Architect1776 Loc: In my mind

M4/3 cameras are excellent cameras and are more compact all around because of the smaller sensor. Thus a 200mm lens view on a FF camera looks like a 400mm lens on a M4/3 camera.
Not just a good starter camera but a good keeper system even when doing professional work.

William Royer Loc: Kansas

After many years of shooting Nikon FF, I moved all my digital gear to Olympus. Am extremely pleased that I did. IQ is great. A lot is made of having less bokeh due to the M4/3 greater DOF. I look at that in reverse. Bokeh can be achieved in a number of ways — distance to subject, focal length, subject distance from background, etc. But, in a lower light situation ; like indoor receptions or street photography where flash not used) the main issue often is getting enough light. When shooting FF with a ‘fast’ lens in a situation where I needed more light capture, if I opened aperture to its max (say 1.4) yes I got more light. But often I didn’t get enough DOF for the picture. So, I had to stop back down. On a M4/3, I can open to max aperture (maybe 1.2), get enough light, and still get the DOF required in that case.

mflowe Loc: Port Deposit, MD

Re: A M43 lens that is stamped 50mm has a 35mm format equivalent focal length of 100mm. Yes, but it's still a 50mm lens, so he's correct in that regard.

Architect1776 Loc: In my mind

camerapapi Loc: Miami, Fl.

Choosing a camera is a very subjective decision. If you have a nearby camera store it is in your best interest to go there for good advise and you can hold more than one model in your hands and see if one of the cameras has the ergonomics and features you feel comfortable with.
Understand that "full frame" is a term that has become popular meaning that the sensor has the same dimensions a 35mm film camera has. If you use a lens designed for use with a camera sporting an APS sensor, most often called "cropped sensor" the lens will cover the whole sensor.

Among mirrorless cameras, cameras made smaller because they lack the mirror mechanism, Olympus and Panasonic use what is called the micro fourth third sensor. The sensor is smaller than the APS sensor in "cropped cameras." The quality of the camera and their lenses are superb to the point that today many professionals are using those cameras. I am no professional and I use Olympus bodies with lenses made by Olympus and Panasonic. I use the same OM-10 Mk II camera that Linda from Maine uses and I could not be any happier. I also use the Pen EP-5 with an external viewfinder, an older camera but with excellent ergonomics that goes with me anywhere and it is great for traveling. Both cameras are very capable and enlargements of their files have not been a problem showing excellent details and resolution.

Sony, Nikon, Canon and Fuji also make excellent mirrorless cameras. I am sure that if you want to go mirrorless one of them will fit your style and photographic needs. No need to go brand new unless you want to spend your money.
The following shot was made around my neighborhood with my Olympus Pen EP-5 using their Zuiko 12-40 f2.8 Pro lens under a light rain. The original is even better.

There is plenty of information about mirrorless cameras here and in the Web. A Google search should give you all the information you need.

(Download)

mizzee Loc: Boston,Ma

Definitely worth it! I adore my Olympus e-m5 Mark III and the II before it. I’m taking better images than I did with my Nikons, the lighter weight means I take my camera with me way more often, the cameras are weather sealed, the internal stabilization is industry leading, and I can afford a broad range of lenses. What’s not to love? I even get compliments on its looks! If that weren’t enough, I can fit my 75-300 (150-600 FF equivalent) into to a hobo bag with a camera insert.

Dossile

I have used a Panasonic 4/3 since they came out. It is my foreign travel and hiking camera. At home or when traveling by car I shoot a D850. The D850 with lenses is pretty heavy to carry walking 10 miles on cobblestones and in museums. We travel with carry on luggage only and the D850’s bulk with lenses is also difficult for a 10 day trip.

I recently bought a Panasonic GX9, but am selling it and bought the G9. The GX9 takes great images, is small, extremely light and is one of the best travel and street cameras out there. The G9 is a slightly bigger camera, fits my hands better and has a few features that I wanted like a high quality view finder, a port for a remote shutter release and it is legitimately weather sealed. It weighs a few ounces more than the GX9 and adds about 3/4 inches to the width. For me, sports and birding are not the 4/3 camera’s forte’, but for everything else, the format is wonderful.

