Micro Four Thirds Explained – A Beginners Guide

Olympus EM5 Mk 3

What is micro four thirds photography? Well let’s find out shall we?

Micro four thirds explained. In this post I will explain to you exactly what micro four thirds actually is, why the system exists and how it differs from other camera systems. That is the sole purpose of this post. I am very much new to micro four thirds myself, so this is as much for my benefit as it is for yours!

By the end of this post you will have a much better understanding of the micro four thirds camera system. And so will I – this is stuff that I am learning too.

And at the end of this post you will find links to other blog posts I have written about micro four thirds photography.

Olympus OM-D EM10 Mark II

Olympus OM-D EM10 Mark II

Before I go on – who am I?

I am Rick McEvoy ABIPP, MCIOB. I am a professionally qualified photographer and also a professionally qualified construction manager. I am based in the south of England in the lovely county of Dorset.

It should come as no surprise to you that I therefore specialise in photographing buildings. That sort of makes sense.

I also photograph buildings and their surrounding environments in other places on this wonderful planet of yours. That is travel photography. And this is very relevant to micro four thirds photography.

Yes, travel photography has a lot to answer for and is the main reason I am looking into micro four thirds photography.

More on all that good stuff later.

The first part of this post is a bit technical, but I need to go through this stuff to explain micro four thirds properly. If anything in here does not make sense drop me a line and I will try to explain.

1 – What is micro four thirds?

Micro four thirds is a camera system.

The micro four thirds camera system was released by Olympus and Panasonic in 2008. Micro four thirds is the evolution of the four thirds system which was created by Olympus and Kodak in 2008.

So micro four thirds has some big names involved, Olympus, Panasonic and Kodak. This system included both DSLR and mirrorless camera bodies with a universal lens mount – you could put anyone’s lens on anyone’s body. And that is something I am struggling to get my head around!

Four thirds was created in the digital age, DSLRs are an evolution of film cameras called SLRs.

Micro four thirds is the evolution of four thirds, but without the mirror box.

The mirror box allows you to look via the viewfinder through the lens on a DSLR. Remove the mirror box and you have a mirrorless camera!

Genius I know.

Remove the mirror box though and you need something else to be able to view images.

This is where the wonderful EVF comes. EVF stands for electronic viewfinder. Once you have removed the optical viewfinder you need to replace this with something else or rely solely on the screen on the back of the camera, which is not a good idea.

The sensor in micro four thirds cameras is smaller than in APS-C and full frame cameras – more on that below.

Basically, micro four thirds cameras are smaller than other systems, but designed from the ground up in the digital age. There is no mirror but instead an EVF, and the cameras have smaller sensors.

2 – What types of cameras are there?

There are two basic groups of cameras. There are others out there, but these are the two main groups.

DSLR cameras

Digital Single Lens Reflex cameras have a mirror on top of the camera. This allows the user to look, via the mirror, through the lens at the scene being photographed. This is an evolution of film cameras, SLRs.

Mirrorless cameras

Whilst some terms in photography are confusing, mirrorless is a good term. A mirrorless camera does not have the mirror that DSLRs do.

I know – and phones.


3 – What other types of camera are there?

DSLRs and mirrorless can be further sub-divided into three further categories

  • Full frame
  • APS-C
  • Micro Four Thirds

You can, in theory, get mirrorless cameras in all these formats, but only find DSLRS in APS-C and full frame formats.

These different formats relate to the size of the sensor. Bear with me, I am nearly at micro four thirds!

What does the sensor do?

The sensor is the bit that records the photo. Think of the sensor as doing the same job that film did.

Now I know that this is a huge over simplification, but I hope you get the point.

Sensor sizes

There are here are three principal sensor sizes. There are others such as medium format and large format, as well of course as sensors in smart phones. This is about the main camera systems though.

Full frame

Full frame refers to cameras which have a sensor that is 36mm wide x 24mm high. This is the exact size that 35mm film negatives are and were back in the days before digital.

My Canon 6D is a full frame camera.


