Budget Lens for Canon Rebel T2i?
November 22, 2011 7:46 PM   Subscribe

Budget lens for my Canon Rebel T2i?

I bought a Canon T2i a couple months back, and I'd love to upgrade the kit lens (which isn't great--wish I'd just bought the camera body and skipped the package deal). I'm thinking that with Black Friday deals and holiday discounts coming up, now might be the time. I'm looking to spend ~$200-300 at the most.

I tend to take nature and "action" shots--specifically of roller derby events that involve a lot of movement with not-so-great lighting. I don't have an external flash, and am very new at digital photography, so all advice is much appreciated!
posted by prior to Technology (11 answers total) 7 users marked this as a favorite
You want a fast lens. That means a lens with a low f-stop. f/2 or lower is where you want to be here.

Your sensor has a 1.6 crop factor (typical of consumer-level digital SLRs) so whatever lens you get is going to be naturally more "zoomed in" than it would be on a 35mm film camera or "full sensor" digital. What this means is that your whole camera setup is slanted toward the telephoto and away from the wide-angle side of things.

In your price range, I'd look for this prime lens or its predecessor, used. I have it's predecessor, and I love it to pieces. On a full-sensor camera or a film camera, this lens is supposed to capture more-or-less the human field of view. On yours it will be zoomed in a bit. If you really want the wider field of view, maybe this prime lens will be more what you're looking for. I bet you can find either of these used in your price range.
posted by gauche at 8:14 PM on November 22, 2011 [2 favorites]

The best bang for your buck is the 50mm f/1.8. You'll get results effective of an 80mm lens due to the difference in sensor size vs 35mm. It's way faster than any zoom lens you could get outside of spending serious money, and assuming you can get decent proximity to the roller rink events, you'll get good results in low light.

You can bump up to a f/1.4, which is just one stop faser than the 1.8, but three times the price. Personally, I think it's worth it, but that's after shooting on a f/1.8 for a long time.
posted by ndfine at 8:20 PM on November 22, 2011 [2 favorites]

ugh. that should be "one stop faster."
posted by ndfine at 8:22 PM on November 22, 2011

Or, what gauche said! (I'll go now...)
posted by ndfine at 8:24 PM on November 22, 2011

There are tons of options. Have a look at some of the previous posts tagged photography for general advice.

Covering fast movement in poor lighting is basically very difficult, as the light has to come from somewhere. There are four things that make up the brightness of a picture:
  1. The amount of light being reflected from the subject towards the camera.
  2. How long the shutter is open. Obviously, the longer it's open, the more light will enter.
  3. The aperture of the lens. This means, literally, how much light can enter through that lens over a given space of time. Perversely, the smaller the number, the more light can come in. It also increases on a logarithmic (?) scale, so f/1 lets in double the light of f/1.4, which lets in double the light of f/2, then f/2.8, f/4, f/5.6, f8 and so on.
  4. The sensitivity of the film or digital sensor. As they become more sensitive, more noise (or grain) appears. Eventually, you end up with large blotchy splotches, which is undesirable. So let's try and keep the sensitivity (ISO rating) of the sensor as low as possible.
In many situations, you don't have control of 1. You have control of 2 and 3. Let's look at these briefly.

Firstly, having a camera shutter open for a longer length of time. The downside is that you'll start to see motion blur if the shutter's open long enough. This will depend on how fast the movement is and how long the lens is open for. For general wobbling around the place, 1/125th of a second is enough to provide a certainty for a sharp image, and 1/60th for people standing "still". For the sake of information, 1/100th of a second will produce a picture twice as bright as 1/200th of a second.

You also want to make sure that you're on roughly 1/(thelenslength x 1/6) to eliminate blur from your hands shaking the camera. So if you're on 28mm, you'd need to be at least 1/45th of a second to guarantee a sharp frame. In practise, you often want to be a bit on the safe side, so let's call it 1/60th. IS (or Image Stabilisation) can seriously help with camera shake, but it doesn't compensate for the first type of motion blur I described.

