A7r 24-70 vs Nex-7 16-70 vs EM1 12-40

Started Mar 2, 2014 | Discussions thread
GaryW Veteran Member • Posts: 8,702
Re: EM1 12-40 vs Nex 5r speed booster with 24-105L

LTZ470 wrote:

GaryW wrote:

forpetessake wrote:

LTZ470 wrote:

forpetessake wrote:

LTZ470 wrote:

forpetessake wrote:

bigley Ling wrote:

forpetessake wrote:

Not just unscientific, it's flawed. The 12-40/2.8 is full equivalent (disregarding aspect ratio) of 24-80/5.6 on FF, not just DOF. You set it on f/2.8, i.e. f/5.6 on FF. And 24-105/4+SB on APS-C is full equivalent of 25.6-112/4.26 on FF, which you set at f/4, i.e f/4.26 on FF. So what are you comparing?

The best argument against democracy is a five-minute conversation with the average voter -- Winston Churchill

The 12-40mm pro lens I believe still takes in light at f2.8 ,and yes the effective DOF is 5.6.

Takes in light at f2.8, and has more noise in the result due to a smaller sensor surface area.


Then explain why the shutter speed is faster on m43 at f/2.8 vs APS-c or FF at f/4?

Because you chose non-equivalent ISOs. You can have any shutter speed when you compare apples and oranges.


Lol...you never explained why the f/2.8 has a faster shutter speed than f/4?

He said that the key is that the ISOs aren't equivalent, but it's really due to the fact that at the equivalent ISOs, there is more noise in the M43 version. (Comparing ISO is further confused by the fact that the manufacturers drift from the ideal standard.) When you use a lower ISO to make the noise look similar, then the shutter speed will slow, making everything equivalent again. So, if you're after equivalence, f2.8 on M43 should give about as good results as f4 on APS-C.

The fact that cameras have different shutter speeds for the same settings is unfortunately because they don't stick to a strict standard for ISO. If ISO 100 is really ISO 150, then the shutter can be faster. It's CALLED ISO 100, but what it really is, is another thing altogether (a noisier result than a true 100 would have been). If you go the other way, say, ISO 1600 is really closer to 800, then the noise level is much better. Everyone compares 1600 of this camera to 1600 of that camera, but the one that is really secretly close to 800 has less noise -- what do you know, it's a stop improvement in noise! What a fantastic sensor! Only, it was just a shell game.

Shutter Speed is it pure and simple...add to that IBIS and voila...low ISO and Fast Shutter Speed the combo...

If you need to match shutter speed, the APS-C camera can dial in a stop higher ISO. Noise results will be about the same, shutter the same but f4 vs. f2.8.

If it didn't work this way, why not just use an even smaller sensor than M43? 1"? Let's just use cell phones. Why are we here on the Nex forum?

Now you are coming as a typical m4/3 troll. As I said, I can explain to the ignorant willing to learn, but as a good book said, "neither cast ye your pearls before swine".

It took a while before I got the hang of how this works. IMO, it's not straightforward.

But look at the IQ of the shots above, a FF at ISO 100 1/800 shutter f/8...a humble 1/4 size sensor at 1/4000 shutter speed f/4 ISO 200 with much better results in the comers and sides (and believe me I did not post extreme corners of the A7r 24-70 shots as they are atrocious)...

So ISO equivalency is misleading for ALL practical purposes...the shots above were all at an advantage for the A7r...

Judging by that chart, Sony is actually at ISO 75 and Oly at ISO 125 -- I guess about 1/2 stop slower for Sony?  And the aperture difference of f4 to f8 is 2 stops.  So, that explains the 1/4000 shutter vs. 1/800 -- close to 2.5 stops difference.  I would have flipped it the other way and tried to use the Sony at ISO 800 vs. the Oly at ISO 200, and the shutter speeds would have been close.  Anyway, shutter mystery solved.

As for the IQ, when I looked at the original photos, I have to agree with the others that the oversharpening is not flattering to the Oly.  If the Sony lens is softer in the corners, that's a shame, although, comparing sharpness in the corners is problematic (field curvature, DOF combined with the point of focus, etc.), so I'm  not sure I would be too quick to judge.

At any rate, if you prefer the Oly, then you don't have to convince us!  I would have expected that the cameras should both be good in the broad daylight, though.  Shoulda also used a P&S camera and a cell phone.  

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Gary W.

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