Speed Booster

Does anybody think Metabones will ever do a EF-->EF Speedbooster or maybe even an EF-->RF Speedbooster. Canon is bound to have given up a lot of information with the 3 adapters they have just released. All these Manufacturer A to Manufacturer B and nobody's doing anything to help same systems get a whole 'nother stop of light and maybe even more benefit.

Seems a lot of potential revenue is being left on a table that all you'd have to do is rake the money off it.

Why wouldn't somebody do this or tell me why I'm losing my mind and something obvious? Anybody?

No idea what a "speed booster" is, but reverse engineering takes time and it's only been weeks since the r system was announced. Give it time...

No. Speed boosters work when a lens designed for a larger sensor is adapted to a smaller sensor.
eg a lens designed for full frame (35mm) adapted to a micro four thirds sensor. EF and R lenses are designed for the same size sensor.

You could not do EF to EF for both the above reason and also because you can't just add distance between the lens and the sensor. (well you can, but that's an extension tube and you lose the ability to focus at infinity or in the case of some wide angles, lose the ability to focus on anything that is not inside the lens)

You also need a closer focal plane distance so EF to EF-S is also not possible.

Thanks folks. I knew I was obviously missing something. I just didn't know what it was. Good information.

The fundamental concept behind a Speedbooster is that it converts the FL of the fundamental optics to a shorter FL, while the aperture of the lens is unaltered. As Metabones claims, "Speed Booster® increases maximum aperture (hence its name), increases MTF and makes lens wider."
Starting with a 50mm f/2 lens, we know its aperture diameter is 25mm. So if we mount a speedbooster that (hypothetically) does 0.7x magnification of the fundamental FL, we end up with 35mm FL with 25mm aperture or 35mm f/1.4.

The patent explains the effects of FL reducers,

"many have wondered why it isn’t possible to build an “inverse” teleconverter that would reduce the focal length...The short answer here is that the reflex mirror of DSLR’s gets in the way, and makes the design of a true general purpose DSLR focal reducer essentially impossible.

... the spectacular rise of so-called mirrorless cameras. Since these cameras have no need for a reflex mirror, they typically have a very short lens flange to image plane distance compared with SLR cameras with a similar image size....The large difference between the flange distance of 35mm SLR cameras and mirrorless cameras allows for the design and implementation of a wide range of adapters to mount SLR lenses onto mirrorless cameras.

...(An) unavoidable consequence of adding a focal reducer is that the new image is reduced in size compared to the original image formed by the objective. ... if a 0.7x focal reducer is added to an objective and the resulting system must cover a DX format sensor with a 28mm diagonal then the objective by itself must be capable of covering a 40mm diagonal format. Fortunately, all fullframe
35mm SLR lenses meet this requirement since they cover a 43.3mm diagonal format.

Kodak made an interesting attempt to design a focal reducer that maintained the working distance required in SLR cameras, but the system was very complex and was completely unsuitable for large apertures. A little over a year ago it dawned on us that mirrorless cameras might offer a unique opportunity to develop a true general purpose photographic focal reducer with full
correction of all aberrations at a very large aperture. Much to our surprise, after a couple of months of frantic design and patent filing effort we had a pair of designs that were promising enough to proceed to the prototype phase. Actual testing of those prototypes fulfilled all of our expectations.
"

I've had a Metabones Ultra Speedbooster (EF lens to EFM mount) for several weeks now. It's available directly from Metabones through their website (metabones.com) Delivery from Hong Kong took all of 4 days. Works with every Canon EF lens I've tried on it - I have more than a dozen Canon FF lenses going back more than 35 years. It also works well with a Tokina 12-24 APS-C lens, a Tamron 180mm f/3.5, a Rokinon 14mm f/2.8 (a manual focus lens), a Peleng 8mm f/3.5 (ditto). I've done some comparison testing, and in most cases sharpness matches or exceeds the native resolution. It even works well with a 1996 vintage Tamron 28-200mm F/3.8-5.6 Aspherical IF LD Super (171D) lens I bought in a bundle with a 50mm f/2.5 Macro and assorted other goodies. The reviews I've read state that the center resolution of the Viltrox is comparable to the Metabones, but in the edge and corner resolution, the Metabones is a LOT better. My favorite combo is the EF 35mm f/2.0 IS , the Metabones Ultra, and the M5. This give me a FF equivalent of a 40mm f/1.4 IS - very useful for existing light work.
For less exacting work, my ancient EF 70-210mm f/4.0 push pull, which is quite mediocre on the M5, becomes a fairly good FF equivalent 80-240mm f/2.8 lens. Yes, what they claim is true here - at equivalent focal lengths, the resolution with lenses such as this actually increases.

I'm quite happy with mine.

The speedboosting thing and the relative long flange back distance of the Canon EF mount was the reason while I bought 4 years ago a Sony Alpha 7II.
Since then I use a lot more different speedboosted lenses than with Canon EOS 5D.

Choderboy wrote in post #18766560
No. Speed boosters work when a lens designed for a larger sensor is adapted to a smaller sensor.
eg lens designed for full frame (35mm) adapted to a micro four thirds sensor. EF and R lenses are designed for the same size sensor...

While nearly correct, it is not completely exact.
A lot of lenses designed for 24x36mm actually have a lot larger image diameter than 43mm. Beacuse of this I can use for example some Canon FD lenses with 0.7x speedboosting on the my Sony fullframe camera.
Or others use fullframe lenses on GFX "medium" format cameras.

I have the $150 viltrox booster for the M series and it is very nice. It only works with FF image circle lenses, thus not for the EFS lenses which already have image circles just fitting the APSC sensor.

I love my new Sigma 35mm f1.0 lens!

Wilt wrote in post #18766737
The fundamental concept behind a Speedbooster is that it converts the FL of the fundamental optics to a shorter FL, while the aperture of the lens is unaltered. As Metabones claims, "Speed Booster® increases maximum aperture (hence its name),

Well, they didn't word that very well. Speed boosters and TCs do not change apertures; they change focal lengths and f-ratios. What they should have said is, "Speed Booster® decreases minimum f-ratio (hence its name)".