Let's combine that knowledge with lens apertures. Basically, the more light a lens can let in over any arbitrary amount of time, the brighter the picture will be. Remember how f/2.8 is twice as bright as f/4? Well, that means that an exposure of 1/100th of a second will be twice as bright at f/2.8 as it would be at f/4.

Why is that useful? Well, say you want to achieve some arbitrary standard of brightness (BTW 18% grey is what your camera often looks for.) Let's make up a unit of measurement, the Thingie of Light for our Arbitrary Example. You'll need to get 100 thingies of light in to achieve a satisfactory amount of brightness in your picture, and you can either use f/2.8 or f/4. You can either get enough in by opening your shutter for 1/50th of a second at f/4, or 1/100th of a second at f/2.8. What if you were using your lens at f/2? Well, remember that will let double the amount of light in, so the exposure time should be 1/200th of a second. Remember, the shorter the exposure time, the more chance that your roller derby subject will be in nice sharp focus.

Now, there are other effects to using different apertures. The wider the aperture, the shallower the plane of focus will be. This can lead to some very pleasant effects when used correctly, but it does mean your subject will very easily move out of focus, and may not even be entirely in focus at any one time. If you want lots of detail throughout your image, like in a landscape photo, you might want a smaller aperture, so you'd set it to something like f/8, or smaller. If you wanted a very shallow depth of field (plane of focus), you'd set it to something wider, like f/1.4.

What if the subject is relatively dark, but is moving? Well, you want a wide aperture, but not so wide that you can't focus on your subject, and the exposure can't be too slow, as you want them to be sharp. Where do you compromise? You might turn up the sensitivity of the sensor (or put in more sensitive film, if you were using a film camera), but that will reduce the image quality, giving you more grain and noise. You might choose to open up the lens aperture as far as it'll go, and hope that you manage to hit the focus on one or two shots. You might make the exposure longer, and hope that you hold the camera steady (or stick it on a monopod/tripod) and that the subject stays still for a moment. You might go bug the management and ask them to turn the lights up. Something has to give.

Now, you might be saying "I need a wide aperture lens! Now!", and you might be right. However, it's an expensive proposition. It takes very fine glassmaking and high quality engineering to produce a lens that lets lots of light in. That obviously costs money. It's also a more complicated decision than that. You need to consider lens length.

Lenses will have a length in millimetres attached to them. Your kit lens is probably 18mm-55mm. As you may well know, the smaller the lens length, the wider the field of view. Your lens goes from a wide angle (wider than what you'd typically see) to a telephoto (smaller than what you'd typically see). The received wisdom is that a 50mm on a full frame (same size as a film camera) sensor is approximately what a human sees. This equates to about 30mm on your smaller (1.6th of the size) sensor. Yes, lenses behave differently depending of what size sensor you're using. A smaller sensor will essentially lengthen the lens. Your 18mm-55mm will give similar results to a hypothetical 28mm-88mm lens on a full frame camera. Now, you need to think about utility. Do you want to get closer to the subject? You need a longer lens. Do you want to see wider views? You need a shorter, wide-angle lens. It's worth bearing in mind that you'll see much, much more difference between a 15mm and a 20mm lens than between a 95mm and a 100mm lens.

Hopefully you should have a basic knowledge of photography terminology by now. There's tons and tons of information around the internet, and I heartily encourage voracious experimentation. Set your camera to manual mode and play around. You get instant feedback and every picture's free!

With all that in mind, I'll make a few tentative lens recommendations:

Tamron 17mm-50mm f/2.8
This will give you similar functionality to your current lens, but with higher quality glass and a consistent aperture throughout the zoom range. It's a lot brighter than your current one, especially at the telephoto end of the zoom.

Canon 55mm-250mm f/4-f/5.6
This is the telephoto brother to your lens. If you feel that you need to get "closer" to the action, then this will provide it. But what it gives in length, it lacks in everything else. The build quality is not very good, the aperture is pretty small (making it poor in low light, though perfectly fine in daylight) and the optical quality is mediocre. Having said all that, if you need a long telephoto lens, there's nothing else in your budget worth considering (I believe.) By the way, that aperture rating means that the longer the lens length, the less light it lets in. This is a consequence of the optical design of budget zoom lens. Your kit lens suffers from the same issue.

