TV MODE

[deeter]

Can anyone explain to me why when I set my 5D II to TV mode, set a shutter speed of say 1/800 and take a picture it adjusts the shutter speed? Shouldn't it stay where I set it? I had an epic wildlife photo today but missed it because my camera adjusted my shutter speed. I was shooting in TV mode at 1/800 ISO 200 100-400 4.5-5.6 Lens and when I took the shot it adjusted to 1/20?? I am obviously missing something. Thanks for the advice in advance!!

[dr croubie]

Look in your menu for something called 'Safety Shift' (I don't know where it would be on the 5D).
Basically, 1/800s didn't give you enough light with iso200, even with wide-open aperture. If the camera hadn't adjusted it to 1/20s, you would have a black photo.

I always use Tv (around 1/400s) on my 7D in conjunction with AutoISO. The aperture pretty much always stays wide-open (because i'm using a slow lens, 70-300L), the iso goes between 100 and 3200. As it gets dimmer in the evening, the iso hits 3200 then the shutter speed starts going down. Only in the brightest sunlight (ie never), it stays on iso100 and the aperture might go up to f/8.

I'm not sure how well the 5D2 handles AutoISO though, so you may be out of luck and have to go back to Av wide-open and set ISO manually based on the light...

[gjones5252]

C.FN I exposure
Under category 6 it has safety shift. Works in only tv and av obviously. Now when you take a picture with not sufficient setting the value that cannot go low or high enough will blink saying your exposure is off.

[wockawocka]

Sounds like Safety shift.

You've put the camera in a position where it cannot take the shot within it's limits set by you.

You can get around this easily by selection Auto Iso on the camera...much better chance that the safety shift won't cut in that way. You can disable it though.

In a way it's a good thing, when you pull up the files n Lightroom you can see the setting it used and you can ask why they ended up being what they were.

[Mt Spokane Photography]

Can anyone explain to me why when I set my 5D II to TV mode, set a shutter speed of say 1/800 and take a picture it adjusts the shutter speed? Shouldn't it stay where I set it? I had an epic wildlife photo today but missed it because my camera adjusted my shutter speed. I was shooting in TV mode at 1/800 ISO 200 100-400 4.5-5.6 Lens and when I took the shot it adjusted to 1/20? ? I am obviously missing something. Thanks for the advice in advance!!

The image would be black at those settings.  You would not have had anything at 1/800 sec but black.
You likely needed ISO 12800.
If you look thru the viewfinder or top lcd display, you will see the aperture flashing to tell you that you can't get the image at that setting.