I am using Nikon D850 which is working perfectly fine with my Nikon 50mm f/1.4 lens. Recently I purchased 28-300 lens. I noticed that on mounting this new lens view finder looks quite dark and dim. Same is not the case when other lens is mounted. Is this an issue with lens ? Please advise.
View finder images (unless in depth preview mode) are produced using fully open aperture, and f/1.4 is a really fast lens. Your 28-300 will have only a fraction of that maximum aperture, probably something like f/4 which would be 3 stops slower and thus admit only an eighth of the light your 50mm prime does.
If you want the viewfinder brightness to reflect actual exposure, your only option is to:
- Ditch the viewfinder, use the rear LCD in live view mode
- Purchase a mirrorless camera with an electronic viewfinder to replace the old technology DSLR
No optical viewfinder reflects actual exposure. (Want proof? Set the exposure to a totally ridiculous value so that the image should be completely dark or completely white. You won't see a completely dark or a completely white scene in the viewfinder.)
As others have said, viewfinder shows the view with lens wide open. A 28-300 zoom has relatively small aperture, much smaller than a fast f/1.4 prime.
To answer your question:
Is this an issue with lens ?
Yes, it's an "issue" with the lens, as much as it's an "issue" with the camera. The issue is, that your lens is not fast enough. A constant aperture 24-70/2.8 zoom would be somewhat faster, but then again I wouldn't choose the lens based on viewfinder brightness. I would choose the lens based on image quality, focal length, etc.