1. Focal Length:
* Why it Matters: Focal length affects the perspective and compression of your subject. It also influences how much you need to move to frame your shot.
* Popular Focal Lengths:
* 50mm: The "nifty fifty." Versatile, relatively inexpensive, and provides a natural-looking perspective, close to how the human eye sees. Good for head-and-shoulder shots and environmental portraits. Can require you to get closer to your subject.
* 85mm: A classic portrait focal length. Provides pleasing compression (backgrounds appear closer to the subject) and a flattering perspective. Excellent for headshots and close-up portraits, but requires more space.
* 100mm-135mm: Offers even more compression than 85mm. Good for isolating the subject and creating shallow depth of field. Ideal for headshots and tight portraits, but requires a good distance from the subject.
* 70-200mm (Zoom): Highly versatile. Allows you to adjust your focal length on the fly, making it good for shooting in varying locations and capturing different types of portraits (from wide shots to tight headshots). Typically more expensive and heavier than prime lenses.
* Wider than 50mm (e.g., 35mm, 24mm): Used for environmental portraits, showing more of the subject's surroundings. Can distort facial features if you get too close. Requires careful framing.
* Crop Sensor vs. Full Frame: If you have a crop sensor camera (like most entry-level DSLRs and mirrorless cameras), you need to account for the crop factor. Multiply the focal length of the lens by the crop factor (usually 1.5x for Nikon and 1.6x for Canon) to get the equivalent focal length. For example, a 50mm lens on a camera with a 1.5x crop factor will behave like a 75mm lens.
2. Aperture (f-stop):
* Why it Matters: Aperture controls the amount of light entering the lens and the depth of field (how much of the image is in focus).
* Wide Apertures (e.g., f/1.4, f/1.8, f/2.8):
* Advantages:
* Shallow depth of field (blurry background) - great for isolating your subject.
* Excellent low-light performance.
* Creates a creamy, beautiful bokeh (background blur).
* Disadvantages:
* Shallower depth of field can make it harder to get the eyes perfectly in focus.
* More expensive.
* Narrower Apertures (e.g., f/4, f/5.6, f/8):
* Advantages:
* Greater depth of field - more of the image is in focus.
* More forgiving for focusing errors.
* Generally less expensive.
* Disadvantages:
* Less background blur.
* Not as good in low light.
3. Image Quality:
* Sharpness: How sharp the images produced by the lens are. Look for reviews that specifically mention sharpness, especially at different aperture settings.
* Aberrations: Optical imperfections like chromatic aberration (color fringing) and distortion (barrel or pincushion). Good lenses minimize these.
* Vignetting: Darkening of the corners of the image. Can be corrected in post-processing.
* Bokeh Quality: The quality and smoothness of the background blur. Subjective, but generally smoother is preferred.
4. Autofocus Performance:
* Speed and Accuracy: Important, especially if you're shooting portraits of moving subjects (children, pets).
* Focus Modes: Look for features like eye-detection autofocus, which can help you nail focus on your subject's eyes.
* Manual Focus Override: Allows you to fine-tune the focus manually if needed.
5. Build Quality & Features:
* Construction: Metal lenses generally feel more durable and premium than plastic lenses.
* Weather Sealing: Important if you plan to shoot in challenging conditions.
* Image Stabilization (IS/VR): Helps reduce camera shake, especially at slower shutter speeds. Less crucial for portraiture when using fast shutter speeds or flash.
* Minimum Focusing Distance: How close you can get to your subject while still maintaining focus. Important for close-up portraits.
6. Budget:
* Price Range: Portrait lenses can range from a few hundred dollars to several thousand.
* Prioritize Features: Determine which features are most important to you and prioritize your budget accordingly.
* Consider Used Lenses: You can often find excellent deals on used lenses in good condition.
Recommended Lenses (General Suggestions - *Always check compatibility with your camera system*):
* Budget-Friendly:
* 50mm f/1.8 (Canon, Nikon, Sony, etc.): Excellent value for the price.
* Yongnuo 50mm f/1.8 (Canon, Nikon, Sony, etc.): Even more budget-friendly, but image quality may be slightly lower.
* Mid-Range:
* 50mm f/1.4 (Canon, Nikon, Sony, etc.): Better image quality and wider aperture than the f/1.8 versions.
* 85mm f/1.8 (Canon, Nikon, Sony, etc.): A great balance of price and performance.
* Sigma 56mm f/1.4 (For Sony APS-C, Micro Four Thirds, and Canon EF-M): A good equivalent to an 85mm on a full-frame camera, for those systems.
* High-End:
* 85mm f/1.4 (Canon, Nikon, Sony, Sigma, etc.): Exceptional image quality, beautiful bokeh.
* 70-200mm f/2.8 (Canon, Nikon, Sony, Sigma, Tamron, etc.): Pro-level zoom lens with excellent versatility and image quality.
* Sony FE 135mm f/1.8 GM: Considered one of the sharpest portrait lenses available.
How to Decide:
1. Determine Your Style: Do you prefer tight headshots, environmental portraits, or something in between?
2. Consider Your Shooting Environment: Do you mostly shoot indoors or outdoors? In low light or bright light?
3. Set a Budget: How much are you willing to spend?
4. Research Reviews: Read reviews from reputable sources (e.g., DPReview, Photography Life, LensRentals).
5. Rent Before You Buy (Highly Recommended): Rent a few different lenses that you're considering to see which one you like best. This is the best way to make an informed decision.
6. Test in Real-World Conditions: When testing, take the lenses out and shoot in the kinds of situations you usually photograph. Pay attention to sharpness, autofocus, and bokeh.
Ultimately, the best portrait lens is the one that helps you achieve your creative vision and fits your budget. Good luck!