There is an ongoing debate among many photographers. What’s the preferred file type, RAW, DNG, TIFF, or JPEG? If you break the process down into 4 areas, each one of these files has a valid, useful purpose.
1) Capture Mode:
Shooting in RAW allows a photographer to capture more detail than if they were to shoot in JPEG. The RAW capture format also provides photographers with more control over the image in the digital darkroom. The ability to change the white balance on a RAW file can make an immediate impact on the overall look of the photo. For instance, by choosing a white balance setting of cloudy, or shady, your photo will take on a warmer tone. If your indoor pictures have a yellow color cast, simply select the Tungsten White Balance preset. Since RAW files do capture so much detail, they will take up more space on your memory card, and hard drive. For example, a 10 megapixel camera with a 4 GB Compact Flash card can hold about 135 RAW files in comparison to 420 JPEG/FINE images. If you decide to shoot RAW, you will want to pick up a few extra memory cards. If you would prefer to shoot in JPEG, be sure to have it set to the highest quality setting. Your camera manual will detail how to do this.
2) For Archival Purposes:
The DNG format was recently created by Adobe in an effort to unify the various RAW formats created by different camera manufactures. For example, Canon’s RAW files are known as .CRW, and Nikon’s are .NEF. Many photographers feel this can potentially become problematic in the long term. They argued that their RAW files may not be future proof in newer software applications. Programs like Adobe Lightroom have an option to backup your RAW files as .DNG. If you want to protect your digital negatives (RAW files) for many years to come, DNG is well worth the effort.
3) For Making Prints:
For those special images that you want to print and display, the preferred file format is TIFF. By saving your completed image as a TIFF, you are using a lossless file which is capable of producing high quality enlargements. JPEG is a compressed file which can degrade image quality slightly. While this may not be noticeable on the computer screen, it will likely show on large prints. By starting with a RAW file, and converting to a TIFF, you are not compressing the file, or losing data. For prints, TIFFS should be saved at 300DPI.
4) For Email and Web Posting:
JPEG is the recommended format for sharing images on the web, or by email. Here are some guidelines to help prepare your files for the web:
Start by opening an image in Photoshop.
Select "Image" from the menu bar, and then select "Image Size".
You will get a pop up box to enter your desired image dimensions.
You can set this by pixel size, or by actual inches. For this example, let's use inches.
Set the image size to 5x7 or 4x6.
Make sure the Resolution is set at 72 DPI. This is ideal for web viewing.
Next, go to FILE, and select "SAVE FOR WEB".
Set the quality to "60", and be sure that the box marked "Optimized" is checked.
Hit Save, and rename the file, (for example, if your original file was "beach", name it beachforweb). Your original file will remain unmodified, and you will have a second file ready for the web.
You can also do this in Lightroom 4, which is detailed in this video.