topic Re: 580EX II and C.FN in Speedlite Flashes

Speedlite 580EX II always shows C.Fn icon

Dirtnapper — Wed, 26 Nov 2025 14:15:35 GMT

I have two 580EX II flashes. One of them always shows the C.fn icon and I can not remove it. It is displayed in ETTL, Multi and Manual mode. I can click the 2nd curtain buttton, that icon turns off and on ok. Any ideras? Thanks.

Re: 580EX II and C.FN

deebatman316 — Wed, 26 Nov 2025 13:25:13 GMT

The Custom Function Icon is only displayed when a Custom Function has been set. Pressing and holding the light bulb/ C.FN will allow you to change it. Or when the flash is mounted on a camera released in or after 2007. The speedlite control menu can be used to change custom functions. Look for the Speedlite Custom Functions menu. Then you can select the default option which is 0.

Re: 580EX II and C.FN

Dirtnapper — Wed, 26 Nov 2025 16:56:28 GMT

I checked both flash units, and all the customs funtions are the same on each. My question is why one unit always shows the C.fn icon. I know how to change using my 5DM3 as well as on flash. Thanks.

Re: 580EX II and C.FN

deebatman316 — Wed, 26 Nov 2025 17:04:51 GMT

I would ensure you really do have custom functions set the same. There have been countless times where someone thought they changed something but didn’t. 0 is the default for all custom functions.

Re: 580EX II and C.FN

p4pictures — Wed, 26 Nov 2025 17:27:23 GMT

If you clear all the Speedlite settings using the camera menu while the Speedlite is on the camera, then C.Fn 00 is not reset. You can only set this one manually I would check either directly on the Speedlite itself or if it is listed in the camera menu displays. C.Fn 00 is the one that determines if the distance shown on the Speedlite is in feet or metres. The default is metres with C.Fn 00 = 0.

Re: 580EX II and C.FN

deebatman316 — Wed, 26 Nov 2025 17:41:00 GMT

Thanks for the reminder @p4pictures (Brian) I forgot that CF isn’t reset. Does this only apply to older cameras or all cameras? Since I don’t own that particular speedlite.

Re: 580EX II and C.FN

p4pictures — Wed, 26 Nov 2025 17:57:37 GMT

This is a Speedlite issue, not dependent on the camera. When you clear the settings of a Speedlite either with a camera menu, or using the combination of buttons on the Speedlite C.Fn-00 is not changed. I checked a few Speedlite manuals and they all seem to follow that convention. I guess the idea is that once you change from meters to feet you want to stay in feet even if you reset the Speedlite.

Re: 580EX II and C.FN

Dirtnapper — Wed, 26 Nov 2025 17:59:05 GMT

Hi,

I am not sure how the C.fn 00 relates to my issue. I checked both units and they are set at "1" (feet) using pg. 27 of flash manual as my guide. Again, the C.Fn icon is always visible on one unit and not the other. Seems to me that it should only be visibile when in the custo function setting and disapper when "mode" button is pressed to return to shooting, correct? Thanks.

Re: 580EX II and C.FN

deebatman316 — Wed, 26 Nov 2025 18:13:28 GMT

If you change that CF to 0 (Meters) then the CF indicator will go out. Unless you’ve changed other CF. Any CF you change the CF indicator will be visible. Unless all of the CFs have been reset to 0 which is the default.

Re: 580EX II and C.FN

deebatman316 — Wed, 26 Nov 2025 18:17:42 GMT

I just checked on my 470EX-AI if I change any CF from default the CF indicator comes on. Even if I switch from Meters to Feet. I usually set my speedlites to Meters (even though I’m from the U.S.). My job field uses the Metric system. So mistakes can’t be made between units.

Re: 580EX II and C.FN

Dirtnapper — Wed, 26 Nov 2025 19:09:40 GMT

This I understand...both units have C.Fn-00 set to "1" (feet). So, with that I assume as you state, and makes sense, that both units would have the C.Fn icon visisble. So, I cleared all C.fn's on both units, went back again made C.Fn-00 set to "1" for feet, as they were before the clearing. Now, the icon is gone. To test both units ,I changed C.Fn 13 to "1" and icon was visible on each. Somewhere something must have needed to be cleared, looks good now. Thanks.