Is HDR superior to JPG when digitizing 24 x 36 mm camera slides?

For HDR three things are to consider, the sharpness, and the photometric resolution and the colour resolution.

• The sharpness should be the same for HDR mode or normal mode, provided the camera is fixed to tripod when taking the photo. As you know, a HDR image is a fusion of more than one photo, and you will get the best sharpness, if the camera does not move while taking the exposure series. Otherwise you might get ghostly motion blur, particularly, if the slides are very grainy or there are scratches and dust.
• The photometric resolution will be much better for the HDR version - you will get more detail in the shadows and the highlight. This will give an impression of a sharper image, but also might create artifical structures in smooth regions, like the sky.
• HDR will bring out more colours in the shadows and the highlights. It might look unnatural, as the colours tend to be very saturated. YOu may need to adjust the saturation afterwards.

While I still had my iPhone 5s, where I could set the Camera to keep both the normal version and the HDR version, I compared both the normal and the HDR photos for each photo and kept the most pleasing one. It depends on the kind of scene, which will be best.

I prefer to scan and archive paper images as 600 ppi 48-bit .tif and then edit and export as .jpg (small slides need more than 600 ppi). That is somewhat overdo but scanning is so laborious that I prefer to do it well once.

You're welcome 😊