Exposure question... trust the camera?

Discussion in 'Photography Beginners' Forum' started by paulpippin29, May 16, 2009.

  1. paulpippin29

    paulpippin29 TPF Noob!

    Joined:
    Nov 2, 2008
    Messages:
    184
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    Hi all. I've been debating this for some time now, and can't seem to answer this myself, so I thought you all might could be of help.

    When using my XSI, I never use LiveView at all, always the viewfinder, period, and when I depress the shutter halfway, I wait for my focus beep, and then I adjust the exposure until my "needle" is perfectly in the center. Very basic stuff here, that we all know and do.

    Now, when reading the C&C post on here, one of the biggest critiques that I see is either the image is "under exposed" or "over exposed", which is true at all times for the given image, but what if you recieve that critique, which I have in the past, but when you took the photo, according to your camera, it's exposed perfectly for the given light, etc...

    I've heard people say "expose for the sky" here before. Would that mean to basically aim the lense at the sky, put the needle dead center representing proper exposure, then aim the camera at what you were going to shoot originally?

    I'm posting two examples below. Both were taken a few weeks ago, both were outdoors, and both were in the same location. These were actually just test shots, so no C&C required, as they're not meant to be good. I was mainly trying to see if I could focus in on these small weeds, or whatever you'de like to call them.

    Notice in this first shot.... the sun is out in full (late afternoon), and the exposure seems dead-on to me. You can really see alot of detail in everything.

    [​IMG]

    Now for the second. This shot was taken almost in the same spot, but turned around completely, heading in the other direction, but a cloud had went over and provided some shade.

    [​IMG]

    Now to me, this shot is under-exposed, with hardly any detail at all, but is that true? and if so, why? According to my camera, it should be perfect, and I know that the shade did this, so does that make it a simple lighting issue that can't be fixed? Would it be fair to say that lighting and exposure are the same thing, or at least, very close? I was using a polarizer for both of the shots also, could that have helped make this happen?

    I know I sound absolutely brand new here again, but, I'm just staring to notice this on alot of my outdoor shots, particularly with flowers and plants, and particularly when dealing with shade.

    So, if one can "expose for the sky" can one "expose for the shade"?

    Thanks in advance for the help.
     
  2. photogincollege

    photogincollege TPF Noob!

    Joined:
    Aug 4, 2007
    Messages:
    706
    Likes Received:
    0
    Location:
    Grand Rapids, Michigan.
    Can others edit my Photos:
    Photos OK to edit
    Well what I see, is that the first one, there isnt much sky or bright spots in the picture, even though the sun is out, where in the second there is a BIG patch of the bright sky directly in the front. The camera probably took that for the metering and therefore underexposed for the part you wanted. Generally if your taking a picture of something, and there is a bright sky i view, but not what you want the picture to be of, overexpose a stop or two.
     
  3. KmH

    KmH Helping photographers learn to fish Supporting Member

    Joined:
    Apr 9, 2009
    Messages:
    38,209
    Likes Received:
    4,999
    Location:
    Iowa
    Can others edit my Photos:
    Photos OK to edit
    Your camera probably has 3 different light metering modes, small spot, larger spot and matrix. Which one do you use?

    In your second image, with the aperture you used there is just very little in the scene that is in the DOF range. Also you have a very bright background sky that the camera is trying to expose for which is why your foreground is underexposed.

    The camera is only a crude approximation of your eye and the electronics are not really all that smart. In this case the way to have gotten a proper exposure was to spot meter the sky and use flash to illuminate the foreground and keep both in balance.
     
  4. paulpippin29

    paulpippin29 TPF Noob!

    Joined:
    Nov 2, 2008
    Messages:
    184
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    Ok, some good explanations of my problems here, and thanks for that :)

    Now, as for the "3 different light metering modes" I have the following 4 options: (Rebel XSI)

    1. Evaluative Metering (which is what the camera is set to by default, as I've yet to change this)
    2. Partial Metering
    3. Spot Metering
    4. Center-Weighted Average

    Going to have to check my manual on these, as I never studied these options previous to this time, though I'm hoping someone will explain them to me here, as I'm sure the explanation will be much better than the manual.

