Nx 50-150 is it really F4.2

ttbek wrote:

You and I, I believe, understand the ins and outs here. We know the definition, we know it is f/2.8 and that it acts in some ways as a f/4.2 would on full frame. For people first discovering that it acts as a 4.2 in those ways, it looks like a duck, it sounds like a duck, it is a duck. I agree that there shouldn't be sides, but there are. So do we want simply insist to people that this duck (in their eyes) is a swan (I think they'll still have doubts), or should we also explain why this swan looks like a duck?

The problem is you are not going to learn about this on an internet gear forum. The original question has been answered that a f 2.8 lens is the same whatever camera it goes on and is not in any way a f 4.2 lens.

The only way to learn is to get a spreadsheet and turn those f numbers in to actual apertures and compare them to see what light is getting in. Your equivalent full frame lenses will have larger apertures because they have longer focal lengths for the same field of view and f number.

To work out depth of field for a particular lens look up the formulae for hyperfocal distance in Wikipedia and from that derive depth of field. You will also need the circle of confusion which is interesting as the statement that a small sensor has a deeper depth of field goes a bit awry here as if you put the same lens on a full frame or smaller sensor the depth of field id shallower with the small sensor.

You are never really going to sort these hard mathematical things out on a gear forum as there is so much brand worship, gear angst, gear sneering and marketing going on and poor knowledge, and I do not exclude myself from these faults. Full frame is being heavily marketed as Sony have put all their chips on it in ILC. I see the format as a highly specialised niche area. Time will tell.

I just cannot see any point in anyone not owning full frame or intending to buy it thinking at all about what full frame does once they have bought the lens.

Edit: The thing is I do find the equivalent aperture graphs useful but they should call them equivalent aperture ratio rather than aperture which causes such confusion. The OP point is gear angst from what I can see and that is where these equivalency ideas fall down as there are so many opposing factors.