Tips & Tricks: Lenses Part 1

I was going to do a post on Depth of Field because I get asked about that more than anything else but then I thought that might be jumping the gun a bit and perhaps I should cover off some of the gear basics first.

My camera bag is neither big, full or fancy.  (check out the FAQs section for a current complete list of gear that I use)  And that’s ok.  One of the things I wanted to focus on was how to take great photos without breaking the bank.  So today, I’m going to talk about lenses.  Don’t worry, if you use a point and shoot you can still learn something here!

I shoot about 90% of my food shots with the Canon 50mm 1.8 prime lens (shown on the left).  It is… a great lens.  And it retails for about $120 CDN/$110 USD.  If you own a Canon DSLR, this lens should be in your bag.  It’s small, light, and what we call “fast” hehe.

Fast Lenses

When photographers talk about “fast” lenses they are referring to the maximum aperture (light opening) size of the lens.  The smaller the f-stop a lens has (the 1.8 number) the larger the aperture size it has.  The larger the aperture, the more light it can let in, thereby giving you a faster shutter speed in low light conditions (shutter speed is the amount of time the lens is open when you click the shutter.  The less time it’s open, the faster it is.).

Have you ever noticed how when you take a photo in dim light, it often looks blurry?  The reason is because in order to capture the scene as you see it, the shutter needs to be open longer to allow more light in.  So you have what’s called a “slow” shutter speed.  The problem is, while 1/20th of a second might sound very fast to you, it’s actually very slow.  It is virtually impossible for the human hand to stay steady for more than 1/30th of a second while holding a camera and clicking the shutter.  Some even say you need a shutter speed of 1/60th to stay steady. So when you have a slow shutter speed, you introduce handheld camera shake into the photo and you get a blurry shot.

Lenses with Image Stabilization (IS) help… to a degree.  But even so taking a shot with a shutter speed slower than 1/30th really requires a tripod.  (Although, I confess I often try to get away with it because I’m too lazy to carry a tripod around all the time… but every time I get the photo up on the computer, the screen tells me that I was only kidding myself… sigh)  Where that small f-stop number helps is it means you’ll be able to shave off valuable 10ths of a second from your shutter speed in a dim light situation, and hopefully get a clearer shot.

There is a flip side to using a very small f-stop.  While you will get more light and a faster shutter speed, you will also get a much larger part of the image that isn’t in focus.  Sometimes, that’s exactly what you want (and often do want when shooting food).  And that’s where we get into a Depth of Field discussion, which I will leave for another day.

Prime Lenses

The 50mm I use is also known as a prime lens or a fixed focal length lens (FFL).  This lens has a focal length of 50mm.  A 70-300mm zoom lens has a focal length that ranges from 70mm t0 300mm.  Virutally all point and shoot cameras use a zoom lens.  Essentially, without getting all technical, using a prime lens means I can’t zoom in and out.  If I want things to look closer, I have to walk closer to them.  If I want them to appear further away, I have to walk further away!

You might wonder why a person would choose to shoot with a lens that, in some ways, seems very limiting compared to a zoom lens.  There are lots of reasons.  Primes tend to be lighter and smaller making them easier to handle and carry.  They also tend to be higher quality glass and less expensive (fewer moving parts).  A prime will often give you a much sharper image than a zoom set at the same focal length.  They are also, generally, faster lenses, as I discussed above.  These are generalizations but if you stick with a manufacturer known for their lens technology, like Canon or Nikon, it’s usually a safe bet.

Point & Shoot Cameras

Most of what I’ve talked about here can be applied to a point and shoot camera.  Point and Shoots use a zoom lens instead of a prime but if you want to learn more about your lens, take a look at the front of it.

You will see something like:

5.9 – 17.9mm 1:3.2-5.8

This can be a bit confusing because the focal length (5.9 – 17.9mm) in point and shoot cameras is very different than a DSLR because they use much smaller sensors than DSLRs do.  The principals are the same though.

The aperture size is still there (3.2-5.8) and as you can see, unlike the 1.8 on my 50mm lens, this one has a range.  That’s a characteristic of a zoom lens, which I’ll talk about in my next post.  The aperture number changes depending on how far the lens is zoomed in.  But for the purposes of this post, you can see that 3.8 is the smallest f-stop (or largest aperture opening) the lens can have.  It might not sound like a big difference compared to 1.8 but it’s actually a huge difference.  This is one way that a DSLR with a fast lens can really outshine a point and shoot.  But understanding this can make a big difference to how you approach a shot with your P&S!

Next time I’ll talk more about zoom lenses and THEN we’ll get into some tips and tricks for learning how to use some of the things I’ve talked about here to make your photos pop more!