1. Focal Length:
* 35mm: Great for environmental portraits, showing the subject in context with their surroundings. Can distort features if you get too close. Good for street photography style portraits.
* Pros: Wide view, good for storytelling.
* Cons: Can be unflattering up close, less background blur.
* 50mm: Often called the "nifty fifty," a versatile and affordable option. Offers a natural perspective, similar to human vision. Good for head and shoulder shots and environmental portraits.
* Pros: Affordable, versatile, natural perspective.
* Cons: May not provide enough background blur for some. Might require you to move more than desired.
* 85mm: A classic portrait focal length, striking a balance between flattering perspective and background compression. Ideal for headshots and tighter compositions. Often cited as the "classic" portrait lens.
* Pros: Flattering perspective, good background blur, good for headshots.
* Cons: Requires more space between you and the subject.
* 100mm - 135mm: Excellent for headshots and tighter portraits, providing excellent background compression and flattering facial features. Creates a more intimate feel.
* Pros: Excellent background blur, very flattering perspective, great for tighter compositions.
* Cons: Requires significant distance, can be less versatile for other types of photography.
* 70-200mm Zoom (at 200mm): Offers maximum background compression and isolation, creating a dreamy, blurred background. Good for studio and outdoor portraits where you have plenty of space. Also great for candid portraits from a distance.
* Pros: Incredible background blur, allows for comfortable shooting distance, zoom versatility.
* Cons: Can be large and heavy, typically more expensive.
Key Considerations for Focal Length:
* Shooting Distance: Think about how much space you typically have to work with. Small spaces favor shorter focal lengths (35mm, 50mm), while larger spaces allow for longer lenses (85mm, 100mm+).
* Desired Background Blur (Bokeh): Longer focal lengths (85mm and above) generally produce more background blur, isolating your subject. Wider apertures (f/1.8, f/1.4) amplify the blur.
* Subject Distortion: Wider lenses (35mm and sometimes 50mm) can distort facial features if you get too close. Longer lenses are more flattering.
2. Aperture (f-stop):
* Wider Aperture (e.g., f/1.4, f/1.8, f/2.8):
* Pros: Shallow depth of field (blurry background), better low-light performance, brighter viewfinder image.
* Cons: Can be more expensive, shallower depth of field requires precise focusing, especially with fast lenses.
* Narrower Aperture (e.g., f/4, f/5.6, f/8):
* Pros: Greater depth of field (more in focus), easier to get sharp results, less expensive lenses.
* Cons: Less background blur, less effective in low light, dimmer viewfinder.
Considerations for Aperture:
* Bokeh Preference: If you crave creamy, blurred backgrounds, prioritize a lens with a wide maximum aperture (f/1.8 or faster).
* Low-Light Shooting: A wider aperture lets in more light, allowing you to shoot at lower ISOs and faster shutter speeds in dim conditions.
* Budget: Lenses with very wide apertures (f/1.4 or faster) are typically significantly more expensive.
* Number of Subjects: If you frequently photograph groups, a narrower aperture (f/2.8 or f/4) will help ensure everyone is in focus.
3. Budget:
* Entry-Level: 50mm f/1.8 lenses are incredibly affordable and offer a great starting point. Used lenses can also be a fantastic way to save money.
* Mid-Range: 85mm f/1.8 lenses offer a good balance of price and performance.
* High-End: 85mm f/1.4, 70-200mm f/2.8, and similar professional-grade lenses can be quite expensive.
4. Image Stabilization (IS/VR):
* Pros: Helps reduce camera shake, allowing you to shoot at slower shutter speeds (useful in low light). Beneficial for handheld shooting.
* Cons: Can add to the cost and size of the lens. Less critical if you primarily shoot in bright light or use a tripod.
5. Autofocus Performance:
* Fast and Accurate Autofocus: Crucial for capturing sharp portraits, especially of moving subjects. Look for lenses with advanced autofocus motors (e.g., USM, HSM, STM).
* Manual Focus Override: Important for fine-tuning focus or shooting in situations where autofocus struggles.
6. Crop Sensor vs. Full Frame:
* Crop Sensor (APS-C): Lenses appear to have a longer focal length due to the crop factor (typically 1.5x or 1.6x). A 50mm lens on a crop sensor camera will behave more like a 75mm or 80mm lens.
* Full Frame: Lenses perform as their focal length indicates.
7. Other Factors:
* Build Quality: Consider the durability and weather sealing of the lens, especially if you plan to shoot outdoors frequently.
* Lens Coatings: Look for lenses with multi-layer coatings to reduce flare and ghosting.
* Personal Preference: Ultimately, the best portrait lens is the one that feels most comfortable and produces the results you envision. Rent lenses to try them before buying.
Recommendations Based on Common Scenarios:
* Budget Beginner: 50mm f/1.8
* Versatile All-Around: 50mm f/1.4 or 85mm f/1.8
* Professional Headshots: 85mm f/1.4 or 100mm
* Outdoor Portraits with Background Compression: 70-200mm f/2.8
* Environmental Portraits: 35mm f/1.8 or 50mm f/1.8
How to Test Lenses:
* Rent Before You Buy: This is the best way to experience a lens firsthand.
* Shoot Test Shots: Take portraits at different apertures and focal lengths.
* Check Sharpness: Examine your images closely for sharpness, especially at the edges of the frame.
* Evaluate Bokeh: Assess the quality and smoothness of the background blur.
* Test Autofocus: Focus on moving subjects and assess the speed and accuracy of the autofocus system.
By carefully considering these factors and testing different lenses, you can find the perfect portrait lens to capture stunning and memorable images. Good luck!