APS-C is Advanced Photo System I will not go into that in this post. The point here is that an APS-C sensor is smaller than a full frame sensor. APS-C sensors are roughly 23.5mm x 16mm.

Micro four thirds

Micro four thirds sensors are smaller again, being approximately 17.3mm x 13mm.

Like I said there are other sensor sizes and camera types, but these are the main ones.

A word on the cost of sensors

Sensors are expensive things to make. Smaller sensors are therefore cheaper to make than bigger sensors. Cameras with smaller sensors are generally cheaper than cameras with bigger sensors.

5 – What does this all mean?

Continuing with camera sensor, there is a physical implication of having these different sensor sizes. This is called the crop factor.

If we start with a standard lens, this has a focal length of 50mm. On a full frame camera 50mm means 50mm. And 50mm equates to pretty much the same field of view that we see through our eyes. A full frame camera does not have a crop factor, as the full frame is not cropped.

If you put a 50mm lens on an APS-C camera, as the sensor is smaller we have to apply what is called a crop factor. For APS-C cameras the crop factor is 1.5 (1.6 for Canon APS-C cameras). No idea why the difference.

What does this actually mean in actual English?

To explain.

You multiply the focal length of the lens by the crop factor of the sensor – 50 x 1.6 = 80.

A 50mm lens on an APS-C camera has an actual focal length of 80mm.

Let’s apply the same principle to micro four third cameras, which have a crop factor of 2, as the sensor is a quarter of the size of a full frame sensor.

The same 50mm on a micro four thirds camera is actually 100mm.

I hope that this makes sense. The implications of this are a separate subject which I am not able to cover in this post.

6 – Lenses

I have explained the crop factor. The implications of this are that you have to think about lenses a bit differently. The 2x crop factor is great for telephoto uses but means that wide angle photography needs much wider focal lengths.

I have a 12-40mm lens, which equates to 24-80mm on full frame. This is my standard lens.

Lenses for micro four thirds cameras are much smaller than for APS-C and full frame cameras.

And the quality, comparing like for like lenses is very much as good.

And they are cheaper which has to be a good thing!

And you can put a Panasonic lens on an Olympus camera! Still struggling to get my head around that!

7 – Why are there different camera systems?

Well why not? It is good to have choices. Back in the film days there were various different film sizes, and these choices have been expanded in the digital age which has to be a good thing.

Different camera types and sizes serve the differing needs of different photographers.

A sports photographer has different from needs from a landscape photographer for example – they will probably use completely different gear.

8 – Are the different camera systems interchangeable

In general terms no. This is because the lenses are designed for the specific sensor sizes. This is a matter of optics and science. Not to be messed with!

9 – Who makes micro four thirds cameras

Olympus and Panasonic are the main makers of micro four thirds cameras. According to Wikipedia you can also get micro four thirds camera bodies from Blackmagic, DJI, JVC, Kodak, Sharp Corporation and Xiaomi. I have never heard of some of these companies to be honest.

10 – Why doesn’t anyone else make micro four thirds cameras?

I am not sure. I guess that companies who produce APS-C cameras are happy with that as the smaller format. These companies include Canon, Nikon, Fujifilm, Pentax and Sony.

11 – Why should I choose micro four thirds?

Personally, I have invested in an Olympus micro four thirds camera system for my travel photography work, and also for personal work in the UK.

My micro four thirds camera and lens combination is much smaller and lighter than my Canon gear.

And I love using it.

12 – What cameras and lenses do I use

I use a full frame Canon 6D with Canon 17-40, 24-105 and 70-200mm lenses.

I have recently bought an Olympus OM-D EM10 Mk 2, and now have Olympus 12-24, 14-42 and 40-150mm lenses.

I have more telephoto range on the micro four thirds system, but less wide-angle capabilities.

This is deliberate – I am going to use the Olympus for travel and personal photography but continue to use my Canon gear for commercial work. I need the width for interior shots of buildings, which is less of an issue with travel and personal work. Sure, I would love the Olympus 7-14mm lens, but that is one for another time.

13- Are the results as good as with my full frame camera?

