I was talking with a fellow T2i owner over on my Facebook page and she was wondering which lens would be best for shooting portraits and group shots. I thought it would be beneficial to share our conversation with all of you...
Tracy's Question: I have a T2i and am doing my best to learn how to use it to it's full potential (I'm an amateur, to say the least). I'm wondering about lenses (the Tamron 70-300-mm f/4 - 5.6 or the Tamron 18-270mm f/3.5 - 6.3). Which would you choose and why? Mostly I photograph the kids and family. Possibly some sports or dance recitals, but only on rare occasion. I'm leaning more towards the 18-270mm but not sure how much of a difference there is with them. Is the 300mm vs. 270mm a huge difference? As well as f/3.6 vs. 4? I just don't know enough about the features to choose wisely.
Moose's Answer: All-in-one lenses like the Tamron 18-270mm are great, because it gives you the ability to capture everything from wide-angle to telephoto all with a single lens. I use this lens anytime I'm on vacation and don't want to lug around a bunch of specialty lenses.
In your situation, I would strongly consider a "bright" lens and an external flash. "Bright" lenses allow you to capture a very shallow depth of field (small area in focus) which is great for portraits and small group shots where you want the subject in focus and the background blurred. They're also great in low light situations, allowing you to use a low ISO (reducing image noise/grain) while obtaining a fast enough shutter speed to freeze subject movement. Generally speaking, "bright" lenses are labeled with a maximum aperture between f/1.4 to f/2.8. The Canon 50mm f/1.8 is a great starter lens if you're on a budget. The only hangup is that this is a prime lens, which means you'll always be shooting at 50mm. You won't be able to zoom in or out. Later on you could upgrade to something like the Tamron 17-50mm f/2.8, which would give you the ability to zoom from wide-angle to medium telephoto.
In regards to the external flash, most people don't realize that it can actually give you more natural looking shots indoors under low light. If you angle the external flash upward towards the ceiling, the light will spread evenly throughout the room. When using an external flash, coupled with a bright lens, you'll be able to capture really beatiful portraits and group shots in an environment that is usually very hard to get nice looking images. The Canon 320EX is a great starter speedlight. Just attach it to the hotshoe and your T2i will take care of the rest.
To answer your original question, I would go with the 18-270mm versus the 70-300mm. Image quality is very similar between the two and you won't notice any difference between 270mm and 300mm. The ability to have a much larger zoom range at your disposal is a better advantage in my opinion.
