Go Back   Steve's Digicams Forums > Digital SLR and Interchangeable Lens Cameras > Canon EOS dSLR

Reply
 
Thread Tools Search this Thread
Old Jan 18, 2006, 7:44 AM   #1
Junior Member
 
Join Date: Jan 2006
Posts: 1
Default

Hello
I have several questions about the built in flash.
1.Is it true that taking a picture with the flash in Auto/P mode, can select
Shutter speed too low that can cause blur picture?.
How can i take pictures in Auto/p mode with shutter speed fast enough?.
2.I saw that in Av mode i can select sync flash speed of 1/250.The shutter speed stay in that speed even if i change the aperture to any value, and the picture is well exposed.
How can it be that changing aperture to any value does not change the shutter speed and the picture is OK?.
3.Can someone explain me please how to work with the flash and the Sync functions?.
Thanks
orela is offline   Reply With Quote
Sponsored Links
Old Jan 18, 2006, 1:49 PM   #2
Moderator
 
Join Date: Aug 2004
Posts: 8,529
Default

Quote:
1.Is it true that taking a picture with the flash in Auto/P mode, can select
Shutter speed too low that can cause blur picture?.
How can i take pictures in Auto/p mode with shutter speed fast enough?.
Whether or not the flash will stop motion blur depends on how much exposure difference there is between the ambient light and your flash. In general terms, if things are dimly lit, a flash with a shutter speed of 1/60 is enough to stop motion. If the ambient light exposure is close to the exposure with your flash then it won't freeze the motion. P and Auto mode don't concern themselves with setting shutter speeds to stop action. Now, as for blur from camera shake (where your hands move rather than the subject) - I believe the camera selects a shutter speed of 1/60 - so for very long lenses that could cause camera shake. Again, the exposure with flash vs. without comes into play here - since the flash is really around 1/10000 camera shake isn't really an issue if your exposures are very different.
Quote:
2.I saw that in Av mode i can select sync flash speed of 1/250.The shutter speed stay in that speed even if i change the aperture to any value, and the picture is well exposed.
How can it be that changing aperture to any value does not change the shutter speed and the picture is OK?.
The reason the speed can stay at 1/250 is because the flash is adjusting power output to properly expose the subject. If you choose a large aperture (small f-number) the flash will output less power. If you choose a smaller aperture (large f-number) the flash will need to output more power to expose properly. The problem with this is the internal flash isn't really that powerful. So, I wouldn't suggest using this function with the internal flash - I think you'd get too many underexposed shots. In the long run I highly recommend an external flash - the internal one is just too weak to be of much use - other than as a fill flash.
JohnG is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 4:47 PM.