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 Yohan Pamudji, Apr 12, 2013

Yohan Pamudji 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).

One day I might experience a brief moment of industriousness and do such a comparison with my Canon 5DIII and Olympus E-M5.  Anecdotally from using both cameras I have a feeling that when you start reaching into the really high ISOs the E-M5 will be better than the 5DIII at 2 stops higher ISO.  For instance E-M5 at 3200 will probably be better than 5DIII at 12800, and E-M5 at 6400 will almost definitely be better than 5DIII at 25600.  I have a feeling that E-M5 at 1600 might even be better than 5DIII at 6400.  At lower ISOs though the difference is small enough that it doesn't matter--for all intents and purposes both produce very good output for the same DOF and shutter speed (i.e. 2 stops different aperture and ISO).

Well, if you ever get around to it, it would be great to see.  My guess is that a 5D3 at 50mm f/2.8 ISO 12800 will outperform an EM5 at 25mm f/1.4 ISO 3200 -- once NR has been judiciously applied to the 5D3 photo to normalize the detail in the resulting photos.

However, as Anders noted, if we are comparing 50mm f/5.6 ISO 12800 on the 5D3 to 25mm f/2.8 ISO 3200 on the EM5, perhaps the tables will turn.  In either case, I think the differences will be small enough to not be worth worrying over.

Also of interest to me would be comparing with the 5D3 using the 50 / 1.4 and comparing with the 5D3 using a 24-70 / 2.8 zoom.  I wonder how much of a difference that would make.

The advantage of the FF kit will be the option for a more shallow DOF when shallow DOF is desirable, or using a more shallow DOF when the lower noise that accompanies the more shallow DOF in lower light matters more than the deeper DOF.

The advantage of the mFT kit, of course, is size, weight, and cost, not to mention IBIS (although there is the Tamron 24-70 / 2.8 VC).

Thus my gut feeling is that for low ISOs where one isn't DOF limited because it's easy enough to get enough DOF the 5DIII is better, but at high ISOs where you want to achieve a certain amount of DOF the E-M5 is better.

Perhaps -- moreso with the 5D3 than with the 6D, though.  However, I'd be curious to see how the D800 fits in the mix, since it should resolve a lot more detail and thus be able to handle a lot more NR, possibly more than offsetting the higher read noise, even compared to the 6D.

The wrinkle is that at high ISOs where you don't so much care about the DOF as you do getting a usable shot the 5DIII is better because you can use faster glass on it and/or shoot at a smaller DOF, sacrificing DOF for shutter speed or having less noise from lower ISO.

When a deeper DOF is desirable in low light, there's always the balance between DOF and noise, and where that balance point lies will depend on the desired amount of DOF and the amount of available light.

Just reinforces the point that there is no such thing as one perfect or best camera for all situations.

Huh -- news to me!  I thought it was a Leica. 

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