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

Started Mar 2, 2014 | Discussions thread
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GaryW Veteran Member • Posts: 8,344
Re: EM1 12-40 vs Nex 5r speed booster with 24-105L

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.

That's what stubborn people on m4/3 forum believe, they invented perpetuum mobile and don't even realize that. To calculate the light received by the sensor you need to integrate the light flux hitting the sensor over the area. The size does matter. In the final analysis, it's the lens physical aperture that collects the light, f-stop is just a ratio = aperture/FL, so you can as well integrate the incoming flux for a given field of view over the aperture area of the lens, there is no magic in the world that can make 12mm/2.8=4.28mm aperture on m4/3 to collect more light than 24mm/4 = 6 mm aperture on FF for the same FOV.

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.

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Gary W.

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Sony E 16-50mm F3.5-5.6 PZ OSS Sony E PZ 18-105mm F4 G OSS Sony Cyber-shot DSC-V3 Sony Alpha DSLR-A100 Sony Alpha NEX-5 +8 more
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