There is no magical size/weight advantage

Started 9 months ago | Discussions thread
razormac
Contributing MemberPosts: 724Gear list
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Re: There is no magical size/weight advantage
In reply to Hifromhere, 9 months ago

I should probably just shut up since I can see I am only wasting my time, but I will call one final witness:

Nikon 1 10-30mm f3.5-5.6 vs Sigma 1-20mm f4.0-5.6

N1 10-30mm (2.3x1.7in) and 116g (4.1 oz)

Sigma 10-20mm (3.4x3.5in) and 520g (16.1 oz)

About 1/2 the size and 1/4th the weight despite having a longer zoom range and faster max aperture at the wide angle. How do you explain that?

Ah . . . I see it because the N1 actually has a pseudo-aperture because DOF is far more important than anything else, to include equivalent light exposure density.

Today's sensors regardless of size, CX, DX, FX, whatever use basically the same semiconductor technology. To borrow the phrase, there is no "Magic" that makes FX photo sites behave any differently when struck by Photons than those on CX or DX sensors.

Larger Photo sites are better, in that all else being equal, they have inherently better signal to noise ratios. But, when photo site density is equal, baseline signal to noise ratio is also going to be equal, and thus usable sensor sensitivity is also equal.

CX and DX (and M4/3rd for that matter) sensors typically have smaller photo sites, resulting in lower usable Maximum ISOs (before noise eats the image). So, the point is the TRUE f number equivalence is that which forms a part of the computation of ISO and Shutter Speed to generate a proper exposure. This is essentially equal for all sensors, regardless of size, assuming equivalent photo sites (and thus equivalent signal to noise).

So, yes, I know your FF sensor is bigger than a CX or DX sensor. We agree, but that doesn't mean every other sensor out there really has a pseudo aperture . . . if so, then we should really be judging of of MF sensors, after all they're bigger yet.

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