EOS DSLRs: How do you get the right exposure?

[Sam North]

I bought myself the 300D/Digital Rebel and a Sigma zoom to get myself into DSLRs for the future. I’ve been really surprised at how good the images are and how well the camera performs. It’s great to see ISO 100 images with continuous tone totally free of grain.

The only difference I’ve noticed is in nailing the exposure – with the 300D it’s just a bit tricky at times. I’ve trawled the Web to see what I could learn and found that using all 7 focus points is recommended. I tried this and found that the camera has a habit of focusing on the wrong subject.

I also discovered that Canon’s method for correct exposures was more challenging – for me anyway. In fact the logic of it escapes me: “…metering is concentrated around the subject” found by the focusing point, which is fine if the subject’s a useful mid-tone.

The same site (http://photoworkshop.com/canon/lessons_1-5.html) reassures me that images taken using the camera’s AE lock “will show your main subject properly exposed.” For this to work you really need to know your mid-tones, although this basic technique is not mentioned in context. (The site also has interesting captions: “Light subjects can be fooled by a camera’s metering system.” So can dark subjects apparently…)

Anyway, when handholding my old EOS camera (50), I mostly use a button on the back to focus, then lock in the mid-tone exposure with a half-press of the shutter button. This method is very successful and delivers very, very few under- or overexposed shots on slide and print film. So, I now do the same thing with the 300D – first lock in a suitable mid-tone, focus with the centre point, recompose and shoot – and have found that my success rate is very good. It’s surprising how quickly this can be done. So far it seems possible that the 300D tends to overexpose just a little, so at times I have to take this into account. (My technique changes slightly when I use a tripod.)

What’s your approach for correct exposures? I've read quite a bit of exposure complaints over the last few months and I'm thinking the problem is really technique, especially if someone is stepping up from a P&S camera.

It does seem as if Canon have a touch too much faith in their evaluative metering and seven-point auto focus systems.

Sam

[defordphoto]

Everyone has their own approach and I appreciate Canon giving us so many options with these killer dSLRs. I rarely use 7-point focus with my 10D. 99% of time you'll find mine on center-point focus. I'll point at my subject for focus and exposure and half-depress, then recompose the frame how I actually want it and shoot. About the only time I use 7-point is when I'm putzing with DOF stuff.

There's nothing wrong with the camera. The camera makes its best guess on what your subject actually is, but it has no way of knowing if you want to focus on the tree or the bush.

When using 7-point focus the focus points the camera chooses will flash red as the camera beeps. That will let you know where it's trying to focus. You can recompose slightly and the camera may select totally different points. Or not.

Remember it's just a computer and can only make guesses.

Hope that helps...

[sdommin]

I've read quite a bit of exposure complaints over the last few months and I'm thinking the problem is really technique, especially if someone is stepping up from a P&S camera.

P&S cameras only have a few advantages over DSLRs, and this is one of them (meaning that you can see and adjust the final exposure before you take the shot). I find that I need to rely more on experience (and bracketing) with my 10D.

[Sam North]

"I'll point at my subject for focus and exposure and half-depress, then recompose the frame how I actually want it and shoot." The problem with this method is the tone of the subject.

I recently took a test shot of a white house against a bright sky with dark trees in the foreground making up most of the frame. The subject for focusing was the house which meant with centre-point focusing the metering was all wrong . You have to lock in a mid-tone first, then focus and recompose. Seven-point focusing was not an option in this case with so many trees in the foreground.

I read this on another forum: “Evaluative metering takes some getting used to, but it can be excellent. If you are trying to use it with center focus ONLY, you will undoubtedly have inconsistent exposures. However, learning to effectively use the 7 AF points is an art.” I would add that using the seven-point system for many shots is unnecessary if you learn to look for the mid-tone.

Sam

[defordphoto]

Well, if you had been that specific with your question I would have answered it quite differently. ;) The reason we have so many choices on our cameras is that we will run into so, so many different lighting, focusing, white-balance, etc, etc, etc, situations that we are given the option(s) of changing any and or all of those option(s) the fit the particular scene.

There is not one perfect setting on any camera that will work perfect for every setting. And different cameras will require different settings. What works for a 10D might not work for a 1D. And there are usually several different methods offering different results dpending on the effect you're looking for.

