ISO bracketing for HDR

Discussion in 'Image Processing' started by johnagon, Aug 17, 2013.

  1. johnagon

    johnagon New to FujiXspot

    5
    Apr 21, 2013
    I've been doing HDRs for a long time and with my X-E1 it easily does 3 exposure brackets. After using the camera for awhile I noticed there is an ISO bracket option when you press the Drive button. Initially I thought this would be no good because it would change the aperture or shutter speed and give problems for HDR. I tried it recently on a whim and was astounded at what happened. It feels like the camera only takes one exposure but creates three versions; there is no triple exposure like regular exposure brackets. If this is true (and I don't know yet) then this becomes very useful for HDRs because it eliminates worrying about wind or other movements between exposures. My first HDR tests looked very good.

    I plan to do some more complete testing but thought I would check with the community to see if my impression re "one exposure" is true. If so, what are the implications...

    John
    johnagon.com
     
  2. entropic remnants

    entropic remnants Solving for X

    718
    Jul 28, 2013
    Except it's not "real" HDR that way -- it's pulling/pushing a single exposure. You can do that with (wait for it) a single exposure.

    If it is one exposure, then you won't get the dynamic range enhancement you need when the light is really off. I do a ton of urbex HDR with very high light extremes and often need shots very far apart to capture the whole dynamic range.

    That said, I don't know if you use HDR as a special-effect, or to capture a wide range of light in a photo-realistic presentation. If you are just using the HDR software to make a special-effect photo (which is what most pervert HDR to do nowadays, lol) then the ISO bracket method will work for you just fine because you're interested in a "filter" of sorts, not actually capturing a wide range of light.

    It just depends on what you're doing.
     
  3. entropic remnants

    entropic remnants Solving for X

    718
    Jul 28, 2013
    Here's an example of what I'm talking about. This scene has a simply unbelivable dynamic range and required about a 5 to 6 stop spread to get all the information into the final image. Note the lack of "special effect HDR" look.

    This is the sort of thing HDR is intended for, but a surprising number of folks have no clue. They believe the extreme tone mapped HDR represents the "true" representation and meaning of HDR -- but it's only a single flavor. Some who use the special effect form don't need the extra dynamic range at all. They just need multiple shots from dark to light to feed to their HDR engine.

    8503232979_0e1466c28c_b.
    Throwing Klotz: Outside, the World Moved On by Entropic Remnants, on Flickr
     
  4. bilzmale

    bilzmale FujiXspot Veteran

    353
    Feb 3, 2013
    Perth, Western Australia
    Bill
    The exposure comp dial on all but the newest Xs together with a tripod means we can widen that bracket range. Say 3 exposure bracket at -2ev gives -3, -2 &-1 plus a second 3 exposure bracket at +1ev gives 0, +1 & +2 giving a six exposure bracket.
     
  5. flysurfer

    flysurfer X-Pert

    Feb 1, 2013
    Nuremberg
    Rico Pfirstinger
    • Like Like x 1
  6. Luke

    Luke FujiXspot Top Veteran Subscribing Member

    865
    Jan 31, 2013
    Milwaukee, WI USA
    Luke
    I wish Fuji would allow for bracketing 3 shots at +2, 0, -2. Bill, I like your workaround for slow and deliberate tripod work. But sometimes a few seconds is all you've got. I can do 3 shots bursts handheld most the time with some of the great anti-ghosting algorithms out there these days. But a 3 shots blast and a turn of the exposure comp dial and then another 3 shot blast....there no way.

    And with how easy it is to push/pull highlights and shadows isn't the 1/3 EV exposure bracket fairly useless anyways?
     
  7. entropic remnants

    entropic remnants Solving for X

    718
    Jul 28, 2013
    Very nice but the scenes are so different it's difficult to draw any sort of conclusion from them. The first one looks like a single exposure without a lot of shadow lifting.

    The problem with ISO HDR if you are printing large (as I do) is that the noise will show. The whole reason for NOT going to a higher ISO for the "overexposed" shots is to keep that from happening when taking the shots that are supposed to capture the shadow detail.

    Many shortcuts are possible when producing low resolution final products -- but larger prints are akin to a certain amount of pixel peeping. If you try to lift the shadows and restore contrast in the shadows much from a single exposure (which is what happens with ISO bracketing for this work) I think you'll soon find that unacceptable levels of noise will occur and you'll have to take steps in the lifted areas to smooth them out.

    There really isn't -- if you're serious about HDR -- any shortcut to getting clean shots. Any such shortcut is simply equivalent to processing a single exposure and if that's the case, just make a single exposure, lol!


     
  8. johnagon

    johnagon New to FujiXspot

    5
    Apr 21, 2013
    OSO bracketing

    Thanks for all the thoughtful feedback and comments. I understand the noise issue and the limitation of a single exposure, however, there may be more going on in the processor than some are assuming. I agree we can do a 6 stop HDR capture but it is awkward compared to the auto single three. This also can worsen the blur created by wind not to mention the cloud that just popped over the sun. I wish Fuji would listen to us and allow more than 3 auto exposures and let us choose the EV spacing.

    I've just got back from shooting my own test but haven't processed anything yet. If I find out anything interesting to discuss I'll post an artcle on my blog and come back and post a link here. If you live in a windy climate like me (westcoast BC) and shot landscapes then I think this is a topic worth exploring until we are sure of what the ISO bracket can and cannot produce. And why did Fuji even think it was important enough to put on the drive button?

    Cheers,

    John
     
  9. johnagon

    johnagon New to FujiXspot

    5
    Apr 21, 2013
    Your urbex work

    Fantastic shot. I've never had the chance to go inside these kinds of buildings. I understand "good HDR" vs something extreme although there is a place for the grunge look and some of the spots inbetween. As a landscape guy, I can improve my work with 3 exposures but I am outside in the daylight. There are high contrast scenes where I could use more than three but it would have to be a special situation for me to "manually" do several triplets. I like the wireless controllers that allow for many combinations and hope to find one that will work with my Fuji and wallet.

    John
     
  10. RFPhotog

    RFPhotog FujiXspot Rookie

    21
    Aug 9, 2014
    Oshawa, ON Canada
    Robert Fisher
    ISO bracketing doesn't, as has been mentioned, give you the dynamic range extension that HDR is meant for. Now, if you like the result, then use it. But just remember that it's not giving you the real benefit of HDR.
     
  11. Bernie Gibson

    Bernie Gibson FujiXspot Regular

    136
    Jan 18, 2016
    Australia
    Bernie Gibson
    .....using Aurora HDR 2017 you can do single image HDR and get nice results