't understand the terms "sync speed" or "HSS."

The sync speed being mentioned above is the highest shutter speed at which the sensor is fully uncovered by the shutter curtains. There are two curtains, one opens to start the exposure, the second follows it to stop the exposure. The time between the first and second curtains is the shutter speed.

The shutter curtains have a minimum amount of time it takes them to cross the sensor's surface, which is much less than your camera's fastest shutter speed. If your shutter speed is set to a speed faster than that travel time, then the second curtain follows the first across the sensor, basically allowing a slit gap to scan down the sensor.

The shadow is caused by the second curtain closing during your exposure. At 1/400 shutter speed, the second curtain starts before the first curtain has completed its opening, and since the flash is fired when the first curtain reaches the open side, part of the sensor is blocked by the second curtain.

The sync speed is the fastest shutter speed on your camera that has the first curtain fully open before the second curtain starts to close. That's the fastest speed at which the shutters don't interfere with the flash.

Some cameras and flashes have "high-speed sync" capability, or HSS. Both the camera and the flash have to support it; having it in the camera doesn't make the flash capable, and vice versa. In HSS, the flash actually pulses in sync with the shutter gap moving across the sensor, so even though the shutter is never fully open, the entire image is exposed by flash. You lose some available flash power in HSS because of the need for rapid multiple firings, but the ability to add light in a scene with high ambient light that makes 1/200 or slower shutter speed unusable is an advantage for those situations. Without HSS, you have to use the sync speed or slower on your shutter, in your case, no faster than 1/200, and that shadow will not be there.

Camera-brand flash units that communicate fully with the camera will not let you set an invalid shutter speed, or if capable, will automatically go into HSS mode. With third-party lights, though, you have to know what's going on.