When I get ready for a photo session I have three must have lenses in my bag. My 85mm, 50mm and my 17-55mm all of these lenses are ultrasonic canon lenses and the 17-55mm has an image stabilizer. So you may be thinking “that sounds nice” but why and when do you use these lenses.
I use my 17-55 to get a wider shot to capture more of the environment as well as my subject. It also allows me to be versatile because I can zoom in as well and get a more cropped image. I must admit I use this more than I thought I did. It is a good lens to have because it can range from a wide angle to more cropped lens. I love it.
My 85mm is a great portrait lens because compresses my pictures which allows me to blur out as well as causes less distortion in faces. This way you can see my subject while not being distracted by the background. (Also I can use my little gems to add color and distortions without them being too much in the detail.)
I use my 50mm in almost the same way as my 85mm. I will use it as a portrait lens but I can also step back and get more detail in the scenery around the subject. Still, I can use my gems to make light bounce around in the camera to make lovely distortions.