So I traded my Tamron 17-50 for a Sigma 30mm and all I can say...

is despite what everyone saying for me not to do so I'm super glad I did! This thing is sharper at 1.4 than my tamron was at 2.8. This little bugger at F4 is just stupid sharp. Completely in love with this lens. Focus is very quick, damn near the same speed as my 85 1.8 and performs flawlessly. I did need a -2 however to dial in this lens. I mean I loved the Tamron but the focus noise sucked but the speed was ok however it really took a 3.2 to get a decent result even though 2.8 was still very usuable which I did use it there a ton HOWEVER this lens is sharper period at 1.4 and the tamron just can't touch it at 2.8. Here are a few quick shots and I'll try to upload my FOCAL 100% crops of the test chart showing you the difference in sharpness from the tamron to the sigma. I'm not sure if there is any optical difference but I have the older version textured lens but this thing is mint! Traded a fellow POTN member here.

1.4

It's definitely an awesome lens, but aren't you missing the wide side now? Any plans for a wider lens to supplement the 30-1.4?

F2 was my favorite aperture on it. Great balance of depth, speed and sharpness

FEChariot wrote in post #14957282
It's definitely an awesome lens, but aren't you missing the wide side now? Any plans for a wider lens to supplement the 30-1.4?

I'll definately pick up the Sigma 17-50 later down the road as I really want the OS in a zoom lens. For now though I think in a few months I'll RE-buy a sigma 10-20 and that will handle widER stuff.

I made a similar trade a couple of years ago. I traded the Tamron 28-75 for the Sigma 30mm. I had the same results. I found that the Sigma 30mm was significantly sharper. It is fantastic at F2.0 and above. I was never happy with the Tamron at 2.8.

You will not be disapointed in the Sigma 17-50 either then. I think my next lens is going to be an UWA. I am waiting to see how well the new Tokina 11-16 handles flair with the new coatings, but the Sigma 10-20 is on the short list too. I'll be watching for your posts on that one if you go that way in the future.

Sigma 30 was my favorite on crop camera. I much preferred it over the standard 2.8 zoom.
Now on FF I don't really use the Sigma 50 much simply because the tamron 28-75 2.8 zoom has small enough DOF for my taste and PQ is very good.

In all honesty, all those lense, Sigma 30, 50, tamron 17-50, 28-75 are all stupidly sharp at f/4.