1. Understanding the Key Features:
* Focal Length: This is the most crucial factor. It determines the perspective and compression of the image.
* Shorter Focal Lengths (e.g., 35mm, 50mm):
* *Pros:* Wider field of view, good for environmental portraits (showing more of the background), more natural perspective.
* *Cons:* Can distort facial features (especially at 35mm), require you to get closer to your subject.
* Medium Focal Lengths (e.g., 85mm):
* *Pros:* Classic portrait focal length, flattering perspective, good subject isolation, comfortable distance from the subject.
* *Cons:* Requires more space to shoot, less background context.
* Longer Focal Lengths (e.g., 100mm, 135mm, 200mm):
* *Pros:* Excellent subject isolation, very compressed perspective, flattering for faces, great for headshots.
* *Cons:* Requires significant space, can feel detached from the subject, makes background compression very pronounced.
* Aperture (f-stop): Aperture controls the amount of light entering the lens and the depth of field.
* Wide Aperture (e.g., f/1.4, f/1.8, f/2.8):
* *Pros:* Shallow depth of field (blurred background), excellent for subject isolation, good in low light.
* *Cons:* Requires precise focusing, can be more expensive.
* Narrower Aperture (e.g., f/4, f/5.6, f/8):
* *Pros:* Greater depth of field (more of the image in focus), forgiving of focusing errors, often sharper overall.
* *Cons:* Less subject isolation, requires more light.
* Image Stabilization (IS/VR): Reduces camera shake, allowing you to shoot at slower shutter speeds. Useful for handheld shooting, especially in low light.
* Autofocus (AF) Speed and Accuracy: Important for capturing sharp portraits, especially of moving subjects. Consider lenses with fast and accurate autofocus systems.
* Build Quality: A well-built lens will be more durable and last longer. Consider factors like weather sealing if you shoot outdoors frequently.
* Bokeh: The quality of the out-of-focus areas (background blur). Look for lenses with smooth, creamy bokeh for a pleasing aesthetic.
* Sharpness: While not *everything*, sharpness is still important. Look at reviews and sample images to evaluate a lens's sharpness across its aperture range.
2. Deciding on Focal Length:
* Consider Your Style:
* Environmental Portraits: If you want to show your subject in their environment, 35mm or 50mm are good choices.
* Classic Portraits: 85mm is a popular choice for flattering portraits that isolate the subject from the background.
* Headshots: 100mm, 135mm, or even 200mm can be excellent for isolating the subject's face and creating a very shallow depth of field.
* Think About Your Space:
* Limited Space: If you often shoot in small studios or indoors, a shorter focal length like 50mm or 85mm might be more practical.
* Plenty of Space: If you have ample space to work, you can use longer focal lengths like 135mm or 200mm.
* Crop Factor:
* If you're using a crop sensor camera (APS-C), you'll need to multiply the focal length by the crop factor (typically 1.5x or 1.6x) to get the equivalent focal length on a full-frame camera. For example, a 50mm lens on an APS-C camera will have a field of view equivalent to a 75mm or 80mm lens on a full-frame camera. This is important to consider when choosing your focal length.
3. Aperture Considerations:
* Low Light Performance: If you often shoot in low light, a lens with a wide aperture (e.g., f/1.4, f/1.8, f/2.8) is essential.
* Depth of Field Control: A wide aperture allows you to create a shallow depth of field, blurring the background and isolating your subject.
* Stopping Down: Even if you have a lens with a wide aperture, you can always "stop down" to a smaller aperture (e.g., f/4, f/5.6) to increase the depth of field.
4. Lens Types and Recommendations (Examples):
Here are some popular portrait lens choices, categorized by focal length:
* 50mm Lenses:
* *Pros:* Versatile, affordable, good in low light, decent for environmental portraits.
* *Options:* Canon EF 50mm f/1.8 STM (cheap and cheerful), Nikon AF-S 50mm f/1.8G, Sony FE 50mm f/1.8, Sigma 50mm f/1.4 DG HSM Art (more expensive, sharper).
* 85mm Lenses:
* *Pros:* Classic portrait focal length, flattering perspective, good subject isolation.
* *Options:* Canon EF 85mm f/1.8 USM (great value), Nikon AF-S 85mm f/1.8G, Sony FE 85mm f/1.8, Sigma 85mm f/1.4 DG HSM Art (premium option).
* 135mm Lenses:
* *Pros:* Excellent subject isolation, very compressed perspective, flattering for faces.
* *Options:* Canon EF 135mm f/2L USM (legendary), Sigma 135mm f/1.8 DG HSM Art (exceptionally sharp).
* 70-200mm Zoom Lenses:
* *Pros:* Versatile focal range, good for portraits and other types of photography.
* *Cons:* Can be heavy and expensive.
* *Options:* Canon EF 70-200mm f/2.8L IS III USM, Nikon AF-S 70-200mm f/2.8E FL ED VR, Sony FE 70-200mm f/2.8 GM OSS. (f/4 versions are lighter and cheaper).
5. Research and Reviews:
* Read Reviews: Check out reviews from reputable sources like DPReview, Photography Life, and LensRentals. These reviews often include detailed sharpness tests, comparisons with other lenses, and real-world shooting examples.
* Watch Videos: YouTube is a great resource for lens reviews and comparisons. Look for videos that show sample images and discuss the lens's strengths and weaknesses.
* Look at Sample Images: Search for sample images taken with the lens you're considering on websites like Flickr and 500px. Pay attention to the image quality, sharpness, and bokeh.
6. Try Before You Buy (If Possible):
* Rent a Lens: Renting a lens is a great way to try it out before committing to a purchase. Companies like LensRentals and BorrowLenses offer a wide selection of lenses for rent.
* Borrow from a Friend: If you have a friend who owns the lens you're interested in, ask if you can borrow it for a test shoot.
* Visit a Camera Store: Visit a local camera store and try out the lens on your camera body. Take some test shots and see how it feels in your hand.
7. Budget:
* Lenses range in price from a few hundred dollars to several thousand dollars. Determine your budget before you start shopping and prioritize the features that are most important to you. Used lenses can be a great way to save money.
In summary, here's a simple checklist:
1. Focal Length: Decide what perspective you want (environmental, classic, headshot).
2. Aperture: Prioritize low light performance and depth of field control.
3. Autofocus: Ensure it's fast and accurate for your subject matter.
4. Build Quality: Consider durability, especially if shooting outdoors.
5. Budget: Determine how much you're willing to spend.
6. Research: Read reviews and look at sample images.
7. Try Before You Buy (If Possible): Rent or borrow the lens.
Choosing the perfect portrait lens is a journey. Be patient, do your research, and find the lens that best suits your style and needs. Happy shooting!