Photo Tips #3 : Which Camera? (Part 3)

Posted on Saturday 10 September 2011

So far I’ve posted about Compact Cameras, Superzooms, and Micro Four Thirds. Now it’s onto the big boys – the DSLRs. This is what most people think of when they consider a serious or professional-style camera, and while the top end models are still priced for the Pro only, there are now many much more affordable options.

Nikon D300s DSLR

So what exactly makes a camera a DSLR? Well it’s all in the name. The “D” obviously stands for Digital, whilst the “SLR” bit is “Single Lens Reflex“. That means that there’s a single lens on the camera, and it’s used both for lining up the shot (with the viewfinder) and actually taking the photo. The “Reflex” part of the name is referring to the fact that in order to accomplish this there needs to be a mechanism to move the light beam inside the camera between the viewfinder (at the top of the camera body) and the sensor (which is located directly behind the lens) when you take a shot. Usually this is a mirror, and it’s this mechanism that accounts for a large part of the bulk of the camera, and indeed that distinctive sound when you press the button.

SLR cross section
A Cross Section View of an SLR

This diagram is a cross section view of a DSLR. Notice the lens (1) and the mirror (2) which can direct light between the sensor (4) and the viewfinder (8) depending on whether it’s dropped down, as shown here, or pushed up horizontally (5). The big blue blob (7) is called the pentaprism, and it’s a solid piece of glass which flips the image around so it’s in the correct orientation for looking through the viewfinder. It’s directly behind the “Nikon” logo on the photo above, and accounts for the distinctive bulge on the top of all DSLRs.

Why go to all this bother? Why not just use a separate viewfinder like many compacts? There are a number of issues with this approach. Obviously the whole point of a viewfinder is to let you see what the photo is going to look like – what’s in the picture and what isn’t (called “framing”). Having the viewfinder to the side of or above the main lens will always show you a view slightly offset from the real image – not a big deal for shots such as landscapes but awful if you’re taking something close up. Furthermore, for a camera with interchangeable lenses you’d need equivalent interchangeable viewfinders to replicate the zoom factor of each lens, and that’s pretty impractical.

Another approach to getting rid of the bulk and complexity of a traditional Reflex design is to use an LCD screen hooked up to the sensor as the viewfinder. This approach is very commonly used these days in Compacts, Superzooms and Micro Four Thirds cameras, but many people (myself included) find an LCD screen to be a poor substitute for a real optical viewfinder when it comes to checking lighting, color and focus. Many modern DSLRs do allow for the rear LCD screen to be used as an additional viewfinder (Canon call this “LiveView” for instance) but we’re unlikely to see the death of the optical viewfinder any time soon.

Size Matters

There is reason to this madness though, and the biggest reason DSLRs are the choice of most serious amateurs and professionals is simply image quality. That same large size allows for large lenses and large sensors, and those are both key. Large lenses allow more light though them, and that means better low light performance as well as faster shutter speeds – which equates to the ability to freeze fast moving objects. Larger lenses are also less likely to distort the image (I’ll talk about distortion in more detail in a later post), meaning Great Aunt Mildred won’t look quite so wide when she stands at the edge of the family photo!

Sensor Sizes
Common Sensor Sizes – courtesy Moxfyre (Wikipedia)

The sensor is the part of the camera which actually turns the light into data, and it’s size is also very significant. Most compact cameras have sensors around 5mm wide (smaller than your smallest finger nail!) – compared to the common APS-C size used in many DSLRs which is around 27mm wide. That’s around 15x more area, and that makes a huge difference. The reason is how a sensor works – you can think of them as a tiny grid with millions of individual little buckets which photons (light) are collected in. For the same number of buckets on a larger grid, they can obviously be larger and further apart than on a smaller grid. Bad things happen when those buckets overflow, so that extra space makes for lower noise and higher dynamic range. This is, as an aside, why I was warning you about buying compact cameras with too many megapixels earlier – the more buckets you try to cram onto that tiny compact sensor the worse the problem gets.

