flash synchronization - DPChallenge Forums

Canon EF 17-40mm f/4L USM

12/07/2007 01:17:36 PM · #1

I'm messing with the flash compensation on my camera and notice that there is a shadow created where there shouldn't be one. I was using shutter speed 1/125 f5.8 and flash compensation of -1.0 when the shadow appeared. I know it has something to do with the shutter speed but I don't remember how it works.... could someone give me a quick lesson on what I'm doing wrong? Isn't your shutter not supposed to be above/below a certain # when using the flash? don't remember..

renefunk

Canon EOS-5D

12/07/2007 01:21:23 PM · #2

maybe its the shutter, try take the pic in 60

Canon EF 17-40mm f/4L USM

12/07/2007 01:27:08 PM · #3

I was taking a pic of my running 2 year old so couldn't really use slower shutter. Maybe I just can't do flash compensation at high shutter speeds... ??

sea2c

Canon EOS-50D

Canon EF 50mm f/1.8 I

12/07/2007 01:28:33 PM · #4

Depending on your camera type, the flash sync will be either 1/250 or 1/500. Could be lower, again in depends. Most DSLR's are at least 1/250.

Essentially, the sync speed tells you at what speed your camera has the shutter fully opened at once to allow the flash to light the entire scene to the sensor.

Higher than the sync speed and the shutter will block part of the sensor. The higher the speed, the more blocked.

Saw a great video on it last week but for the life of me, can't find it.

soup

Canon EOS-30D

12/07/2007 01:36:59 PM · #5

what kind of shadow? - could be you're using a lens too long for the flash. where the lens end blocks some of the flash light from reaching the subject.

i don't think it would have anything to do with the FEC.

then again you dont have a camera so i'm not even sure how you ran into the issue to begin with...

Message edited by author 2007-12-07 13:37:37.

Nikon AF-S Nikkor 70-200mm f/2.8G ED VR II

12/07/2007 01:57:05 PM · #6

You're right Soup! I'm magic.... Now back to my question....

MattO

Nikon D4

12/07/2007 01:59:10 PM · #7

Originally posted by wannabe:

You're right Soup! I'm magic.... Now back to my question....

Tell usyour equipment setup and you will get better help. Onboard flash? what camera? what lens?

MattO

Canon EF 24-70mm f/2.8L USM

12/07/2007 02:04:11 PM · #8

Gotcha - non paying members can't put that kind of info in the profile, will remember to post next time.

Nikon D40 in camera flash. 18-135mm lens, lens length was 20mm for the shot.

Telehubbie

Canon EOS-40D

12/07/2007 02:41:51 PM · #9

Do you have a lens hood on that 18-135?