Mirrorless Interchangeable-Lens Camera (MILC) vs Digital SLR

May 31, 2012

There’s the thing, you are planning to purchase a new camera and breaking your head against the wall whether it will be a DSLR or Mirrorless ILC camera. Some people might have told you to go with mirrorless for many reasons that one of them is probably the size. Although DSLR cameras quickly lose market share in favor of more compact and high performing ILC cameras, still, DSLR cameras are still a better tool for many photographers who choose a DSLR for professional work.

You might ask yourself: “Why someone will actually shoot with a bulky camera?”, “Does the mirror is really necessary?”, etc. There are a lot of questions that need to be answered. In this article I want to give you the two sides of the coin and help you out making a decision.

I will separate this comparison into several subject:

  1. Introduction to Mirrorless ILC cameras
  2. Size, Look and Feel
  3. Image Quality
  4. Lens Selection, Accessories & Professional Use
  5. Final Words

1. Introduction to Mirrorless ILC

First of all, A Mirrorless camera is mainly referred to Mirrorless Interchangeable-lens camera or MILC in short. The thing is that that compact digital point-and-shoot cameras are also mirrorless, but doesn’t offer the option to change lenses.  MILC camera is also referred to as Compact System Camera (CSC), Mirrorless System Camera, Digital Single Lens Mirrorless (DSLM) and there is also Electronic Viewfinder Interchangeable Lens (EVIL), that refers to mirrorless cameras with electronic viewfinder (some mirrorless cameras are not equipped with a viewfinder).

As for the time of writing this article, there are six companies who manufactures MILC cameras: Panasonic, Olympus, Samsung, Sony, Fujifilm, Nikon and Pentax.  Yes, this list is correct, Canon is no in the least for now, but some say that they soon will be. For those who are interested in figures, I recommend reading the Mirrorless market share 2011 / 2012 article.

Without writing the whole history of mirrorless cameras, let’s looks at the most important peaces of information.

Mirrorless cameras where designed from the ground up to be digital. It was all started when Olympus and Panasonic introduced the Micro Four Thirds system and introduces the Panasonic Lumix DMC-G1 in October 2008.  Since then both Olympus and Panasonic continue to expand the Micro Four Thirds system with new cameras, Micro Four Thirds interchangeable lenses and accessories. Right now Micro Four Thirds cameras have the largest market share and are mature products that can compete against DSLR cameras in many aspects regarding camera performance (ie. image quality, AF speed, etc.).

The Mirror in reflex cameras was the one component that prevent cameras from being small and lighter and that has to be removed to help cameras manufacturers to develop new products to the new digital edge.  The mirror in reflex cameras serve an important role by transferring the light that passes through the lens towards the optical viewfinder.

Without the mirror, the photographer wouldn’t get a real-time view of the scene. Of course conventional digital cameras have long been utilizing LCD to project the image, but that solution wasn’t suitable for professional use and had many problems like: composing the shot in harsh sunlight, the size of the screen is relatively small, it has high refresh rate, etc. Enthusiast and professional photographers felt more connected to the subject that they are shooting when they view it via the OVF (Optical Viewfinder). Some people just felt ad nostalgic connection to film cameras and wanted to continue that tradition but still move up to digital.

As the technology continues to improve, more high-resolution and advanced electronic viewfinder and LCD technologies have introduced to the market. If we look at the Sony NEX-7 for example, it comes with a new Sony OLED EVF with 2.4-million dot resolution. That certainly shrink viewing experience gap between OVF and EVF, but the differences are still there.

The whole idea behind mirrorless cameras was not to create a compact camera with a large sensor. So at the final result we should looking at a compact digital camera that was built from the ground up to be digital, has a relatively large sensor for better image quality and it can support interchangeable lenses for better image quality and flexibility.

All sound very promising, and it is. The market accepted this new technology with open arms and open wallets.  Still the announcement of the first MILC camera, the Mirrorless market continues to grow and biting into sales of DSLR cameras.

MILC cameras combine some of the advantages of DSLR cameras along side the compactness, features and ease of use of point-and-shoot cameras.

