Speed Boosters®

When I attach a 50/1.4 lens, my camera displays F/1.4 instead of F/1.0. Is this a bug?

No, this is not a bug, but a deliberate design decision on our part. Many cameras do not support apertures faster than (numerically smaller than) f/1.0. Therefore, with a Speed Booster®, the boosted aperture is displayed on the LCD screen only when a f/1.8 or slower lens is attached. If a fast lens (f/1.4 or faster) is used, the original pre-boost aperture is displayed, even though the actual aperture used is faster. Please take this into account when transferring exposure settings from a light meter. Also rest assured the boost is there both optically and with respect to automatic exposure.

In our experience, many cameras have erratic aperture operation and unpredictable behaviour when the lens reports an ultrafast aperture electronically. Note that the EXIF standard itself does not define apertures faster than f/1.0 (i.e. It is not possible to have a standard-compliant image file with metadata saying that the aperture is, say, f/0.9), so even if the camera body accepts f/0.9 correctly we are still unsure but we cannot guarantee that all software you use to post-process your images downstream in your workflow will play just as nicely. Between being falsely accused of being "buggy" or risking your valuable work, we have absolutely no qualms going for the former.

This "feature" is testament to how revolutionary the Speed Booster® is! Who would have thought that the "f/1.0 barrier" would not only be breached (for digital photography) but become commonplace, were it not for the advent of Speed Booster®?

Help! I want to go to f/22, but now I can't!

Note that Speed Booster® boosts not only the maximum aperture of the lens, but minimum aperture as well.

I want to use my Leica M, Contax G, Contax rangefinder and Nikon rangefinder lenses on Speed Booster®!!!

Sorry folks, but there is not enough room for the optics. An SLR lens is required, such as Leica R or Contax C/Y. Rangefinder lenses won't work.

Will there be Speed Boosters® for DSLR camera bodies?

No. The mirror gets in the way but there is no room for the optics.

No. Unfortunately, it is not possible to fit the optics inside the Samsung NX mount owing to flange distance and physical interference issues

Why don't we have a 0.5x MFT Speed Booster® for Micro Four Thirds?

With the amount of available room prescribed by the MFT mount, 0.71x is the lowest we can go while maintaining compatibility with the broadest range of MFT cameras. Our MFT Speed Booster® XL 0.64x has a protruding rear element which does not fit every MFT camera and it is the lowest we can go without compromising image quality. We do have a 0.5x Speed Booster® but that is for the Pentax Q mount, made possible by its smaller sensor.

Does Speed Booster® for Nikon G lens work with Nikon F lens?

Yes! Nikon G supports not only Nikon G lenses, but Nikon F mount lenses, too, including non-AI, AI, AI-S, AF, AF-D, AF-I, AF-S, etc., etc. However it does not have any electrical contacts and does not support autofocus, optical VR, or E-series Nikkors with electronic aperture diaphragms.

Do the aperture rings on some Speed Boosters® have click stops?

Contarex, Nikon G and Sony A-Mount Speed Boosters® have integral aperture rings to adjust the aperture of the lens. The aperture ring on Contarex Speed Booster® has no click-stops.

Since September 2013, Nikon G Speed Boosters® are shipped with no click-stops, with optional parts included to convert it to clicked operation. Cinematographers who purchased the first batch of Nikon G Speed Boosters® may contact Metabones for conversion to clickless operation.

How does Speed Booster® affect the depth-of-field?

The short answer is Speed Booster® on an APS-C sensor gives essentially the same depth-of-field effect as if a full-frame camera body were used.

The long answer is complicated. If we are referring to depth-of-field in the mathematical sense, that depends on the aperture, magnification and circle of confusion (CoC). Magnification in turn depends on distance and focal length. The 50mm lens now becomes a 35mm lens which behaves very differently in terms of perspective. The question is, do we still keep the distance the same? Should the CoC be kept the same? There are many missing variables we need to choose and fill-in before we could get a meaningful answer. When people claim Speed Booster® does not change the depth-of-field, they usually neglect to state the implicit assumption that the distance is kept the same (thereby changing the object size) and the CoC is kept the same. The same logic would lead to the conclusion that an APS-C camera has the same depth-of-field as a full-frame camera, too, which under the same implicit assumptions is mathematically true (the depth-of-field formula is format-size-agnostic, after all), but with which many people would disagree from practical experience.

However, when most people ask about depth-of-field, they are not interested in mathematics, but rather, they are after a certain kind of shallow depth-of-field "look". If this is the case, the short answer above applies.

How does Speed Booster® affect bokeh?

