EOS R EF lenses reduce image resolution and aspect ratio

[ttssingleton]

I recently upgraded to an EOS R I purchased an adapter to use my EF lenses but whenever I use canon branded lenses my image quality is only 12 mp and the aspect ratio is 1.6 I cannot change it and it only happens with Canon branded lenses. Is there something I may be missing or doing wrong since I’m still learning this camera functions?

[Tronhard]

Hi and welcome to the forum:
I just realized you mean the R rather than the R1 (apologies)
Can you please also be VERY PRECISE as to the lenses you are using - especially if these are EF or EF-S lenses?

[ttssingleton]

I Have The EOS R 30 MP full frame. I am trying to use an  EF-s 18-135 mm with this camera via the adapter but the image quality is only shooting 12 MP cropped at 1.6  but when I connect my Tamron 70-300 lens it shoots full frame 30MP

[rs-eos]

When using EF-S lenses on a full-frame R-series camera, it will go in to crop mode.  The size of the EF-S lenses are such that they cannot cover the full area of a full-frame sensor.

EF-mount lenses are designed to fully cover a full-frame sensor.  So best to stick with those lenses.

[Tronhard]

Hi again.  Thanks for your prompt response.
The Tamron lens is compatible with a FF sensor, but the EF-S 18-135 is designed for the smaller APS-C (crop sensor) format and will not project onto the full area of the R's Full Frame sensor.  To get a full image, you would need to consider something like the RF 24-105 STM lens, which is native to the R platform.

[ttssingleton]

It also will not allow 4k video with that lens either 

[Tronhard]

The same issue that I explained previously will also reduce your resolution for video, see P616 of the Advanced User Guide:  Link in previous post.

[Tronhard · Accepted solution]

In anticipation of your reply that you have been using EF-S lenses, there is an issue with using those lenses, which are designed for an APS-C camera, as they behave on a Full-Frame one like your EOS R. 

In the DSLR platform you could not put those lenses on a FF body, as an EF-S lens projects too close to the sensor and fouls the mirror.  While there is no mirror on the EOS R, the image that is projected from an EF-S lens is still going to be the size of an APS-C sensor and thus will not use the whole area of the FF sensor.   This causes the area covered to be reduced from 30MP to just under 12MP, which is what you are experiencing.
See P610 in the Advanced User Guide and refer to the column under 1.6 crop for the values you are experiencing.

There is no work around this except to use EF or RF (not RF-S) lenses if you want to use the full area of the R sensor.

[ebiggs1]

To gain full function of you new R series camera you will be far better off buying RF lenses.

[ttssingleton]

Thanks for feedback wasn’t aware the effect different lens types would have on the camera ,will do more research next time