The main advantages are:

  1. A relatively compact and lightweight  interchangeable lens camera
  2. Utilizes a relatively large sensor (Micro Four Thirds, APS-C)
  3. Achieve better control over depth-of-field (blur the background while keeping the subject in focus)
  4. Many (not all) MILC cameras has in-camera sensor-shift image stabilization (no need to buy special image stabilized lenses that cost more)
  5. Being able to produce smaller and lightweight lenses
  6. EVF can allow the photographer to view the exact image that he would get when pressing the shutter release button. For example, you can set White Balance (WB) and see how they look in the final image


With the new camera design there are also disadvantages, including:

  1. Some MILC cameras have a sensor smaller than APS-C (although some utilize APS-C sensors) which can result in a lower image quality compare to Full-frame DSLRs for example
  2. MILC cameras use contrast-detection based AF, which is slower than phase-detection AF. MILC companies like Olympus introduced their own implementation to the contrast-base AF, and actually make it perform faster than the top leading DSLR camera. That suggests that technology continues to improve, and the limitations of mirrorless cameras will be solved with new technology innovations
  3. The viewing experience of EVF is not on par with OVF.  EVF is a little LCD screen in the camera where the live image is streamed to
  4. Shorter battery life
  5. Some professional grade accessories might not be comfortable to use, like using a professional large Flash unit

* partial list

When we look at the disadvantages, we need to remember that for many of us this might not count. Also remember that MILC cameras are mainly targeted for those who move from point-and-shoot cameras. Of course as more “professional” models start to appear (Olympus O-MD- E-M5), more enthusiast start using MILC cameras. If I’m reading the map correctly, in a few years time the gap between DSLR cameras will shrink considerably, and with more pro bodies being released, more professionals will begin looking and even replacing their DSLR camera with a mirrorless one.

It really depends on the specific way you use your camera, what type of subjects you are shooting, under which lighting conditions, whether you need weather-sealing, how important is the portability (camera size) and so on.

I also mentioned the sensor size in this article. I”ve mentioned that in order to produce smaller and lighter cameras, a smaller sensor has to be used.  A smaller sensor and the lack of reflex mirror means that more compact lenses can be produced.  If you look at the Micro Four Thirds lens selection, you can clearly see it utilize lenses that are relatively more compact than the DSLR ones.

dslr vs mirrorless

Some Mirrorless vs DSLR lens and camera size comparison (via camerasize.com)


All in all, MILC cameras have come a long way since the introduction of the first mirrorless camera. Image quality has been improved, we have higher quality EVFs,  some comes also have weather-resistant body and MILC cameras will continue to shrink the gap from DSLR cameras.


2. Size Look and Feel

Between you and me, who wants to walk around a heavy and bulky camera? – No many. I do agree that in terms of ergonomics, sometimes it’s better to have a relatively larger camera than a more compact one. I have large hands and I prefer the Olympus O-MD E-M5 over a more compact Sony NEX-5N camera body.

digital cameras in various sizes

Mirrorless cameras alongside DSLR cameras

You can view that comparison and add or subtract more cameras using camera size comparison website.

Above image left to right: Panasonic Lumix DMC-GF5, Sony NEX-F3, Nikon D7000, Canon EOS Rebel T3i, CAnon EOS-1D C. The first two are mirrorless cameras, other three are DSLR caemras. The last one (EOS-1D C) is a full frame DSLR camera, the other two DSLR cameras have APS-C size sensor (smaller than 35mm).

In terms of look, mirrorless cameras do look compact and stylish, especially when you hold them next to DSLR cameras. Some mirrorless cameras are quite pocketable, and can easily fit into your jeans back pocket or a small bag. The thing that you need to remember is that Mirrorless Interchangeable-lens Cameras need a lens to be attached to them. They don’t come with a lens that ingests into the body and it certainly gives the camera a longer profile. That means that if you use a small pancake lens, you might be able to put the camera in your pocket, however, if you use larger lenses, you will need a small bag for this.

Some might say that it loses the whole purpose of having a compact camera in the first place, after all, if I am carrying a bag, I could also carry a DSLR instead. The thing is that you if you are planning to purchase more than one lens and carry it with you, you already need to purchase a small bag for it. It also depends which lens and other equipment you need to carry with you. If you taking just one lens, you can just grab a really small and light shoulder bag and it would be more comfortable than carrying a DSLR with one lens. In terms of portability, it really depends which and how many lenses you are going to carry with you. With more gear, you will still need a bigger bag to store the equipment.


Canon PowerShot A4000 IS and Panasonic Lumix GF5

Canon PowerShot A4000 (compact camera) IS and Panasonic Lumix GF5 (MILC)

At the above image you can see the Canon PowerShot A4000 compact point-and-shoot camera (pocketable) alongside the MILC Panasonic Lumix GF5 – not a huge difference isn’t it?


A bigger and heavier camera can stabilize a large lens much better and help reduce camera shake. Of course that is related to the weight and size of the attached lens. ILC have some lenses that aren’t that small, like telephoto-zoom lenses. Those lenses weight more and are bigger than normal or some wide angle lenses. It won’t be as easy to stabilize the lens weight if you mount a long telephoto-zoom lens on the GF5.

