Perhaps the most visually significant update in the 4.3 release was the introduction of HiDPI support. As Apple began rolling out Retina displays on their MacBook Pro lineups, existing software looked pixelated and blurry. Adobe Photoshop Lightroom 4.3 Final was the update that brought full Retina resolution support to the Develop module. This was critical for photographers who needed pixel-perfect accuracy for retouching and sharpening, making the software future-proof for the new generation of high-resolution screens.
If you are shooting with a Canon R5, Nikon Z9, or Sony A7RV, Lightroom 4.3 will not read those files. You will need to convert your modern RAW to DNG using the free Adobe DNG Converter (a separate download) or stick to JPEG. Adobe Photoshop Lightroom 4.3 Final
Added dedicated lens correction profiles for the Apple iPhone 4S and iPhone 5 to instantly eliminate inherent barrel distortion and corner vignetting. Perhaps the most visually significant update in the 4
The "Highlights" recovery in 4.3 was, at the time, black magic. While modern software recovers 5+ stops, 4.3 reliably recovers 2-3 stops of bright sky without banding. This was critical for photographers who needed pixel-perfect