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Is it possible to reverse-mount a mirrorless lens on a DSLR

Started 10 months ago | Questions
Dunlin Senior Member • Posts: 2,593
Is it possible to reverse-mount a mirrorless lens on a DSLR

Obviously a lens designed for a CSC won't work (or mount) on a DSLR, but I'm wondering:

Would a mirrorless lens (canon EF-M) mount on a DSLR (canon EF-S) when reversed?

Thanks

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philzucker
philzucker Forum Pro • Posts: 10,390
Re: Is it possible to reverse-mount a mirrorless lens on a DSLR

Jethro B-UK wrote:

Obviously a lens designed for a CSC won't work (or mount) on a DSLR, but I'm wondering:

Would a mirrorless lens (canon EF-M) mount on a DSLR (canon EF-S) when reversed?

Thanks

I'm not familiar with EF-M mount lenses, but I think it has - as most modern mounts - no mechanically controlled aperture, so the problem in reverse mounting is not the mechanical coupling (no problem here using the right adapter), but control of the aperture.

There are ways for EF-S and Sony E-mount lenses to unmount them with a specified aperture (e.g. IIRC for Sony lenses you must unmount the lens with the desired setting active while the body is still powered on) - I'm not sure if EF-M lenses can be handled comparably. So if you find a way and you can live with a fixed aperture this can work.

It's easier though to reverse mount an older lens with mechanically controlled aperture and dedicated aperture ring. Doesn't matter which mount, then.

Phil

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OP Dunlin Senior Member • Posts: 2,593
Re: Is it possible to reverse-mount a mirrorless lens on a DSLR

Thanks.

But, I'm not doing it, I'm just curious.

Would the (backwards) lens being mirrorless matter?

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philzucker
philzucker Forum Pro • Posts: 10,390
Re: Is it possible to reverse-mount a mirrorless lens on a DSLR

Jethro B-UK wrote:

Thanks.

But, I'm not doing it, I'm just curious.

Would the (backwards) lens being mirrorless matter?

The lens is a lens - it doesn't matter for what system it was designed for. It only matters if you can control its aperture using it reversed. For some lenses with electronic aperture control the aperture can be fixed to a desired value (as I described in my first answer).

And if you stay within the same system, you can use (expensive) retro adapters to use lenses backward with fully automatic aperture control, see e.g. here: https://www.novoflex.de/en/products-637/macro/reverse-lens-adapter-canon-eos.html

Hope this helps!

Phil

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OP Dunlin Senior Member • Posts: 2,593
Re: Is it possible to reverse-mount a mirrorless lens on a DSLR

Gracias.

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ThrillaMozilla Veteran Member • Posts: 7,658
Re: Is it possible to reverse-mount a mirrorless lens on a DSLR

You will probably need the full aperture, or close thereto.  There's the problem.  Many of them close the aperture when they're not mounted on the camera.

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