Would a 17-55mm EF-S work on a Lumix G7 with a speedbooster?

I have a Canon 17-55mm f2.8 EF-S lens and I was considering using a viltrox speedbooster ef-m2 to mount it on my G7. I know that it has a protruding plastic thing but I've seen some videos of people removing it and it might work but I've never seen actual footage of it working (video tests etc.)
Has anyone tried this? Would it be reliable and how much vignetting will there be.

I believe EF-A lenses will not fit on a speedbooster. (The back of the lens protrudes too far and would hit the lens of the speedbooster.)

Sure the plastic ring can be removed. But the ring is there because EF-S lenses can have a rear element that can protrude further backwards. So the rear element may touch the front element of the speedbooster. Not every EF-S lens protrudes equally far back though, so some may work and some may not. (It's been too long since I used Canon with the 17-55, 18-200, 17-85, 10-22... so I cannot tell you which goes back the furthest.

Tom Caldwell wrote:

Paul De Bra wrote:

Sure the plastic ring can be removed. But the ring is there because EF-S lenses can have a rear element that can protrude further backwards. So the rear element may touch the front element of the speedbooster. Not every EF-S lens protrudes equally far back though, so some may work and some may not. (It's been too long since I used Canon with the 17-55, 18-200, 17-85, 10-22... so I cannot tell you which goes back the furthest.

These EF-S lenses were made specifically for the Canon dslr bodies that used the aps-c sensor with a smaller mirror. Their FF camera bodies used a larger mirror and there was a potential issue in use of an EF-S lens on FF bodies as the rear protrusion might be hit by the mirror operation when mounted. EF-S had a slightly different mount connection but was compatible with the EF mount. Canon satisfied the collision issue by simply specifying that a rear baffle was added to the rear of the mount so that they simply could not be mounted on a FF dslr body.

This baffle prevents the same lenses being mounted on focal reduction adapters.

Happily none of the third party manufacturers adopted the EF-S specification and used a baffle for their aps-c image circle lenses for Canon dslr bodies. They simply made them in EF mount specification and carefully made sure that the rear protrusion did not interfere with the mirror action.

Note that this was all done to protect the mirror/rear-element of aps-c EF mount lenses for dslr bodies. Nothing to do with normal rear protection and implemented well before electronic focal reduction adapters were introduced.

I have seen how-to instructions for modifying one of the Canon EF-S lenses by surgically removing the baffle. I don’t have this lens, and have no intention of getting one. I do have the Canon EF-S 55-250 STM lens which works very well on standard EF-M4/3 electronic adapters in general. I have carefully looked at this lens and decided that there is no way that the baffle can be removed without destroying a perfectly good lens in the process.

I suppose that other EF-S lenses also have their baffles constructed in such a way that they are very hard/impossible to remove in order to be able to use focal reduction. I believe that only one can have the baffle removed without destroying the integrity of the mount construction.

But I have happily bought four Sigma DC (aps-c) lenses in EF mount and they fit and focal reduce S-AF happily without any modification needed.

Therefore if you have EF-S lenses they are not really suitable for mounting on any focal reduction adapters. But glassless adapters are ok.

As Tom nicely stated, the glassless adapters work well.  Try the Viltrox M1 for your EF-S and EF lenses.  All my Canon lenses work well on my EM10II using the M1 adapter.

RobBobW wrote:

...

As Tom nicely stated, the glassless adapters work well. Try the Viltrox M1 for your EF-S and EF lenses. All my Canon lenses work well on my EM10II using the M1 adapter.

A glassless adapter is not a speedbooster. The speedboosters have glass to concentrate the light onto the smaller m43 image circle, thus getting more light and hence a "speed boost". An adapter with glass may have problems with EF-S lenses where the rear lens element does come further back than in EF lenses. But they also pose the problem that the image circle reduction performed by the speedbooster adapters may cause vignetting because the input image circle is not full frame.

Paul De Bra wrote:

RobBobW wrote:

...

As Tom nicely stated, the glassless adapters work well. Try the Viltrox M1 for your EF-S and EF lenses. All my Canon lenses work well on my EM10II using the M1 adapter.

A glassless adapter is not a speedbooster. The speedboosters have glass to concentrate the light onto the smaller m43 image circle, thus getting more light and hence a "speed boost". An adapter with glass may have problems with EF-S lenses where the rear lens element does come further back than in EF lenses. But they also pose the problem that the image circle reduction performed by the speedbooster adapters may cause vignetting because the input image circle is not full frame.

Thanks for the clarification.  I was offering the OP a way to use their lenses without a speed booster.