Fotodiox Pronto – auto focus vintage lenses on your Sony Alpha

The Fotodiox Pronto is an adapter that lets you auto focus vintage lenses on a Sony Alpha series camera.

It’s not a magic trick

Surely you can’t get a manual focus lens to auto focus. It’s not some sort of magic, but rather a clever trick where the Pronto uses Sony’s Phase Detection auto focus data to position the lens so that accurate focus can be obtained. All you need to do according to Fotodiox is set a compatible manual focus lens to infinity and attach it to your camera, and presto, auto focus.

Everything old is new again

Fotodiox Pronto adapter
Pronto adapter on a 120 year old Bausch & Lomb lens

Some old lenses can be difficult to focus, due to their soft optics and mechanical design. Pronto is designed to let you use Nikon G, Contax, and Leica R lenses just to name a few on cameras such as the a7 II, a7R II and a6500. The Pronto comes in Leica M mount and you need to use another adapter to make it work with other lens mounts. So for example, if you were going to use a Nikon G lens you would need to use a Nikon G to Leica M adapter and then mount it to the Pronto.

Above you can see the Pronto adapter mounted to a Bausch & Lomb large-format film camera lens from 1897. It’s crazy to think you can auto focus a lens that is more than 100 years old.

How to use

Fotodiox Pronto adapter
Fotodiox Pronto adapter

Once you attach the lens and set it to infinity all you need to do is half-press the shutter button to activate AF and the Pronto adapter will focus your lens just like any other AF lens. The way it works is the adapter physically moves your lens backwards and forwards, changing the focal plane. Fotodiox say that performance is optimal with 50mm and wider lenses. Telephoto optics with require coarse manual focusing before use of the adapter for fine tuning via autofocus.

The adapter even lets you improve close focusing by attaching your lens and setting it to the closest focus distance possible. This setup will allow you to use the Pronto adapter as a 4.5mm extension tube with autofocus capabilities that will significantly shorten the minimum focus distance of your lens. The wider the lens, the stronger the effect will be.

Auto focus modes

Fotodiox Pronto adapter
The Pronto adapter supports AF-S and AF-C focusing. You can change the Focus Area from Wide to Center or Flexible Spot (S/M/L). Decreasing the focus area comes with a significant reduction in speed and may produce some focus hunting. Face detection and 5-Axis Stabilisation are also supported. The Pronto will not work using it with Contrast Detection AF only cameras such as the Sony NEX, α6000, Sony α7, Sony α7R, Sony α7S, Sony α7Sii, etc.

The adapter relies on phase-AF, and does not support all the AF features of your camera. The Eye AF & Lock-on AF do not function properly.

Things you need to be aware of

• The motor, which changes the length of the Pronto adapter, will make some noise. This noise is said to be minimal and should not be a hindrance in most situations.
• If the adapter seems slow to respond, disassemble the lens and adapter. Clean both sides of the adapter’s signal contacts with technical grade alcohol. Allow to completely dry before re-assembly.
• In bright lighting situations the adapter focuses nearly as fast as a native AF lens however, in lower light the autofocus slows significantly.
• The Pronto adapter may slowly drain your camera battery even when the camera is turned off. To prevent this issue when the camera is not in use simply remove the battery briefly and insert it again.
• The weight limit for attached lenses is specified to be 680g or less. Using lenses with a greater weight may result in extra strain on both the motor and the mount.

Compatible Cameras
Sony α7(II) , Sony α7R(II) , α6300 , α6500 and α9

Compatible Lens mounts
Alpa 35, Contax/Yashica, DKL, M39, M42, Nikon G, Olympus OM, Pentax K, Leica R, and T-Mount

The Pronto adapter retails for $329.95US and is available to purchase right now. What do you think of the adapter? Is it a clever idea or a bit of a gimmick? Let us know in the comments section below.

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