topic Re: 4k HDMI out to PC without crop in General Discussion

4k HDMI out to PC without crop

briank33 — Sun, 20 Sep 2020 00:03:19 GMT

Hello everyone, I have a very specific need and hoping I can get some help.

I would like to have a 4k image output from HDMI on the camera to a PC (using Elgato Camlink 4K), with clean HDMI out. I know this is possible with Canon EOS M200 and Rebel SL3 / EOS250D. However, both of these cameras crop the image when the video is changed from HD to 4K output.

I am curious about two options:

Is there a higher model that does not crop for 4K video?

Would either of these cameras output 4K from the camera mode (not video) without cropping the image?

It may help to have some background of what I am trying to achieve, and what I have already tried. I am developing a picture framing visualization application for my frame shop. The camera should send a video feed over HDMI to my PC. The HDMI is connected to the PC with Elgato Camlink 4K. Through this connection, my application uses the camera as a webcam, and I can capture a video frame. Using that capture we then design framing for the customer.

I have all of this working and tested with a Canon EOS 7D. The 7D only outputs in HD (1080p), and I would like to have higher resolution. The HDMI output works whether the camera is in video or camera mode. Even though the camera can capture a higher resolution image, the HDMI only outputs in HD. So I was hoping a camera with 4K output may allow the camera mode to output a 4K image, but I am worried these cameras will still crop. I need to keep the wider angle to capture images of large items without moving the camera farther away (20-25mm lens is sufficient)

Quoted from a review of the Rebel SL3:

"As a matter of fact, the SL3 is the first camera from the EOS line-up that shoots 4K. However, as I mentioned earlier, it comes with a catch. There’s a massive crop of 2.64x when shooting 4K, which is the same problem we saw in the Canon EOS M50. This means that your 18mm lens is going to have a similar field of view to a 45mm on full frame."

And for the EOS M200:

"Unfortunately, a 1.6x crop is applied to the image during 4K recording. That means that the 15-45mm kit lens, which gives an effective focal length of 24-72mm in stills and Full-HD video recording, captures 4K video that looks like it was shot using a 38.4-115mm lens on a full-frame camera."

Any suggestions to get around this cropping issue?

Re: 4k HDMI out to PC without crop

Waddizzle — Sun, 20 Sep 2020 08:17:14 GMT

"I would like to have a 4k image output from HDMI on the camera to a PC (using Elgato Camlink 4K), with clean HDMI out. I know this is possible with Canon EOS M200 and Rebel SL3 / EOS250D. However, both of these cameras crop the image when the video is changed from HD to 4K output."

Are you making a false assumption? What makes you so certain that the cameras should not crop in 4K mode?

Re: 4k HDMI out to PC without crop

briank33 — Sun, 20 Sep 2020 10:47:56 GMT

That's not what I meant, let me clarify. My assumption was only that those 2 cameras have 4K HDMI output to the PC. I know they have a crop for 4K video. I want to be able to view 4K over HDMI without the crop, keeping a wider viewing angle.

My camera is planned to be about 60 inches above a table. The table is about 84" long. I would like to be able to get the entire table in view. It seems with these cameras the crop factor means that I could not capture the entire table with the stock lens.

For example regarding the review I posted about the M200, the effective focal length of 38.4mm which only lets me view about 56 inches width. Without the 1.6x crop for 4k the 15mm lens would be able to view 90 inches width.

I think I am either going to need a shorter focal length lens(worried about fisheye effect), or a camera that does not crop the 4K video.

Re: 4k HDMI out to PC without crop

PLee — Sun, 20 Sep 2020 15:50:59 GMT

EOS Rebel T8i will have full sensor width 4K and output a clean 4K signal from its HDMI port. The EOS M6 Mark II will also do what you ask if you prefer that form factor.