Originally posted by tokyoso golden rule of thumb: when in doubt, buy them all..
There goes all the gold...
Hey, I just started using a very different sort of 'portrait' lens. Originally US$2000+, I got this new-in-the-package for US$70 on eBay last year. It's a Schneider-Kreuznach Betavaron 3,5...11/0,08 that weighs 820g and has an objective about 65mm across. What? It's a friggin 2-pound enlarger zoom, 50-125mm, and it's kinda hard to say just the aperture is because the stops are just marked 1-2-3-4-5.
In fact, it's kinda hard to tell ANYTHING about the optics, other than it's a complex zoom. Fixed-focus, but zooming changes the focus point. It's meant for production darkroom work, where you need to make a zillion prints with the enlarger at the same focus but you use the lens to quickly change reproduction sizes. Right now I have it on M39-M42, flanged M42-PK, and tubes, with extension about 28mm, and it focuses about 0.5m (18 inches) to beyond infinity. With a bit more extension, it'll be wizard for macro work. And that flanged adapter enables it for trap-focus.
Wide-open (whatever that is) it is NOT soft. Stopped-down at all, it is brutally crisp and contrasty. Even with its pentagonal iris (star-shaped when stopped down) the bokeh is utterly smooth. This is not for romantic lovey-dovey sweetheart portraits; it's for HE-MAN pictures.
[/me makes simian noises, thumps chest, scratches armpits, etc]
It's not easy to use. Of course, I only really started last night, and I suppose I'll learn a few tricks soon. But since you zoom to change focus, it's hard to be quite sure of what will be in the frame. It takes a lot of bobbing back and forth. On a tripod, subject at a known distance, it's OK. Walking around, the trap-shoot is a crap-shoot. But at least it's not boring.
Back to the subject: Yeah OP, get the Tamron. It's only money. Keep the 50. Buy more lenses. Buy them all. Get the complete set.