Yes. I did an architectural shoot recently where I took photos with both my Canon 6D and my Olympus camera. I used the same camera settings and compositions and took each shot with both cameras.

I used the Olympus 12-40mm F2.8 Pro lens pitched against the Canon 17-40mm F4 L lens.

I imported both sets of images into Lightroom, processed them the same (virtually) and could I tell the difference?

Arnewood School photographed with my Olympus OM-D EM10 Mark II

Arnewood School photographed with my Olympus OM-D EM10 Mark II

My client did not notice that this set of images was taken with a different camera!

So, the answer to the question is yes!

If you are making large prints you will lose detail in an image taken on a micro four thirds camera before you do with the same image taken using a full frame DSLR, but who really does that?

Most of my work only ever sees the internet these days. The only time I got prints done was for my portfolio review with the BIPP.

So, is the small sensor really a concern?

Technically yes – in reality no.

14 – Can I shoot video with micro four thirds cameras?

Yes of course, although I have not tried this yet. I barely shoot video with my Canon 6D to be fair. I tend to do all my videos on my iPhone as the connectivity is obviously incredible.

15 – How much do micro four thirds systems cost?

Prices are constantly changing, but micro four thirds cameras and lenses are generally cheaper than their equivalent APS-C and full frame lenses.

There is a great website that I always go to called Camera Price Buster – check out their website and see how the prices stack up.

16 – Can I really fit a micro four thirds camera in my pocket?

Yes, I can. My OM-D EM10 with 14-42mm lens actually fit in my coat pocket which is very cool.

I cannot however fit my EM10 into my pocket with the 12-40mm Pro lens though.

So yes and no.

17 – What is the future of micro four thirds photography

Now that is a question that is a separate post all on its own. For me it is travel photography and personal photography.

18 – Will I use micro four thirds for my commercial architectural photography work?

Maybe. Not yet but maybe in the future.

If I do I will have to buy the Olympus 7-14mm lens, which will give me 14-28mm in full frame terminology. Which is 3mm wider than I currently have.

And 3mm at the wide end of things is massive, much less so at the telephoto end of the scale.

I did try the Panasonic 7-14mm lens but had problems with purple lens flare so had to return it to the shop.

19 – Do you want to see some of the images taken with my micro four thirds camera?

I have a micro four thirds gallery on my website, which I am adding to regularly. Check out this page and please keep checking back to see the new stuff that I hope to share every week.

20 – Other reading

As you have got this far down you might be interested in some other posts on my blog about micro four thirds photography.

My Micro Four Thirds Travel Kit – Travelling Light In Style

Micro 4/3 Architecture Photography – is this a viable option?

Professional photographers who use micro four thirds – really?

21 – Final thoughts

If you are looking to get into photography or want to upgrade from your phone to an actual camera micro four thirds is not a bad place to start. The cameras are generally smaller and lighter and cheaper.

The image quality is excellent – as I have said no one will know that you did not use a full frame fancy expensive DSLR when they look at your photos – trust me I have proved this with a client which was interesting.

Don’t believe all the negativity in the press – sure there are technical reasons to not use micro four thirds but there are so many positives.


I have enjoyed researching the background to the micro four thirds camera system. This is the continuation of my brave new works of actually researching things and learning them properly rather than just buying some gear and going off and using it.

I am enjoying my dive into micro four thirds photography and some of the things that my Olympus OM-D EM10 gives me.

Please get in touch with any questions you may have, and also please join me on my blog next Tuesday afternoon.

No, not Monday – check out yesterdays post if you want to know more!

Rick McEvoy Photography – photographer, blogger, website creator

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Id like to see you fit my GH5 and a 14-60 lens into your pocket !!!

Rick McEvoy

I am Rick McEvoy, an architectural and construction photographer living and working in the South of England. I create high quality architectural photography and construction photography imagery of the built environment for architects and commercial clients. I do not photograph weddings, families, small people or pets - anything that is alive, moves or might not do as I ask!! I am also the creator of the Photography Explained Podcast, available on all major podcast providers. I have a blog on my website where I write about my work and photography stuff. Rick McEvoy ABIPP, MCIOB

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