Gunzorro wrote:
My best zoom at the moment is the Canon 24-70/2.8L II, and close runner up is the Sony 24-105/4G, but it is slower and slightly less blisteringly sharp, just by a smidge.
Even though not a pressing issue for me to buy the new Sigma, it is very appealing. I will probably buy the 14-24 Art and 35/1.2 Art before I buy this new mid-range Sigma zoom.
IMO, Sigma is doing everything right on their lenses. I'm super-impressed with the 24/1.4 Art and 50/1.4 Art lenses, so it's all looking good for me coming from Sigma!
Yes, it took a while for Sigma to wake up but it looks like they did their homework.
Not sure that the Sigma is weak at the corners compared to Sony. Sigma is better over much of the frame, and in the corners the Sony has higher tangential contrast at 30lpm, but not better saggital contrast, so Sony probably shows more astigmatism in the corners, so Sigma may be preferable even there.
EDIT:
Of course all this is modulo trying to compare two sources of data.
It's a bad idea in general; but I did it in this post because the Sigma published stuff has often been close to Roger's tests, and that's what we are comparing here.
The Sigma being a little better over most of the frame is the claim I am least confident about for these reasons.
But the general shapes have been comparable between Sigma and LR data, so the astigmatism difference, which was the point of my post, I'm more confident about.
I don’t think the Sigma will beat the GM in all aspects (ie sharpness, AF, bokeh), as the GM is also designed to include smooth bokeh even for f2.8 (though the Sigma’s 11 blades vs GM’s 9 blades is interesting). Maybe one or so. But when considering the $1100, the Sigma seems like the better choice unless you really want those incremental improvements in a standard zoom.
There’s a lot of positive reviews for the Sigma 14-24, but even by Sigma’s standards, the MTF charts for the Sigma 24-70 isn’t as great as that of the Sigma 14-24. We’ll see how the it is with user reviews when it comes out.
The Nikkor looks to be the better lens from the MTFs. Maybe Nikon could have traded some center performance for improved peripheral performance in the MTF graphs, to yield amore balanced package?
Comparing Sony and Sigma MTFs with all caveats. The Sony lens looks to have more astigmatism and even to be optimized for wide performance. Sigma seems to have paid a bit more attention to telephoto performance. Notice that the tangential and sagittal lines cross and become intertwined on the Sigma lens, I seem to recall that this could also be a sign of chromatic abberation? Which is the least preferrable, chromatic abberation or astigmatism? Then there is distortion, vignetting and bokeh to be considered as well as colour reproduction.
Also AF drive, electronic compatibility and possible aperture chatter have to be considered.
vdo1 wrote:
What is your criteria for “better”? Speed, precision, noise, drawn power, reliability?
I don't know much about focusing systems besides excellent article on lens rentals. https://www.lensrentals.com/blog/2016/04/a-look-at-electromagnetic-focusing/
All I know that Hyper Sonic Motor (HSM) on Sigma 100-400 is not as fast and accurate as dual linear motor SSM combo on Sony 100-400.
So my question is - how does stepping motor compares with SSM motor on Sony 24-70? Speed and accuracy is my main concern. Noise, power consumption or reliability are secondary factors to me.
samosh wrote:
I don't know much about focusing systems besides excellent article on lens rentals. https://www.lensrentals.com/blog/2016/04/a-look-at-electromagnetic-focusing/
All I know that Hyper Sonic Motor (HSM) on Sigma 100-400 is not as fast and accurate as dual linear motor SSM combo on Sony 100-400.
So my question is - how does stepping motor compares with SSM motor on Sony 24-70? Speed and accuracy is my main concern. Noise, power consumption or reliability are secondary factors to me.
You can make a lousy lens with any motor type, so if you want to discuss a particular implementation (not the general principles), then we’ll have to wait until the lens becomes available and reviewed/tested.
MAubrey wrote:
If MTF charts are from three different testing sources, then they're not comparable to each other.
The Sony MTF is an actual test (Lens Rentals), whereas for Sigma it comes from the manufacturer. Unless you believe Sigma is understating the MTF performance of their new lens then the points made are still valid.
snapsy wrote:
The Sony MTF is an actual test (Lens Rentals), whereas for Sigma it comes from the manufacturer. Unless you believe Sigma is understating the MTF performance of their new lens then the points made are still valid.
It isn't about tested vs. theoretical (thought the Nikon S addition is certainly theoretical!). It's about two entirely different systems for measurement that produce different results.
Sigma's results are useful for comparing Sigma lenses that have been tested with the same methods/equipment (using a Foveon sensor).
Lensrentals results are useful for comparing lenses that have been tested with their methods/equipment (using their optical machine).
Zeiss's results (to add one more tested MTF example) are useful for comparing lenses that have been tested with their methods/equipment (using their K8 machines).
They're all different. Sigma produces different results for the same lens vs. Lensrentals. Zeiss produces different results for the same lens vs. Lensrentals.
MAubrey wrote:
It isn't about tested vs. theoretical (thought the Nikon S addition is certainly theoretical!). It's about two entirely different systems for measurement that produce different results.
Sigma's results are useful for comparing Sigma lenses that have been tested with the same methods/equipment (using a Foveon sensor).
Lensrentals results are useful for comparing lenses that have been tested with their methods/equipment (using their optical machine).
Zeiss's results (to add one more tested MTF example) are useful for comparing lenses that have been tested with their methods/equipment (using their K8 machines).
They're all different. Sigma produces different results for the same lens vs. Lensrentals. Zeiss produces different results for the same lens vs. Lensrentals.
snapsy wrote:
The Sony MTF is an actual test (Lens Rentals), whereas for Sigma it comes from the manufacturer. Unless you believe Sigma is understating the MTF performance of their new lens then the points made are still valid.
I'm not familiar with Sigma's MTF testing methodology but their graph 'pattern' is usually similar to my own experience when testing their lenses at infinity distance. Same goes for LensRentals, Leica and Zeiss. Not so much the case with other manufactures where their computer generated MTF's tangential and sagittal lines sometimes do not even correspond to what I see when taking a real picture at infinity.
Take the Sony 50/1.4 ZA for example. Sony's MTF shows a minor dip toward the mid-field for the tangential line whereas LensRentals shows a more severe dip. I've tested this lens at infinity and the results are very aligned with the latter's data.
I think it could be useful to compare MTFs from the same brand since their lenses should share the same testing methodology but I would never compare MTF graphs among brands.
I’m curious why Sigma hasn’t put this into the hands of more photographers for reviews. The guy on the video said his copy was the only one sent to the United States. I’m not a marketing guy, but it seems that if this lens is as good as it looks they would want the good word out through online reviews and YouTube.
Agree with MAubrey's point here. Even expert assessments of MTF at infinity using high end equipment can have great variations, enough so that they are simply irreconcilable - making both series unreliable. LR's 22/10/2019 comparo of the Tamron-Zeiss-Sigma f1.4 35mm lenses being a case in point.
Unlike many LR results (esp. the field graphs), which can often reflect the cross-frame performance of Zeiss lenses as seen in CZ's own MTF data sheets, this one, the Milvus 35/1.4, looks like an entirely different (and rather poor) lens.
