I don't understand...RAW and exposure

Discussion in 'Photography Beginners' Forum' started by DrunkenGiraffe, Jul 31, 2010.

  1. DrunkenGiraffe

    DrunkenGiraffe TPF Noob!

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    Hi :) I have had my DSLR for a few weeks now and decided I wanted to try using RAW. I have my camera set to take both a RAW image and a JPEG. But when I open the RAW image is it heaps more underexposed than what it looked like when I took it and what the JPEG looks like.
    Just using this picture as an example.
    The JPEG I get is:
    [​IMG]
    But if I open it up in ufraw, it looks like this
    [​IMG]
    If I click autoadjust exposure I get this
    [​IMG]

    I know that I can just adjust the exposure compensation to what I want, but I don't understand why every picture comes out underexposed whereas the jpeg is fine.
     
  2. Taylor510ce

    Taylor510ce TPF Noob!

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    Because your JPEG is being processed by the camera, whereas RAW needs to be adjusted afterwards. RAW is not compressed though and holds MUCH more information than that JPEG file, useful with things like highlight recovery. ( if you overexpose slightly, you can regain some lost detail ). Unless in a bind for time, I wouldn't click autoadjust, I would learn how to adjust myself. Autoadjust is oftentimes, very inaccurate. Besides, the post processing to a degree is about your personal taste and what you want out of the shot. So give yourself some control of that. Hope this helps.

    By the way, I adjusted the photo here ( did not adjust any color cast, just setting black and white points ) and this is what I came up with manually.
    [​IMG]

    Your original RAW image was underexposed. Sometimes your cameras metering can be slightly off. You may find it is underexposing in most instances, so you can set the exposure compensation to always overexpose half a stop or something from what the meter is saying is the correct exposure. Also make sure that you have "Evaluative" or "Average" metering chosen.
     
    Last edited: Jul 31, 2010
  3. edouble

    edouble TPF Noob!

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    I will also add that any picture control settings that are adjusted will be seen on a JPEG image but not on the RAW. Such as color saturation, contrast and brightness. You can also have automatic picture control settings set at vivid, nuetral and others, that will be seen in JPEG but not in RAW.
     
  4. Overread

    Overread has a hat around here somewhere Staff Member Supporting Member

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    MY first advice is to go into your camera menu and set all the auto editing settings to neutral/standard. That way your camera is doing very little to nothing to the JPEGs it processes. This is important as even when you shoot in RAW mode only you get a JPEG made and it is this JPEG that is displayed on the back of the camera body (it can't display a RAW since a RAW is not an image but just data that needs processing).
    That should help give you as faithfull a reproduction of the RAW as possible within the camera body. The next stage is to understand two things:

    1) your meter

    2) your histogram

    Understand that in certain situations your meter is going to get confused and give you a false reading. Reviewing your shots in the field (using the histogram) should help you come to understand in what lighting conditions the meter is being fooled in. For example its often the case that in very bright light the meter will overexpose and you will have to use exposure compensation to underexpose the shot a little to keep the highlights from blowing out.

    The histogram is critical for this and its one of the most powerfull tools in your camera body. Set yor display to show the histogram when you review shots ad you get a graph - the left side is pure underexposure (black) and the right is pure overexposure (white). Ideal you want to avoid hitting either end of the graph with the lines - though of course in certain conditions you are going to get black and white areas on a photo (note these areas have no details to restore to when you edit).

    The main bulk of the data in the histogram wants to be as far over on the right side of the graph as possible without hitting the right side limit. This means that you have the most light data possible to edit with. Of course limits at the time mean that you might not be able to get a shot like this every time. Also there are times when the graph will look very odd indeed and its true that there is not set appearance that you really want to aim for. Just try to avoid having too much on the left and also avoid hitting the left and right hand limits (normally you can get away with underexposure in a shot more than you can overexposure)
     

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