Originally posted by Class A I have a problem with the term 'myth' here.
There is no larger-sensor advantage if you always must keep DOF the same for the same FOV. But no-one ever mandates that, and in fact '
accepting less DOF for the same FOV' often turns into '
welcoming less DOF for the same FOV' in a lot of cases, once you shoot for a while.
That thread is very good in that the OP lays out the equivalence involved. He does state very clearly that there's no 'noise' advantage
if you intend to keep DOF the same (among the other things, like FOV and F-stop.) (Maybe at that time (2009) that was still a revelation?)
Saying it's a 'myth' confuses the issue, and IMO is misleading - if it can be stated like that, then it's also a 'myth' that aps-c sensors will give you better noise performance than 1/2.3'' P&S sensors can give you. While technically true, it's only true if we attach the odd mandate that we need to keep DOF the same in all cases (assuming for a moment the available lens disparity was less.) No-one ever says, "
well, your aps-c DSLR is no better than my P&S because you have to stop down your lens to f/32 to match my P&S DOF, this negating the noise advantage!" You would always respond, "no, I don't
need to stop down to f/32, I'm happy with my DOF at f/4, thank you."
Same argument applies to FF vs. aps-c.
So... 'myth' is misleading, for these two reasons:
1) You are never
required to keep DOF the same. If you can accept or welcome 1.3 stops less DOF for the FF shot for the same FOV and F-stop, you gain the noise advantage.
2) There simply are not always lenses fast enough available for aps-c that can match what's available for FF (linear aperture for the same FOV.) (& The greater the difference between sensor sizes, the greater this disparity is - see aps-c vs 1/2.3'')
IMO, '
often misunderstood' is 15 characters longer than 'myth', but worth the effort in accuracy payback.
Quote: Now, there are indeed scenarios where an FF camera can be better in low light, but whenever that's the case this is always due to faster lenses being available for FF (provided sensor technologies are comparable). A 50/1.4 on FF would require a 33/0.9 on APS-C to achieve the same low-light performance. However, there is no 33/0.9 and this is the only reason why you may -- in certain scenarios -- be better off with an FF compared to an APS-C camera.
It comes into play a lot also with the f/2.8 constant zooms. Until Sigma made the 18-35 1.8, there was no comparison anywhere in that range, if you needed to use a zoom for whatever you were shooting.
Quote:
...If you compare the cameras at DxOMark, the Df looks quite a bit better, but that's because DxOMark uses the same f-ratio for all formats. Hence, the SNR advantage for the Df is mainly reflecting the surplus of total light let in by an FF lens set to the same f-stop as an APS-C lens.
Which is
what you do as a photographer, most of the time just naturally - and 100% of the time when you're specifically trying to take advantage of the larger sensor to reduce noise.
.