Variable Image scaling in slideshow

[jopasnyt]

When I look two images, the other one cropped the other original size, in Develop Module they appeare equal size. When I run a Slideshow, those two images being a part of the show, the cropped one appeares a lot smaller than the original one.

How to fix this phenomena?

Thanks

[F. McLion]

Did you select 'Zoom to fit' in the slideshow?

What is the size in pixel of the smaller one? There are some limitation with zooming in a slideshow.

[jopasnyt]

Thanks

No I had not selected the "Zoom to fit" in the slideshow.

The smaller image size is   2235 x 1490 and the bigger one is 6480 x 4320 px.

Forgot to mention that I have a 4K screen

[jopasnyt]

If I choose "Zoomto fit", it cuts the heads of for some people photos.