Priority Mode Metering Issue

Hi,

I'm using a Canon 7D and have a question about metering in certain modes. When I'm in Aperture Priority mode, for example, with Auto ISO and a speedlight attached, the camera gives me no form of warning whatsoever if my exposure is way off before I take the picture. For example:

I walk outside mid-day and set the following:

f2.8
ISO 100
1/200 shutter
Speedlight attached on camera hot shoe

If I half-press the shutter to update the light meter, it just has the line locked on the center of the meter at EV 0. Now I understand that is what the purpose of a non-manual mode is; to tell the camera to maintain a certain metering. But without a ND filter on my lens with the above settings, the shot would be WAY overexposed if I snapped a picture. However, before I snap the picture there is no form of warning whatsoever that the camera is not capable of achieving that exposure.

This was a little difficult to explain in words so I hope I made it clear.

I am confused. If you are in aperture priority, with Auto ISO, and the ISO has bottomed out, the camera should increase the shutter speed to obtain the standard exposure. I am also not sure how the flash is being used in this case.

If you look at the bottom right of the VF while you are metering you will see two right triangles 'facing' each other. This is the camera telling you 'don't take the shot, the light metering is off'.

By having the flash on, you limit the SS to 1/200 or less. You have also selected f2.8 and ISO 100 (and say you need SS 1/800). This will result in an overexposed shot.

The camera knows that you have over-restricted the problem. You have to know how it is telling you.

Flash ready to fire locks your ISO to 400 with AUTO-ISO. Not having HSS engaged limits your shutter speed to 1/250 (what Gerry meant, max). When I shoot in bright sunshine with flash, I set my ISO to 50 (6D, no 1/8000) and HSS. For the most part, it works.

The 1/200 puzzles me. Options are: 1/250, 1/60 to 1/250 floating, unrestricted. In your described situation, you should never see 1/200. If the camera were saying OVEREXPOSURE, and raising the shutter speed, why not raise it all the way to 1/250? Granted that would not be enough, but something odd is going on here.

EDIT: Is the flash in Manual mode? That would explain the overexposure, but not the 1/200.

I kind of rushed my original post and wasn't concise enough.

In A/V mode, yes. So the shutter would not be set at 1/200; I apologize.

My main question I was trying to get at is this:

In A/V mode with the flash turned OFF and let's say I set the aperture to 2.8, the camera decides the shutter, but let's say I jack the ISO up to something ridiculous like 6400. The light meter in the viewfinder will flash the shutter telling me that if I proceed with the shot it will be way overexposed.

Once I turn the flash on, things change. I can initiate a similar situation - let's say it's during bright sunlight and even at 2.8, 1/250 and ISO 100 the shot would still be overexposed. However, I would have to actually take the picture and review it to realize it; with the flash turned ON there is all the sudden no form of flashing warning letting me know that I'm way off.

I understand in manual mode the arrows will show me that it's out of exposure range, but in A/V with the flash on then there's no clues given that exposure will be off. Even in situations like the camera will still use ISO 400 for some odd reason and then REALLY blow the exposure way out (it can't at least automatically go down to ISO 100?!?!)

*Important edit: I am not trying to figure out a way to take pictures in bright sunlight at these settings. I am simply trying to understand why the camera is not helping out with exposure warnings with the flash on.

Try that shot in P mode.

GeoKras1989 wrote in post #17596764
Try that shot in P mode.

I don't think that will answer the question in any way given that the question specifically relates to Av mode. As the Op said, he isn't trying to work out how to take the photo, only to work out why the camera doesn't display a warning in Av mode.

Thanks. What I was getting at was that the shot may have too many conflicting variables. Av, auto-ISO, ETTL-II, each impose their own restrictions. Perhaps the camera just isn't programmed to make that many judgements when each restricts the others to some degree. Putting the camera in P mode tells the camera that you want IT to make ALL the decisions. And a way to find out how the camera handles all those variables when it has total control.

Try it without the auto ISO.