Head to head
Tamron SP 90mm f/2.5 Macro (52BB) Adaptall-2 vs Nikon Micro-Nikkor 55mm f/2.8 AIS
Both turn up on the same shortlist for anyone who wants a sharp, affordable manual macro for a film body, and both have a cult following decades after they shipped. The 90mm Tamron is a half-life-size lens that doubles as a portrait optic. The 55mm Nikkor is a flatter, shorter working tool that gets you to half life-size on its own and to full 1:1 with a tube. The single biggest split is focal length, and everything downstream (working distance, look, what else you can shoot with it) follows from that.
How they differ
Working distance is where you feel the difference first. The 90mm gives you noticeably more room between the front element and the subject at the same magnification, which keeps your shadow off the frame and makes skittish bugs easier. The 55mm makes you lean in close, fine for flat copy work, coins, and stamps, less fun for live subjects.
Rendering also diverges. The Tamron is famous for creamy, smooth out-of-focus areas and flattering skin, and plenty of people buy it purely as a 90mm portrait lens that happens to focus close. The Micro-Nikkor is more clinical, very flat-field and high contrast, exactly what you want for reproducing documents and artwork edge to edge. On cost and availability both are common on the used market and sensibly priced; the Adaptall-2 mount means the Tamron can ride almost any body with the right adapter, while the Nikkor stays on F mount.
Choose Tamron SP 90mm f/2.5 Macro (52BB) Adaptall-2
Pick the Tamron 90mm if you shoot living things up close (insects, flowers, food) or want one lens that handles both macro and portraits. The extra working distance matters in the field, the bokeh is genuinely lovely wide open, and the Adaptall-2 mount lets you move it across Nikon, Canon FD, Pentax, Olympus, and more by swapping a cheap adapter. Good if you own several bodies, or expect to.
Full Tamron SP 90mm f/2.5 Macro (52BB) Adaptall-2 guide →Choose Nikon Micro-Nikkor 55mm f/2.8 AIS
Pick the Micro-Nikkor 55mm f/2.8 AIS if you shoot Nikon, want a compact lens that lives on the camera, and do a lot of flat-subject or copy work where corner-to-corner sharpness and contrast win. It is small, robust, and superb for stamps, coins, documents, and general close-up. Note the AIS f/2.8 needs a matching extension tube to reach true 1:1; on its own it stops at half life-size.
Full Nikon Micro-Nikkor 55mm f/2.8 AIS guide →The verdict
Neither is wrong. If you mostly photograph things that move or want a portrait lens in the bargain, the Tamron 90mm is the more versatile, more forgiving tool. If you live in Nikon land and shoot flat subjects, the 55mm is tighter, sharper at the edges, and pocketable. It comes down to focal length and working distance more than image quality, since both are excellent.