This is a question that I get asked all the time and I never have a simple or straight forward answer for. I always end up asking more questions than the person asking me!
What is your budget? I’ve bought some old manual lenses for old film cameras for $15.00 and they work great on my new digital cameras as long as I shoot in full manual mode. There are also many lenses that are thousands of dollars. Most new autofocus lenses are a couple hundred dollars; so if you are not planning on spending that much, you might want to save up a little more unless you are comfortable shooting on manual exposure mode and manual focusing.
What will you be using it for? I categorize lenses into 4 categories. Portraits/low light. Sports/wildlife. Wide angle/landscape. All around zoom lenses.
Portrait/Low light. I put portraits and low light lenses in the same category because most people want nice “bokeh” or a blurred background when shooting portraits and a big aperture helps with decreasing your depth of field and giving you nice bokeh. A big aperture also helps in low light because it captures more light than a smaller aperture. Here is an example of a nice blurred background caused by using a big aperture compared to using a much smaller aperture (reminder, a BIGGER number means a SMALLER aperture)
The most popular portrait lens is the 50mm F/1.8. With an aperture of 1.8 this lens has a nice smooth background. I also have an 85mm F/1.4 which has an EXTREMELY shallow depth of field. Remember that the more zoomed in you are, the shallower your depth of field is also.
Drawbacks of big aperture lenses- Neither one of the lenses listed above can zoom, but that is alright for portraits because usually you can move closer to the subject. If you want a nice zoom lens with a big aperture such as F/2.8 be prepared to spend over $1000.00. The Nikon 70-200mm F/2.8 is over $2000.00. That lens is often used for weddings to get nice bokeh without having to get distracting close to the bridal party. You may have noticed that 70-200 does not have that much range, that is because it has such a big aperture. Big aperture lenses don’t cover much focal length so be prepared to switch lenses while shooting weddings.
So if you are looking for a portrait lens or a lens to use in low light. Look at the 50mm F/1.8. It is only around $100.00 for Nikon and Canon and it is great for portraits. Other options are the 35mm and the 85mm both at F/1.8. They are usually around $300.00. Want a lens with a big aperture that can also zoom? Nikon has a 24-70 and a 70-200 both at F/2.8 but they are well over $1000.00! All of these lenses also work great for low light because of their big apertures.
Sports and wildlife lens- These lenses are known for having a large focal length. Most of the time a sports or wildlife lens is anywhere from 200mm to 500mm or bigger. These lenses are used to zoom in far so you do not have to disturb wildlife to walk out onto the playing field. Since the majority of the time you will be outside and since you will already have a shallow depth of field because of the long focal length, you do not need a big aperture. Nikons 70-300 lens has an aperture ranging from F/3.5 to F/5.6. Nikon also has many very large and expensive fixed focal length telephoto lenses such as the 500mm F/4. A cheap telephoto is Nikons 55-200. If you want a little more range and better glass,look at the 70-300.
The drawback of these lenses is that they do not work so well in low light or indoors in general. If you wanted to take a picture with a 300mm lens, you and the subject couldn’t even fit in the same room unless you just wanted a picture of just their eyeball.
Wide angle and landscape- These lenses are the least popular because most zoom lenses are pretty wide and super wide angles are not usually needed. These lenses are used most often for landscape and architecture. These lenses allow you to take a picture of an entire room from the doorway or an entire building from the sidewalk right outside. These lenses are so wide that you sometimes shoot your feet! Most standard kit lenses zoom out to 18mm which is already pretty wide and sufficient for most everyone. There are some super wide lenses such as an 8mm that allow you to see 180 degrees. My favorite is the 14mm F/2.8. This lens has a big aperture and is really wide so I can shoot an entire bridal party from the front row. You usually don’t need a big aperture with a wide angle lens because you want a large depth of field to capture landscape and architecture.
The only drawbacks of this lens are obvious, you don’t use it for a whole lot of things and most kit lenses are plenty wide for the average photographer.
All around zooms- These lenses are the most popular of all lenses. They have a very wide zoom range. Some popular zoom lenses are 18-55 and the 18-105. These lenses are for people who don’t want to bother changing lenses or don’t have time to. I use my 18-270 during weddings to get a variety of shots from very wide angles of the entire bridal party to a close up of the rings. These lenses are convenient and easy.
There is also many drawbacks to these zoom lenses. The most obvious and common is the small aperture. My 18-270 lens can only go as big as F/6.3 at 270mm which is extremely small. I have to use a flash or a very high ISO when shooting indoors. Because of the small aperture, the depth of field is bigger, which means the bokeh is not as good and the background is more distracting for portraits. Another drawback is these lenses usually aren’t as sharp and they have more problems with the glass such as vignetteing and chromatic aberration. For these reasons, they don’t make good portrait lenses and are better suited for outdoor use such as sports or wildlife.
This is a best lens for the common photographer. It has a wide zoom range which means you can survive with only one les. They are also cheaper and more widely available.
Other things to think about-
Some more things to think about are overlap, which means, do you already have a lens covering that focal length?? If you have the 55-200mm I would not get the 70-300mm just for the extra 100mm. You would have about 200mm of overlap. It doesn’t make sense financially or when trying to carry it all around. If you have a 18-55 the 55-200 would be a great choice because there is no overlap. Overlap is ok of you are getting a portrait lens such as the 50mF/1.8. You would use your 18-55 or 18-105 for pretty much everything except portraits.
What about off brand lenses or old manual focus lenses?? I have quite a few off brand lenses. Off brand lenses are almost always cheaper than name brands. My 18-270 is one of my favorite all around zoom lenses but it is a tamron lens. I got this lens because it was sharper and covered more focal length than the Nikon 18-200. My lens is autofocus and has VR just like Nikon’s lenses. Some off-brand lenses do not autofocus, which means you much focus it by turning the focus ring on the lens. Some older lenses (even old Nikons) do not autofocus and some will not even work on cameras unless its exposure mode is set to manual. Since I shoot in manual all the time anyway and I don’t mind manually focusing, off brand lenses are a great value because they are cheaper (sometimes 75% cheaper!) My 14mm lens is made by Samyang (Japanese company; Nikon also makes their lenses in Japan) was about $300.00. I have to shoot on manual exposer (which I do already) and I have to manual focus but Nikon’s 14mm lens is $1700.00… Autofocus is not worth $1400.00to me.
Something to watch out for is a lot of off brand lenses are not as sharp or clear. You really have to do your research and look at reviews to make sure that the lens is good. The 14mm I have is actually sharper than Nikon’s lens but many lenses are not. I have a vivitar 70-210mm that I got for $15.00 and it is extremely blurry. I would never use it for portraits but it is a fun and cheap telephoto lens.
You must also make sure that the lens will fit your camera. Sigma and Tamron are two popular third party lens manufacturers. They make lenses for Nikon, Canon, Sony, Olympus, Pentax, and more. You have to make sure that the lens you are buying is made for your camera brand.
With hundreds of different lenses and hundreds of different brands, it is hard to choose which of the thousands of lenses to buy.