The Sony NEX3 and NEX5 cameras are ultra-slim interchangeable lens models, referred to as ‘ultracompact’ or ‘compact system camera’ models by Sony. The lens flange to film distance is only 18mm, compared to 44.5mm for the Alpha system and very similar figures for all popular SLR brands.
 
The Leica M and screw mounts, with under 1mm difference between them, are 10mm greater than this at around 28mm. Screw mount Leica lenses can be adapted to M even though there is only 1mm difference. With 10mm difference, almost any lens ever made for any camera – even the Robot system, original Contax, maybe even the Pentax 110 SLR – can probably be adapted to fit the E-mount. In fact it will probably accept 16mm and 35mm (half-frame) ciné lenses, C-mount CCTV lenses, lenses like the 4.5mm Tegea designed for navigation through drains on the end of a mole camera.
 
You name it, the NEX will be able to do it. Telescopes, microscopes, endoscopes, whatever. And Alpha lenses, and MD lenses. There is even enough ROOM with over 25mm the spare to fit a true retrofocus format reduction converter – that is, a 0.66X optical unit which condenses the image from a full frame lens to fit the APS-C sensor. It is already done in the video and ciné world, and these converters have a wonderful bonus. Your 24-70mm f/2.8 SSM lens becomes, with a 0.66X reducing converter behind it, a 16-46mm f/2. That’s right – the same way a teleconverter loses you a stop or two, a format reduction converter gains you a stop.
 
The same converters also increase resolution, much as teleconverters reduce it. Zeiss can achieve 400 line pairs per millimetre from high grade 35mm format movie lenses when rear-converted to reduce on to 16mm or video.
 
Will Sony ever make such a converter? Do they even know that Zeiss have designs, and make exactly this type of converter for Arriflex and other systems via Angenieux? Do they realise that rear fitting format-reduction converters can also perform an AF function, allowing a manual focus lens from Nikon, Canon, Contax, Minolta or whoever to be mounted on a converter which has an ultrasonic AF mechanism of its own?
 
Imagine that – your 50mm f/1.2 Rokkor becomes an autofocus 33mm f/1.0 on the NEX. This is not blue sky thinking, it’s an optical practicality not a mere possibility. However, you don’t want to know the price of Zeiss converters.

The Sony NEX3 and NEX5 cameras are ultra-slim interchangeable lens models, referred to as ‘ultracompact’ or ‘compact system camera’ models by Sony. The lens flange to film distance is only 18mm, compared to 44.5mm for the Alpha system and very similar figures for all popular SLR brands.
 
The Leica M and screw mounts, with under 1mm difference between them, are 10mm greater than this at around 28mm. Screw mount Leica lenses can be adapted to M even though there is only 1mm difference. With 10mm difference, almost any lens ever made for any camera – even the Robot system, original Contax, maybe even the Pentax 110 SLR – can probably be adapted to fit the E-mount. In fact it will probably accept 16mm and 35mm (half-frame) ciné lenses, C-mount CCTV lenses, lenses like the 4.5mm Tegea designed for navigation through drains on the end of a mole camera.
 
You name it, the NEX will be able to do it. Telescopes, microscopes, endoscopes, whatever. And Alpha lenses, and MD lenses. There is even enough ROOM with over 25mm the spare to fit a true retrofocus format reduction converter – that is, a 0.66X optical unit which condenses the image from a full frame lens to fit the APS-C sensor. It is already done in the video and ciné world, and these converters have a wonderful bonus. Your 24-70mm f/2.8 SSM lens becomes, with a 0.66X reducing converter behind it, a 16-46mm f/2. That’s right – the same way a teleconverter loses you a stop or two, a format reduction converter gains you a stop.
 
The same converters also increase resolution, much as teleconverters reduce it. Zeiss can achieve 400 line pairs per millimetre from high grade 35mm format movie lenses when rear-converted to reduce on to 16mm or video.
 
Will Sony ever make such a converter? Do they even know that Zeiss have designs, and make exactly this type of converter for Arriflex and other systems via Angenieux? Do they realise that rear fitting format-reduction converters can also perform an AF function, allowing a manual focus lens from Nikon, Canon, Contax, Minolta or whoever to be mounted on a converter which has an ultrasonic AF mechanism of its own?
 
Imagine that – your 50mm f/1.2 Rokkor becomes an autofocus 33mm f/1.0 on the NEX. This is not blue sky thinking, it’s an optical practicality not a mere possibility. However, you don’t want to know the price of Zeiss converters.