From practical experience, Speed Booster® has negligible effect on bokeh. In most cases the resulting bokeh is that of the lens alone. Speed Booster® does not leave its own "character" or "signature" in the pictures. It is very neutral.

Why is there so much confusion about all these focal length multipliers?

"Equivalence" has always been a confusing topic. Speed Booster® does not make it any more confusing than it already is!

Focal length, maximum aperture and depth-of-field are physical quantities that do not care about the size of the sensor sitting behind the lens. Speed Booster® physically reduces focal length and increases maximum aperture (smaller f-number) of the lens.

The "35mm equivalent focal length" is not a focal length at all, but a measure of field of view (FoV). Speed Booster® physically reduce focal length by a factor of 0.71x and the APS-C camera body reduces FoV by a "cropped factor" of approx 1.52x, so the 35mm equivalent focal length (cannot be overemphasized this is a FoV measure) of the combined system is approximately 1.08x.

Once we are very specific about whether we are referring to a physical quantity or a 35mm equivalent measure, it is no longer confusing!

Does the Speed Booster® increase only T-stop of the lens leaving F-stop unchanged?

This is one of the common misconceptions about the Speed Booster®. However there is a contradiction right within that assertion since T-stop cannot be any faster than F-stop. It is not possible to experimentally observe a T-stop increase unless the lens has a corresponding F-stop increase.

The logic of the allegation is that since the depth-of-field of the lens does not change, therefore neither does the F-stop of the lens (untrue). What had never been under any dispute was that the T-stop of the lens did increase, as could be seen with the increased exposure in the resulting footage or photograph.

Before we clear up this misconception, let's find out why there is so much confusion in the first place. Focal length, maximum aperture and depth-of-field are physical quantities that are independent of sensor size. These quantities do not care whether a full frame, APS-C or m4/3 sensor sits behind the lens.

Speed Booster® makes the focal length 0.7x shorter. F-number is simply focal length divided by entrance pupil diameter. Since the former reduces by a factor of 0.7x but the latter remains the same, F-number also becomes 0.7x smaller, or one stop faster. The F-stop increase is real.

Note that a 35/1.0 lens (from 50/1.4 + Speed Booster®) will always have shallower depth-of-field than a straight 35/1.4 lens at any given distance.

Compatibility (Canon EF lens)

Is my Speed Booster® or Smart Adapter™ compatible with full-frame camera bodies?

Smart Adapter™ I, Smart Adapter™ II, Speed Booster®, Speed Booster® ULTRA, Speed Booster® ULTRA II and CINE Speed Booster® are NOT compatible with Sony E-Mount full-frame camera bodies. If the full-frame camera body is configured to auto-crop mode, cropping will be automatically applied and only the center of the frame will be used.

Smart Adapter™ III/IV/V and CINE Smart Adapter™ have a large rectangular opening and is compatible with full frame camera bodies. It will detect whether the Canon lens used is a full frame lens or a cropped lens and inform the camera body accordingly, if the camera body is configured to auto-crop mode.

Can I use a manual focus lens with the Smart Adapter™ or Speed Booster® for Canon EF lens?

When a manual focus lens with no electronics whatsoever is attached to the Metabones EF Lens to E Mount Smart Adapter™/Speed Booster® , the electronics of Smart Adapter™/Speed Booster® is completely turned off, and behaves as a dumb adapter.

However, proceed with caution when stacking another mount adapter on top of Smart Adapter™ or Speed Booster®. The following is a non-exhaustive list of common issues found in the past.

Some Canon EF mount adapters with focus-confirmation "chips" may be incompatible with Smart Adapter™ or Speed Booster®. Remove the "chip" from the Canon EF mount adapter before using on Smart Adapter™ or Speed Booster®.

Some improperly-made M42 screw mount lens to Canon EF mount adapters may short the electronic contacts of the Smart Adapter™ or Speed Booster® which may cause serious damage.

Some manual focus lenses (e.g. OM 28/2.8, OM 50/1.8 and Leica-R 15/3.5) have rear protrusions which may scratch or damage the optics or the housing of Speed Booster®. Such lenses need to be modified before they can be safely deployed.

Check and make sure there are no rear protrusions before attaching the manual focus lens/adapter combination onto the Speed Booster®. Any damage caused by rear protrusions is NOT covered by warranty.

Does Canon Lens Image Stabilization (IS) work?

Yes, IS is supported. The Canon IS lens is powered by the camera body and no external power source is required.

Is this adapter going to be compatible with all future cameras and all future Canon lenses?

