How to improve this image ?

Technical Details
Camera Nikon F60 at 200 mm, F8, Shutter speed 90, Flim Fuji 100 (converted to Blank and white)

Byte size: ZERO | Content warning: NOT AN IMAGE

The image looks to small to judge but my guess is it will be hard to pull any significant detail out of the underexposed areas of the image. I would recomend you try OpenEXR, for this one. http://www.openexr.com​/photoshop_plugin.html

I would rescan the image in colour, leaving it quite flat in terms of contrast. This should keep as much detail as possible Then I would work on all areas seperately to improve rnage of tones and contrast using adjustment layers in PS before converting to B&W. Darken the shadows, bring out the midtones in the people and brighten the highlights.

The again, you can only achieve as much as the detail contained on the slide gives you.

Retake it with a Canon

I'm sorry, but you would have gotten this comment anyway.

Seriously, it's difficult to judge a pic this small, but it seems like the dynamic contrast is not large enough. Tedious photoshop work could repair that, but I don't know a magic filter for this kind of stuff.

P.