December 07, 2012, 3:49 PM — Apple updated the new 21.5-inch iMac with Intel Ivy Bridge processors, a RAM boost, and new Nvidia GeForce graphics processors. But the two most significant changes to the new iMac are its thinner design--which introduces compromises you'll need to make--and the option to upgrade to Apple's Fusion Drive technology.
Using a process called friction stir-welding, Apple designers figured out a way to connect the front and back of the iMac's aluminum case while reducing the width to just 5 mm at the edges. Apple also reduced the weight by more than 7 pounds. The new iMacs are positively striking when viewed from the side, and many curious co-workers came by Macworld Lab to admire the new iMac's svelte profile and run their fingers down the super-thin edge.
When viewed from the front, however, it's difficult to see that reduced thickness. One noticeable difference is the reduction of glare from the display, which Apple says has been reduced by 75%. Looking at the display of a powered-down 2011 iMac is like looking at a mirror, but on the new iMac, the reflection is much less pronounced. I used a flashlight and looked at the reflection on the wall behind me and the reflected light was much, much brighter from the 2011 iMac than on the new iMac. This is a result of Apple's new anti-glare coating technology that lowers reflection without darkening the screen or affecting color.
Apple eliminated the 2 mm air gap that used to exist between the iMac's glass cover and the LCD panel. Now, the glass is directly adhered to the panel, which helps to further reduce glare and reflection, but also makes replacing the front glass more expensive. If the glass breaks, you now have to replace the whole display.
Colors still look vibrant and photographic images pop, with dark blacks adding the appearance of depth. The iMac's LED backlit IPS display, with a native resolution of 1920 by 1080 pixels, has a wide viewing angle that lets you and several others collaborate around the iMac screen with very little loss of contrast or color shifts as you move from the center of the screen.