Question 1

What does the 0.8x Speed Booster do to my M645 lenses on GFX?

Accepted Answer

A 0.8x speed booster is a focal reducer — it compresses the image circle from your M645 lens onto the GFX sensor. In practice, this means your lens behaves like a shorter focal length (multiply by 0.8) and gains roughly one stop of effective maximum aperture. So a 150mm f/2.8 M645 lens effectively becomes around a 120mm f/2 equivalent on your GFX body.

Question 2

Which Fujifilm GFX bodies work with this adapter?

Accepted Answer

The Kipon Baveyes 0.8X is designed for the Fujifilm GFX mount, so it is compatible with GFX-mount bodies such as the Fujifilm GFX 100S, GFX 50S II, GFX 50R, and GFX 100. Always confirm your specific body's mount clearance, but any camera using the GFX bayonet mount should accept this adapter.

Question 3

Which M645 lenses work with the Kipon Baveyes GFX adapter?

Accepted Answer

The adapter accepts lenses with a Mamiya M645 mount, which covers the wide range of manual and auto-focus lenses made for the Mamiya 645 system over the years. These lenses are widely available second-hand and are well regarded for their optical quality, making them a popular pairing with modern medium-format mirrorless bodies.

Question 4

Do I lose autofocus when using this Speed Booster?

Accepted Answer

Yes — M645 is a legacy mount and the adapter does not relay electronic signals, so you will be shooting in manual focus. That said, Fujifilm GFX bodies offer excellent focus peaking and magnified live view, which make manual focusing with adapted lenses very workable, especially in portrait and studio setups where you control the pace.

Question 5

Is buying a used Kipon Baveyes Speed Booster worth it?

Accepted Answer

Absolutely, especially for an all-mechanical adapter like this one. A speed booster has no electronics or moving parts beyond the mount mechanism, so wear is minimal if the adapter has been handled with care. This particular unit comes in very good condition, has been individually inspected, and includes a minimum 12 months warranty — so you get the peace of mind of a checked, covered purchase at a used price.

Question 6

How is the Kipon Baveyes different from a basic GFX-to-M645 adapter?

Accepted Answer

A standard adapter simply spaces your lens at the correct flange distance — it changes nothing about focal length or aperture. The Baveyes version contains an optical element that acts as a focal reducer, actively shrinking the projected image circle. The result is a wider effective angle of view and a brighter effective aperture, which a plain adapter cannot offer. If you just want mechanical compatibility without the optical benefit, a basic adapter costs less; if you want more light and a wider field, the Baveyes is the upgrade worth paying for.

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Kipon Baveyes 0.8X Fujifilm GFX - M645 Speed Booster

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About the Kipon Baveyes 0.8X Fujifilm GFX - M645 Speed Booster

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