Shooting Landscapes with a mirrorless camera?

I would like to get into landscape shooting. I have a Nikon d3000 and i was wondering if i got an Olympus om-d em-5 if there would be any difference other than the focal length of the lenses

The camera you mention is one of the finest in its category.
The other difference is 1. You would be spending much more than d3000
2. And you would be using a light weight system.
It is a good option.

The maths is harder, but aperture gets kind of 'cropped' too. I shoot mostly at the wide end and 2.8 behaves more like 3.5, 3.5 more like 5… And so on, sort of. Some look at this as a disadvantage because you are losing the shallower DOF, but for me I prefer to get the light advantage and still a little latitude in focus. Remember, that's just DOF not brightness.

You may find it also works the same way for you. Much landscape uses higher f stops, or stopping down to control light, it maybe a bonus too. Check out how you use aperture and consider where that would leave you.

I can certainly say there are no flies on that camera image quality wise. I spent aeons considering mirrorless, then jumped to Panasonic just before the em-5 came out, if I had my time over, etc. The glass for these cameras (Pana, Oly, Sigma and Voitlander) is very good-excellent. But you might really reap the benefits due to the more considered nature of landscape, of using adapted lenses, a real bargain too as well as quality.

I'd check out some of the groups dedicated to this camera on flickr.com, see what sort of images people are getting, maybe post your questions in the forum.

First and foremost the focal length of a lens never changes. What changes is the equivalent angle of view which is dependent on the "crop factor" of the camera being used. On your D3000 the "crop factor" is 1.5x while on the Olympus 4/3 format camera the "crop factor" is 2.0x.

So on your D3000 a 50mm lens would have the equivalent angle of view of a 75mm lens on a 35mm film camera or full-frame DSLR and on the Olympus a 50mm lens would have the equivalent angle of view of a 100mm lens on a 35mm film camera or full-frame DSLR.

Since the sensor in your D3000 is larger than a 4/3 sensor it would be the better choice for landscapes.

For landscape photography a lens wider than the 18mm end of your 18-55mm zoom would be nice although you can make some nice landscapes with 18mm. The key is in knowing how to maximize your Depth of Field. These sites will help you:

http://www.cambridgeincolour.com/...-field.htm

http://www.dofmaster.com/dofjs.html

I consider a tripod as mandatory for good landscape photography. I use ISO 100 and shoot in Aperture Priority with my camera always on my tripod when I shoot landscapes.