When choosing a DSLR one of the things you’ll hear about is “crop factor”, which is another way of talking about sensor size. However, all models aimed at non-professionals (e.g. Canon Rebel/600D or Nikon D3100) use the same size – APS-C, so there’s not really much to think about. So-called “full frame” cameras which use a 35mm sensor (such as the Nikon D3S) are considerably more expensive, and in some ways are actually less desirable for many users.


This is a big topic, but it’s worth mentioning that video is a big feature of recent DSLR models, and in fact the combination of extremely high quality lenses and large sensors leads to some truly stunning results. Many movies and TV shows are now shot using Nikon and Canon DSLRs instead of traditional movie or video cameras.

Selecting a DSLR

The first question is budget – these things aren’t cheap, and don’t think you’re done when you’ve bought the camera. A decent entry-level DSLR is typically around $600 (these are US prices, they’re typically a little higher in Europe and elsewhere), and this will come with an included lens. Some people will say that included “kit” lens is junk, and compared to most lenses they’re correct – but it’s something to get started with. The “semi-pro” models come in between $1000 and $2000, and then the pro level goes up from there to around $5000. If you have a budget of (say) $1000, I’d aim to spend maybe $600-700 on the camera body, and keep the rest for a lens upgrade. You’re paying a lot (in terms of money and weight) for the ability to change the lens – you might as well use it! Looking at my current kit, I probably have 2 to 3 times as much money invested in lenses as actual camera bodies, and for many photographers it’s a higher number than that. You don’t need to buy them all at once (and shouldn’t – take time to decide what you need) – but you really shouldn’t rely on that kit lens any longer than you have to. Stay tuned for an article on lenses coming soon!

So now you know how much you’re spending – how about a brand? Well it’s really simple here: Canon or Nikon, pick one. That’s not to say there aren’t other manufacturers putting out perfectly good cameras (Olympus, Sony, Pentax, and so on) but when you’re starting out you’re not really choosing a single camera – you’re choosing every camera and lens you’re ever going to buy. This is because once you’ve spent thousands on a set of lenses, flashes, and other accessories it’s going to be very hard to get up and switch to a new brand as basically nothing is compatible.

Both Canon and Nikon have a great legacy of producing excellent equipment, and they have huge ranges of cameras and lenses, guaranteeing that as you grow in the hobby you’ll always be able to find what you need. To be honest which of those you choose is not as important – most pro sports photographers use Canon because of their excellent long range lenses, and Nikon are probably more popular for portraits etc. But until you reach the pro levels (and even then in many cases) they’re really equally good.



  • Fantastic image quality
  • Extremely flexible controls
  • Interchangeable lenses for nearly infinite options
  • Better viewfinder
  • Longer battery life
  • Shorter time to take a shot and faster high speed shooting – better to catch that perfect moment


  • Size
  • Cost

What Matters?

  • The bigger sensor allows for more pixels, so look for 16 megapixels or more
  • Low light performance is much improved in recent models – look for something which has low noise at high ISO settings
  • Many DSLRs use Compact Flash memory cards instead of the smaller SD Card format. If you have a lot of SD cards already, you might want to pick one which takes them.
  • Pick either Canon or Nikon unless you have a very good reason not to!
  • Remember the kit lens is rarely very good, either plan to buy a new lens soon or even better buy the camera “body only” and choose a good lens to go with it
  • If you want to shoot video look for at least 720p at 24/30fps, 1080p is better
  • Don’t forget a decent case/bag, memory card, spare battery and maybe tripod and flash

You Should Buy One If…

  • You want to experiment with creative photography as a hobby
  • You have any plans to try and make money from photography
  • You value image quality highly
  • You have a requirement for specialist lenses or other accessories


    September 11, 2011 | 5:41 am

    Looking good, and sounds like I’m on the right track! Looking forward to the next blog on lenses, as i’m looking at buying some more.


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