Exposure problems

Discussion in 'Photography Beginners' Forum' started by ktmurph, Dec 26, 2007.

  1. ktmurph

    ktmurph TPF Noob!

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    I shoot fire scenes as a fire investigator. Have progressed from 35 mm SLR to Canon A75 point and shoot digital to Canon 20D w/ 430 EX Speedlite. Prior problem was not enough flash and the A75 did not have a hot-shoe. I thought new equipment and Speedlite would provide better lighting but many shots are dark around the periphery.

    Can shoot in manual, but in the past the camera has been smarter than I when in Programme or Auto and speeds the photo process. Images are used as evidence and do not get altered/improved with software.

    Any thoughts on improved exposures? Scenes and rooms are very often dark, often with strong contrasting light (an open window on a black burned out wall)
     
  2. joecap

    joecap TPF Noob!

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    You need to tonemap your images using something like Photomatix.
    Their URL is hdrsoft.com.
    If you look through this forum you will find a TON of info about it. The program would be an excellent candidate to do what you need.
     
  3. Digital Matt

    Digital Matt alter ego: Analog Matt

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    Did you even bother to read the original post? He's a fire investigator. The photos are used as evidence. That is the most useless advice.

    ktmurph: It's hard to help without some more information. Are you shooting an entire room, or specific areas? Are you bouncing the flash, or shooting straight on? Are you diffusing at all? Program mode should give you a fairly good exposure with an E-TTL flash. You can also adjust the flash exposure compensation on the camera. This info should be in your flash and/or camera manual.
     
  4. JerryPH

    JerryPH No longer a newbie, moving up!

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    I use to have a friend that did forensic photography, and sometimes did arson cases.

    I am not sure what is best for your needs, but he drove around with a single camera and 2 flashes on stands. From the little that he divulged (it was always unusual for him to ever talk about "work"), one of the most important things was that he had no shadows or hotspots of the areas he shot. He often used diffusers or bounced (whre possible), when larger areas were shot and softboxes when smaller areas were needed. He also had several 1 million candle power "constant on" battery powered lights to assist in larger/taller buildings. He told me that though umbrells lit better, they always got dirty and he stopped using them. He would use bare flashes or diffusers or softboxes on rare occaissions.

    Thinking back more closely... he did not do much more than use standard basic portrait techniques, but instead that of taking pics of people, he took pics of parts of walls, doorways and buildings of an alleged crime scene for forensic evidence.

    Sometimes the flashes were pointing towards a single area, other times he placed them several feet apart but both pointing ahead to light up a wider area.

    One could "assume" that if the person taking the pictures had a solid base in photography and stobes, this would be a big advantage in re-using the pictures to recreate needed visual information without going back to a scene.

    My suggestions is that if photography and off camera lighting is vital to your line of work, visit http://strobist.blogspot.com for some good basics. With practice, you can become more intelligent than your camera in auto mode. Look for links specific to the Lighting 101 archive and the Lighting 102 archives. It may be more than you need... but better more, than not enough.
     
  5. joecap

    joecap TPF Noob!

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    I didn't realize my advice was useless. The program I mentioned does an excellent job of displaying scenes with large contrasts in a realistic way as actually viewed by the human eye. I understand it is also used to create surreal scenes, but if used correctly it shows a true scene that would fit his needs exactly.

    OK, so I missed the boat, his images can't be processed.

    But it was kind of hurtful of you to be so mean to me on my first post when I was only trying to help him. I'm sure you could have chosen a more sophisticated way to inform me.

    What a nice welcome to this forum.
     
  6. ktmurph

    ktmurph TPF Noob!

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    Thanks, keep the suggestions coming. Tried bouncing the flash, but the ceilings are usually burned too. Shooting a wall with a bright window, I've set the exposure on the floor and then moved to the wall which has helped. Better scene lighting may be what I need to add. General procedure is to start outside, move from areas of least damage to most. A stovetop fire would begin w/ four sides of the house, with sequential photos of say inside the front door, move toward the kitchen, get all four walls, the ceiling, shoot the stove, the stove-top, the burner, the knobs etc. moving closer to the point of origin each time. So, the work covers outside, full rooms, down to an outlet or electrical wire shot close-up. Full room shots, especially a large room or commercial have given me the most problems for exposure. Not all bad news though, subjects don't move (don't talk back either).
     
  7. Patrice

    Patrice No longer a newbie, moving up!

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    I'm not familiar with your flash but the problem you describe, darkness around the edges, suggest that when you are using a wide angle focal length to shoot a room the flash does not provide wide enough illumination. Did your flash come with a little plastic clear cover that snaps on the front of the flash head? Sometimes these are separate and on other models it slides out from a slot on top of the flash. These are usually used to disperse the light from the flash to a wider angle. See if your flash has one.

    Good luck and Happy Holiday to you and yours.
     
  8. Fliphishermon

    Fliphishermon TPF Noob!

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    Hi, joecap.

    Just keep posting...
     
  9. ktmurph

    ktmurph TPF Noob!

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    Thanks Patrice, the flash does have a wide panel that can be pulled out or retracted. I'll try it. ktmurph
     

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