Rethinking 4/3 Depth Of Field

Started Apr 11, 2013 | Discussions thread
Great Bustard
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Re: I'm not convinced...
In reply to Anders W, Apr 11, 2013

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

al_in_philly wrote:

I do the majority of my shooting in very low light situations without a flash.  I started out shooting at night with a (then brand new) Olympus e-510 and a Pan/Leica 25mm f1.4.  I know, great lens choice, not best choice for a low-light camera, but that's what I happened to own when what became a three year nightime photo-shoot opened up for me.  Those photos BTW have been published in a variety of newspapers & magazines, as well as having two gallery shows of them.  Now I'm shooting different very low-light subjects with an OM-D and the m4/3 version of the PL 25 1.4, and I couldn't be happier.  Why?  A big part is because of the depth of field that combo gives me.

Like many others, I too like to seperate my subjects from their background a bit by using the selective focus which wide apertures afford.  But often, I don't want to obliterate all the background, or foreground, definition, just soften it enough to tell my viewers wher to plant their gaze in the picture.  So, if I'm shooting in a dimly lit bar or a city street at midnight, my OM-D produces "just right" images at f1.4 and an ISO of 3200, typically yielding a shutter speed of between 1/30 and 1/80 sec, depending on how dark the lighting is.

Of course, I could shoot FF at 2.8, but then I'd also be shooting at an ISO of 12800 for the same shutter speed.  Even as good as FF images are, the OM-D at 1/4 the ISO will always look better.

...about your last sentence above.  It would be interesting to see a comparison between a modern FF DSLR with a 50 / 1.4 at f/2.8 and the same shutter speed, and see which comes out ahead.  I am far from convinced that it would be the EM5 (which is not to say that I am convinced it will be the FF system).

On what grounds are you not convinced?

Image quality.

As I know you are well aware, any current FF camera would lose out to the E-M5 for DR/shadow noise in this comparison (except the D4 which would break even).

I think the 6D comes out the same.

OK. You are right about that. But not the 5D3, the D800, or the D600, nor any older FF camera.

In terms of SNR at higher light levels, it would be a tie. So are you thinking about how the PL 25/1.4 at 1.4 compares to a 50 mm FF lens at 2.8 or what?

I'm thinking that a FF camera at 50mm f/2.8 would resolve more detail everywhere in the frame than an EM5 at 25mm f/1.4, and, if the EM5 did have less noise for equivalent settings (same DOF and shutter speed), the judicious application of NR (noise reduction) to the FF photo would result in a photo that was both more detailed and less noisy (albeit not significantly so, in my opinion).

Could be although at these ISOs, I am not at all sure. Even if the FF lens at f/2.8 would clearly outdo the 25/1.4 for MTF, little of that difference is likely to register in view of the noise levels we are talking about here.

Well, that is something I'd like to see put to the test.

Further, if we compare at apertures slightly smaller than these, e.g., f/2.8 versus f/5.6, the difference in MTF becomes close to insignificant in the first place.

Let's put that to the test, too.  I'm honestly curious to see the results from a competent test.  As I said, no matter which way it falls, I'm of the opinion that the differences are nothing to fret over.

In any case, if you are always going for the deeper DOF in low light, seems to me that the size and bulk of the FF system compared to the EM5 system makes the EM5 system the overall winner, although there may be operational advatanges that may substantially favor one over the other.

To that end, I think it would be interesting to see a comparison with competently processed photos.

P.S.:  I think the EM5 would come out significantly ahead in situations where it could use IBIS and a longer shutter speed and FF could not use a tripod.

And, yes, don't forget the awesome IBIS in the EM5.

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