MFT Users: Do you miss the shallower depth-of-field of bigger sensor cameras?

Started Feb 8, 2014 | Discussions thread
Great Bustard Forum Pro • Posts: 40,847
Re: Light gathering, aperture, and DOF all go hand-in-hand.

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

Yes -- if you are comparing to the 36 MP A7R. So, if you do a lot of shadow pushing for a given DOF and shutter speed, this is a point to consider.

Or if you shoot at higher ISO where (as already demonstrated) you don't need to push anything for the poor shadows to show anyway.

At low ISO and without shadow pushing, everything will be fine regardless.

Sure. That said, it's my opinion that the vast majority prefer lower noise to deeper DOF.

Honestly, I don't care much what others prefer. I just go by my own preferences.

A kindred spirit!

In the past, where I had a film with a fixed low ISO (somewhere between 50 and 400 as a rule), I used to prefer a correctly exposed shot to an underexposed one. That sometimes meant shooting my fast FF primes wide open in spite of the DoF being too shallow. But that was only because there was really no other way to get the shot at all.

Today, when exposure is not determined by the film and we are no longer so desperate for more light (since the sensors have become very good), I typically prefer the results I get with my fast MFT lenses wide open to those I would get with FF at the same f-stop. This effectively means that I often prefer more DoF to less noise.

Not merely more DOF, but depending on the particular lenses being used, you get more resolution wide open to wide open. For example, the 25 / 1.4 at f/1.4 on an EM1 will resolve better, even for the portions of the scene within the DOF, than the Canon 50 / 1.4 at f/1.4 on a Canon 6D.

Of course, it depends on the f-ratio and the lens, but I'm just sayin'.

In other words, the opportunity structure has changed whereas my preferences have stayed relatively constant. Today it is much easier to get reasonably noise-free images even in low light than it used to be. Consequently, it is easier to give DoF its due.

Makes sense.

Of course, for static scenes and a tripod, it's simply a matter of how many exposures you want to take to get the IQ you want.

Right. So for this type of shot, the signal-noise performance of the sensor is simply not an issue.

Not an IQ issue, but it is a convenience issue.

and the greater read noise per area of FF sensors is a direct consequence of the greater pixel count.

I am afraid it's not that simple.

Of course it isn't that simple, but the greater pixel count has a lot to do with it.

See below.

First, let's have a look at the same graph when substituting the 16 MP Nikon Df and the 24 MP Sony A7 for the 36 MP Sony A7R.

First, although the A7 has significantly fewer pixels than the A7R, it doesn't do better relative to the E-M1 than the A7R does. Second, while the Df, with the same pixel count as the E-M1, does better than the A7/A7R at high ISOs, it a) doesn't bridge the gap fully at these ISOs (i.e. DR remains lower than that of the E-M1 at the same DoF), and b) does worse than the A7/A7R at lower ISOs.

But we do see that fewer pixels results in greater DR, which was my point.

In parts of the range for 16 versus 24/36 MP. In other parts, it is the other way around. In the comparison between 24 and 36 there is no difference.

Well, the A7 looks to be ISOless, whereas the Df doesn't become ISOless until ISO 800. If both were ISOless, the Df would have the DR advantage all the way through due to the lower pixel count.

The problem with this reasoning is that you assume that the transition from non-ISOlessness to ISOlessness would necessarily imply that the DR at low ISOs would improve and that at high ISO stay the same. I think the opposite scenario (or something in-between) just as likely. In other words, I think the Df sensor (pioneering in the D4 which is targeted to a certain pro audience) might well be optimized for high ISO at the expense of low ISO. Other sensors, like that of the A7/A7R may be tuned more with an eye to both ranges.

I started a thread that addresses this point, the conclusion of which is that it would work out as I stated. If you feel otherwise, let's discuss this point further in the PST forum.

Well, there is variation in the read noise per area between current sensors, as you know, which also varies as a function of the ISO. However, as a general rule, the greater the number of pixels, the greater the read noise per area for sensors of a given generation.

Got any good statistics to show the validity of this generalization across sensors more generally, and across the entire ISO range, not just parts of it?

As above, whether or not the sensor is ISOless or not plays a huge role at the low ISOs. However, if we compare sensors of the same generation at ISOs where they are ISOless, do you disagree?

See above.

Read the thread.

Of course, if your photography will generally require you to shoot the larger format at the same DOF and shutter speed you would use with the smaller format, then you will almost invariably be better served with the smaller format, unless the larger format has some particular operational advantage that the smaller format does not offer.


In the end, that's the bottom line, really. I mean, why would someone purchase a FF DSLR simply to shoot photos equivalent to what a smaller format could do?

Exactly. Especially if the smaller format can do those photos better than FF.

Indeed. In fact, in some situations a cell phone will outperform a FF DSLR!

Hmm. Save for the cell phone being smaller, I can't really think of any situation where I'd be better off with it than with my E-M5. What would that be?

Let's say you needed the DOF that the cell phone gave wide open.  If the cell phone had a significantly more efficient sensor (say 70% QE and a read noise of one electron per pixel), it would outperform the EM5 and FF.  And while the numbers for the sensor efficiency are realistic, I think, the premise of needing the DOF the cell phone gives wide open would, methinks, fall under the heading of most preferring less noise to more DOF discussed above.

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