how exactly do you bracket your exp. for HDR?

Discussion in 'Photography Beginners' Forum' started by theregoesjb, Mar 7, 2012.

  1. theregoesjb

    theregoesjb TPF Noob!

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    im trying to take some pictures to use for an HDR image

    i know i need to take at least 3 shots, one at correctly metered exposure, one under exposed, and one over exposed. But what do you use to gauge how much under/over you go? I imagine referencing the histogram is key but what sorts of rules of thumb do you go by? How far do you make sure to push the exposure one way or the other?

    if it makes a difference, this will be during a two hour window around sunset, should get fairly good lighting

    i was reading one tutorial on how a specific HDR was done and his under was 1 1/3 stops while his over was only 1/3.

    please share your experience/tips!


     
  2. Big Mike

    Big Mike I am Big, I am Mike Staff Member Supporting Member

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    You could specifically measure different parts of the scene with a light meter or the spot metering function in your camera. This would allow you to figure out the dynamic range of your scene...and should give you a good idea of how far each way, you'll want to bracket.

    Or you can just estimate how many shots/how far off you'll need to go...then just take a bunch of shots and figure it out later.

    This is digital, it doesn't cost you anything to just take more more shots than you'll need.
     
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  3. Geaux

    Geaux No longer a newbie, moving up!

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    First off, you left out what camera are you shooting with? My d90 has bracketing built in so I can tell it go from -1 to 1 and it does it.

    If your camera doesn't have it, you can always use exposure compensation and do -1 and +1 and take a properly exposed shot. That's how I used to do it on my old P&S lol
     
  4. ann

    ann No longer a newbie, moving up!

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    You shoot as many as is necessary to cover the contrast range. THink from shoulder to shoulder on the histogram. This might mean 3 shots it might be 20 and anything in between.
     
  5. theregoesjb

    theregoesjb TPF Noob!

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    thanks, yeah i guess theres no harm in taking too many.... metering the different areas is a good point
     
  6. analog.universe

    analog.universe TPF Noob!

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    So, my approach, which doesn't have nearly as much field time as a lot of other folks' here, is as follows:

    In manual mode, start with an exposure that makes sure the darkest shadows are well clear of the left side of the histogram. This is the brightest frame.
    Then, adjust the shutter speed 1 stop faster (or whatever interval you want to use), and expose again.
    Repeat the shutter adjustment and exposure until you get a frame where the brightest highlights are well clear of the right side of the histogram. That's your darkest frame.

    Depending on the dynamic range of the scene, this will get you any number of frames, and when it comes time to process them, you can choose as many or as few of them as you need to get the effect you're going for.
     
  7. theregoesjb

    theregoesjb TPF Noob!

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    its a canon t2i

    and now im looking for a live histogram setting, anyone know if it has this option? so i can see the histogram before taking the shot?
     
  8. jonathon94

    jonathon94 TPF Noob!

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    If its anything like my Canon t3 you can do it in live view

    -Please ignore typos I'm currently on my phone-
     
  9. 480sparky

    480sparky Chief Free Electron Relocator Supporting Member

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  10. DiskoJoe

    DiskoJoe Been spending a lot of time on here!

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    Here is an easy solution. Take 5 pictures each one full step apart from -2 to +2. This will cover all the range for the most part. From here you can use all five which I do sometimes or you can pick your favorite three. YOu could go -2, 0, +2 or -1, 0, +1 or something off like 0, +1, +2 which I have done for some night shots with the sky is black (not optimal when the sky is still blue).

    Dont do 20! I have done shots with up to 12 exposures at 1/3 steps apart and you really just dont need that much info. Using this many shots tends to muddle the pictures due to slight variances that might be caused by slight shake. Good tonemapping and some additional detail work with PS or maybe topaz would get the job done.

    Never knock just using one exposure and doing faux hdr. Most people cant tell the difference if you do it right and you can still get plenty of info in a nicely exposed RAW file to do it very close to the real thing without having to take so many exposures. Not really much of an issue during the day but when your doing it at night with long exposures it can take a while.

    I did this with only one exposure.
    [​IMG]
    View to the West by DiskoJoe, on Flickr

    Also using one exposure can give you better clouds when conditions are windy like in my shot. If you use three or more shots you are going to lose a lot of that or it may not come out good at all. I have a friend that will take the time to basically hdr stuff like buildings in a cityscape and then cut out the sky with the best looking cloud formation to use for the sky.
     
    Last edited: Mar 7, 2012

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