Rethinking 4/3 Depth Of Field

Started Apr 11, 2013 | Discussions thread
Great Bustard Forum Pro • Posts: 41,736
Re: It really isn't.

Rriley wrote:

Great Bustard wrote:

But even when DOF doesn't matter (either because we don't care, or the whole of the scene is well within the DOF even at wide apertures), it's still not about exposure, but about the total amount of light collected:

exposure is the only governance left if DoF doesnt matter

Once again, not exposure, but total light collected:

Total Light Collected = Exposure x Effective Sensor Area x QE

So, exposure is relevant only inasmuch as it is a component of the total light collected.

'exposure is relevant only inasmuch as it is a component of the total light collected' - ridiculous long winded pedantry,  - 'exposure is the relevant component of the light collected'

Seems we're making progress -- a step up from your previous mantra, "Total Light = Total BS".  But, no, "exposure is the relevant component of the light collected" is not quite right.  Exposure is one of three components:

Total Light Collected = Exposure x Effective Sensor Area x QE

You may have seen that somewhere before.

If for some reason greater DoF is required (including part of a landscape) smaller sensors are likely to benefit from this restraint having inherently greater DoF, for a given shutter speed and limited widest aperture (f/2.8).

Smaller sensor systems have not "inherently greater DOF" except when we are in apertures deep into diffraction territory (past f/22 equivalent on FF).  For example, if someone is shooting f/8 on mFT for DOF reasons, then the FF photographer would simply shoot f/16.

why do you imagine anything else that what Ive given the restraint is an exposure 20 secs or less as fstops at any aperture are immaterial given that, what on earth do you think you would be doing shooting at f/22

Well, you were talking about the "inherently greater DoF", and I was simply explaining that there was no such thing, except for apertures well into diffraction softening territory.

In short, there is simply no advantage, whatsoever, to having a deeper DOF at the widest aperture.  That's as foolish as saying that an f/4 lens is superior to a f/2 lens because, wide open, the f/4 lens has a deeper DOF.

On the other hand, if the mFT photographer was shooting f/22, the FF photographer cannot shoot f/44 (f/45), so the mFT system would have a DOF advantage.  That said, if "high IQ" is important, then both the mFT and FF photographers would make use of focus stacking, which, incidentally, was just discussed in a nice article here on DPR:

you dont seem to grasp what the issues are here.

So desuka?

you dont get the opportunity for more than one exposure as the earth has rotated relative to the ground, ie the sky ~ 'stars' are now in another location, another exposure is worthless

I posed a question to you some time back:

In terms of the visual properties of the final photo, what does 50mm f/2 1/100 ISO 400 do for you on 4/3 that 100mm f/4 1/100 ISO 1600 on FF doesn't?

Your response was:

Answers are voluntary, not compulsory.

In any case, you seem keen on the subject of astrophotography.  Tell us, then, what might be the ideal settings for an EM5 and 6D if two competent astrophotographers were photographing the same scene from the same spot, and why do those settings result in a better photo with the EM5?

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