[rant]
Well, f2.8 is f2.8, whether you like it or not. Of course, a FF lens has a narrower DOF than an APS-C lens at equivalent focal lengths and the same aperture, but the light transmission of the lens is still roughly the same. Now, if you are into narrow DOF, the 70-200 f2.8 will give you that over the 50-140 2.8. But at the same time, the 50-140 gives you one extra stop of light for the same DOF (give or take) than the 70-200. You prefer the narrow DOF. Fine. Others prefer the extra stop at given DOF. Neither is objectively better. Now whether the Fuji is too expensive, is a completely different matter, and mainly determined by production cost and demand (says the economist in me).
Also, to be honest, I don't understand this obsession with FF, other than a "my sensor is bigger than yours" attitude . Different sensor sizes have different advantages. Neither is more serious. We should be looking at the images we produce with given system, rather than some arbitrary sensor size. After all, if larger was automatically better we would all be shooting 8x10 film.
[/rant]
Disclaimer: I love my Fuji (for anything but sports), use Nikons mostly for work, and would be shooting MF film all the time if I could
Arbitrary sensor size ... I started photo with a Minox and... I'm below 40 Yo. APS-C is an error, a forced format. Back in the days I remember when those strange films was introduced and it was just a nightmare. By today costs of production (see Sony), every body should profit of 24x36, it is a minimum. I do not really care about maths, I only trust my eyes, experience and what I learnt in many traineeships (Louis lumière). I do not say that the fuji system is bad (it is a dumb proof camera) but I say it is kinda a waste of money. Some ppl see only fun in camera and some see only tools (and some both). I see the tools... as the real photo schools see it. If you want progression in overall IQ you have no choice than jumping into larger formats (this is a fact, not my own delirium).
When you go out of a long photo traineeship in well known photo schools (not local clubs), they almost lead you into MF, directly. Those schools and your status of student give you large advantages on refurbished MF gear (hassy, in France). A lot of those students establish themselves pro asap and already have : skills, adequate material, address book >> more than many of us can build in 10 years. They can almost teach photo.
APS-C and below are just niche markets. Fuji, Sigma, Pentax are just niche markets. APS-C from the big brands like Canon or Nikon are for ppl who enter photography and sometime they do not even know what is APS-C and FF (true story). So at the end APS-C
was for ppl with no big money to invest seriously at first. Pro APS-C body's was for wildlife photo, more light lenses and reach (this time is now over).
The larger the sensor the better the transitions. Smooth yet sharp.
A D700 churn out more pleasing pictures than the fuji, overall. A D800 >> you take a blast. A 645D or equivalent in Hassy or Phase >> you take a big blast. Larger sensor >> you take even more a huge blast. Linoff technica >> you scream and cry just looking at the reversibles. Above ?? >> it start to be epic.
My wish is that most of you can own and use sensors even more large than 24x36 and this will maybe be true. What I see is that APS-C is slowly dying and 24x36 slowly resurrecting. In big brands you have almost the same choice of gear between APS-C and 24x36 [(
and it is just a start)+(
it is a good thing)].
The second hand market of used 24x36 dslr or Milc is starting to explode. For a newcomer in photography what is the best deal, IQ wise ? investing in a niche APS-C system or in a slightly used D610 or A7 ?? you know the answer.
It is why I think that before 5 to 7 years, brands such as mamyia/leaf, fuji (yes fuji), sony and maybe some other big boys will produce compact fixed lens MF cameras for under 4k. So the equilibrium will be restored : MF and FF. All the rest will be done with smartphones.
If tomorrow Leica say : "Ok, after long studies, we decided to resurrect the R system, using the M9 sensor". HA !! So many ppl will fancy this new (if correctly priced).
So I do not rant, I just wish that most of us can enjoy real IQ (modeling, transitions) for less money and my little finger tell me this is what's going on actually.