Part of the process is experimenting with your particular camera and learning its limitations. What it can do and what it can't do. Experiment with all the different lighting setups (on the camera) in this case can produce drastically different results. White balance, metering, etc.

Other options are:

Shoot two exact shots of the same scene with two different lighting settings. One for the dark trees and then one for the white house. Then layer them in Photoshop.

You can also just take the one shot and then use a shadow recovery action or CS's new options that help recover shadowed scenes. Heck, Photoshop Elements' fill flash option does quite a nice job of recovering lost details in shadows.

I hope that helps.

[Motorsports Photo]

Exposure: One of the most annoying problems with my Canon DSLR's.

With my film SLR's, I had no problems with this. Print or slide almost EVERY exposure was spot-on and I never did any compensation. Then when I get digitized, exposures are all over the place even when shooting the same thing in 2 subsequent frames!!

My best correction is to underexpose by 1/2 to 1 stop. I have to check the histogram every so often to make sure the "trend" stays the same. If cloudy turns to sunny, you have to check it again and make sure its OK.

I hate throwing out images because they cant be saved because of gross overexposure. A front focus problem only mildly annoying compared to WRONG exposure.

-Pete

[scottbergerphoto]

"I'll point at my subject for focus and exposure and half-depress, then recompose the frame how I actually want it and shoot." The problem with this method is the tone of the subject.

I recently took a test shot of a white house against a bright sky with dark trees in the foreground making up most of the frame. The subject for focusing was the house which meant with centre-point focusing the metering was all wrong . You have to lock in a mid-tone first, then focus and recompose. Seven-point focusing was not an option in this case with so many trees in the foreground.
Sam
If you're a student of the Zone System, you don't ned to lock on to a mid- tone. Put your 10D in partial metering mode, center focus point, manual exposure. Fill the central circle in the viewfinder with the tone you most want to capture correctly. Depress the shutter half way to get a reading. Adjust the reading from the camera meter up or down based on the number of zones it is from 18% Grey. Once you have set the exposure correctly for a given tone, the other tones should be exposed properly as well. I use a modified 5 zone system.
4.5% Grey(White) - 9%Grey - 18%Grey - 36%Grey - 72%Grey(Black)
So if your shooting snow, overexpose by about 2 stops. A black tuxedo, underexpose by about 2 stops.
If you'd rather let the camera do more of the work, switch to Partial Metering in Av or Tv, Exposure Lock *, and use exposure compensation using the same zone system. Always check the histogram to make sure it represents the exposure you want.
Regards,
Scott

[Sam North]

Jim, thanks for that. Appreciate it. Sorry if I wasn’t too clear.

There are indeed various ways to get around exposure extremes, on a shoot and in software, but I’m more interested here in what actually is the most accurate way to get exposures in the first place, and isolating mid-tones is usually our best bet. Of course, much can depend on your subject, but by and large, in very many situations, mid-tones will deliver more accurate exposures. I have a very high success rate using this method, going back to my early days in the 70s with centre-weighted average Minoltas like the 101 ST.

A few summers ago I was on the top of Mont Blanc in France and I ran off a stack of shots all based on a dialled in manual reading of a spectacular blue sky. Every shot in the snow and bright sunlight was dead on.

I’ve had reservations about evaluative metering for some time and found that locking onto the mid-tone is by far the better option. It’s like exposure insurance, if you like.

The shots below are not quite ideal, but nevertheless I’m certain the 300D’s evaluative metering system should have made a much better job of it. I used the tree, which at 24mm is a lot closer than it looks, for 7-point focusing and evaluative metering. What do you think?


http://www.theimageplane.net/300dpartial.jpg
Shooting Mode
Aperture-Priority AE
Tv( Shutter Speed )
1/125
Av( Aperture Value )
8.0
Metering Mode
Partial


For the above image I took a reading off the grass next to my feet, focused on the tree and shot. For the shot below I used evaluative metering and focused on the tree (that's what the camera focused on).

http://www.theimageplane.net/300deval.jpg
Shooting Mode
Aperture-Priority AE
Tv( Shutter Speed )
1/400
Av( Aperture Value )
8.0
Metering Mode
Evaluative


So I’m interested in other opinions here about essential exposure techniques with these modern EOS DSLRs. I agree that if you rely on centre-point focusing for exposures you’re much more likely to be disappointed. There are many ways of looking at the problem, but we all need to do the best we can before the shutter fires.

