Weird question regarding camera getting it very wrong

[Squidy]

Hi all,

Canon 6D, Canon 24-105mm F4

I have a bit of a weird question. On the weekend my fiance and I went to some old settler's village here in Sydney, Australia to shoot some photos. I usually use my camera on auto ISO when using TV or AV mode. I was shooting an old abandoned house with a stormy sky behind it. It wasn't dark that day, just overcast a bit. The weird thing is when I went to focus on the house I was on F4.0 as I was using my 24-105mm. When I focused on the house it went to 100 ISO and 1/4000 shutter speed. Needless to say the photos looked very, very dark. I tried a few shots and the same thing happened. I went changed the ISO to 800 and the shutter speed still went to 1/4000. I turned around to take a photo of the orchards under the same sky and the camera functioned perfectly on auto ISO, but back again towards the house and it went out of whack again.

I was able to get some good shots when I switched to manual and made all the settings myself (4.0, 125ms, ISO 800) but in auto ISO and even with the camera on 800 ISO it still went to some incredibly fast shutter speed and made the whole photo look pitch black.

I also turned off auto lighting optimiser but still no luck.

Any ideas what could cause this? I'm happy to shoot in manual for this kind of thing if I can but I was hoping to be able to use AV mode especially if I'm in a hurry (ie with a fiance getting bored pretty quickly.

[HDNitehawk]

My first guess is metering and how you set it up.
Most likely the camera was metering off of the background sky not the building.
If that is the case though once you shot the building correctly your background sky or some part of the picture should be completely blown out.

Edit: My guess is you are using Evaluative or Center Weighted.

[Dave Throgmartin]

I personally like center weighted, but it's necessary to watch the histogram like you did.

Can you post the image?

Dave

[Squidy]

Oh, and I wasn't watching the histogram, I still don't know how to read it properly

[Dave Throgmartin]

Oh, and I wasn't watching the histogram, I still don't know how to read it properly

re: histogram

http://www.bhphotovideo.com/explora/...eras-histogram

I prefer center weighted because it is predictable. Evaluate uses an algorithm to try and predict what the proper exposure is. If what I'm getting doesn't match my expectations I dial in EV compensation or put in manual mode.

Dave

[Busted Knuckles]

So now begins the lessons in ETTR. Exposure to the right - in a set shot like this - take a moment, once you are practiced that moment will be about .5 seconds. .

Pick AV/TV and an ISO - you will be adjusting one against the other two.

The sky is what overwhelmed the AE. For landscapes, I am a fan of spot metering and spot metering only. I meter the most crucial element of the pic, double check the highlights ( brightest sky in this case). Set the exposure for just barely below the clipping point (this you have to double check your gear on). With the over exposure blinkies on, take a pick, there should be the very smallest portion dot of a blinky -- come down 1/3rd a stop from this. There are couple of ways to do this. Some version of manual - or some version of exposure compensation - with practice you will be able to see the difference between what you are metering and the clipping points in the scene. You can use ISO as your variable or I typically use shutter speed. I set a low ISO and then the aperture I want for the effect and fiddle w/ shutter speed 1st and then ISO second in the games of compromises.

What this exposure does is maximize the information to the sensor. It most likely ends up with something that looks overexposed, it is much easier to pull down the exposure in post than pull it up - there simply isn't any information in the shadows. Remember we set the scene with minimal if none blown highlights.

If the scene can't be overexposed using this method it is time for an HDR effort or know that you will have blown/clipped highlights.

Again, with a bit of practice - just sit somewhere on a morning you are lounging and take 10 minutes to play with this and compare the settings and highlights of the same scene - it doesn't take hours and hours, just a few moments of attention to the topic and it will become 2nd nature.

[Busted Knuckles]

A little update on the ETTR and blinkies - the blinkies are a jpg conversion of the raw, typically you can get a bit more out of the raw file than the jpg conversion.

[Squidy]

http://i.imgur.com/o44n28u.jpg

This is the image, it's F4.0, ISO 100 (selected by auto iso) and 1/4000

And apologies about the watermark, I forgot to turn that feature off

[Squidy]

I'll load it up into Lightroom at work and upload it.

What kind of metering should I use in these instances? I think it was evaluative

[HDNitehawk]

Spot maybe in that one instance. But there is no right answer, only that you know what the camera is doing and pick the one that works for you.
I keep mine on spot metering because it suits me. But that might give me the opposite problem in that if I do not pay attention it blows out the background.
I know this so if I am shooting landscape I stick with manual mode, meter the background with spot and meter the subject then decide what exposure I want.
Evaluative is supposed to sort that out for you.