Sigma 18-35mm f/1.8 FX equivalent

Started 9 months ago | Discussions thread
OP vwsjr Contributing Member • Posts: 507
Re: Sigma 18-35mm f/1.8 FX equivalent

Six months later I finally made my decision . I picked up the Tamron 24-70 f.2.8.G2 It was as close as I could get to the Sigma, and so far (not a wide enough range of shots with it yet) I'd say it's as good or better than the Sigma in almost every way. I have the newer Nikon 50mm f/1.8 so that's also a basis for comparison, at least in terms of sharpness.

Some reviews indicate the FX corners are soft with the Tamron, I have not seen that so far, but I haven't shot it much at f.2.8. At f/3.5, corners are not as sharp as the center, but I would definitely not say they are soft.

Overall I think the lens is as sharp as the Sigma 18-35 at all comparable focal lengths, both in the center and at the edges. Distortion at 24mm, something else I was a bit worried about, also does not appear to be any worse than the Sigma. There's definitely barrel distortion at 24mm, but unless you have straight vertical lines at the edges of the frame, it's not noticeable. Stabilization works great and contrast/color are excellent. Near silent and autofocus is fast and accurate. The lens is a serious brick, very much like the Sigma 18-35 is, very solid construction.

Probably the most significant thing I've noticed so far is that the CA is very well controlled. I shoot a lot of large trees, where I'm shooting from underneath and straight up, so I get as much of the trunk and canopy in the photo as possible. Leaves at the top of the tree in bright sun are always going to have some CA, and I can say that it's less with this lens than any lens I have shot similar photos with. Even though I'm usually shooting with apertures in the sweet spot, around f/5.6, and focus point is usually fairly close, the leaves that are furthest and at the edges of the frame still look good, particularly in web-size photos, but even at full res they are better than with the Sigma. Part of that is surely the D850 compared to the D500 too, but my goal was to get as good or better than the Sigma 18-35 for the D850 and I think the Tamron definitely accomplished that.

Compared to the Nikon 50mm f/1.8, I'd say the Tamron is at least as sharp and as good all around, probably better. Focus is actually faster, I've been somewhat disappointed with the autofocus of the Nikon, it seems a bit slow and a bit more unsure, at every aperture. That's all just subjective. At some point I'll do some more extensive testing to determine whether I feel like there's any advantage with the prime at exactly the same apertures and focal length. The full stop advantage of the 50mm is a bit less significant to me, as I'm not usually shooting action with that lens and the stabilization of the Tamron makes up for the one stop difference in low light. The ability to blur the backround also isn't that big a difference, neither lens does a great job with that wide open and it's not a frequent need for me with a lens in this focal range.

The only negatives I can think of is the weight and size if you care about that. It's a tradeoff, but for me it's better than carrying two or more primes. The lens barrel extends to zoom, unlike the Sigma. Most of my shooting is outdoors in very dusty conditions and I'm sure that zooming in and out will suck in dust, but on the other hand, I've even had dust in my prime lenses, so I never feel like any lens is sealed well enough to handle the kind of conditions I expose them to.

I'm comparing more than the lenses, comparing the SIgma on the D500 and the Tamron on the D850, so keep that in mind, but I think it's a great lens and I feel like I gained a good bit on the Sigma/D500 combo without giving up anything.  I could do different tests like comparing the Tamron on the D500 and the Sigma on the D850 (with a crop), but that's all irrelevant to me.  Overall the combo is significantly better than the D500/Sigma combo the stabilization and the slightly greater focal range are both significant, and being able to at least match the Sigma in sharpness is not at all trivial.

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 vwsjr's gear list:vwsjr's gear list
Nikon D500 Nikon D850 Nikon AF-S Micro-Nikkor 105mm F2.8G IF-ED VR Nikon AF-S Nikkor 50mm F1.8G Sigma 18-35mm F1.8 DC HSM Art +12 more
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