This image was taken 8 years ago in Paris with a 16 MP 4/3 sensor and has been enlarged nicely for a friend to 16X20. The lens used was not a particularly good one, but I still like the sharpness. The newer sensors are 20 MP and the newer lenses, like the Leica 12-60 f2.8-4, are much sharper. The 4/3 are a fun camera to shoot. Easy to carry, image stabilized, with multiple sharp, light lenses, with the downside of a shorter battery life and the diminished capability of sharp poster sized prints versus full frame.

billnikon Loc: Pennsylvania/Ohio/Florida/Maui/Oregon/Vermont

Here you go, everything you need to know about sensor size comparisons.
https://www.bing.com/images/search?q=full+frame%2c+cropped+sensor%2c+four+thirds+camera+sensor+comparison&qpvt=full+frame%2c+cropped+sensor%2c+four+thirds+camera+sensor+comparison&FORM=IGRE

And yes, a professional photographer is a person who makes the majority of there money from photography. Your question begs the fact that you are not even close to being ready to make the majority of your money from photography.
With that said I would suggest a full frame camera, like a Nikon D850, Nikon D750, Sony a9, or similar Canon product.

bleirer

He was correct in pointing out a that a 50mm lens has the same image circle no matter which sensor is involved, any any extra reach is due to cropping.

rstrick2 Loc: Beverly Hills, FL

after a lot of research and many hours watching videos, I decided to buy the Lumix G9 camera with a 100-400 Panasonic Leica lens. There are so many features and modes that is a little hard to understand at first. one of the features is the camera is the burst, pre and post burst. some others are high res photo, 4/6K photo and 4/6kk video. even though the sensor is small you are capable of getting quality photos and video out of it. The biggest advantage to this micro 4/3 is the weight, the camera and lenses are significant lighter.
here is a review of the camera https://www.forbes.com/sites/davidphelan/2017/11/12/panasonics-new-lumix-g9-super-fast-wildlife-friendly-camera-hands-on-review-price-release-date/#3ea546ed7d4b

RichardSM Loc: Back in Texas

Thank you.

joer Loc: Colorado/Illinois

M4/3 is smaller than APS-C and has a crop factor of 2, so a 300mm lens becomes equivalent to 600mm. It's ideal if you want to get into bird and wildlife photography without the huge price tag, size and weight.

Olympus and Panasonic have a wide range of cameras and lenses and lead the pack in computation imaging.

Because of the small sensor size they don't provide as much large imaging/printing or cropping as the larger formats, but its more than adequate even for professional work.

burkphoto Loc: High Point, NC

Do not confuse the current MICRO 4/3 format with the very old, obsolete Olympus 4/3 format. The sensor size is the same, but the lenses have different mounts.

That said:

If 35mm film exposed area = “full frame,” then APS-C is “half frame,” and Micro 4/3 is “quarter frame.”

These formats have different uses. Micro 4/3 is great for travel, general photography, and video.

Over 110 lenses are available to fit BOTH Panasonic Lumix and Olympus bodies.

There are generally three types per brand. The compact “fashion and travel” bodies are small, light, inexpensive, and limited. The midrange bodies are more expensive, but very well equipped. The pro bodies have the latest technologies and best performance.

I’d start in the middle. Look at the Panasonic Lumix G95, and the Olympus OM-D E-M5 Mark III.

The chief advantage of Micro 4/3 is the overall system weight. It can be 1/4 to 1/3 of a full frame kit of “equivalent” gear.

The chief disadvantage is that low light sensitivity is two f/stops lower than full frame, and one stop lower than APS-C, on average, for the same megapixel count sensors.

Lenses are HALF the focal lengths of full frame for the same fields of view. Depth of field on m43, at the same distance and FOV is, therefore, “two stops deeper” at the same aperture. This is a disadvantage in some cases, and a big advantage in others.

I hope that helps. Go to http://www.dpreview.com ...and search for Micro 4/3 cameras. They’re all there.

burkphoto Loc: High Point, NC

Micro 4/3 lenses are engineered precisely for Micro 4/3. The sensor crops nothing significant from the image projected by native glass.

http://wrotniak.net/photo/m43/lenses.html

You only get a crop if you adapt full frame lenses to m43 (or mount them on APS-C bodies). As I’ve done that (full frame to m43), I’ll caution that for many reasons, it is not a great idea. Buy lenses engineered for your camera format, regardless what you use. You’ll be very glad you did! you’re get better performance, native features, full EXIF data, firmware upgrade ability...

If you have full frame Canon EF dSLR lenses, they adapt well to EOS R mirrorless cameras. Nikon full frame G dSLR lenses generally adapt well to Nikon Z mirrorless cameras.

burkphoto Loc: High Point, NC

A good Micro 4/3 midrange camera should outperform your 70D, mainly due to the difference in age of the sensors. I’d consider trading the 70D kit at some point. I know I would do that. As good as the 70D is, the design is seven years old. That’s retirement age in camera years!