    Also, that was an interesting tip on using the flash... I would have NEVER thought to use flash outdoors, would have never seen a need for it, but now, I do. How powerful should one set the flash to for this type of thing? (built in flash btw)
     
  5. paulpippin29

    paulpippin29 TPF Noob!

    Joined:
    Nov 2, 2008
    Messages:
    184
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    Ok, sorry for this, but manual has opened up some interesting things.... A run down of the metering options as according to the manual:

    1. Evaluative Metering

    This is an all around metering mode suited for portraits and even backlit subjects.The camera sets the exposure automatically to suite the scene. This metering mode is set automatically in the Basic Zone modes. <-- Which I do NOT use...

    2. Partial Metering

    Effective when the background is much brighter than the subject due to backlighting, etc.

    3. Spot Metering

    This is for metering a specific part of the subject or scene. This metering mode is for advanced users.

    4. Center-Weighted average metering

    The metering is weighted at the center and then averaged for the entire scene. This metering mode is for advanced users.

    Ok, so after reading KmH's reply about spot metering, then after reading the above info from the manual, I tried 4 pictures of the same subject here in my bedroom with the main light source being a desk lamp. The subject was nothing more than a stick of deoderant :) Out of all 4 metering modes, no flash used, the "Spot Metering" mode won the contest. The image just looked so much better than the other 3. I'm not sure if Spot Metering is something that will apply to everything, in every situation, but I'm surely going to try.

    Also, something else I've discovered... my camera has a "custom functions" setting, and I knew it was there, but had never played with it, and still haven't, but according to the manual, I can set "Exposure Level Increments" from 1/3 stop to 1/2 stop. According to the manual:

    "Exposure Level Increments

    0: 1/3 stop
    1: 1/2 stop

    Sets 1/2 stop increments for the shutter speed, apuerture, exposure compensation, AEB, etc... Effective when you prefer to control the exposure in less fine increments than 1/3-stop increments.

    Is this something I should be concerned with also, since we're dealing with exposure here?
     
  6. KmH

    KmH Helping photographers learn to fish Supporting Member

    Joined:
    Apr 9, 2009
    Messages:
    38,209
    Likes Received:
    4,999
    Location:
    Iowa
    Can others edit my Photos:
    Photos OK to edit
    Camera manuals are pretty dull but they have a ton of useful information in them if you're willing to study it.

    Most professionals rarely make images without using strobes, speedlights or continuous lights indoor or out.
     
    Last edited: May 16, 2009
  7. paulpippin29

    paulpippin29 TPF Noob!

    Joined:
    Nov 2, 2008
    Messages:
    184
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    Understood, but do you or anyone else for that matter, have any advise on the above post? Particularly the "Exposure Level Increments"? I'de really appreciate some more details here, and thanks for the details so far :)
     
  8. Steph

    Steph No longer a newbie, moving up!

    Joined:
    Oct 18, 2006
    Messages:
    1,314
    Likes Received:
    0
    Location:
    Steventon, Oxfordshire, UK
    Can others edit my Photos:
    Photos NOT OK to edit
    You need to understand how your camera light meter works in each metering mode. When you understand what it is trying to do, you'll be able to use it much more effectively, by either pointing the camera to a particular object to measure the light levels and then recompose to take your shot or by using exposure compensation. Any book about photography basics will help you to achieve this. 'Understanding Exposure' by Bryan Peterson would be a good start.
     
  9. paulpippin29

    paulpippin29 TPF Noob!

    Joined:
    Nov 2, 2008
    Messages:
    184
    Likes Received:
    0
    Can others edit my Photos:
    Photos OK to edit
    And again, metering is mentioned, along with the all famous "Understanding Exposure" book. I'de love to read it, but have been laid off from my job, can't afford to spend a single dime on anything other than pure survival at the moment.

    I appreciate the recommendations to the book ,really do, but just cannot buy it right now, no matter how inexpensive it might be.

    What I'm looking for here is some detailed explanations of the things I metnioned in my previous posting's, things I can work with immediately, if at all possible.

    If not possible, I understand... though I can't believe that out of all the pro's on here, someone can't highlight the benefits of each metering method offerered via my camera, along with the "exposure compensations increments" section as well. All I'm searching for here are some basic details, that's all.

