Beginner Struggling With Manual Exposure

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saintj

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Hello!

Okay, so I've had my 40D (with the 17-85 IS zoom lens) for a while now and decided prior to getting the camera to learn how to use it in manual. I think I'm having problems with metering more than anything. Can you help?

I've been out and about and shot in Av, Tv and P with evaluative metering and had good success simply by checking the histogram. However, as soon as I go into M everything goes mad! the histograms look the opposite of what they should (bell curve) and I'm generally left floundering and totally unsure what I'm doing, what to meter and what to set.

I just cannot seem to shoot a sky and a darker/shadowy foreground in M. I have tried metering the sky as suggested by Bryan Peterson in his book Understanding Exposure and then recomposing but I get a correctly exposed sky and a darker foreground subject. This suggests that the camera cannot cope with the range of brightness of that scene if I understand correctly. I understand I may need to use ND Grad filter to darken the sky but I've taken shots in one of the priority modes and gotten good results so I'm inclined to think I'm messing something up in the settings.

I know experience comes from years and years of practice. I'm not asking for the definitive answers just some tips/links or anything. I fear I may be getting disillusioned already and may get stuck in shooting only in Av, Tv and P as has been suggested to me by at least 2 friends :thumbsdown:

I really want to totally understand what and why I'm doing something but I'm failing miserably at the moment IMO. Can some of you more experienced guys throw me a few pointers re: metering and understanding exposure. The aforementioned book hints at it being ‘dead’ easy and simply pointing the camera at the sky or grass to get a reading but I think he must be compensating further after taking these readings - its not clear, at least to me if he is doing this. Oh and for good measure, the whole 18% gray/mid tone thing is a little lost on me too – I guess that’s the grass thing from Peterson’s book?

Sorry for a long post especially as it’s my first ever post here...

Regards

Jason
 
Hey Steve,

thanks for the quick reply! However, thats the book I have and mentioned in my original post. I kind of get where he is coming from and I've read the book 3 times now - I don't know if its just me but he seems to miss out a stage because when I simply select an aperture I want, say f/8 and meter the sky - recompose etc after adjusting my ss for a correct exposure of the sky I get under-exposed forgrounds etc. If I try and rectify this by adjusting the ss I get blown skys... Does he meter the sky to be underexposed to take into account the foreground subject?

Hope that makes sense?
 
Or alternatively you could read the post properly steve lol ;) He already has the book!

The problem is that Dslr's can only cope with smaller range of contrast compared to film. If you have a bright sky and deep shadow then one or the other is going to be wrong. The solution, as you mentioned above is ND grad filters. Or merging 2 exposures in Photoshop. Or not shooting in high contrast situations eg mid-day. Or using flash to balance the contrast if your shooting portraits for instance.

Failing all of those, you will be best off either a) deciding which part of the image is most important to have exposed correctly and then expose for that by using spot metering off of that part of the frame or b) exposing for the sky so you none or very little in the way of blown highlights and then recovering the shadows in RAW development later. This latter option is only useful if the level of contrast isn't too high, otherwise you will just end up introducing noise into the shadow areas.

Hope that helps a little?

Finally, if you're shooting jpeg and not RAW then you need to make sure that in the image parameters in the camera that the saturation and contrast are set as low as possible as this will also help retain some detail. Most cameras auto-adjust this but I don't trust 'em!


It's never an ideal situation with digital but you will get used to, and learn to cope with it's limitations.
 
I know thats what you get for rushing to answer with a couple of sherberts inside :beer:.
I've edited and think we agree :thumbs:

Steve...
 
This is a huge question and really outside of the scope this forum to answer adequately - it needs a book and the book has been written many times. ;)

Regarding the 18% grey thing, generations of photographers have established that a reading from an 18% grey card gives good exposure for scenes with an average range of tones. Obviously if a predominant or important part of your subject was darker than 18% grey then you'd need to increase exposure somewhat from your basic 18% grey reading, and give less exposure if that part of your scene was significantly lighter.

A reading from an 18% grey card will give the perfect exposure for photographing 18% grey cards and acceptable exposure for lighter and darker tones within a given range on either side of 18% grey.

I really don't know why people advocate that you shoot in Manual mode or why people worry that they should be using Manual Mode. There are occasions when Manual mode has it's advantages, but I shoot in AV mode the vast majority of the time. You have the facility in AV mode to adjust exposure compensation anyway, or to use the Exposure Lock Button to meter from a specific tone and then recompose your shot.

I'm not too sure where you're getting into difficulty. The metering modes are the same in manual Mode or AV etc. As long as you zero the exposure display at the center in Manual mode you'd get the same result as a straight reading in AV mode, assuming you were framing both scenes identically.

The best advice is really to get a good book on the subject and read and thoroughly digest the basic principles. :)

EDIT
OK, ok, you got the book!! :D
 
As CT said...

"I've been out and about and shot in Av, Tv and P with evaluative metering and had good success simply by checking the histogram. However, as soon as I go into M everything goes mad! the histograms look the opposite of what they should (bell curve) and I'm generally left floundering and totally unsure what I'm doing, what to meter and what to set."

I may have mis-understood your op but...

Re-read camera manual, check exif and bracket shots.

Don't mean to teach you to suck eggs...

Modes are:

P. Auto. Camera does all the work. point and shoot mode.
Av. Semi auto. You set aperture - camera sets shutter.
Tv. Semi auto. You set shutter - camera sets aperture.
M. Manual. You set both aperture & shutter. Only input from camera is the meter reading.

For a static shot e.g. a landscape the shutter and aperture values will/should be the same or equivalent.
As to the histogram in manual it won't read correct until you adjust A & P to the correct value.

