Why does “haze” appear when focusing on macro photography?

Question

Photo

I decided to reshoot the old slides from the film. I built something like this:

I have an old lens af nikkor 28-85 / 3.5-4.5
Nikon D90 carcass
I shoot in macro mode.
The problem is the following. When you manage to aim at the slide so that the image on it becomes sharp, you get some kind of haze. If you bring down the aiming a little, then the haze disappears, but the objects are slightly blurred and details are lost.
Here are examples:
Clear details and haze.

Blurry details, less haze

What's the problem? In the lens? In crooked hands? Tell me how to solve?

Answer 1

I think the problem is in the lens or in your tube. Such illumination from internal re-reflections can be.
I shot with a real macro lens - everything was fine (zoom cannot be a true macro lens)

Answer 2

for reshooting slides or film, there is a macro bellows with a pzf prefix - much more convenient than self-made pieces :)