Arguments for a 70-200mm lens:
* Compression: This is the biggest draw. The longer focal length compresses perspective, making subjects appear closer to the camera and blurring the background more effectively (creating pleasing bokeh). This is particularly beneficial for flattering portraits, especially headshots and environmental portraits where you want to isolate the subject.
* Working Distance: You can get flattering portraits from a greater distance than with shorter lenses. This is useful for shy subjects, candid shots, or situations where getting close isn't feasible or desirable.
* Faster Apertures: Many 70-200mm lenses offer wide maximum apertures (e.g., f/2.8), allowing for beautiful shallow depth of field and better low-light performance.
Arguments against a 70-200mm lens (or at least, delaying its purchase):
* Cost: High-quality 70-200mm lenses, especially those with f/2.8 apertures, are expensive. There are more affordable options, but they may compromise on image quality or speed.
* Size and Weight: These lenses are relatively large and heavy, making them less portable and potentially tiring to use for extended periods.
* Alternatives: Other lenses can achieve similar results. A 50mm prime lens is excellent for portraits, and a good 85mm prime offers similar compression to a 70-200mm at a lighter weight and often lower cost. Depending on your camera's sensor size, even a versatile zoom like a 24-70mm can produce pleasing portraits, especially when shooting tighter crops.
Conclusion:
A 70-200mm lens is a fantastic tool for portrait photography, but not a mandatory one. Starting photographers can build a solid portrait portfolio with other lenses. Consider these factors:
* Your budget: Can you afford a high-quality 70-200mm lens *without* compromising on other essential gear?
* Your shooting style: Do you frequently shoot environmental portraits where background separation is crucial? Do you prefer working at a distance from your subjects?
* Your shooting locations: Will you often be in spaces with limited room to move around?
If your budget allows and your style demands the benefits of a 70-200mm lens, then it's a worthwhile investment. However, many successful portrait photographers have built impressive careers without one. Focus on mastering your lighting, posing, and post-processing skills first, and then decide if the 70-200mm lens is the right next step for *your* photography.