We can see that digital cameras like the Olympus O-MD E-M5 have the HLD-6 Battery grip as an optional accessory. This grip will give you room for extra battery, but will give you a better grip when shooting with heavier and longer lenses, especially if you have larger hands.

I always buy a grip because I have large hands. When I bought my Canon EOS 450D and the 60D, I always bought a grip with the camera too. Felt much more comfortable and I really enjoy using it.

Even with its small size, Interchangeable lens cameras have a large screen at the back, same 3-inch one that you can find on DSLR cameras. One problem with small-size cameras is that it doesn’t have enough room for many quick-access buttons. Because DSLR are larger, it’s easy to put many buttons for easy and fast access to favorite camera settings. That’s also why professional photographers prefer DSLR cameras. You can see taht even

camera buttons

Olympus E-M5 vs Nikon D7000 and Canon 7D - look at the total amount of buttons at the back of the cameras

Looking at the above image you can see that both the 7D and the D7000 have many buttons. That is used to prevent frequent access the setting via the menu system, which can take some time. For example, a professional photographer might want fast access to WB, shutter speed and ISO settings with just a press of a button, instead of diving into menus which can take quite a long time.

Because Mirrorless cameras are mostly targeted to advanced photographers rather than professionals, it’s not a big problem. I personally prefer having quick access buttons rather than going to the menu to set them, even if it’s a touch-screen user interface.

For professional photographers it’s all about catching the moment, and they don’t have time to play around with the camera. The camera is a tool that suppose to answer their professional needs.


3. Image Quality

Image quality has always been one of the reasons people bought DSLR in the first place. A larger sensor means better low noise performance and higher dynamic range. Larger sensors gathers more light and that results in a better image quality, you just can’t get around this with current technology, or do you?

High ISO Performance

Digital imaging technology has vastly improved and with it are the sensors. If back then the maximum ISO that lead to acceptable image quality was around ISO 800, now you can shoot with some DSLR cameras up to ISO204,800, and get usable shots even at ISO25600. Backside-illuminates sensors have improved the image quality for small sensors as CMOS technology improved over CCD. We are moving forward and moving very fast.

The fact is that different mirrorless cameras utilize different sensor sizes. For example, Sony NEX cameras use APS-C size sensors (~23.4 x 15.6 mm), Olympus and Panasonic Micro Four Thirds digital cameras use a Micro Four Thirds sensor (~17.3 x 13 mm), Pentax Q utilize an even smaller sensor (6.17 x 4.55 mm) and Nikon 1 cameras utilize a sensor size somewhere in between (~13.2 x 8.8).

sensor size comparison

Sensor size comparison

It was proven by many camera lab-test reviews that Mirrorless cameras with APS- C sensors (ie. Sony NEX-5N) can lead to a higher image quality overall.  The Olympus OM-D E-M5 pushes the image quality even further for the Micro 4/3, but cameras like Sony NEX-5N outperform it by probably two stops.

The thing is that cameras like the Oly E-M5 are already giving some tough competition to APS-C DSLR cameras, and cameras like the Sony NEX-5N are coming very close to the image quality produced by full frame cameras. So it’s not only the size of the sensor, but its design quality. Still Mirrorless and APS-C based cameras can match the image quality of a full frame camera (have you looked at the high-ISO image quality of the Canon EOS 5D Mark III yet or Nikon D3s?)

So by choosing to go with a MILC you make a small compromise in image quality, but mainly when it comes to high ISO performance. For some of us it’s not a reason to choose a DSLR over MILC because we don’t intend to shoot over ISO1600 anyways. Others my think it is crucial and prefer picking up a DSLR and even upgrade to FF camera in the future.


Depth of Field

Another reason and an important reason why people buy a large-sensor camera is to have better control over depth-of-field. Without getting into to much technical aspects, in short, it means that with large-sensor cameras you ca blur the background completely out of focus (in various degrees), what’s impossible to do with point-and-shoot cameras, at least not to such a high degree.

So what is it good for? – Background blur (also known as Bokeh effect) was used since the first film cameras to separate the main subject from the background. The sensor size by itself doesn’t effect DOF. There are three main factors that do effect DOF: 1) aperture opening, 2) focal length of the lens, 3) camera/sensor distance from the subject.  That means that if you take a full frame camera and point-and-shoot camera and both have the same settings (35mm equivalent), they both will result in the same DOF.  The thing is that to achieve the same 35mm equivalent focal length on P&S cameras, we are using a much smaller focal length that is multiplied by the factor of the size of the sensor (35mm = 1x multiplication, Micro Four Thirds = 2x multiplication).