    I know I need to own and read the book, but, I don't have it, wish I did, but don't. Looking for a bridge between myself and the book here, which certainly is not impossible to build.
     
  10. KmH

    KmH Helping photographers learn to fish Supporting Member

    Joined:
    Apr 9, 2009
    Messages:
    38,209
    Likes Received:
    4,999
    Location:
    Iowa
    Can others edit my Photos:
    Photos OK to edit
    It would seem you have an Internet connection. Is that a pure survival item? You could always sell some blood plasma. I've done that before, back in the day.

    Understanding Exposure doesn't contain the information you want, but your camera manual does. However a couple of other sources for photography information are search engines and the local library.

    But hey, maybe you don't know how to search for stuff online: Read This About Metering and Exposure Compensation
     
  11. Josh66

    Josh66 Been spending a lot of time on here!

    Joined:
    Oct 31, 2007
    Messages:
    14,604
    Likes Received:
    1,236
    Location:
    Cedar Hill, Texas
    Can others edit my Photos:
    Photos NOT OK to edit
    Exactly. But the way you describe it, the sky would need to actually be in the final composition (imagine a typical landscape shot). If you did that, then took a picture of a flower at your feet, it would probably be under-exposed.

    If you had looked at the meter for the second shot (you probably didn't even notice it, since you just set it up) you would have noticed that when the cloud passed overhead the needle was slightly on the negative side of zero.
    Direct sunlight and shade may not seem like a big difference to you, but it is to the camera. In this situation you would have had to zero your meter out again to get the same exposure.

    Yes, and that is what you should have done on the second picture. You could just point it at a shady patch of grass and zero your meter out on that. Now anything in the shade will be exposed properly. Sunny areas will be over-exposed though. For that, meter on a sunny patch of grass.

    No, not really. You'll probably want to leave it on the default 1/3 increment adjustments. The reason for this is that many film bodies only adjust in 1/2 stop increments. This gives you the ability to do things the way you're used to if you've been shooting film for years. I don't think you'll really notice much difference anyway. To me, the main difference is how many clicks of the wheel it takes to go one stop (2 clicks for 1/2 stop increments, 3 for 1/3).
     
    Last edited: May 17, 2009
  12. dxqcanada

    dxqcanada Been spending a lot of time on here!

    Joined:
    Dec 4, 2008
    Messages:
    5,500
    Likes Received:
    700
    Location:
    Woodbridge, Ontario, Canada
    Can others edit my Photos:
    Photos OK to edit
    Learning to work with light metering takes time ... but most importantly it takes knowledge (as others have mentioned here).

    A light meter measures all light that hits it's sensor.
    It takes that and calculates an EV level based on the ISO you have set ... which it provides to the internal computer in your camera. The computer takes that and provides you with a Shutter speed and Aperture number.

    Most camera's (as you have noticed) have different metering capabilities.
    Matrix metering is the most common default. The camera takes multiple readings from portions of the view and feeds the value to it's computer. The matrix metering program (coded by the manufacturer) attempts to figure out the best overall value to use. In most cases it is correct.

    Under unusual lighting conditions, the calculated value may not be the best one. This is where the human takes over.

    In your second shot ... the human will look at the scene and see:
    bright sky in the background
    darker foreground subject
    The human would use the camera light meter to expose for the darker foreground and let the background sky become overexposed. The camera will provide a meter value that balances the entire scene.

    The human would use spot metering area to obtain an exposure value of just the foreground grass only ... for those that do not have spot metering, just point the camera so that the background sky does not appear in the viewfinder. This exposure value, of just the grass, would expose it for middle (18%) grey ... though this also may not be the best exposure also, but probably the most usable.

    The more experienced you get with thinking/using exposure, the better the images will be captured. The exposure computers in camera's have no idea what you want to expose, as it assumes that everything in the scene is what you want balanced.

    You also have to understand exposure latitude. The image sensor can only keep exposure within a specific range, so you may find that exposing for the grass to be lighter may cause the background to get so overexposed that it makes the overall scene a waste.
     

Share This Page