Any mft's shooters thinking of jumping ship for FF nex

Started Jul 22, 2013 | Discussions thread
Forum MemberPosts: 69
There's everything equivalent between 35-100 f2 (FT) and 70-200 f4 (FF)
In reply to dougjgreen1, Jul 25, 2013

dougjgreen1 wrote:

You claim FF users accept bulkier systems for some benefit, but how does that explain all the APS-C users of the Canon/Nikon systems who use the same lenses in similar bodies? Or heck, how about Four Thirds, with it's, say, 35-100mm f/2.0 lens. It's more than double the weight of Canon's FF equivalent (70-200mm f/4) and 25% heavier than the f/2.8 version. And that's not cherry-picked: Aside from the 3 kit versions, every zoom for Four Thirds was over 400g, and often nearly 1000g.

Lenses like that are primarily used for shooting fast moving action at high shutter speeds. A two full f-stop difference means that the shutter must be open for 4 times as long at the same ISO - meaning, it will be much tougher to freeze action in all but very bright daylight, or very high ISOs.

Technically accurate, but not actually true because neglect the most important thing here: the sensor. Do you think that a 16Mpx fullframe sensor performs the identically to a 16Mpx FT or 16Mpx digicam when they are set to "ISO400"?

If you look at a comparison you'll see that at the noise performance of the full frame is consistently almost two stops better than the FT sensor. Which is to say that the quality of a full frame sensor at, say, ISO 3200 is about as good as a four thirds sensor at ISO 800.

So theoretically the following produce identical shots (including motion blur) of identical quality:

FT: 100mm f/2, 1/200, ISO 400
FF: 200mm f/4, 1/200, ISO 1600

In reality there are sources of noise beyond shot, so for similarly 'good' sensors the FF image will be a little (~1/3stop) behind the FT version but it's pretty minor. You probably couldn't tell the differences between those two shots even pixel peeping.

It's also worth noting that those shots are shutter/light limited and if we were to add additional light the FF user could just drop their ISO and have their quality improve more than FT could.

So, no... These lenses gather exactly the same light; the numbers only look different because they focus it differently. They are equivalent and produce basically equivalent shots. The only difference is that in good light the FF will perform 2 stops better while in limited light the FT will be about 1/3 stop better.

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