EOS 5D Mark III/3 Blinking Green Light

[gary6557]

I live on the coast about 40 miles south of Cape Canaveral.  When Falcon rockets head due south I can photograph them from my balcony except at night.  Tripod mounted, MF, focus set on horizon etc etc,  but when I  press shutter it will not take a picture and there is a flashing green light in the lower right corner of view finder.  Scoured pages, internet etc, missed plenty of great shots and just need some guidance or direction.  Thankyou.

[jrhoffman75]

That blinking indicator means autofocus is operating and can’t achieve focus. Are you using a Canon brand lens? What exposure mode are you using? Does camera indicate correct exposure? If you aren’t in M mode camera won’t fire if correct exposure can’t be achieved. 

[gary6557]

Canon 24-70 lens set to MF and camera is in manual mode.  Exposure is set to F8, ISO160

[jrhoffman75]

I just tested with my 1D X.

With lens in MF mode I manually focus - green dot is off until I get focus and then it turns on.

In AF mode it blinks green until it focuses and then it turns solid.

Sorry, but I can't help.

[stevet1]

gary6557,

Try putting your camera in Servo mode. See if that makes a difference.

Also, do you experience this across all lenses, or just this one?

Steve Thomas

[gary6557]

Shooting at night along the coast in pitch darkness except for distant light outside of focus points.  This is so I can get a good 3 minute exposure through the view finder from one side to the other.  Thought that if I pre focused during light in Manual mode and MF on lens that that would be sufficient, apparently not.

[jrhoffman75]

Do you have any Custom Settings or Functions set? Maybe reset camera. What you did is exactly how I take my astrophotography shots - Milky Way and star trails. I focus on a distant point, set the lens to MF and gaffer tape the focus ring so it doesn’t change. M mode with my desires Tv and Av.