| Author | Thread |
|
|
02/21/2006 08:03:02 PM · #1 |
| I am aware of the flash sync of my camera is 1/200th of a sec. But, does increasing the ISO change anything? Would you ever increase the ISO when using a flash? How are the two related? |
|
|
|
02/21/2006 08:04:27 PM · #2 |
| putting up the iso basically just makes your flash seem stronger. |
|
|
|
02/21/2006 08:12:43 PM · #3 |
You need to get a "certain" amount of light to your sensor for proper exposure. There are 3 factors that determine that - how much light your lens lets in, how long the shutter lets that light in for, and how "sensative" your sensor is. Apeture and shutter speed control the first 2, ISO is the last.
If you expose at 1/100 at f/5.6 at ISO 100, you can move to ISO 200 (2x as sensative) and then either speed up the shutter by a factor of 2 (to 1/200) to compensate, or close down the apeture to f/8 (which is a hole 2x as small - area wise which is why the numbers are funky).
Flash - this is a source of light. It is not directly related to ISO per se, but as above - if you get the right exposure with one shutter/f-stop/ISO combination, you can vary the ISO and compensate with the other 2.
Usually you vary the ISO (increase it) so you can take a picture in low light that you couldn't otherwise get.
So I guess that's the long way of saying it basically just makes your flash seem stronger... |
|
|
|
02/21/2006 08:28:28 PM · #4 |
Higher ISO increases how sensitive your sensor is to light...you do the math.
|
|
|
|
02/21/2006 08:52:20 PM · #5 |
Actually with E-TTL, increasing the ISO would decrease the duration and/or intensity of the flash as the camera senses that the shot was properly exposed and shuts off the flash.
Increasing ISO effectivly increases the reach of the flash. Going from ISO 100 to 400 doubles the reach of your flash. If I remember correctly, quadrupuling the ISO doubles the reach.
BTW a synch of 1/200 is mainly to prevent too much exposure to the background. If you set it to auto or in Av (I think) it is generally 1/60 sec, so that there is more time to allow ambient light to expose the background, while the flash exposes the subject.
Message edited by author 2006-02-21 20:54:20.
|
|
|
|
02/21/2006 09:16:02 PM · #6 |
Originally posted by yido:
Actually with E-TTL, increasing the ISO would decrease the duration and/or intensity of the flash as the camera senses that the shot was properly exposed and shuts off the flash.
Increasing ISO effectivly increases the reach of the flash. Going from ISO 100 to 400 doubles the reach of your flash. If I remember correctly, quadrupuling the ISO doubles the reach.
BTW a synch of 1/200 is mainly to prevent too much exposure to the background. If you set it to auto or in Av (I think) it is generally 1/60 sec, so that there is more time to allow ambient light to expose the background, while the flash exposes the subject. |
Thanks Yido. That was the answer I was looking for. |
|
Home -
Challenges -
Community -
League -
Photos -
Cameras -
Lenses -
Learn -
Prints! -
Help -
Terms of Use -
Privacy -
Top ^
DPChallenge, and website content and design, Copyright © 2001-2024 Challenging Technologies, LLC.
All digital photo copyrights belong to the photographers and may not be used without permission.
Current Server Time: 04/18/2024 08:31:25 PM EDT.
