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Digital Photography Myths and facts*

 

* At least the facts according to the web site's author.
 

Myth:
Unsharp Mask will make a blurry image sharp.

 

Fact:
USM usually makes a blurry image worse.  Sharpening is used to retain sharpness, not create it where it does not exist.

 

Myth:
You can never have too much resolution.

 

Fact:
The resolution needed depends on how the file is to be used.  For example, sending a file to a printer with too high a resolution will cause the printer to resample the image downward so it can process it.

 

Myth:
JPEG is the official file format for digital photography.

 

Fact:
There is no official format.  The format one chooses should be based on how the file is to be used.  JPEG is popular in point-and-shoot digital cameras, for email and web because it compresses the file and smaller files transmit faster over the Internet and more of them will fit on a single flash memory card.

However, JPEG uses a lossy compression algorithm.  Lossy methods achieve very small file sizes.  But they do so by throwing pixels away each time the image is saved by an application.  In addition, JPEG does not support layers.  Digital master images are usually stored as TIFF or Adobe Photoshop PSD files.

 

Myth:
Pixels are the little people in your camera that operate all the gears.

 

Fact:
The little people in your camera are known as pixies (with a few gremlins thrown in), not pixels.  Pixel is short for picture (pix) element (el).  It is the smallest, complete unit of information in a digital image.  A single pixel contains the hue, saturation and tonal information for a single point in an image.  For IT types, pixels and bytes are not synonymous.  It takes one or more bytes to store a single pixel.

 

Myth:
PPI and DPI are the same.

 

Fact:
Many people, including the experts, use them interchangeably.  However, the difference is important when discussing printing.  PPI, or pixels per inch, is file resolution.  It denotes how many pixels on both the width and height dimensions can be found per inch in an image.  For example, a 300 ppi file has 300 pixels for every inch in width and 300 pixels for every inch in height.  DPI, or dots per inch, is print resolution.  It denotes how many ink dots an inkjet printer can lay down on a piece of paper.  The ppi of the file being printed does not have to match the dpi the printer is using.  For example, my printer is set to print 1440 dpi but the files I send to the printer are 360 ppi.  In fact, if I sent my printer a file with a resolution of 1440 pixels per inch, the printer would down sample the image so that it could process it.

 

Myth:
The Digital darkroom is much easier than printing in a traditional chemical darkroom.

 

Fact:
“Making a fine print digitally requires every bit of the skill and experience needed for photo darkroom printing.” “…digital printing is easier is not true. …the sheer number of possible controls makes the job much more complex.” “It may look simpler, and it actually is faster, but it is definitely not easier.” --quotes from various industry-recognized, traditional darkroom practitioners who have turned digital.

 

Myth:
Once I calibrate my hardware, my prints will exactly match my monitor.

 

Fact:
Monitors use red, green and blue (RGB) light to create an image on their screen.  Most professional grade printers use a variant of cyan, magenta, yellow and black (CMYK) inks to create an image on paper.  Monitors have a wider color gamut than a printer.  Monitors emit light, prints reflect light.  A monitor has one sheen, printers can print on matte, semi-gloss and gloss papers.  However, in spite of these differences, hardware calibration is critical to having a color managed workflow.

 

Myth:
Since prints will never match a monitor, there is no need to calibrate.

 

Fact:
Calibration and a color managed workflow give you control.  Without it, you are leaving to chance what comes off your printer.  And chances are, you will not be happy.

 

Myth:
Once I calibrate, there is no need to do it again.

 

Fact:
Devices, especially monitors, drift out of tolerance over time.  Recalibrating regains the control in your workflow.

 

Myth:
Digital cameras are better than film based cameras.

 

Fact:
The good news is the biggest variable in photography is not equipment.  Therefore, you do not have to buy the latest technology to improve your photography.  Even better news is the fact that the biggest variable in the quality of your photography is You.  Therefore, when you take a breath-taking image, you get to take full credit for it.  Not your latest piece of gadgetry.  So, give some thought in spending time to improve your skills before spending money to upgrade your equipment.

 

Myth:
Digital SLR cameras increase, or multiply, the effective focal length of a lens.

 

Fact:
If the size of the image sensor in a digital SLR camera is smaller than the size of a 35mm frame, then the camera is cropping the image projected by the lens more so than a conventional 35mm camera.  This gives the illusion that the image is being magnified by the camera.  Thus, leading to the assumption that the camera is increasing the effective focal length of the lens.

Figure 1 below shows an image as it would be projected into the camera by a lens.  Figure 2 shows the area of the image that would be recorded by a conventional 35mm camera.  Figure 3 shows the area that would be recorded by a digital SLR camera whose sensor is smaller than a 35mm frame.  By examining Figure 3, one could assume that the effective focal length of the lens has been increased by the digital camera.  In fact, the digital camera is recording a smaller area, which gives the impression of a greater focal length.

 

As seen by lens

As seen by 35mm camera

As seen by digital SLR

Figure 1.  Image as projected by a lens

Figure 2.  Image as recorded by a conventional 35mm camera

Figure 3.  Image as recorded by a digital SLR camera