Compulsory Flash Mode?

KED

I don't know if this is exactly the right place for this, but . . . lately my EXIF data (at least as displayed on SmugMug) has shown, under "Flash": "did not fire (compulsory flash mode)". I googled Compulsory Flash Mode and got a bunch of posts on various forums from shooters who did, in fact, have flash attached in their contexts. I didn't have a flash within two miles of the shoot in question. My results were fine, but I want to make sure that I haven't inadvertently reset something that is causing this EXIF to register this way, and which could come back to haunt me.

ziggy53

I think the best source of information about what EXIF is supposed to represent is found at:

http://www.exif.org/

Unfortunately the coded EXIF data has to be decoded by software and the meaning of the data can become confused and even distorted.

I don't think that the "Compulsory Flash Mode" data always means what it probably should mean. I don't personally look at that field.

Although I recommend double-checking your camera's settings, especially the flash related settings, as long as the camera is doing what you wish I wouldn't be too concerned about the "Compulsory Flash Mode" field data or messages.

KED

ziggy53 wrote:

I think the best source of information about what EXIF is supposed to represent is found at:

http://www.exif.org/

Unfortunately the coded EXIF data has to be decoded by software and the meaning of the data can become confused and even distorted.

I don't think that the "Compulsory Flash Mode" data always means what it probably should mean. I don't personally look at that field.

Although I recommend double-checking your camera's settings, especially the flash related settings, as long as the camera is doing what you wish I wouldn't be too concerned about the "Compulsory Flash Mode" field data or messages.

You are a true renaissance man even knowing about the existence of that site, all the more so if you have actually waded through it. I think I'll go with your last advice and ignore it, at least until something goes wrong. Thanks for responding.

JGD

Ked,
On my 5D, when custom function 07 (Flash firing) is selected you get two choices, Fires or Does not fire. When set to Fires, and no flash is present (the 5D does not have a built in flash) the exif will show Flash mode-compulisory, did not fire.

I leave mine set this way so that when I do want to use a flash, I don't have to remember to go to the custom function menu to change this setting. If you have this function set to Does Not Fire, and you attatch your flash it still won't fire unless you change the setting.

If you never use a flash then you can set Does not Fire and avoid the did not fire message in the exif data.

This is how it seems to work to me.

KED

JGD wrote:

Ked,
On my 5D, when custom function 07 (Flash firing) is selected you get two choices, Fires or Does not fire. When set to Fires, and no flash is present (the 5D does not have a built in flash) the exif will show Flash mode-compulisory, did not fire.

I leave mine set this way so that when I do want to use a flash, I don't have to remember to go to the custom function menu to change this setting. If you have this function set to Does Not Fire, and you attatch your flash it still won't fire unless you change the setting.

If you never use a flash then you can set Does not Fire and avoid the did not fire message in the exif data.

This is how it seems to work to me.

Thanks -- I did recently change my custom flash settings for a very specific purpose which then ended up not happening -- but I think you have pointed me in the right direction. As an aside though, the custom settings you describe seem kinda ridiculous -- if you want flash you attach it; if you don't, you don't. Not sure why one would ever want to incur the extra brain damage of remembering whether that CFn was enabled and then doing the "opposite". I am a Canon guy for life (no choice at this point), but sometimes they overthink things, IMO.

salazar

OK, how is this for a suggested explanation for that setting? Say your flash has a focus assist light which will assist the camera/lens to focus in low light situations. Say you want to use the focus assist light but don't want the flash to fire during the expoxure. Perhaps this setting takes this senario into account?

Another possibility, you have remote strobes. This setting allows the user to instantly switch back and forth to a custom function with the strobes set to fire and to one where the remote strobes do not?

I'm sure there are more applications, I just thought about this for a minute or two.

KED

salazar wrote:

OK, how is this for a suggested explanation for that setting? Say your flash has a focus assist light which will assist the camera/lens to focus in low light situations. Say you want to use the focus assist light but don't want the flash to fire during the expoxure. Perhaps this setting takes this senario into account?

Another possibility, you have remote strobes. This setting allows the user to instantly switch back and forth to a custom function with the strobes set to fire and to one where the remote strobes do not?

I'm sure there are more applications, I just thought about this for a minute or two.

Your scenarios may also trigger this, but not for me; no remotes, no stand-alone focus assist light usage. I still haven't had a moment to revisit the CFn changes that I made related to flash, but I think the answer is in there. Fortunately, my shots seem unaffected.