sensor size - Is there a noticeable difference in image quality between Micro Four Thirds and APS-C entry-level DSLR cameras?

I am thinking about either buying a Nikon d3400 (APS-C or an Olympus OM-D EM-10 mkii (M4/3).

In principle I would prefer the Olympus, as it is much smaller and could fit in a jacket pocket. However I am concerned this lack of size may come at the cost of image quality due to the smaller sensor size. So how noticeable would the difference be?

Answer

I'm sure you've heard the old saying, "The best camera is the one you have with you."

Some of my favorite photos are shots I've taken with my three-year-old Samsung Galaxy Note 4, a phone with a decent camera but not a spectacular one. But it's in my pocket all the time, and when there is only a moment to grab a shot, there it is.

You can certainly get some fine shots with a Micro 4/3 camera. Here's one I like:

Pumpkin Brownie

(Olympus E-P5, Olympus 75mm f/1.8 lens, crop of JPEG straight from the camera.)

One thing I would ask yourself, especially for mountaineering, is what kinds of lenses you plan to carry. Do you plan to bring several prime lenses, or just one zoom or two? Even more than the sensor, the glass is what will make the difference.

And what's your tolerance for extra bulk and weight vs. convenience and light weight?

One nice thing with Micro 4/3 is some of the specialty lenses you can get for it that are both light and compact and inexpensive too. The Olympus 60mm macro is a real treat to use, as is the Samyang fisheye (also sold under a few other names; mine is Rokinon) that sells for less than $300.

I would even consider going a notch smaller. You can get some very nice compact cameras like the little Fujis or Sony RX100 series that fit into a tiny case and take great photos. I have an RX100M2 that I use a lot - great little camera with a not so great menu system. For example you have to dig around to get to the place down in the menu where you can aim the camera at a gray card and shoot it to set the white balance - something I do all the time.

You may want to try renting some equipment so you can really give it a good workout and see how you like it. BorrowLenses.com and LensRentals.com are a couple of reputable rental outfits (they do rent cameras as well as lenses).