50mm:
* Pros:
* Wider field of view: Allows for more of the environment to be included in the shot, useful for environmental portraits.
* More versatile: Can be used for other photography genres besides portraits.
* Generally more affordable and lighter.
* Better for tighter spaces: The wider angle allows you to get closer to your subject without needing as much distance.
* Cons:
* Can distort features slightly: Especially noticeable at closer distances, potentially creating a wider-looking nose or face. This is less of an issue on full-frame cameras due to the larger sensor.
* Requires closer proximity to the subject: This can feel less intimate or comfortable for some subjects.
85mm:
* Pros:
* Beautiful compression: Creates a shallower depth of field, resulting in pleasing background blur (bokeh) and a more flattering, three-dimensional look to the subject.
* More flattering perspective: Minimizes distortion, making faces appear more natural and attractive.
* Ideal working distance: Allows for a more comfortable shooting distance and a more intimate interaction with the subject.
* Cons:
* Narrower field of view: Less of the surrounding environment is included. Requires more space to shoot.
* More expensive: Generally more costly than comparable 50mm lenses.
* Less versatile: Primarily used for portraiture.
Sensor Size Matters:
The effective focal length changes depending on your camera's sensor size. A 50mm on a crop-sensor camera behaves more like a longer lens (approximately 75-85mm on an APS-C sensor), while an 85mm on a crop sensor becomes even longer (around 127.5mm on an APS-C sensor). This shifts the characteristics, making the 50mm on a crop sensor closer to an 85mm's performance in terms of compression and background blur.
In short:
* For full-frame cameras: The 85mm is generally preferred for its flattering perspective, beautiful bokeh, and comfortable working distance. The 50mm is a great alternative for more versatility and tighter spaces.
* For crop-sensor cameras: The 50mm often provides a similar aesthetic to an 85mm on full-frame, making it a more versatile and affordable option. The 85mm becomes a very long telephoto lens, useful for very specific types of portraiture but less versatile.
Ultimately, the best lens is the one that best suits *your* shooting style and preferences. Consider renting both lenses before committing to a purchase to see which one you prefer.