We are not sure. We are not licensed, approved or endorsed by Blackmagic Design, Canon, JVC, Micro Four Thirds, Olympus, Panasonic or Sony. Our Smart Adapter and Speed Booster® were developed independently without any involvement by the aforementioned companies. We do not have complete specifications of the respective mount communication protocols and we are unable to foresee what will happen with every future camera or Canon lens. The firmware stored inside our Smart Adapter is upgradable. If a compatibility issue does arise in the future we will attempt our best to come up with a resolution.

Operation (Canon EF lens)

Why is the mount so stiff? It is hard to attach the lens!

Your Metabones® adapter is optimized for video work, and one very important requirement is for the mount to not wobble or move while the zoom and focus rings are operated. This means lens mounting is tighter than OEM. Unfortunately this leads to a slight inconvenience when mounting and dismounting the lens. You may want to disassemble the mount ring on the adapter and weaken the 3 leaf springs underneath using a plier if your application is still photography and you prioritize ease of use over solid mounting.

[Micro Four Thirds] I lost iris control on Panasonic/JVC! How come?

The most likely explanation is that the jog lever on the adapter is accidentally flicked, which activates iris control using the jog lever on the adapter instead of controlling iris by the camera. In this situation, simply push the jog lever inward and it will relinquish control, giving iris control back to the camera again.

[E-mount] When I open up the iris the footage becomes very bright momentarily before going back to normal. Is there a problem?

If you have an older camera, such as NEX-VG10, you may use the Advanced mode instead.

If you have a newer camera, such as the A7 series, update the firmware to version 41 or newer.

Technically, this is not a bug, but behaviour carried-over from Sony's own LA-EA1/LA-EA3 adapters, which exhibit the exact same "flicker" behaviour when opening up the iris. Whenever the camera opens the iris it always go all the way to wide open first, and then stop down to the selected aperture.

Owing to popular demand, however, adapter firmware V41 has new logic to detect and eliminate that flicker, even in Green mode, except for older camera models such as NEX-VG10.

Why does Auto-Magnify work with only some of my lenses?

The Auto-Magnify MF Assist feature requires the AF/MF switch of the Canon EF mount lens to be set to the MF position and also requires a Canon EF mount lens that supports distance information. Virtually all Canon lenses introduced in the last 20 years support distance information, but a number of notable lenses, such as EF 35/2 (non-IS), EF 50/1.0L and EF 50/1.4, do NOT support distance information and do NOT support auto-magnify MF assist on a Sony E-mount camera body. In addition, the Smart Adapter or Speed Booster® needs to be configured to run in Advanced Mode to enable the auto-magnify feature.

Image Stabilization remains activated even when I am just browsing the camera's Setup menu.

Resolution (E-Mount): put the Metabones Smart Adapter in Green Mode.

For MFT, multiple suppliers of camera bodies each with a slightly different methodology for IS support means Metabones® tends to err on the safe side and turns on IS more than necessary to ensure that it is always activated when required. We had experimented with heuristics which correctly turned off IS when not required on one camera body that did not work on another camera body. We could only ship features and optimizations that work across all cameras we claim to support.

Is stepless aperture supported?

No. Canon EF lenses are originally designed for still photography and do not support certain advanced features required for cinematographic use. The aperture diaphragm moves in 1/8 stop steps. However, the latest lens models (Canon 2009+, Tamron 2013+ and Sigma 2016+) support a feature called (by us) smooth iris. The iris still moves in 1/8 stop steps, but in video mode it moves smoothly to avoid abrupt changes in the footage. In addition, we support Canon CN-E lenses with our E-Mount and MFT Speed Boosters® and Smart Adapters and being designed exclusively for cinema use the CN-E series does support "stepless" aperture.

Is an external power source required?

No. The Canon lens is always powered by the camera body and no external power source is required, unless the camera itself has no electrical contacts, as is the case of the passive MFT mount of the original Blackmagic Cinema Camera.

Why does the camera body display f/1.3 when I use the EF 85/1.2L wide open?

Different cameras may display aperture values differently.

Some cameras display the apertures as F1, F1.1, F1.3, F1.4, F1.6, F1.7, F2 and so on, but a Canon camera body displays the exact same apertures as 1.0, 1.1, 1.2, 1.4, 1.6, 1.8, 2.0 and so on.

They are the exact same apertures, but different companies choose to round them and display them differently. Mathematically speaking you multiply each f-number by 1.122462 to get the next f-number 1/3 stops down. The actual f-stop sequence, rounded to 2 decimal places, would then be 1.00, 1.12, 1.26, 1.41, 1.59, 1.78, 2.00.

Why does the camera body display f/5.7 when I put on a f/5.6?

Another example of rounding error. f/5.6 is four times the square root of 2, or 5.657. If you round up it becomes 5.7.


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