There is no magical size/weight advantage

Started Mar 5, 2014 | Discussions thread
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Re: What "exactly" is an equivalent lens as regards to the sensor size?
In reply to nigelht, Mar 9, 2014

nigelht wrote:

nigelht wrote:

olyflyer wrote:

That's exactly it. Not only to you, but to everybody else. Those lenses are not equivalent, only equivalent to the half... or one third if you are generous, ignoring other, sensor and IQ related issues, like same ISO = more noise if the sensor is smaller.

This is false and assumes that the sensel sensitivity is identical across large and small sensors. There are 1" BSI sensors in production consumer cameras. Are there FF BSI sensors in production consumer cameras?

The LENSES are indeed equivalent in terms of exposure or the ISO would be different. The fact that noise changes at the same ISO is true if I stuck the same lens on a 1" Nikon camera vs 1" Sony camera.

LENS equivalence never has anything to noise performance of a sensor since what sensor it is paired with changes over time or between manufacturers.

Otherwise no lens is rarely ever even equivalent with itself whenever it is placed on a different body and that's just silly.

No, it's not silly. Look at it like this: if I have a D610 and a 50/1.8 and a V1 and 18.5/1.8, I can use the same ISO and aperture with both to achieve the same shutter speed, but the FX combination offer 2.7 times shallower DOF and 2.7 times less noise at the same settings. It was shown many a time, that sensors of different sizes, that are on the same tech level (which means the opposite of comparing the V1 with the D200...), the noise difference is indeed equal to the difference in size.

Practical example: D610+50/1.8 @ ISO3200 and f/1.8 will have 2.7 times less noise and shallower DOF than V1+18.5/1.8 at the same settings.

NOW, if you want to achieve the same level of noise and DOF in the same situation with the V1, you would need a 18.5mm f/0.67 lens. That would be an equivalent lens to the 50/1.8 on the D610.

You have to show me evidence that noise and size is a linear relationship for same generation sensors.

I chose the number 2.7 for simplicity. In practice a D610 will have orders of magnitude better noise performance than the V1. DxOMark rates the D610 still acceptable at ISO2952, while the V1 is rated acceptable at ISO346.  That's over 3 stops of high ISO advantage, even though the D610's sensor has 2.4 times as many pixels.

You also assume that all FF sensors performs identically as well as all 1" sensors.

No I don't, but it's not important, whether one particular FX sensor is 3 stops better than one particular 1" or 3.1 stops better than the other. It's important that the advantage is that huge.

Except they don't. Nikon traded IQ for PDAF vs the route Sony took.

Even Sony's sensor is nothing compared to a FX sensor.

Likewise an entry level dslr sensor is not as good as the flagship dslr sensor.

Again, the difference between the D800's 36MP and D6x0's 24MP sensor at high ISO is very, very small.

Finally, at base ISO the noise difference will be far less than at the extremes.

Even at base ISO V1's files have a lot of noise, especially if you do a lot of PP.

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