IDEA: Anamorphic Metabones Adapter

[Guest]

Hey everyone! had an idea...

 

What if for lenses that go from full frame to APS-C or M4/3 sensor cameras, why doesn't metabones (or any other comapny) make a rear end speedbooster, that instead of decreasing the whole image to fit the sensor size, they only focus the horizontal part of the image, leaving the vertical part uncompressed.

 

For APS-C lenses, this would result in a 1.6 squeeze factor from a full frame lens. That would be an excellent aspect ratio, as it is just over the isco 1.5x standard squeeze.

 

Think about it! You could turn any full frame lens in to an anamorphic lens, with just an adapter! Now of course it would be nearly as bright as a normal metabones adapter, since not all of the light is being focused on to a smaller area, but this was just an idea I had.

 

I have no background in lensmaking so I have a feeling im being horribly ignorant about this. Still, fun to dream huh?

 

Thoughts?

[Timotheus]

Cool idea. No idea about feasibility though. The designer of the Metabones Speedbooster actually visits this forum: @Brian Caldwell. Perhaps this mention invites him to a reaction ;-)

[valid]

part of the issue is that rear anamorphics (these are already a thing - often used on zooms) don't create the traditional anamorphic artifacts/aesthetic in the image...

[BrooklynDan]

It's probably feasible, but it wouldn't be cheap. In the past, rear-adapted zooms were used out of necessity since it's just not possible to build a front anamorphic zoom with a 10-to-1 ratio. That said, they had a reputation for being soft and generally low in quality compared to primes. The rear anamorphic unit costs you one stop of light, and you had to stop down more in order to get a sharp image, rendering these old Angenieuxs and Cookes useless expect in day interiors and brightly lit studios. But what were you gonna do in the 70s without a zoom? It's the 70s, dude! Zoom, baby, zoom!

That said, you can get better results with modern adapters, but they don't come cheap. The ones Duclos makes go for $11K a piece, and they're not just slipped on to the lens. They have to be adjusted by a lens technician and semi-permanently attached. The alignment must be perfect or the image goes to mush. You're inside the flange focal distance of the lens, so there's no room for error. Not sure how you would go about doing with with flimsy, shaky DSLR mounts.

And as others said: no flares, no oval bokehs, no real anamorphic characteristics.

[Brian Caldwell]

On 2/25/2016 at 2:24 PM, Timotheus said:

Cool idea. No idea about feasibility though. The designer of the Metabones Speedbooster actually visits this forum: @Brian Caldwell. Perhaps this mention invites him to a reaction ;-)

The main technical hurdle is that focal reducers reduce the physical length of a lens in addition to reducing the focal length.  So if you simply build a focal reducer from cylinders you would wind up with many millimeters of astigmatism throughout the image.  An even bigger concern, as valid points out, is that you don't get any of the desirable anamorphic artifacts with a rear anamorphic attachment. 

[tweak]

This one comes up every few months .