Crop Factor, Low Light and Aperture with m4/3 lenses?

Started Jun 15, 2014 | Discussions thread
Anders W Forum Pro • Posts: 21,468
Re: A picture is worth...
2

eyeswideshut wrote:

Anders W wrote:

What about subject motion and camera shake?

What about it? I already accounted for that when I said you could play with sensitivity.

No you didn't. You didn't say you could "play with sensitivity". And such play wouldn't help.

What are you talking about? You are simply contradicting yourself. Varying ISO was YOUR idea:

"Suppose the MFT user can take a certain photo at 25 mm, f/2.8, 1/100 s, and ISO 3200. To capture the same photo, the FF user needs 50 mm, f/5.6, 1/100 s, and ISO 12800. Do you get it?"

I see no contradiction here. That's my original example which you criticized by saying that the FF user could simply use a longer shutter speed instead of increasing ISO.

I'm not criticizing anything. Merely pointing out that longer exposure is the classic way to compensate for smaller aperture. You know that?

Sure.

Plus it won't embroil you in EV debates (vide your exchange above) and Noise considerations.

Sure. But this thread is precisely about these considerations for the purpose of choosing between camera systems.

For reasons already spelled out, that's not always possible and the example simply assumes, for good reasons, that the shutter speed requirements for the FF shooter are the same as for the MFT shooter.

Well if you assume that, all your talk of equivalence simply becomes nonsense.

On the contrary, it makes perfect sense in view of that assumption.

Motion blurr and camera shake are just not factors in equivalence, they are factors only in REAL photography.

They are factors that must be controlled (kept constant) in comparisons between camera systems.

I'm merely pointing out, that if you want to avoid arguments over noise in your contrived example, a photographer will simply vary exposure time. Surely that is not difficult to understand?

One could only hope you would understand that shutter speed cannot always be varied without penalty.

Absolutely, in the REAL world one cannot. But I'll remind you again, YOU are setting up an equivalence situation between ff and mft. So what have considerations of fast moving subjects or cameras swaying on tripods have to do with that? Nothing.

See above.

However, you set up an equivalence between ff and mft, which already assumes equally efficient sensors and lenses. So to avoid interminable discussions about noise, a photographer would simply extend exposure time.

All you need is 50mm, f/5.6, 1/25, and ISO 3200. Voilá.

Again, what about subject motion and camera shake? If the shot requires 1/100 s to get that right, how does it help to lower shutter speed to 1/25?

What about it?

Yes, what about it? Please just answer the question you are dodging all the time.

You must have noticed that I have answered this already.

Yes, you finally recognized that there are shutter speed restrictions. And these must be kept constant when comparing camera systems.

But again: In a contrived equivalence setup, these things play no role. You set up two cameras for equivalence and then you bring in Blurr and Shake? They are just not part of the tenets of equivalence. Again, that is real world photography.

See above.

YOU are setting up a controlled equivalence situation between ff and mft. What's subject motion and camera shake have to do with that?

Most shooting situations impose limits on shutter speed due to camera shake and/or subject motion. I simply keep that limit constant as should be the case in a controlled comparison.

That is no longer a 'controlled comparison' within the equivalence paradigm.

It certainly is precisely that.

But anyway, obviously you can leave the shutter speed at 1/100 and increase sensitivity.

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