Are Full Frame SLRs Obsolete?

Started Jan 4, 2014 | Discussions thread
ultimitsu Veteran Member • Posts: 6,650
Re: Are Full Frame SLRs Obsolete?

Colin Smith1 wrote:

Accurate, fast tracking autofocus is also a difficult problem for MFT manufacturers to overcome.

Actually it isnt. on-sensor PDAF is become the normal. Once it is matured, which is soon, mirrorless should have the same accurate AF tracking.

On the other hand, inherent lag in LCD view finding may be harder to overcome.

Also I wonder if the effect of shutter shock is increased by longer focal lengths? Maybe that is why no MFT companies are currently offering a fixed focal length lens over 300mm that is not a zoom???

It is important to understand two things:

First, m43 has no inherent "reach advantage". A 300mm lens is a 300mm lens, it only has the optical magnification of a 300mm lens, on any camera. M43 happens to have higher pixel density than FF cameras, that can translate into reach advantage. But there are several caveats:

  1. in 16mp vs 16mp (e.g. Df vs EM5) there maybe 100% more reach in everything was perfect, but in 36 mp vs 16mp (e.g. D800 vs Em5)  there is only 33% more reach.
  2. in reality 4 fold of pixel density does not translate into 4 fold of resolution because lens imperfection eats up some of that extra resolution. For example, when using 50 F1.8G wide open, D800 only delivers extra 60% resolution while having extra 200% the pixel density. Very roughly, I would estimate 4 fold pixel density lead to about 80-100% resolution increase in real world. and you have to square root that to get the "reach", so it is about 30% to 40% more reach even for EM5 vs Df
  3. there really is no theoretical limitations stopping FF cameras from having equally high pixel density. I think soon we could see FF sensors with higher pixel density in the center, allowing more resolution in "cropped mode", while in "full sensor mode" it would use pixel bining for the centre.

Second, as lenses get longer, optical magnification becomes a lot more important than the optical perspective. What I mean is, for example, some people would prefer the look of 85mm over 70mm for portrait, so they buy 85mm for portrait; or they prefer 35mm over 40mm for photo journalism. Optical magnification does not matter at these FL, every lens will produce very sharp images. but as you move into 300mm+ FL, optical magnification is all that it matters, people do not choose 500mm over 400mm because they like the compressed look more, but because 500mm has extra 25% reach. while m43 companies can argue their 45mm will produce close enough results as 85mm on FF, they cannot argue their 400mm lens will produce close enough results as 80mm on FF. the optical magnification just isnt there.

The only partly answr your question, there are yet more reasons why long lenses dont exist on M43.

1, while you can get away with F5.6 equivalent lenses for slow moving subjects - like F2.8 zoom for casual people shooting, you cannot get away with F11 equivalent lenses for fast moving subjects. like 400mm F5.6 for birding on M43

2, longer lenses uses more power to drive AF,

3, large aperture long lenses defeat m43 size advantage.

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MOD Mako2011
MOD Mako2011
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