So the ART series has become very highly regarded as an outstanding bang for your buck rivaling many OEM and other luxury exotic makes for a fraction of the price. Case in point the much heralded 50 and 35mm lenses, and now the 24. The rumor mill has been circulating a few upcoming products:
24-70mm f2.8 optically stabilized
85mm f1.4
135mm f2.0
Lets say they all sit in the $900-$1100 range based on previous model pricing....how tempted would you be to ditch some of your Nikon glass and replace with these new ART series? If you were missing some lenses from your kit, how tempted would you be for these new lenses?
Myself personally, if I did not have the Nikon 24-70mm f2.8 currently I would probably wait for the Sigma to come out if I could so I could compare. It would have to meet the Nikon in AF motor speed, and it would be very hard to top it optically...but I'm sure it would be the Tamron version.
For the 50mm I already know what happened... I no longer have my 50mm f1.8 G, I have an ART on my camera. I thought I would keep the Nikkor due to size and weight.... but at the end of the day if I want something small and light I have my Pentax.
I'm VERY tempted by the 24mm as I really miss my 24mm f2.8D...
I rarely if ever have a use for 35mm.
The 85mm, if I used that focal length a lot, I would probably be seriously considering. That said for $500 the Nikkor 85mm f1.8 is pretty close to flawless...
As for the 135mm... I think I would actually trade in my Nikon 135mm f2.0 DC for it. The DC is a beautiful lens, but on the D810 it's just soft and the DC is nice...but kind of gimmicky. I use that lens a lot though, and it is my main prime lens. I do think I would add the Sigma to my bag, but would I keep the Nikon?
I would probably at that point move to almost a full Sigma lineup. My bag would probably look like:
Nikon D810
Nikon 70-200mm f2.8 VRII
Sigma 50mm ART 1.4
Sigma 135mm ART 2.0
Sigma 24mm ART 1.4
vs the current
Nikon D810
Nikon 70-200 f2.8 VRII
Nikon 24-70 f2.8 G
Nikon 135mm f2.0 DC
Sigma 50mm ART 1.4