Pekka Potka's take on the A7R and the EM1

Started Nov 12, 2013 | Discussions thread
Anders W Forum Pro • Posts: 21,466
Re: Pekka Potka's take on the A7R and the EM1

blue_skies wrote:

LTZ470 wrote:

You cannot be posting articles like this…there is way too much common sense written and observed here…FF rocket scientist's, physicist, and brain surgeons will not be able to comprehend…it MUST be about equivalence!!!!

I take that as humor

I mean:

  • "Actually A7R loses compared to OM-Ds when it is forced (because of dim light) into high ISOs. Namely, OM-Ds can stay at ISO 200 for handheld shots up to the situation where A7R is forced to go up to 3200 (EM-5) or 6400 (E-M1) with same field of view and depth of field in each image. Crazy? No, tried and true, and and actually a quite conservative statement in the benefit of A7R."

and

  • "With E-M1 I can have an almost all green field at 1/6 seconds with the same field of view. There are three possible explanations for so many shaken images with A7R. The first being of course me. The other ones are A7R´s mushy shutter button and noisy shutter."

and

  • "I wanted to love A7R, and it is still quite tempting, but I simply need my depth of field. No image stabilization and bigger sensor leads into a lot higher ISOs than I am now using with E-M1.Down the drain goes the benefits of bigger sensor."

Some observations:

OM-D and A7r at same DOF means that A7r is stopped down by two stops, but that ISO is raised by two stops, for same result. That is, the shutter speeds are identical....

IBIS is rated at three stops. Adding IBIS to OM-D and not to A7r is confusing. The A7r would have been better compared with an OSS lens, such as the 28-70 or 24-70 zoom. Since he is stopping down, lens speed does not matter.

1/6th sounds impressive, but it translates to 1/24th for a WA FOV. Most photographers can shoot a 35mm lens on FF at 1/35th, so 1/24th is close to normal... and with OSS this would be 1/6th on FF as well.

But the photographer measures 5 stops between the two formats. Either he does not understand what he is doing, or he is deliberately confusing the issue. Perhaps he was merely comparing JPG's at 100%, not realizing that the A7r is far more detailed?

To summarize:

  1. An OSS lens on the A7r would have yielded same stabilization as IBIS on OM-D (3 stops).

Sure. But then the A7R isn't such a small and light camera any more. Nor does it offer anything in terms of DoF or signal-noise that an E-M1 with a fast prime can't do equally well. On the contrary, the E-M1 would still have a signal-noise advantage since its sensor is more efficient on a per-area basis than that of the A7R.

  1. Selecting two stops smaller aperture on the A7r would match OM-D DOF, and raise ISO two stops - but keep the shutter speed the same. (Technically, the FOV is different due to 3:2 versus 4:3, so there is a bit more to play with here).
  1. The resulting image on both formats would be equivalent in terms of DOF, noise, handheld sharpness, etc.

No it wouldn't be equivalent for noise for reasons explained here:

http://www.dpreview.com/forums/post/52514453

  1. The A7r image would benefit from higher resolution, higher DR, and, if, down-sampled to the OM-D, image, a richer JPG.

Certainly not. On the contrary, for reasons explained in the post I linked to, the E-M1 image would be significantly better (about 1.33 EV) with regard to DR with the images downsampled to the same resolution. The advantage of the E-M1 would become larger still at the native resolution of the respective sensor (about 2 EV advantage for the E-M1).

  1. Noise filtering in JPG can lead to impressive results, but details are lost - a higher resolution image is the holy grail for landscape photographers, hence the high level of interest (8:1 according to SAR) in the A7r over the A7, which is a more practical FF camera.

Higher resolution would be nice for landscapes yes. But for such purposes, I have no difficulties getting it with my E-M5 if I want to, for reasons explained in the post I already linked to.

And also

This (slow speed handheld landscape) is yet one application of photography. The moment shutter speeds are raised, e.g. people photography, the A7r brings nothing but benefits over the OM-D. This should not be ignored when comparing cameras. Also, many photographers would bring out a tripod for such shots, or shoot in layers, to maximize the resulting image (lower ISO to min).

See above.

But then, this seems a repeat of the older D800E versus E-M5 comparison, which naturally favored the E-M5:

  • "I never said that Olympus E-M5 has better sensor specs than Nikon D800E. On the contrary. But really, what I wrote about was about my needs for a camera. Even it was intolerable for many Nikonians. Some wrote that comparisons based on somebody´s needs are stupid. All tests should be objective. Sure. Dream on."

Equivalence? Sure - after he ignores all parameters that make the two products non-comparable...

As demonstrated above, it is rather that you overlooked some pertinent facts.

 Anders W's gear list:Anders W's gear list
Panasonic Lumix DMC-G1 Olympus OM-D E-M5 Olympus E-M1 Panasonic Lumix G Vario 14-45mm F3.5-5.6 ASPH OIS Panasonic Lumix G Vario 7-14mm F4 ASPH +28 more
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