Both Tamron and Sigma have been shaking up the photography industry by releasing one premium lens after another. Many of these lenses are actually better than the Nikon or Canon equivalents. Tamron's 35mm and 45mm 1.8 lenses have created a new segment; wide angle primes with VC (vibration compensation). But does anyone really need this?
Lens stabilization started showing up years ago in telephoto lenses. The longer your lens, the more pronounced camera shake will appear. Most lens manufacturers left stabilization out of wide angle lenses and fast primes because camera shake wasn't as big of an issue.
Tamron seems to believe that VC can help in any lens because they added it to their ultra wide 15-30mm 2.8 lens. They then created a 35mm and 45mm 1.8 lens and added VC to them as well.
The build quality of both lenses is fantastic. They are both a bit bigger than my Nikon 50mm 1.4 and feel much more robust. The focus ring spins very smoothly and feels similar to current Sony lenses (which I think are some of the best on the market). The VC and AF switches on the side snap back and forth in a very pleasing and sturdy way.
I'm not a pixel peeper, and I think most photographers are way too concerned with imperceptible details, rather than actually creating art, but I digress. The 45mm lens seemed very comparable in my tests to my 50mm lens. Obviously the lens will get sharper at f/4 than at f/1.8 but the shots look great to me at any aperture. The VC will help you stabilize pictures at slow shutter speeds, but I personally like the VC more for hand held video shooting than stills and premium lens quality isn't noticeable when it comes to video.
To be perfectly honest, the average photographer probably doesn't have much of a need for a lens like this, and I can't think of any reason to buy both of them since they are so close in length. How often are you shooting at 1/5 of a second at f/1.8 without a tripod? If you're shooting video, won't you have a tripod? Wouldn't you prefer a zoom lens?
This lens is going to be a luxury item for most photographers and a useful tool to a very few. Wedding photographers who are constantly shooting in dim natural light and who prefer primes will love these lenses. Videographers who don't care about zooming will also love the ability to shoot in extreme low light without a tripod.
If you don't constantly find yourself shooting hand held in the dark these lenses probably aren't for you but I'm still excited that Tamron is creating such specialized lenses. Tamron has created a new niche in the market and the photographers who could use this type of lens are really going to love them.