Tuesday 8/7/12: Bridge + Manual Exposure

" What use is having a great depth of field, if there is not an adequate depth of feeling?" - W. Eugene Smith

"Cartier-Bresson has said that photography seizes a 'decisive moment', that's true except that it shouldn't be taken too narrowly...does my picture of a cobweb in the rain represent a decisive moment? The exposure time was probably three or four minutes. That's a pretty long moment. I would say the decisive moment in that case was the moment in which I saw this thing and decided I wanted to photograph it." - Paul Strand 

Bridge

Adobe Bridge is an organizational software that comes bundled with Photoshop and the Adobe Creative Suite package.  Think of it as a more robust file browser...like a basic mac window that's been spiced up!  Among other things, Bridge allows you to rename and organize files, assign colored labels or star ratings to images, edit the embedded metadata, and output to a pdf or web gallery.  Image files can also be shown in different sized thumbnails, slide shows or lists - making it more advantageous than a basic mac window for photographers and designers.

Adobe Bridge Interface

File Formats

• PSD (.psd = Photoshop Document):  Good for layers, but large file size and can only be opened in PS.
• JPEG (.jpg = Joint Photographic Expert Group): Compresses photos into a smaller file size, but degrades photo quality.  Good for email or web and is recognized by almost all software programs.
• TIFF (.tif = Tagged Image File Format): Larger file size, but good image quality.  Best for printing.  Tiff file can be saved with or without layers and is recognized by many software programs.
• RAW (.raw/.cr2/.nef/... = Raw) = Most flexible file format for photographers since no data has been processed.  But you must process a file into a workable file format before using...which requires more skill and knowledge.

Saving Image Files Recap:

•  For Print = Tiff @ 300dpi
• For Web or Email = Jpeg @ 72dpi
• With Layers = PSD @ optimal resolution (usually 300dpi)

Great article explaining the differences in File Formats:

http://www.digitalphotopro.com/business/hi-tech-studio-file-format-decoder-ring.html

Manual Exposure Mode

Metering the light for proper exposure:

For more advanced digital cameras, when shooting in manual mode you will be setting both the aperture and shutter settings while using your in-camera light meter to give you a proper exposure.

Built-in light meters read the reflected light of your subject and give you an averaging of the scenes exposure.  To take an exposure reading, point the camera at your subject and while depressing the shutter button half way, look through the viewfinder for the light meter (or onto your lcd screen, depending on your camera).  With the aperture on any f-stop, inside the viewfinder, some cameras will give you a reading for the proper shutter speed that correlates with the set f-stop to give you a properly exposed scene.  For other cameras, there may simply be an under and overexposure scale as the light metering system.   Check your camera and determine which metering display you have.

In camera metering displays:

-Data panel:  Modern, digital read-out cameras.  Will show on LCD panel.

-Over/Under triangles or arrows: up and down lit triangles with center dot representing proper exposure when lit.  Found on a lot of digital panels.

-Through the viewfinder:  The set aperture is on the bottom and the proper shutter speed is selected with a small light dot next to a list of speeds.

-Over/Under panel.  -2…-1…0…+1…+2  Normal exposure is “0”

-Needle-centering display on older cameras.  Change Shutter and Aperture until needle is centers between over (+) and under exposure (-) for proper exposure.

One stop of exposure = either a doubling or a halving of the amount of light!

 Law of Reciprocity:  E = I x T (Exposure = Intensity x Time)

 Doubling I, means we have to half T  

1s@f8 = 2s(2x)@f11(.5x)  

Exposures are reciprocal – they yield the same density in your image.

f16@1/30  =  f11@1/60  =  f8@1/125  =  f5.6@1/250  =  f4@1/500

Depth of Field

When you focus a camera on an object, the distance between the lens and the image sensor is adjusted.  In theory, you can only focus on one single distance (the plane of critical focus) and the objects at other distances will be less sharp.  But, in most cases, part of the scene will be acceptably sharp both in front of and behind the most sharply focused plane.  The further an object is from the plane of focus, the more it will fall out of focus.  This region within which objects appear acceptably sharp is called the depth of field.

 

Depth of Field is controlled by these factors:

1.       Aperture size (lens opening):

Larger Aperture (Small f-stop #) = Less Depth of Field (Background more out of focus)

Smaller Aperture (Larger f-stop #) = More Depth of Field (Background more in focus)

2.       Focal length of lens:

Longer FL (zoomed in) = Less D of F

Short FL (zoomed out) = More D of F 

3.       Lens-to-Subject Distance (focus distance): 

Close Subject = Less D of F

Far Subject = More D of F

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