topic Re: EOS R EF lenses reduce image resolution and aspect ratio in EOS DSLR & Mirrorless Cameras

EOS R EF lenses reduce image resolution and aspect ratio

ttssingleton — Tue, 13 Feb 2024 14:19:33 GMT

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?

Re: RF to EF

Tronhard — Sun, 11 Feb 2024 21:25:11 GMT

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?

Re: RF to EF

ttssingleton — Sun, 11 Feb 2024 21:27:42 GMT

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

Re: RF to EF

ttssingleton — Sun, 11 Feb 2024 21:29:10 GMT

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

Re: RF to EF

Tronhard — Tue, 13 Feb 2024 02:30:44 GMT

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.

Re: RF to EF

rs-eos — Sun, 11 Feb 2024 21:36:11 GMT

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.

Re: RF to EF

Tronhard — Tue, 13 Feb 2024 01:28:00 GMT

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.

Re: RF to EF

ebiggs1 — Mon, 12 Feb 2024 20:51:02 GMT

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

Re: RF to EF

Tronhard — Tue, 13 Feb 2024 02:33:43 GMT

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.

Re: EOS R EF lenses reduce image resolution and aspect ratio

ttssingleton — Mon, 19 Feb 2024 23:32:21 GMT

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

Re: EOS R EF lenses reduce image resolution and aspect ratio

Tronhard — Mon, 19 Feb 2024 23:37:42 GMT

If this resolves the issue, it might be a good idea to select the most appropriate response as a solution so others with the same issue will find it easily, and you will not get people continuing to send you redundant information.