EKB: This lens is not for me, not because I want a wide-ranging zoom, but because I want a long-ranging one. The 18-35mm range is just not one I use very much.
But if Sigma came out with a 35-70mm f/1.8 ASP-C companion to this lens, then I would WANT it.
I'm not convinced. I still think that the 20-35mm f/2.8 is a proper comparison. Yes, it's harder to get 104º on an FX sensor than to get 73º on a DX sensor, but it's also harder to get 73º on a DX sensor than to get 73º on an FX sensor. So is getting 73º on a DX sensor closer in diffiulty to getting 104º on an FX sensor or to getting 73º on an FX sensor?
I believe that it's much closer to the former (given the same lens mount and flange distance), but I also think that we'll have to agree to disagree about this.
1. I'm not considering a hypothetical 24-70 f/1.8 lens, I'm considering a hypothetical 35-70 f/1.8 lens - and one that APS-C rather than FF, to boot.
2. By your logic here, the Sigma 18-35 f/1.8 couldn't possibly exist either:
Consider the Nikon 17-35 f/2.8 that weights 745g. Now consider a hypothetical 18-35mm f/1.8. The front elements of this lens would have a 2.5x larger frontal area compared to the 17-35 f/2.8. Usually, an f/1.8 lens has a much more complex design (more elements) and is physically longer than an f/2.8. What would be the weight of the hypothetical lens? Possibly more than 3kg, according to this logic.
3. Or to put it this way: The old Nikon 20-35 f/2.8 weighed 588g. The old Nikon 35-70 f/2.8 weighed 664g. The Sigma 18-35 f/1.8 weighs 811g. So a Sigma 35-70 f/1.8 should weigh what? Maybe 900-950g? Or maybe less, because the Nikon lacks the weight-adding 2mm at the wide end.
"Prime lenses for the FF format with focal length below 70mm can have very dissimilar design."
Yes. Exactly so. And the same applies to zoom lenses and to lenses designed for the APS-C format that have focal lengths below 70mm.
"You should compare lenses of similar designs"
Why? Why should I expect a 35-70 f/1.8 to have a similar design to the 18-35 f/1.8?
In fact, I would expect it to have a different design - to *need* to have a different design - in much the same way that, e.g., the Nikon 24-70 f/2.8 has a different design than the 14-24 f/2.8
As it turns out, the 24-70 has about the same cost and weight as the 14-24 - in fact, it's a bit lighter (900 vs 1000g) and a bit less expensive. By analogy, I'd expect a 35-70 f/1.8 to have about the same cost and weight as the 18-35 f/1.8 - not eight times the cost and weight.
@Frank_BRIn the 18mm to 70mm range, the general trend is so weak as to hardly be worth calling a trend at all. In fact, can you even name a single pair of Nikon F lenses of 70mm or shorter focal range that fit this third-power trend?
If I had to guess, I'd guess that a 35-70mm f/1.8 APS-C lens would be somewhat heavier and more expensive than the 18-35mm f/1.8. But not by a factor of 8. In fact I'd be suprised if it were more expensive by a factor of more than 2. On the other hand, I would *not* be suprised if a 35-70mm f/1.8 turned out not to weigh or cost *any* more than the 18-36mm f/1.8.
If the cost and weight of a lens increases with the third power of the focal length, then this implies that there ought to be a big pile of good, cheap wide-angle lenses - that instead of "Nifty Thrifty 50s" there ought to be "Nifty Thrifty 15s". It implies that a Nikon 50mm f/1.8 prime should go for $600 - or even more for an FX version, given the 35mm f/1.8DX that goes for $200. It implies that either the Nikon 17-55 f/2.8 is way overpriced (especially for a DX lens), or the 24-70 f/2.8 is a serious bargain.
Something is wrong with this theory.
This lens is not for me, not because I want a wide-ranging zoom, but because I want a long-ranging one. The 18-35mm range is just not one I use very much.
noirdesir: Did people also complain when the 70-200 mm f/2.8 AF-S VR II was released? Oh no, yet another 70-200 mm f/2.8, we already have one that is perfectly fine.Or about the 80-400 mm AF-S? And those two lenses didn't even get an extra 5 mm.
It is absolutely ok to be disappointed. But to equate Nikon's sales potential with one's own desires is little bit too self-centered a view.
Likewise the 18-135 and 18-105 have shortcomings: Plastic mounts, the 18-135 lacks VR, and both lenses are seen as being not up to par on the new 24MP DX cameras. To the extent that the 18-140 fixes these shortcomings, it's justified.
And it turns out that 18-140 does have a metal mount and a VR system that's claimed to be better than that of the18-105 (4 stops vs 3). The only question remaining is whether it's optically better (and in particular, sharper) than the earlier lenses.
My own modest desire is for customizable front grips on dSLRs, similar in concept to the custom grips available for pistols. Want a small grip for your small hands? A big grip for big hands? A soft & spongy grip? A hard grip with a deep texture? A fancy show-off grip made of ebony, or ivory, or mother-of-pearl? Remove the standard grip and replace it with a new one that matches what you want, either OEM or from a third party.