Shallow depth of field

Background OUT of focus, subject IN focus

This effects is used vastly in portrait, animals and product photography, but is favorite among enthusiast and pros because it really gives another dimension to the image. The background no longer distract the viewer from the main subject. So in short, being able to have better control over depth of field can enhance your creativity as a photographer and can produce more beautiful results for certain type of photos. MILC have that in a great degree.


4. Lens Selection, Accessories & Professional Use



Let’s assume that you are looking for a professional flash for some studio work. You won’t find any strong and professional flashes like the Nikon Speedlight SB-900 or Canon Speedlite 580EX II flashes for the micro Four Thirds. Many of the mirrorless cameras don’t come with hot-shoe at all, some need a special accessory but most will use some kind of accessory port. There are more special accessories that professional must use that aren’t manufactured to MILCs.

Nikon Speedlight SB-910 flash

Nikon Speedlight SB-910 flash (I wish I could have flash like this on my Oly E-M5)

Of course that might change in time depends on the demand. It doesn’t take from the quality of the camera, but certainly helps those who need it. Even the availability for such product will be higher for DSLR cameras. Looks at Olympus PEN MILC cameras, just search for a battery grip for those cameras, you just won’t find it, maybe as a 3rd party product. Most of Canon and Nikon DSLRs do have an optional battery grip of a very high quality. We could see this trend penetrating the mirrorless market with the introduction of the Olympus OM-D E-M5 and the optional (weather-sealed) vertical battery grip.

I recommend checking out what are the available accessories that you might need, so you won’t get stuck when you need them the most.


Lens Selection

A few years ago the lens selection was one of the main concerns and reasons why enthusiast didn’t want to touch a MILC. Since then many new 3rd party manufacturers has start producing new lenses, especially for the Micro Four Thirds. MILC manufacturers have been releasing many new lenses every few months, including some fast prime lenses that was in a very high demand and still are.

Still if you buy a Canon or a Nikon DSLR you will have a wider selection of lenses, but the question that you need to ask yourself is “Am I going to take advantage of this wide selection?” or “How many lenses and which type of lenses I really need?”. Some people find themselves happy and satisfies with just one lens, other will by three (ie. telephoto-zoom, fast prime, normal zoom lenses), others will have even 10 lenses in their camera bag.

Of course it depends on your budget, photography habits and/or professional needs.  As I mentioned earlier, MILC where targeted mainly to those who move from P&S but also towards the enthusiast’s market.  People in this category might have 1-4 lenses max (I assume). When you purchase a MILC, make sure that you looks at the list of compatible lenses and see what fits you best. Some will purchase the camera with the Kit lens(es), others will trade that and add more money to buy faster and optically better lenses. Some lenses are suitable for HD movie shooting, some are better for low light, macro or sports shooting. It all depends on what you need. As for the time of writing this article,  there is a very large selection of lenses, that I’m sure that most of you will find what you need.

Olympus Micro Four Thirds  lenses
Panasonic Micro Four Thirds lenses
Sony NEX E-mount lenses
Samsung NX lenses
Nikon 1 Nikkor lenses
Fujifilm X mount lenses


Final Words

As you can see, there are cons and pros to each side of the equation. Before picking up either DSLR or MILC, make sure that you understand your needs. If you want a easy-to-use compact camera that can take gorgeous photos and videos, MILC is a great camera for beginners. The Electronic Viewfinder is something that you want to experience in first hand, because words cannot describe the experience and differences between EVF and OVF 0 and it’s not absolute, some are good others are much better.

Go to the camera store and try to mount some lenses to really feel how compact and lightweight is the combination of the too. Remember, this is not a P&S camera, and you need to purchase at least one lens so you can use your camera. Mirrorless ILC have conquered the market by storm for some good reasons. They pack a lot of features that you find in DSLR but in a more compact camera body. After all, the all idea behind those type of cameras is the relatively compact size. Having an APS-C mirrorless seems to lose the focus, but those cameras are really small, although the lenses aren’t that much smaller than DSLR’s.

The good thing is that the selection is large. Some MILC are more compact, others are larger, some have features that others don’t have, some are aimed towards advanced photographer, others will remind you a P&S experience. The thing is that I’m pretty sure that you will find what you are looking for. If you read this article to the end, it means that Interchangeable lens cameras looks like a very attractive offer to you. Spend time looking and examining some cameras, I’m sure that you will find something that fit your need. If not, there are excellent DSLR cameras out there, I am using one too.

The future looks very bright for MILC and I am sure that it will be much better in the future. Already waiting for the announcement of new camera and lenses..

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