My RP Mount Adapter is vignetting terribly with EF-S lenses

[pretzelcuatl]

I just gave away my Rebel t3i to my niece and bought an EOS RP, along with the control ring Mount Adapter so I could use my old lenses, which are a Sigma DC 18-250, and a Rokinon 2.8/14mm manual focus.

When I put the Sigma on the adapter, the image is severely vingetted, with a black ring around the whole thing, while the 14mm looks like a fisheye. Now I knew in advance that the EF lenses would be using far less of the sensor than the RF lenses, but I was under the impression that the camera would auto detect the lens and crop the image. All other lens functions are working (auto focus etc), but not the auto cropping.

Is the only way to use this adapter and these lenses is to manually crop all my photos on my computer? Or is there a setting in the camera that I'm missing that allows me to see the cropped image as I shoot?

Camera firmware is 1.4, with 1.0 for the adapter.

I also bought the RF mount Meke 50mm 1.7, which works great.

Thanks.

[Waddizzle]

You are not suing a Canon EF-S lens.  You are using a Sigma DC lens.  If I were to hazard a guess, it probably has a standard full frame EF mount, but it only projects an APS-C size image circle onto the image sensor.

As far as your 14mm Rokinon goes, they look really great on an APS-C body.  They are popular to use for astrophotography, wide angle shots of the night sky.  The trick to using one in daylight is to level the camera.  There will always be some lens barrel distortion on the edges until you apply lens correction with an application like Adobe Photoshop or Lightroom.  Canon's DPP software does not correct third party lenses.

[kvbarkley]

When you use a Canon EF-S lens on an R, the camera uses only an EF-S sized area of the sensor to prevent this kind of things. Since you are using non-canon lenses, it does not know that it has to switch to EF-S size images. Look on the bright side, you are getting full size images. 8^)