New A7 with focusing sensor

[ernesto]

This is just a comment I found in the web, but if confirmed, it will be a great step ahead in the Mirrorless Fullframe category.
The system would consist in a moving digital sensor plane, to perform focus, instead of moving heavy glass elements inside the lens.
This will enable to have an autofocus system with old analog optics, which will have to stay focused at infinit.
This concept is analog to the last move by Sony: their image stabilizer also based in the movement of the sensor plane, so looks like the natural step ahead considering that all the mechanisms were developed, and perhaps just need a simple adjustment to get further to this new use of the moving sensor.

There was a model by Zeiss, Contax RTS III, 1990 which did the same with film rolls. It was a really complex solution at that time.
Here you have more info:

http://www.ayton.id.au/wiki/doku.php?id=photo:kl:dslr:dslr_end6

Ernesto

 

[Huss]

There was a model by Zeiss, Contax RTS III, 1990 which did the same with film rolls. It was a really complex solution at that time.

I think you mean the Contax AX.

 

[rbelyell]

yes, the contax ax, one of my favorite cameras, and a product of brilliant engineering.

btw, wasnt there a hubub a year or two ago when sony applied for a patent for this tech? is this indeed the next A7 incarnation? if so, that is quite an imminent possible game changer...

 

[sevo]

The downside is that it will not get the full performance out of lenses that have multiple focusing elements or which are group rather than unit focusing - making it a non-zoom, slow lens only system.

 

[ernesto]

I think you mean the Contax AX.

yes you are right.

 

[Scapevision]

The downside is that it will not get the full performance out of lenses that have multiple focusing elements or which are group rather than unit focusing - making it a non-zoom, slow lens only system.

I really don't see anything preventing you from setting the lens to whatever you want and having the sensor autofocus on that

 

[splitimageview]

The upcoming Techart adapter will accomplish something quite similar

 

[ernesto]

The upcoming Techart adapter will accomplish something quite similar

What is that? Can you complete the info?
Thanks

E

 

[newst]

ernesto,

Check out http://techartpro.com/

This is supposed to provide auto-focus for M lenses on late model Sony Full Frame mirrorless cameras.

 

[sevo]

I really don't see anything preventing you from setting the lens to whatever you want and having the sensor autofocus on that

Yes, but what for? If the camera can choose to use both the in lens and in camera AF, it will consistently pick the (in the said cases superior) former. That makes it a strictly third party (MF) lens AF solution. It is rather unlikely Sony will add that - other than Contax back then, they do not have any back catalogue of their own MF lenses to cater for (and even the Contax AX was a desperate stop-gap solution that was followed up with a proper AF system within two years)...

 

[Larry H-L]

I've always wondered, when using an "M-mount" close focus adapter on my A7s, if using the len's focus ring rendered differently from using the close focus adapter to move the entire lens forward.

It seems as if there are slight differences in the out-of-focus areas, but maybe that is my imagination.

 

[rbelyell]

im not sure im following the discussion on why this is a non event, but let me correct one thing: many lenses could be adapted to the contax ax, not just their 'backlog' of contax lenses. i adapted many lenses, including if i remember correctly m42 and some medium format zeiss lenses, to very good effect on the ax. unless there is science to the contrary, i do not understand why any lens that can be adapted to E mount wouldnt work just great on this new sony.

 

[Highway 61]

Given the amount of distance the focusing group of some legacy MF lenses (depending on their optical formula) has to run from infinity to close-up I am not too sure that this is even possible to make an in-camera AF system relying on a sensor having to move forth and back, unless that mirrorless camera body is considerably thick.

I'll believe it when I see it. For now I think it's just a hoax.

 

[sevo]

It seems as if there are slight differences in the out-of-focus areas, but maybe that is my imagination.

It probably is - there would only be a difference in lenses that are not unit focusing - but almost all M lenses are. Thanks to the rangefinder coupling (which would create a rather delicate link to the usually very small movements in a interior focusing lens) the M is the one system where IF lenses are scarce. The WATE Tri-Elmar-M is the only IF M lens I am immediately aware of, as they promoted that as a particularly complex feature on its release - perhaps the earlier normal Tri-Elmar does it too, but that might be all there ever were.

 

[splitimageview]

This is supposed to provide auto-focus for M lenses on late model Sony Full Frame mirrorless cameras.

Or any lens that's been adapted to M mount...

I've always wondered, when using an "M-mount" close focus adapter on my A7s, if using the len's focus ring rendered differently from using the close focus adapter to move the entire lens forward.

In theory a lens such as the 35/1.4 FLE would render differently if the camera focused via sensor shift to a close-focus point vs if the lens focused via the helical, which would engage the floating element.

Don't know if this would be noticeable or not.

I guess we'll find out soon enough when the Techart adapter ships. It's technically not sensor-shift, but the entire lens moving in relation to the sensor has the same effect as the sensor moving in relation to the lens.

 

[sevo]

i do not understand why any lens that can be adapted to E mount wouldnt work just great on this new sony.

It sure would. It is not a question of convenience, to a limited set of buyers, but a problem of profitability. A complex (and accordingly expensive) camera that does only cater to users of other makers lenses would have to be priced so that it is profitable on its own, outside the system (regular camera bodies are priced at a fairly low margin, on the strength of the lenses they will sell). But how many people would buy a camera considerably more expensive than the A7RII just for the ability to cut costs in the lens domain by AF-enabling lower end adapted MF lenses? I propose that that would be two different buyer groups - the ones ready to buy a very expensive body would be the same interested in modern expensive top of the line lenses, which however would be below average performers as such a focusing system bypasses their IF.

If we ever see something vaguely similar in a E mount Sony, it will be microfocusing right on the ISS, to supplement lower end Sony lenses with slow AF motors - they just introduced such a lens, so they do now have a application for such a (essentially firmware only) solution that would make these lenses a bit more responsive.

 

[rbelyell]

well, i'm not sure we know it will be 'considerably more expensive than the a7r2'. i am also not sure why it would preclude use of native sony lenses. is there any evidence either is true? if not and we're just 'spitballing', my bet would be neither will be true, and that it will be just another next gen a7 with added capability, just as was the 'new' capabilities of the a7s.

 

[Peter Jennings]

I didn't click on the link, and this thread is my only source of knowledge on this subject, but in reading it something occurred to me. My guess is that this technology is aimed at increasing the speed of autofocus for native lenses. For example, if shooting pics of your kids playing in the grass about 15 feet in front of you where the change in focus distance is very slight, the camera's computer would switch to making slight shifts of the sensor plane - where the autofocus technology already resides - for making focus adjustments. I would think that this has the potential to be much faster than refocussing the lens. Any large change in focus distance would be handled by the lens.

 

[splitimageview]

Yes, and moving a relatively light sensor is much quicker than moving a big piece of glass...

 

[ernesto]

ernesto,

Check out http://techartpro.com/

This is supposed to provide auto-focus for M lenses on late model Sony Full Frame mirrorless cameras.

Great stuff newst!

I have realized that the potential of the moving sensor is huge.

Appart from the focussing function, and stabilization function, there could be more options:

1) For instance you could reproduce a shift and perhaps tilt function without any special lens or adapter.

2) It could be possible to shot a 35mm full frame picture with a small sensor, since it could slide from one side of the frame to the other in a pretty similar way to a shutter curtain covering the full frame. It should work in a similar way as the panorama sweep option, although it will move the sensor rather than the camera.

Perhaps more that I cannot imagine now

Ernesto