HDR....???

Discussion in 'Digital Discussion & Q&A' started by PNA, Feb 1, 2007.

  1. PNA

    PNA TPF Noob!

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    A thought just occurred to me regarding HDR......

    If auto ISO is set, and you bracket 3 shots resetting only the aperture, will the 3 shots be exposed differently to use for merge HDR????? Doesn't the ISO change to accommodate the resetting of the aperture and the 3 shots all expose the same???? :er:

    I haven't tried it yet, but tomorrow is comming.......
     
  2. Maxx RS4

    Maxx RS4 TPF Noob!

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    I believe you dont change the aperture but just the shutter speed. that shouldnt affect your iso.
     
  3. PNA

    PNA TPF Noob!

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    Are you suggesting using shutter priority and adjust only the shutter speed?

    I've been using aperture priority.
     
  4. JTHphoto

    JTHphoto TPF Noob!

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    bracketing is intentionally underexposing and overexposing by a specified number of stops, regardless of whether you change your aperture, shutter speed, or ISO. In your case, the ISO shouldn't change, that's my understanding anyway...
     
  5. Arch

    Arch Damn You! Staff Member Supporting Member

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    you should only change shutter speed when doing HDR... changing the aperture changes the DOF.... not good for merging images ;) ... changing iso would be too noisy for my liking too.
     
  6. fmw

    fmw No longer a newbie, moving up!

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    Archangel is right as long as you are not at infinity focus. Use manual mode and under and overexpose with the shutter speed. Remember, you will use a tripod so the shutter speed doesn't matter as long as the subject isn't moving and moving subjects are not a good candidate for this technique.
     
  7. PNA

    PNA TPF Noob!

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    A point very well taken....I never considered that a change in DOF occurred when adjusting the aperture when bracketing.

    On the D70....Can I then use shutter priority instead of aperture priority??? That way the shutter speed changes when bracketing instead of the aperture???

    Using manual is always an option.

    Thanks....and fmw also.
     
  8. Digital Matt

    Digital Matt alter ego: Analog Matt

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    Shutter priority maintains a set shutter speed and varies the aperture. That's the mode NOT to use. Aperture priority would be the mode that maintains the aperture. You would have to use exposure compensation, or auto bracketing to get the different exposures. To me, this is silly and requires reading the manual way too much. The best way to do it is to use manual mode and bracket manually. A simple change of the shutter speed is all that's needed.
     
  9. Arch

    Arch Damn You! Staff Member Supporting Member

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    edit: matt beat me to it but.....

    yea you should always use manual for attempting HDR..... if for example you wanted to try a HDR made up of three images.... one would be exposed correctly, one would be overexposed slightly and the other underexposed.

    If you tried to do this is in a priority mode, the camera would try and compensate for the under/over exposures.

    Some HDRs may consist of 7-8 exposures... the last of which would be very dark, so you can only really achieve this in manual mode. ;)
     
  10. PNA

    PNA TPF Noob!

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    OK, manual for bracketing!!! understood.

    What about auto ISO.....any effects on bracketing exposures?

    I plan to try all configuration today and report finding......

    Thanks, Guys.
     
  11. Digital Matt

    Digital Matt alter ego: Analog Matt

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    Manual implies that you set everything. I don't know if auto ISO would even work in manual mode. If so, it would be stupid. Use a tripod, and always use the lowest ISO, to get the most noise free picture. As stated, this technique is not for moving subjects, so the duration of the exposure is not an issue.
     
  12. shingfan

    shingfan TPF Noob!

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    say you are using tripod to get different exposures.......i would image between different exposures...there might be a slight shift in the composition if you are pressing the button manual.....or is it better to use wireless control?....or a slight shift in composition is acceptable?
     

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