Resolution & Megapixels, what actually matters? Can my camera beat up your camera?

In the last couple weeks no category has caused more of a stir than the discussions about megapixels and resolution with the new Sony A7 series.  Most of this controversy starts with lens discussions.  There’s some considerable distinctions between the A7s‘s, 12.2 megapixel sensor, the 24mp on the A7, and the monster 36.3 of the A7r.  The sensors in the three cameras are all considered Full Frame(24×36), each measuring just under the 864 sq. mm. mark.  So what’s the difference between the three, if the sensor is basically the same size?  It’s a great question that confuses lots of people including myself….

Larger sensors tend to have larger pixels, which can translate to lower noise levels, and an increase in dynamic range(Cambridge in Colour article on Sensor size).  More light can be gathered by the larger pixel.  That at least makes sense.  How does this relate to the A7s and why is it the new low light king?   It has 12 really big Megapixels!  The light gathering potential is huge!  It becomes a dream camera for those who want to take low light or fast pictures(action, indoor photography, nights, low lit streets) and astral photography.    Somehow Sony has managed to increase the A7s picture quality by utilizing the unique in-camera processor(Bionz X) combined with the new Exmor CMOS sensor.  Does it have more resolution and capture images as sharp as the higher MP cousins…. no.  What it does do is provide a much sharper picture than the typical 12 megapixel camera (Sony A7s William Brawley’s Shooter report) with much more ISO range.   DXO explains that while the A7s performs better than any other camera tested in low light ISO, it actually looses some Dynamic Range compared to it’s partners(DXO A7 series comparison) after camera applies processing.

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Described by one person as a 36 megapixel digital back, the A7r has few full frame equivalents.

That gets us to the A7 and A7r argument and that megapixels don’t matter.    It’s a complicated process to get an image to the SD card,    As the image zooms through the camera, Sensor size, pixel size, pixel density, processor, sensor type….  range of light/dynamic range… OMG!  –all contribute… Nasim Mansurav,(great articles on sensors etc) and others, refer to segments of this interaction as the “Image Processing Pipeline”(IPP). With the shared Bionz X processor, it’s similar in all three A7 cameras.  Suffice it to say that the largest sensor, with the largest pixels and highest pixel density wins, when the IPP is the same.  It’s starting to make sense why each camera performs the way it does.   Both A7s and A7 have better low light performance in some ranges than the 7r.  The 7r crushes in image quality when used in it’s optimum range.  Some things to ponder when the playground bully says his camera can beat up your camera.

  • About 12,000,000 pixel difference between the A7 resolution, 6024 x 4024,  vs  A7r 7392 x 4920.
  • staggering disparity in pixel density
  • 14 bits of color per pixel vs 12, on A7s and A7.  I think that’s good.
  • NO Anti-Aliasing filter
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Ultimate Resolution with the Native FE 55 lens and the A7r.

This information helps resolve why the lens performance on the A7, can seem radically different on the A7r.  Lessor optical quality isn’t realized until placed on the unforgiving 36.3 MP sensor.  On the “R” everything is magnified, good or bad.  It explains why people go to great lengths to defend how good some lenses are!  In the A7 world they are that good.  A bit of a paradox I suppose.

Those of us who live in 7r-ville can hope that the new Loxia lens line, the about to be officially announced FE 16-35 f4 and FE 85 1.8 are capable at 36.3 megapixel levels.

Another good resource for this discussion

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Lens lineup for the A7r, Is this what we’re facing… go prime or go home?

Can Sony hit a home run with any future Zoom (Vario) lenses?  Is Sony neglecting part of their audience(A7r) and catering to the A7, and A7s?   Where does the FE lens Road map lead to…  A little town called Undistinguished?  Doesn’t the worlds best full frame sensor deserve the technology in lens design that compliments, not hinders?  I know I wonder….. and are Sony & Zeiss people listening…

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Most current and believed to be authentic FE lens roll out schedule. Courtesy of Sony.Net

Many A7 owners have poured over the Sony FE Lens, Road map.   The first two releases after the mundane 28-70 kit lens, the FE 35mm 2.8, and 55mm 1.8 showed us they can make small, light compact lenses for the system.  The extremely fast 55mm is an exemplary  Sonnar T* design that performs and gets great ratings.  The 35mm, also of Sonnar design, a bit slower, and ratings were down. It’s still a damn good lens.   This is where Sony starts to waver a bit on commitment in my opinion.  The FE 24-70 Vario Tessar was really designed for video it seems.  It’s very light, extremely sharp in the center, and survives well in most situations.  It’s had many bad reviews and doesn’t rate well.  Clearly isn’t designed for a 36.4 sensor however.  There are more than a few of us out there who thought Sony should of delivered more.  The latest release I’m still very un-decided on, the FE 70-200 G F4.  It shows good ratings for a lens in it’s class, and in the few pictures I’ve taken with it, does really well.  Sony’s “G” designation out performed the Tessar lens.

The next lens, due in August, that has everyone holding their breath for, is the FE 16-35mm, F4 ZA OSS, Vario Tessar.   With it carrying the “Tessar” designation, I’m afraid it will be another lightweight, under performing lens, similar in quality to the 24-70 FE(probably expensive too!).  I was really hoping for the “Vario Sonnar” designation.  They have better build quality, are faster and they’ve designed them already for the A mount cameras.  I’m told that in the mirrorless system, with the lens distance not being as far from the sensor as a traditional DSLR, benefits compact design.  The technology is here to make a compact “Vario Sonnar” lens.  It may be slightly larger, under 700g perhaps(two current A mount “Vario Sonnar” lenses weigh in around 900g), but we’d have the versatility and high quality.  Following the debut of the 16-35 is the “G” 28-135mm F4 OSS which I’m very excited about!  If Sony and Sony/Zeiss would use this build quality as the “entry level” lenses for the A7 system, everyone would be better off.

This quest for better lenses and shout out to Sony Executives and Zeiss R & D Department takes me to…  what do the high end users of the A7 line really want?  The Market segment that wants nothing but compact, light design and ease of use, could be the majority.  These lenses aren’t inexpensive and if you’ll give $5 for a $2 wrench…  well…  That’s kool…

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Shi Shi Beach, WA FE 55 Sonnar T*, @F22 1/5 sec, ISO 64 Circular Polarizer, Grad ND Filter

There is a multitude of Sony A7 users who want to push the quality up and are willing to pay for it!   They get to use their legacy glass and want a native lens or two that performs!!!