85mm Advantages:
* Compression: The 85mm lens provides more background compression, making the subject pop out more and blurring the background more effectively (bokeh). This is a classic portrait look.
* Working Distance: It allows you to stand further from your subject while still achieving a pleasing headshot or close-up. This can be less intimidating for the subject and provides more space for lighting equipment.
* Perspective: The longer focal length creates a more flattering perspective, often minimizing perceived imperfections.
50mm Advantages:
* Versatility: 50mm lenses are often lighter, cheaper, and more versatile. They can be used for a wider range of photography styles, including street photography and environmental portraits.
* Wider Field of View (on full-frame): The wider field of view allows you to capture more of the subject's environment, which can be beneficial for environmental portraits.
* Accessibility and Cost: 50mm lenses are generally more affordable and readily available.
Sensor Size Considerations:
* Full-Frame: On a full-frame camera, the 85mm truly excels at its portrait strengths. The 50mm can still work, but it might feel a bit too wide for tight headshots.
* APS-C: On an APS-C camera, a 50mm lens acts more like an 80mm lens (approximately), and an 85mm acts closer to a 136mm lens (approximately). This makes the 50mm on APS-C a very popular and effective portrait lens, while the 85mm can become quite long and limiting, requiring more distance from the subject.
In Summary:
* For full-frame cameras: The 85mm generally offers superior background blur and compression, making it the preferred choice for most portrait photographers.
* For APS-C cameras: The 50mm is often the more practical and versatile choice, offering a good balance of focal length and working distance. The 85mm can be too long, though some photographers appreciate the extra reach.
Ultimately, the "best" lens is subjective. Try renting both lenses if possible to see which feels better for *your* style and shooting preferences. The difference isn't always night and day, and both can produce excellent portraits.