Problem with Exposure in Aperture Mode

RxForB3

No longer a newbie, moving up!
Joined
Feb 10, 2012
Messages
654
Reaction score
76
Location
Yakima, WA
Can others edit my Photos
Photos OK to edit
I'm trying to do a night time timelapse video with my Canon 6D. When I do simply night shots or night timelapses, I set the camera in manual mode and expose based on my instinct of what the appropriate exposure should be (say 25 seconds at f/2.8 and ISO 1600 to 3200) without looking at the light meter. However, twice now I've tried to do timelapses going from daytime to night time. My problem is that the camera appears to think that a 1 second exposure at ISO 1600 is appropriate in pitch dark. Even with the lens cap on, it says 1 second is enough. If I take a picture of a dark room, it again suggests 1 second. In manual mode, if I set the shutter speed to 25 seconds, it warns me that I'm vastly overexposing even if the resulting picture is perfectly exposed. Any suggestions what might be causing this? Is this normal? It happens with all forms of metering (evaluative, partial, spot, etc.).
 
OP
R

RxForB3

No longer a newbie, moving up!
Joined
Feb 10, 2012
Messages
654
Reaction score
76
Location
Yakima, WA
Can others edit my Photos
Photos OK to edit
The numbers I reference are with the EV centered at 0. If I boost the EV higher, it will choose longer shutter speeds. Which implies that the camera truly thinks the vast underexposure (by 4 or 5 stops) is appropriate.
 

Josh66

Been spending a lot of time on here!
Joined
Oct 31, 2007
Messages
14,593
Reaction score
1,238
Location
Cedar Hill, Texas
Can others edit my Photos
Photos NOT OK to edit
Does the meter work normally in good light?
 

cptkid

TPF Noob!
Joined
Apr 13, 2013
Messages
320
Reaction score
71
Location
United Kingdom
Can others edit my Photos
Photos OK to edit
How are you metering? i.e. what option have you chose.

Also, iso 1600 at night for a long exposure.

You should be using a tripod at night, why the high ISO.

Put it on 100.
 

Gavjenks

TPF Noob!
Joined
May 9, 2013
Messages
2,976
Reaction score
588
Location
Iowa City, IA
Can others edit my Photos
Photos OK to edit
What situation requires 25 second exposures at 1600-3200 f/2.8. Are you photographing black rocks 100 feet inside a cave on a moonless night with a blanket over your head or something? That's like... 21 stops higher than sunny 16. Normal night rule of thumb I remember as 17 or 18, I think?

Edit: Deleted my theory about what was happening. It is late, and I got the problem backward from what was described, so that theory didn't make any sense. Leaving my question above though. What are you actually photographing?
 
Last edited:
OP
R

RxForB3

No longer a newbie, moving up!
Joined
Feb 10, 2012
Messages
654
Reaction score
76
Location
Yakima, WA
Can others edit my Photos
Photos OK to edit
I'm doing landscapes with individual stars, not star trails. I do use a tripod, but in order to avoid trails, you use shorter shutter speeds.
 
OP
R

RxForB3

No longer a newbie, moving up!
Joined
Feb 10, 2012
Messages
654
Reaction score
76
Location
Yakima, WA
Can others edit my Photos
Photos OK to edit
Yes to both. But back to the problem at hand...

If I use manual mode, with the lens cap on, viewfinder covered, at f2.8, iso 100, the camera says 1 second is overexposed almost a full stop. That's not normal, right?
 

Josh66

Been spending a lot of time on here!
Joined
Oct 31, 2007
Messages
14,593
Reaction score
1,238
Location
Cedar Hill, Texas
Can others edit my Photos
Photos NOT OK to edit
With the cap on, the needle should not register on the meter at all (not sure about your camera, but most in-camera meters only show +/- 3 stops), no matter what settings you use.
 

Buckster

In memoriam
Joined
Sep 14, 2009
Messages
6,399
Reaction score
2,341
Location
Way up North in Michigan
Can others edit my Photos
Photos NOT OK to edit
Yes to both. But back to the problem at hand...

If I use manual mode, with the lens cap on, viewfinder covered, at f2.8, iso 100, the camera says 1 second is overexposed almost a full stop. That's not normal, right?
Is light leaking in through the eyepiece of the viewfinder? That can mess with the meter, so be sure it's covered.
 
OP
R

RxForB3

No longer a newbie, moving up!
Joined
Feb 10, 2012
Messages
654
Reaction score
76
Location
Yakima, WA
Can others edit my Photos
Photos OK to edit
I covered the viewfonder with the supplied cover and my hand. Plus, I get the same sort of result at night. I'm thinking this is a glitch in my camera?
 
OP
R

RxForB3

No longer a newbie, moving up!
Joined
Feb 10, 2012
Messages
654
Reaction score
76
Location
Yakima, WA
Can others edit my Photos
Photos OK to edit
I called canon technical support. She tried a 6D and 7D and got similar results. I may start a post in the canon forum and ask for people to try a specific setting on their cameras and see what the results are on various models. It seems to be a failure of the camera to be able to expose properly in extreme conditions...
 

amolitor

TPF Noob!
Joined
May 18, 2012
Messages
6,320
Reaction score
2,131
Location
Virginia
Can others edit my Photos
Photos OK to edit
If it's always Exactly 1 Second, there's probably some hard limit set in the firmware, it's not willing to open the shutter for >1 second.

If you were seeing 0.8, 1, 1.2, and kind of bouncing around that might indicate some different problem, possibly a bad meter or something.
 

Most reactions

ClickASnap

New Topics

Top