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RAW with ISO Bracketing

Discussion in 'Olympus Cameras' started by dennisk, Sep 20, 2011.

  1. dennisk

    dennisk Mu-43 Regular

    110
    Jul 4, 2011
    Bay Area, California
    Dennis
    I want to use RAW with ISO Bracketing where each shot creates 3 files. When I import and open the files, they do look different.

    Are the three files created from the same sensor data? If so, can't I get the exact same results by not bracketing and using post processing on a single RAW file? I guess I'm asking if I'm just wasting space on disk or am I saving extra details by bracketing.
     
  2. EP1-GF1

    EP1-GF1 Mu-43 Veteran

    312
    Apr 12, 2011
    Bump as I'd like to know the answer too.
     
  3. RobWatson

    RobWatson Mu-43 Hall of Famer

    Well, my E-P1 activates the sutter once and produces 3 images so I'm gonna say yes. Kinda don't see the point of ISO bracketing in this context ...

    Should be easy to verify if you can replicate as described.

    Unless there is processing done on RAW in camera it should work.
     
  4. avidone

    avidone Mu-43 Top Veteran

    520
    Jun 24, 2011
    Rome, Italy
    A least on my E-PL1 all types of bracketing involve subsequent separate shots. you can do those shots quickly on continuous shooting, but that is still not enough to get away with handheld if you want to try and combine them after. I tried that once, then using software to try and make an HDR, but it just couldn't align the images which were slightly off from each other. Of course if you just want to choose one best exposure, that is fine, but as I understand it they are coming from separate exposures and not from the same data.

    If you mess up, you can always play around more and turn it into psychedelic art:


    gran caffe by Asher Berry, on Flickr

    Sent from my iPad using Mu-43 App
     
  5. Kiwi Paul

    Kiwi Paul Mu-43 Top Veteran

    729
    Aug 15, 2011
    Aberdeen Scotland
    The camera only takes one shot so in that case the bracketing can only be done by the camera using one exposure at one ISO value then creating the other 2 brackets. So yep you can do the same in PP.
    It would need to take 3 separate shots to using different ISO values each time and also varying the shutter speed or aperture to make the exposure correct to do it properly.

    Paul
     
  6. DougWW

    DougWW New to Mu-43

    5
    Sep 21, 2011
    Alberta Canada
    Now I'm a bit confused.
    We have a computer (in the camera) that is told 2 things:
    1. create multiple images with different settings
    2. save the files as RAW, which is supposed to be straight data from the sensor.

    I'm not sure how to prove this but I will suggest that the camera does both.. first it takes an image and does the normal image processing for ISO. Then it saves the RAW information and discards the processed image as unneeded.

    If the camera is saving the RAW image after having processed it for ISO then it really isn't RAW, is it?

    ..Doug
     
  7. dennisk

    dennisk Mu-43 Regular

    110
    Jul 4, 2011
    Bay Area, California
    Dennis
    It's mentioned below.. but ISO bracketing produces 3 files from one shutter press. All the others like AE bracketing requires multiple shutter presses.

    Olympus E-PL3, 12mm, 14-42mm, Contax T3 :)
     
  8. flash

    flash Mu-43 Hall of Famer

    Apr 29, 2010
    1 hour from Sydney Australia.
    Gordon
    ISO on a digital camera is simply an amplification of the sensor data. This can be done before or after capture depending on the sensor architecture. It sounds like the ISO bracketing is doing this after capture in the Pens. In some systems the amplification is done prior to the exposure. In the case of the Pens you would get the same result in post processing, assuming your skill and the processor are as good as the internal engine in the camera.

    As for raw being the data straight off the sensor, well this is certainly almost never the case. Lens correction, pixel mapping for stuck or hot pixels, vignetting controls via signal amplification and even, in some cases, noise reduction are applied to most modern sensors depending which lens you attach to the camera, before the raw data is written. In most cases you have no control over this. The only "normal" cameras I know of where you have some control of what is done are the Leica M8 and M9. With those cameras you can actually manually select which lens profile data you want applied to the raw files from the menu.

    Gordon
     
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  9. RobWatson

    RobWatson Mu-43 Hall of Famer

    Yup, Think of the light as captured in the pixels. With cmos the signal from those pixels can be read out and not disturb the contents of the pixel (ccd can't do that) so the pixel is read and digitized using a gain setting determined by the ISO selection. Select a new ISO and digitize again, etc. Viola, new images from the sensor data - all raw. Raw is hardly the same as unprocessed data despite the name (see what Gordon describes additional processing above).

    Not exactly the same as taking one shot and replicating the ISO bracket in post but almost.
     
    • Like Like x 1
  10. dennisk

    dennisk Mu-43 Regular

    110
    Jul 4, 2011
    Bay Area, California
    Dennis
    Nice to learn something new about RAW files and how they are created!
     
  11. avidone

    avidone Mu-43 Top Veteran

    520
    Jun 24, 2011
    Rome, Italy
    well, I'll be... I guess I did not try that kind of bracketing before... I stand corrected... now I am not sire whether it is worth trying or if I should just stick with taking single RAW and doing PP