Olympus EM1 vs Nikon D800 systems (continued)

Started Jul 10, 2014 | Discussions thread
PerL Forum Pro • Posts: 13,842
Re: If...

Great Bustard wrote:

Anders W wrote:

Since this thread expired before I had the opportunity to respond to a number of posts, I start a continuation.

My first reply is to the OP of the prior thread, Photo Pete, who said the following here:

I find it interesting how equivalence is used in forum threads.

The 12-40 f2.8 micro 4/3s lens is truely equivalent to a 24-80 f5.6 full frame lens. It will gather as much light, have the same depth of field and field of view.... provided it is used at the equivalent aperture (eg F2.8 on micro 4/3s and F5.6 on FF).

It makes me laugh when posters talk about small sensors having worse low light performance than FF cameras AND not having shallow depth of field, as if they were two separate and cumulative issues. The two issues are the same. Use an equivalent aperture and both depth of field AND low light performance is equalised between the formats.

We are talking about 2 stops difference between truly equivalent performance. In terms of image noise it appears to me to be currently less than that as the latest Olympus 4/3 sensors seem to be performing very well for their size.

If 2 stops of aperture or very high pixel counts are not critical to you then you will gain very little benefit from Full Frame over 4/3s in terms of image quality.

As a personal view I think shallow depth of field is more a problem than a benefit. If critical you can soften many backgrounds in post processing, but you can't add back detail in out of focus areas. 2 stops of noise I can live with.

For those of us who for the most part don't want or can accept more shallow DoF than we can easily get with MFT, things are actually a bit better than equivalence reasoning would suggest. The idea of equivalence rests on the assumption that large sensors are as efficient as small. But as shown here such is generally not the case.

The D800 versus the E-M1 is a case in point here. With regard to the kind of noise most people find most disturbing (shadow noise, which in turn is well indexed by DR), the high ISO performance of the D800 is only about half a stop (rather than two stops) better than the E-M1 at the same ISO. This in turn means that for equivalent photos (same DoF, same shutter speed), the E-M1 is actually about 1.5 stops ahead. Here is an illustration of that fact and here are the facts themselves with regard to DR:

...you are shooting the larger sensor system at the same DOF and shutter speed as the smaller sensor system, then the smaller sensor system will usually have an advantage, primarily due to the lower pixel count:


On the other hand, it has been my experience that given the choice of a more shallow DOF with less noise or a deeper DOF with more noise, most choose the more shallow DOF with less noise:


In my opinion, however, the differences in IQ between modern systems (and many not so modern systems) matters far less than differences in size, weight, cost, and operation.

If you shoot an indoor sports game at ISO 6400 or higher, like many professional users of pro DSLRs do, there is a very real IQ difference.

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