Looking for something at the very least 20mm. Maybe an 18mm f3.5? Manual focus only please. AI-s a plus but not necessary this lens will be used on both d*****l and on a Nikon FM in stop-down mode. The only 3rd party lenses I will take are the Tamron BBAR 17 and Tokina 17.....which to be honest I think are the only 3rd party ultrawides past 20mm anyway
I'm an over-the-road truck driver if you message me and I don't reply I'll probably see it in a day or so I drive in some seriously rural areas.
I have had the Sigma 18mm f/3.5 which I purchased secondhand about 25 years ago, it is a very good lens. I have compared it directly alongside to the Nikkor 18mm unit. The Nikkor certainly had higher contrast looking through the viewfinder and the Nikkor negatives were ever so slightly more contrasty than the Sigma negatives. We shot the same subject with two cameras and two tripods about the minimum possible distance side by side, so it was a reasonable test, not strictly scientific, just normal seat of the pants stuff. The Nikkor was better, but for a price difference of about 3 times more expensive than the Sigma, we concluded the Nikkor negatives were not 3 times better.
I had owned the Tamron 17mm prior to getting the Sigma 18mm. If you go back to the manual focus lens era, then one of the better after market lens manufacturers at that time was certainly Sigma. I wouldn't entertain the thought of any Tamron from that era as that much better than most others of the same ilk.
I also have a Sigma 24mm manual focus lens, it has been mine brand new since 1985. It is not better than the Nikkor lens, but it is not a shabby performer, it has a bonus over the Nikkor version in that it has half stop clicks. Sigma back then was pretty innovative and if not the best of the after market manufacturers, damned close to the best of them.
Mick.