why did this happen?

KTBoom2006-E510

Trying out the flash bracket and sync cord, I came up with this picture when it is above a certain shutter speed. No matter where I am pointing the flash, this is what I get. Anyone know why?




EXIF

File name
IMG_1029.CR2
Camera Model Name
Canon EOS DIGITAL REBEL XSi
Firmware
Firmware Version 1.0.4
Shooting Date/Time
7/25/2008 15:10:15
Tv(Shutter Speed)
1/400Sec.
Av(Aperture Value)
F4.0
Metering Modes
Spot
Exposure Compensation
0
ISO Speed
400
Lens
EF-S55-250mm f/4-5.6 IS
Focal Length
70.0 mm
Image size
4272 x 2848
Image Quality
RAW
Flash
Off
White Balance
Daylight
AF mode
AI focus AF
Picture Style
Faithful
Parameters
Tone Curve : Standard
Sharpness level : -
Pattern Sharpness : -
Contrast : 0
Sharpness : 0
Color saturation : 0
Color tone : 0
Long exposure noise reduction : Enable
High ISO speed noise reduction : Enable
Highlight tone priority : Disable
Color matrix
-
Color Space
sRGB
File Size
16051 KB
Dust Delete Data
No
Drive Mode
Single-frame shooting
GPS Data
Satellite signal status : -
Date(UTC) : -
Latitude : -
Longitude : -
Altitude : -
Geographic coordinate system : -
Owner's Name
-
Camera Body No.
670218512

I put it in every mode with changing the F stop and the ISO along with it, and I keep getting this after 320 shutter speed I think

ziggy53

KT,

This is normal. Your camera syncs flash up to 1/200th. To go beyond this you have to use a flash capable of FP/HSS mode and set the camera in FP mode. Current flash units that allow FP mode on Canon cameras are:

Canon 580EX
Canon 430EX
Sigma EF 530 DG Super

Attempting to use the flash at higher shutter speeds in "normal" sync mode does not allow the shutter to clear the imager. The darkness you observe is just part of the shutter curtain still in the way as a result of the narrower shutter "slit" at higher shutter speeds.

At even higher speeds there would be even more of the shutter in the way.

KTBoom2006-E510

ziggy53 wrote:

KT,

This is normal. Your camera syncs flash up to 1/200th. To go beyond this you have to use a flash capable of FP/HSS mode and set the camera in FP mode. Current flash units that allow FP mode on Canon cameras are:

Canon 580EX
Canon 430EX
Sigma EF 530 DG Super

Attempting to use the flash at higher shutter speeds in "normal" sync mode does not allow the shutter to clear the imager. The darkness you observe is just part of the shutter curtain still in the way as a result of the narrower shutter "slit" at higher shutter speeds.

At even higher speeds there would be even more of the shutter in the way.

I am using a Canon 580EX with my Canon XSi.... it doesn't do it when the flash is on my camera rather than on the bracket

ziggy53

KTBoom2006-E510 wrote:

I am using a Canon 580EX with my Canon XSi.... it doesn't do it when the flash is on my camera rather than on the bracket

It is possible that the off-camera cord is not passing all the signals from the flash to the camera.

If you "can" set the 580EX to FP mode (I think you get an "HS" indication on the flash display) then you should be OK.

dangin

ziggy's dead on with it. (as usual...) what kind of sync cable are you using? if it's TTL/i-TTL compatible, you should see your flash denote that it's in TTL (or i-TTL) mode on the display as you depress your shutter button halfway. if it's not; it's likely your sync cable is to blame. be sure that you shutter speed is set no faster than 1/200 otherwise you're bound to get this artifact of the shutter not completely clearing the frame while you're taking the shot.

KTBoom2006-E510

The cable is the problem, thanks!

Scott_Quier

That shot is interesting - let me explain. My Canon 30D cameras have a sync speed of 1/250. In an experiment, I set the shutter speed to 1/500 and the shutter covered almost exactly 1/2 the frame during the flash - as one would expect.

Katie's camera is documented to have a sync speed of 1/200, yet when shooting at 1/400, only a small portion of the sensor is covered during the exposure.

As I prefer to shoot with off-camera flash more than other-wise (I might eventually try out the RadioPoppers - but that's a discussion for another thread) I would be strongly tempted to run through the shutter speeds from 1/200 to 1/400 to determine, experimentally, what the max sync speed is for this particular copy of the camera. I'm wondering if it might not, in fact, turn out to be 1/250.

pathfinder

I suspect the camera did not even know the flash was there - because, you cannot set a shutter speed higher than 1/250th ( or the native flash sync speed with an EOS flash on board ) UNLESS High Speed Synch is enabled.

Even if my 1DsMkII is in Manual Mode, if I mount a 580ex, and set the shutter speed at 1/500th and the aperture at f8, the camera/flash resets the shutter speed to 1/250th at the moment of exposure. Here - the camera did fire at 1/400th which suggests to me that the camera was totally 'unaware' of the presence of the flash eg: not making contact - interesting that the flash did apparently trigger.
Set that 580ex to HSS, and use a proper cord, and this problem should disappear.