Here’s another view:"What I am going to show you is how to use the Evaluative metering mode for most shooting situations without resorting to using the Partial, Spot or Multi-spot metering options. It all boils down to knowing which AF point is going to be used on the main subject as well as the composition of the scene” (http://www.camera.canon.com.my/archive/photography/art.htm). Well, I’m not sure I agree, but if your subject is the right tone it will work.

Scott, thanks for that - certainly worth thinking about, and the histogram is definitely worth looking at regularly.

Pete, I too found things easier with my film cameras, and although it affects critical sharpness I routinely overexpose film by 1 stop for insurance. The trouble is, WHY should things be any different with digital? Any digital experts out there?

Sam

[dpanicc1]

The first shot is lighter because the grass is so much darker and the exposure system compensted for it by increasing exposure.

The second picture looks like much of the sky was considered by the metering system hence the camera reduced exposure.

Some scenes you just can't expose properly for; this one you could.

How about filling the viewfinder with a gray card, setting exposure, reframe, focus, and take the shot? That should work in tricky exposure situations too.

[timmyquest]

This is why i shoot fully manual 90% of the time.

I look at the scene, subject etc. I then take into account the lighting, make a estimated guess as to what i need to have the settings at, take a pic , look at the histo and shoot away.

When i first started with my drebel it would take quiet a few shots to get it right, now it's never more then two.

[Sam North]

dpanicc1, the grass is something near a useful mid-tone, which is what all SLRs are calibrated for (supposedly!), so the exposure was just about ideal for the overall subject, just like the rich blue sky I mentioned earlier.

The Canon official argument goes that with evaluative metering, because exposure is linked to the focusing point, I should have got a much better exposure using 7-point focusing and evaluative metering, but, as we see, it did very poorly. The camera focused the wide lens on the tree, which isn't particularly bright at all, so if anything the shot could well have been a little overexposed. So, all-in-all, the sky ought not to have been the major factor when the camera automatically judged the exposure.

I've tried grey cards before and much of the trick is getting the same light on it as your subject, and holding it straight. Last time I used a card the exposure was all wrong - my fault I'm sure! Learning to judge mid-tones works much better for me in many, many situations.

timmyquest, yes I like manual too, especially when the camera's on a tripod and the light isn't shifting too quickly.

Sam

[Malaxos1]

quote="Sam North"]"I'll point at my subject for focus and exposure and half-depress, then recompose the frame how I actually want it and shoot." The problem with this method is the tone of
If you're a student of the Zone System, you don't ned to lock on to a mid- tone. Put your 10D in partial metering mode, center focus point, manual exposure. Fill the central circle in the viewfinder with the tone you most want to capture correctly. Depress the shutter half way to get a reading. Adjust the reading from the camera meter up or down based on the number of zones it is from 18% Grey. Once you have set the exposure correctly for a given tone, the other tones should be exposed properly as well. I use a modified 5 zone system.
4.5% Grey(White) - 9%Grey - 18%Grey - 36%Grey - 72%Grey(Black)
So if your shooting snow, overexpose by about 2 stops. A black tuxedo, underexpose by about 2 stops.
If you'd rather let the camera do more of the work, switch to Partial Metering in Av or Tv, Exposure Lock *, and use exposure compensation using the same zone system. Always check the histogram to make sure it represents the exposure you want.
Regards,
Scott[/quote]

This is exactly right. It is the approach that I use 90% of the time. I have found that the zone system works best, if I am shooting a white subject I comensate +1 1/2 to +2 full stops. If I am shooting black I shoot -1 to -1 1/2 stops. The good news is that if you don't over expose the photos and are as under exposed as 1/2 stop, you can recover the photo without loss of detail. Anyway I am a manager of a group that is dedictaed to the D Rebel, here is the site...Dean

http://groups.msn.com/CanonDigitalRebel300DSupportGroup