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HDR - High Dynamic Range Photography.

Getting it right in the first place is better than fixing it later with software. This discussion forum is for our members to create or provide links to Photography Tutorials. e.g. How to set the controls on the camera. Compose a picture. Lighting, using the camera controls etc.

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HDR - High Dynamic Range Photography.

Postby sjj1805 » Sat Feb 28, 2009 2:45 am

Sometimes you just cannot get the right exposure because parts of the scene are too bright and other parts of the scene are too dark.

Here is a picture I took on a cloudy day in February 2009.
Despite the clouds, the brightness of the sky means that when taking the picture at the correct exposure, the grass and tree in the foreground are too dark.

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If you slow the shutter speed to give more exposure then you lose the clouds in the sky:

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Fortunately Corel PhotoImpact contains a function to deal with this:
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However you must prepare your material at the time of taking the picture.

Preparation - "out in the field"

You will need a tripod for this because you need to take at least 3 identical photographs but with different exposure levels.

Picture 1 - Normal Exposure
Picture 2 - Under Exposed
Picture 3 - Over Exposed.

Actually the above statement is technically not quite true - it was a simplification to help you understand what to do. In fact what you should do is determine the correct exposure for the dark area, the correct exposure for the light area and then take at least 3 photographs.

Picture 1 - The correct exposure for the lighter area (Highlights)
Picture 2 - The correct exposure for the dark area (Shadows)
Picture 3 - The correct exposure for the overall scene (Midtones)

If there is a vast difference between the highlights and the shadows then you might need to take more than 3 pictures. The suggested step value between pictures is 2 stops.

1. Set your camera to Aperture Priority and select the desired aperture setting for the scene.
2. Aim the camera at the highlights (Probably the sky) and note the shutter speed suggested by the Camera.
3. Point the Camera at the shadows and take a new reading.

You now know the Aperture setting, you know the lowest shutter speed and the highest shutter speed.

4. Set your camera to Manual Mode. This will enable you to set the shutter speed yourself despite the fact you have already chosen the aperture setting.
5. Set the shutter speed to the slowest setting determined above and take the first picture.
6. Increase the shutter speed by up to 2 stops. Take the next picture.
7. Repeat step 6 until you reach the fastest shutter speed determined above.

You will now have at least 3 pictures:

Image

Image

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Merging the photographs with PhotoImpact.

This is in fact simplicity in iteself because the software does it for you!
Open your 3 (or more) photographs. Do NOT open any other photographs - only the one's you are merging.

Select 'Photo' - High Dynamic Range.
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A message box appears:
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Followed by the following screen
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You will see a drop down list of Camera manufacturers:
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If your camera is not in the list - for example Pentax - then click the item
"Auto Generate Camera Curve" which it will do from the 3 (or more) images you have just provided. You are also given an option to save the camera curve for future use and it will then appear in the list of Cameras available.

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Now click the button to "create a High Dynamic Range Image"
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Sit back and wait a few minutes whilst PhotoImpact does it's work and.....

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sjj1805
 
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