Here's a breakdown to help understand why:
Why a 70-200mm is often RECOMMENDED for portrait photography:
* Compression: This is the big one. Longer focal lengths compress perspective, making the background appear closer to the subject and creating a more flattering, less distorted image of the face. This is particularly useful for headshots and tighter portraits.
* Bokeh: The 70-200mm, especially with a wide aperture (f/2.8 is highly sought after), creates beautiful background blur (bokeh) that isolates the subject and adds a professional, artistic touch.
* Working Distance: It allows you to maintain a comfortable distance from your subject. This can make them feel more relaxed and natural, especially for those who are camera-shy. It also allows you to shoot candidly without being intrusive.
* Versatility: While great for portraits, the 70-200mm can also be used for events, sports, wildlife, and other genres, making it a valuable addition to your lens collection.
* Reach: Allows you to get closer without physically moving, important in crowded situations or when shooting from a distance.
* Variety of Portraits: You can easily switch between headshots, waist-up shots, and full-body portraits without changing lenses.
Why you might NOT *need* a 70-200mm:
* Cost: High-quality 70-200mm lenses, particularly those with a fast aperture like f/2.8, are expensive.
* Size and Weight: They are large and heavy, which can be a burden on long shoots or when traveling.
* Space Requirements: You need a certain amount of space to effectively use the longer focal lengths. Small studios or cramped locations might not be ideal.
* Other Options Exist: Excellent portraits can be taken with other lenses, such as:
* 50mm: Versatile, affordable, and great for full-body and environmental portraits.
* 85mm: A popular portrait lens that offers a good balance of compression and working distance.
* 35mm: Good for environmental portraits, showing the subject within their surroundings.
* Your Style: If your style favors wide-angle, environmental portraits, a 70-200mm might not be the best fit.
Alternatives and Considerations:
* 85mm Lens: Often considered the "portrait prime." It provides excellent image quality, beautiful bokeh, and a flattering focal length for portraits, often at a lower price and smaller size than a 70-200mm.
* 50mm Lens: A budget-friendly option that's incredibly versatile and can produce beautiful portraits, especially in well-lit environments.
* Crop Sensor Camera: If you're using a crop sensor camera, a shorter telephoto lens like a 50-135mm might offer a similar reach and compression to a 70-200mm on a full-frame camera.
* Zoom Lenses in Other Ranges: Some photographers find success with lenses like a 24-70mm, adjusting their shooting distance to compensate.
Conclusion:
While not strictly *essential*, a 70-200mm lens is a powerful and versatile tool that many portrait photographers find invaluable. Its ability to compress perspective, create beautiful bokeh, and provide a comfortable working distance makes it a popular choice for a wide range of portrait styles.
Before buying a 70-200mm, consider:
* Your budget: Can you afford a high-quality lens?
* Your shooting style: Do you primarily shoot headshots or environmental portraits?
* Your working environment: Do you have enough space to effectively use the lens?
* Your camera: A crop sensor camera will affect the effective focal length of the lens.
Ultimately, the best lens for you depends on your individual needs and preferences. Experiment with different focal lengths and find what works best for your style of portrait photography. Don't feel pressured to buy a 70-200mm just because everyone else does. Renting or borrowing one to try it out before committing to a purchase is an excellent idea.