Panasonic makes a compact & light 45–200/4.5–5.6 for m43 that would fit the bill. Optical performance is in the meh (wide open) to decent (f/8–11) range. Olympus' 50–200mm is truly excellent but also larger & heavier. I'd travel with the Panasonic unless taking long-reach pics were the reason for the trip.
It's a dilemma. High quality long-reach lenses are neither compact nor light. For most of my pic-taking life I've stayed away from the long stuff, either out of necessity (with rangefinder cameras, discounting the Visoflex rabbit hole) or by choice. When I did go through a bout of "long lens fever" with the coming of D-SLRs I ended up doing a number nerve-wise on my neck/right shoulder/arm. Anyway, I see the A7(r) as best-suited to the 35mm-format focal length range I've mostly prefered...and if I'm honest where I see best: 200mm tops, with a 1.4x TC on hand just in case. This is in line, I think, with what BJL is saying.
A question for folks who have an A7 or A7r: does the camera offer aspect ratios other than 3:2 and 16:9? (It should since this is trivial to implement with an EVF.) Even though I've used 3:2 for most of my pic-taking I really do prefer 4:3 or even 5:4.
I'm with you, but the aspect ratio for stills is 3:2 or 16:9.
I love long lenses, especially for motion imagery. They're hard to use, hard to direct the talent but when they work, they have a look of importance, that standard lenses don't offer.
I think the best focal length (in 35mm terms) is 150 to 200, or really wide like 20mm, (for motion).
For stills at least for fashion style imagery 105mm is perfect though most of the world has moved to 85m because of the Canons and Nikon and Sigma followed suit.
Though for fashion oriented imagery, it really depends on the talent. If you have a very slender subject with long limbs and a shape that makes triangles, you can use about anything without changing the look of the subject. With real people or less than A grade talent long lenses make for a much more attractive look as actors tend to be short and curvy. Notice how few times short talent is shown full length in films and television and if they do use wide lenses how they frame the subject so they are only part of the frame, which also compresses the talent.
Also notice how on movies and television how talent is shot slightly lower to make the talent seem taller and have more presence.
That slightly lower angle with a heavy camera is brutal on the back, but looks great.