Maybe worth taking the same scene in all modes and check if the exif it will show any discrepancies.
 
Good sky with dark foreground, or good foreground with blown sky, are quite predictable results, as you can only expose correctly for one part at a time. I'm not sure how using an auto mode magically fixed that.

It may be that your metering area is set to Spot or Centre-Weighted when you are in M mode, so that it meters and exposes just what's in the centre viewfinder point correctly and ignores the rest, exposing for either sky or ground, and when you use P, Av or Tv it goes into Matrix metering area mode and accounts for both sky and ground simultaneously, and finding some horrible compromise where both sky is blown out AND foreground is black...

By the way: when you're playing with histograms, I found out that it's easier when you realise that changing the exposure doesn't shift the curve linearly - it shifts points in the centre along a lot, and shifts the edges much less, distorting it.

As I'm sure you've found out, there are some ways of increasing the captured dynamic range - that is, retaining detail in both ground and sky. These are:

Preserving sky by keeping curve off RH edge of histogram and using Photoshop to brighten the ground (has its limits... you may not recover the ground detail well or without noise)
HDR (time-consuming and difficult to do tastefully)
ND grad filters (not useful when the horizon isn't straight)
Polarising filter (will darken and blueify sky somewhat but not as much as an ND grad)

One of these will be a solution for you. Someone please correct me if I've missed one...
 
Thanks guys for all your responses - I really appreciate it.

I'm re-reading the Understanding Exposure book for the fourth time and trying to apply the theories within.

I noticed from a couple of shots taken yesterday, of buildings shot looking up into a cloudy sky, that I was getting blinking highlights on parts of the sky and the histogram was displaying bunched pixels to the left and right without much in the middle. At the time I thought I had got the exposure wrong because of these warnings. Now I'm thinking this scene didn't have much in the way of mid-tones hence my histogram looking like a 'V' shape! Am I never going to get a bell curve histogram in such situations? Perhaps this is where I'm going wrong - trying to do something that is impossible?

I later processed these RAW shots in Photoshop I was surprised to see pretty decent results from my metering of the sky. The histogram looked a lot better with more averaged pixels across the full spectrum. Also - the highlights blowing out in the sky were not prevalent once viewed on the PC. Am I correct in thinking that the highlights warning feature simply shows areas of the image that have pixels of 255 (100% white)? Am I also right in assuming that if I took a shot of some snow I would get the same blinking highlight warning? In other words - if I know something to be white I should ignore this highlight warning?

Its sort of making sense... a bit
 
Are you trying too "hard" to get the right exposure in one take at the expense of your enjoyment and sanity?
Why not take 3-5 bracketed shots, say -1,-0.5, 0.0, +0.5,+1.0, the 0.0 being what the meter suggests as correct
exposure. You can always combine two or more shots to make the "perfect" one.

Photoshop will allow you to manipulate your images more than you may think.

http://www.worth1000.com/tutorials.asp
 
I find the blinking highlight warning in -camera tends to err on the side of safety anyway, and often they're not actually blown when viewed on the PC, or are very recoverable in RAW processing.
 
Slipper-one said:
Are you trying too "hard" to get the right exposure in one take at the expense of your enjoyment and sanity?
Click to expand...

I think *I am*. I had suspected I was but hearing comments here and now your salient point has confirmed things in my head.
 
saintj said:
T


I noticed from a couple of shots taken yesterday, of buildings shot looking up into a cloudy sky, that I was getting blinking highlights on parts of the sky and the histogram was displaying bunched pixels to the left and right without much in the middle. At the time I thought I had got the exposure wrong because of these warnings. Now I'm thinking this scene didn't have much in the way of mid-tones hence my histogram looking like a 'V' shape! Am I never going to get a bell curve histogram in such situations? Perhaps this is where I'm going wrong - trying to do something that is impossible?

I later processed these RAW shots in Photoshop I was surprised to see pretty decent results from my metering of the sky. The histogram looked a lot better with more averaged pixels across the full spectrum. Also - the highlights blowing out in the sky were not prevalent once viewed on the PC. Am I correct in thinking that the highlights warning feature simply shows areas of the image that have pixels of 255 (100% white)? Am I also right in assuming that if I took a shot of some snow I would get the same blinking highlight warning? In other words - if I know something to be white I should ignore this highlight warning?

Its sort of making sense... a bit
Click to expand...


You now see the advantages of shooting RAW. OK it does use up a fair bit of card storage, but the file retains so much more information than a conventional jpeg.

Use the highlight warning, for what it is, a guide. With experience you'll get to know what to accept and what to re shoot.

Remember the digital camera chip can record more information that can be seen on a monitor or print. Using RAW enables you to select what part of the exposure you want to use.

There's a lot of information about RAW on the web, however if you are interested can I suggest the following

http://www.luminous-landscape.com/essays/rawtruth1.shtml
 
Remember that even in manual the camera will still tell you if the exposure is right or wrong, look for the little arrow below the exposure guide in the viewfinder, centre means correct exposure or pretty close.
 
Steep said:
Remember that even in manual the camera will still tell you if the exposure is right or wrong, look for the little arrow below the exposure guide in the viewfinder, centre means correct exposure or pretty close.
Click to expand...
Well... it tells you whether the camera thinks the exposure is right or not. That's not quite the same as whether the exposure is actually correct.

If you're photographing a polar bear in a blizzard, and the exposure is correct, the camera well tell you it's over-exposed. If you're photographing a black cat in a coal cellar, and the exposure is correct, the camera will tell you it's under-exposed. That's because the camera doesn't know that the bear is meant to be white and the cat is meant to be black. But you do know - so take advantage of that!
 
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