Canon 50mm f/1.8
Lots of people love this lens, and with good reason. It's extremely cheap for the quality it gives, and it opens to a reasonably wide aperture. This makes it useful in low light situations. The optical quality is quite high, and I've had some great captures with my (now retired) copy. The build quality is mediocre, but for the price it's forgivable. This will give you a lens length that is a mild telephoto. It's quite useful for portraits, similar to the telephoto end of your kit lens, but with far better results. It should be quite a bit brighter than your kit lens at the same length. How much? Remember, f/1.8 is 1.3 times as bright as f/2, which is 2x as bright as f/2.8, which is 2x as bright as f/4, which is 1.3x as bright as f/4.5 - this means you can go from a 1/10th of a second exposure to a theoretical 1/67th of a second exposure. Enough to bring it from a shaky mess into a confident capture.

Canon also do a 50mm f/1.4, which has higher optical quality, a touch more light, but suffers from being very delicate. It's probably on my camera the most at the moment.

Canon 28mm f/1.8
This lens would be a wide-angle on a full-frame camera, but becomes a pretty normal view on a cropped sensor. I used it extensively when I was on a cropped frame camera. The build quality is higher than the 50mm f/1.8, but the price is significantly higher too. The optical quality is fairly good - I seem to have a very good copy, because general consensus is that it's simply an okay performer. It's simply a very good general purpose lens on a camera like yours.

You may be wondering why the two fixed focal length lenses have a much wider aperture and better optical quality than the zoom lenses. Well, it's simply because of their simplicity. These "prime" lenses are mechanically much simpler prospects than a zoom lens, so they're cheaper to make and you get more for your money. More importantly, and annoyingly, Physics has decided that there are limitations to the aperture of zoom lenses, thus you'll never find one wider than f/2.8. Even these tend to be very expensive, making the previously mentioned Tamron quite a bargain.

Okay, I think I've probably given you enough technical info for now, but feel free to ask any more questions. Have fun!
posted by Magnakai at 9:09 PM on November 22, 2011 [5 favorites]

You might want a flash instead. Nothing has improved my indoor photography more than getting an external flash (a Speedlight 430) and learning good "bounce" technique. Lighting is a huge part of photography, and if you can take control of your lighting, you gain a big advantage.

That said, the 50mm f/1.8 is a good lens. For indoor photography in low light conditions, however, if I had to choose between a good flash setup and a relatively fast (e.g. f/1.8) lens, I'd take the flash.
posted by mr_roboto at 9:49 PM on November 22, 2011 [1 favorite]

The lens you currently own doesn't have a reputation for being particularly lousy.

It's possible that your less than stellar results with your kit lens may in some cases be due to missed autofocus, camera movement, or subject movement.

I'd join others in voting for an external flash first, with, as mr_roboto says, the Speedlight 430 being the obvious choice.
posted by imjustsaying at 4:58 AM on November 23, 2011

Warning that while the 50mm f/1.8 is a fantastic lens, it may not be great for nature and action shots, where you generally want more reach than portrait length. As much as I'm a prime nut, I'd hate to have to use a prime when I don't have that much control of: 1) how close I can get to my subject, and 2) how much room I have to move around to compose my shot.

I wish I were more knowledgeable in Canon or I would have a specific lens to recommend, I just personally don't think the 50mm will work with what you like to shoot. Just my $0.02.
posted by litnerd at 6:50 AM on November 23, 2011

There isn't time to implement this if you are looking to buy on Friday, but I always suggest renting lenses before buying. It gives you a chance to take a real test-drive before committing. I've had great experience renting from Borrowlenses.com. They carry most of the lenses people have suggested.
posted by ambrosia at 7:30 AM on November 23, 2011

Get a 50mm 1.8
That's one of the best lenses a $100 could buy
posted by WizKid at 9:52 AM on November 23, 2011

You people are amazing. Thanks for the clear information and advice!
posted by prior at 7:19 AM on November 25, 2011

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