Advertisement
If you have a new account but are having problems posting or verifying your account, please email us on hello@boards.ie for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact hello@boards.ie
Hi there,
There is an issue with role permissions that is being worked on at the moment.
If you are having trouble with access or permissions on regional forums please post here to get access: https://www.boards.ie/discussion/2058365403/you-do-not-have-permission-for-that#latest

Flash help

  • 26-02-2008 1:04pm
    #1
    bernard0368
    Registered Users, Registered Users 2 Posts: 1,424 ✭✭✭


    I have just introduced a 430 ex flash to my canon 400d. I need a bit of help here. If the camera is in P mode the exposure shows 1/60 f5.6 for example. If I put the camera is in M mode I will get the normal exposure for the conditions say 3 secs. The flash doesnt seem to compnesate. Am I missing something or should I shoot in P mode when using a flash.


Comments

  • #2
    DaireQuinlan
    Registered Users, Registered Users 2 Posts: 6,713 ✭✭✭DaireQuinlan


    bernard0368 wrote: »
    I have just introduced a 430 ex flash to my canon 400d. I need a bit of help here. If the camera is in P mode the exposure shows 1/60 f5.6 for example. If I put the camera is in M mode I will get the normal exposure for the conditions say 3 secs. The flash doesnt seem to compnesate. Am I missing something or should I shoot in P mode when using a flash.

    Depends. I presume Canon has something like Nikon's TTL flash or iTTL flash or equivalent, ie, it'll always try and make sure the flash part of the exposure is correct if the flash is set to use it. If thats the case, then the AMBIENT part of the exposure is entirely up to you in manual. The P (or program auto) is probably intelligent to know that there's a flash attached and defaults to a much higher shutter speed.

    In Manual you're effectively mixing whatever ambient exposure you've set with the flash output. If I'm using a flash and don't want any ambient I normally set my (manual) exposure time to whatever the maximum flash sync of my cameras are (1/250 in the case of both my nikons) and play with the aperture for DOF and just rely on the Nikon TTL system to expose the flash properly.


  • #3
    Borderfox
    Registered Users, Registered Users 2 Posts: 10,263 ✭✭✭✭Borderfox


    If you leave it in P it just worries about the subject and not the ambient, put it in either Av or Tv and shoot that way.


  • #4
    DaireQuinlan
    Registered Users, Registered Users 2 Posts: 6,713 ✭✭✭DaireQuinlan


    Borderfox wrote: »
    If you leave it in P it just worries about the subject and not the ambient, put it in either Av or Tv and shoot that way.

    I think the OP is actually complaining about just the above though, My reading of what he was saying is that he's giving out that if he has it in M the exposure reading he gets is 3 seconds (I'm presuming he's shooting in dim light here !). Putting it into Av will give the same unacceptably long exposure times, Tv will open up the aperture all the way which may or may not be what the OP wants.

    I think a bit of reading is in order. Any good links for flash stuff ? I know the Strobist, might not be the best beginner resource though.


  • #5
    King Eric
    Registered Users, Registered Users 2 Posts: 213 ✭✭King Eric


    This is long, but i would imagine exactly what you need to get reading

    http://photonotes.org/articles/eos-flash/

    there be a test on this on friday


  • #6
    DaireQuinlan
    Registered Users, Registered Users 2 Posts: 6,713 ✭✭✭DaireQuinlan


    ahHa, that's the ticket :-)

    in particular this ...
    http://photonotes.org/articles/eos-flash/index2.html#confusion

    Its good to see that the EOS is clever enough not to go faster than the flash-sync speed in Av mode if there's a TTL enabled flash attached and switched on. This is all assuming that the Canon Digital TTL flash works the same way as the Film TTL flash, Nikon made a big booboo there and managed to make both completely incompatible. Jerks.


  • Advertisement
  • #7
    bernard0368
    Registered Users, Registered Users 2 Posts: 1,424 ✭✭✭bernard0368


    Thanks Eric, That seems to be what I need.


  • #8
    Dr.Louis
    Closed Accounts Posts: 236 ✭✭Dr.Louis


    just remember that you can only control flash exposure with the aperture (and not the shutter speed), of course you can also control it with the actual out put power of the flash and the distance from subject etc... But shutter speed will have no effect on the flash power, only ambient light.


  • #9
    bernard0368
    Registered Users, Registered Users 2 Posts: 1,424 ✭✭✭bernard0368


    See this is the bit that is confusing me. How do you know what aperture and shutter speed should you set in manual to get the correct exposure. I tried the AV and Tv. The AV settings stays the same on the camera with or without the flash. So for example if I set the AV to F7 I still get a 3 sec shutter speed with the flash on and off in low light conditions. Much the same with TV


  • #10
    elderlemon
    Registered Users, Registered Users 2 Posts: 1,014 ✭✭✭elderlemon


    On the Canon the Av/Tv + Flash = Fill. Manual+Flash = normal flash. When you use flash with AV/TV the camera exposes as it normally does and does not take the flash into consideration and simply pops in a fill based on what it sees.

    In manual mode the camera is setting the flash to expose for the scene.
    bernard0368 wrote: »
    See this is the bit that is confusing me. How do you know what aperture and shutter speed should you set in manual to get the correct exposure. I tried the AV and Tv. The AV settings stays the same on the camera with or without the flash. So for example if I set the AV to F7 I still get a 3 sec shutter speed with the flash on and off in low light conditions. Much the same with TV


Advertisement