Sigma 35mm f/1.4 not working with metabones speedbooster xl ef-m4/3

[A-Furry-Peanut]

The aperture seems to only go as far as 1.4, but with the speedbooster xl, this should be larger by 1.3 stops. I checked the metabones website and the lens was not listed in their compatibility list, but they did mention that their speedbooster should work with most ef lenses. Does anyone know if the speedbooster just doesn't work with the sigma 35 or if there is something wrong with my speedbooster?

[cc143]

1 hour ago, A-Furry-Peanut said:

The aperture seems to only go as far as 1.4, but with the speedbooster xl, this should be larger by 1.3 stops. I checked the metabones website and the lens was not listed in their compatibility list, but they did mention that their speedbooster should work with most ef lenses. Does anyone know if the speedbooster just doesn't work with the sigma 35 or if there is something wrong with my speedbooster?

Its not going to show up on the camera as the aperture after accounting for the "crop factor". The lens has been "speedboosted", the aperture you see on your camera is multiplied by your crop factor to give you the resulting aperture, but your camera will still show 1.4. The effect doesn't happen inside the lens, but before the light from the lens hits the sensor. 

 

Like in crop bodies, the lens is still at 18mm, regardless of the fact that your FOV is at 18x1.5(or 1.6 or 2 depending on your camera). 

[A-Furry-Peanut]

52 minutes ago, cc143 said:

Its not going to show up on the camera as the aperture after accounting for the "crop factor". The lens has been "speedboosted", the aperture you see on your camera is multiplied by your crop factor to give you the resulting aperture, but your camera will still show 1.4. The effect doesn't happen inside the lens, but before the light from the lens hits the sensor. 

 

Like in crop bodies, the lens is still at 18mm, regardless of the fact that your FOV is at 18x1.5(or 1.6 or 2 depending on your camera). 

Sorry, I am not sure I follow. I tried my friend's Canon 24-105mm f4L IS, and I was able to stop down to 2.5, how come my camera is able to display that but not the one of the sigma?

[cc143]

3 minutes ago, A-Furry-Peanut said:

Sorry, I am not sure I follow. I tried my friend's Canon 24-105mm f4L IS, and I was able to stop down to 2.5, how come my camera is able to display that but not the one of the sigma?

If it works like that with one lens then it should work with the other as well. Do all other functions work? Does the Focal length change on the 24-105 and/or the 35? Maybe try another prime with a wider aperture. 

 

Do you have access to other adapters? It could be the case that the firmware of the adapter communicates the new aperture to the camera for the 24-105 but not for the sigma, however, given the lens is wide open, the optical transformation should still take place, i.e. effective aperture should be 0.9. The only way that is not happening is if for some reason the lens is limited to only stop down to 2.2, giving an aperture of 1.4 with the crop.

 

My guess though is that the adapters firmware isn't set to display the effective aperture on the sigma, but the lens is still working normally. 

[bob345]

5 hours ago, A-Furry-Peanut said:

Sorry, I am not sure I follow. I tried my friend's Canon 24-105mm f4L IS, and I was able to stop down to 2.5, how come my camera is able to display that but not the one of the sigma?

Its likely just a software thing. If it shows 1.4 and you cant see the aperture closing, then you should be fine

[A-Furry-Peanut]

There is a distinct noise and shift in light when I change the aperture, this suddenly stops when I hit 1.4 so I don't think it is an issue with the camera's display. When I tried the 24-105mm everything seemed to work fine including changing the focal length. I am currently looking for another ef lens to see if the problem will persist. 

[conurus]

On 6/19/2017 at 1:14 PM, A-Furry-Peanut said:

The aperture seems to only go as far as 1.4, but with the speedbooster xl, this should be larger by 1.3 stops. I checked the metabones website and the lens was not listed in their compatibility list, but they did mention that their speedbooster should work with most ef lenses. Does anyone know if the speedbooster just doesn't work with the sigma 35 or if there is something wrong with my speedbooster?

From the online user manual, http://www.metabones.com/article/of/mft-manual-changing-iris

Iris display

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 when a slow lens (f/1.8 or slower) is attached. If a fast lens (f/1.4 or faster) is used, the original pre-boost aperture is displayed.

[A-Furry-Peanut]

On 6/23/2017 at 9:44 PM, conurus said:

From the online user manual, http://www.metabones.com/article/of/mft-manual-changing-iris

Iris display

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 when a slow lens (f/1.8 or slower) is attached. If a fast lens (f/1.4 or faster) is used, the original pre-boost aperture is displayed.

Does this mean that they will not increase the aperture of any lens that is f/1.4 or faster, or that the aperture is already increased (ie: the Sigma 35mm f/1.4-16 is now somewhere around f/0.95-14) but displayed as if it wasn't? I read somewhere that Metabones will not increase any aperture of f/1.4 or faster but this seems to indicate the latter.

[cc143]

16 hours ago, A-Furry-Peanut said:

Does this mean that they will not increase the aperture of any lens that is f/1.4 or faster, or that the aperture is already increased (ie: the Sigma 35mm f/1.4-16 is now somewhere around f/0.95-14) but displayed as if it wasn't? I read somewhere that Metabones will not increase any aperture of f/1.4 or faster but this seems to indicate the latter.

Theoretically, the optical transformation will still take place, the camera just cant read it as such. maybe stop down the lens to the 1.4 equivalent, take into account the cameras own crop fcator and then comapre dof to that of a native camera. If dof is shallower then...