Sigma 105mm F2.8 DG DN MACRO Art

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chris_ma
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Sigma 105mm F2.8 DG DN MACRO Art

Post by chris_ma »

Most of you probably have already heard, Sigma released a new Macro in the Art series, the 105mm F2.8 DG DN MACRO Art.

sigmas info site:
https://www.sigma-global.com/en/lenses/ ... 20_105_28/

they have a info video on youtube as well (a bit bumpy but very informative):
https://www.youtube.com/watch?v=zoMLAvZ9Wbw

since it's a floating lens design, performance above 1x should be better with a teleconverter then with additional extension. they talk about this in the above video, and they even published MTF data on their webpage:
https://www.sigma-global.com/en/lenses/ ... 5_28/data/

looks like one of the best performers coming close to the specialist lenses like printing nikkors etc.
(planing to do a test about that, although I'm sure other people here would be more suited for that)

chris
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Lou Jost
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by Lou Jost »

Wow this is great news! Imagine a Printing Nikkor that can focus bracket automatically at a wide range of m!!!!

Art lenses are mind-bogglingly good.

Lou Jost
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by Lou Jost »

I've just watched Sigma's CEO explaining the features of this lens. It was a surprisingly informative presentation. He explained how the designers paid special attention to the bokeh and ghosting, via detailed computer simulations.

The optical quality was compared to the excellent 70mm Art lens and, to my surprise, the MTF diagrams were nearly identical. I thought they would be significantly better than the older design.

The focusing block has a curious design that may be unique. The aperture moves with the focusing group. I can imagine that this will move the entrance pupil a lot, causing problems for focus-bracketing. I don't know if that is necessarily true; maybe Rik can chime in on this important aspect.

Getting rid of longitudinal CA was a main priority, since it can't be corrected in camera, and they seem to have achieved this. It appears that this may come at the expense of correction of distortion, vignetting, and maybe lateral CA, which will be automatically corrected in software. This is where the lens differs from film-era super-lenses like the Printing Nikkors, which correct everything, because they have to. Some lateral CA comparison shots are given and show no CA, but I think this is after correction in software. I am sure the lens won't work except on the camera it is designed for (either the Sony E mount or Panasonic/Leica L mount), so perhaps not much is lost by relegating the CA correction to software.

There is only one special-glass element out of 17. This compares with the 105mm A Printing Nikkor's 7 ED elements (if I recall correctly) out of 14.

This lens is designed to also work well as a normal medium telephoto. The corner sharpness wide open at infinity is extremely good, about the same as one of their best non-macro lenses, the 105mm f/1.4 at 2.8.

The lens is designed to work well with Sigma mirrorless teleconverters, which could be the best teleconverters ever made for FF since they have not been constrained by the long flange distance of DSLR-era teleconverters.

The price is low for Art lenses.

rjlittlefield
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by rjlittlefield »

Lou Jost wrote:
Wed Oct 07, 2020 7:00 am
I've just watched Sigma's CEO explaining the features of this lens.
Sounds interesting! Do you have a link to that talk?
The focusing block has a curious design that may be unique. The aperture moves with the focusing group. I can imagine that this will move the entrance pupil a lot, causing problems for focus-bracketing. I don't know if that is necessarily true; maybe Rik can chime in on this important aspect.
At this point I don't have enough info to know. It could actually be an improvement. When the physical aperture does not move with a focusing group that's in front of it, the entrance pupil is guaranteed to move a lot. But depending on exactly how the physical aperture does move, the entrance pupil might move more, or less, or even not at all.

--Rik

chris_ma
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by chris_ma »

rjlittlefield wrote:
Wed Oct 07, 2020 8:37 am
Sounds interesting! Do you have a link to that talk?
it's in the youtube video I've linked in the first message:
https://www.youtube.com/watch?v=zoMLAvZ9Wbw

they have quite a few nice lens diagrams etc
chris
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lothman
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by lothman »

Lou Jost wrote:
Wed Oct 07, 2020 7:00 am
The lens is designed to work well with Sigma mirrorless teleconverters, which could be the best teleconverters ever made for FF since they have not been constrained by the long flange distance of DSLR-era teleconverters.
but the teleconverters are only offered for L-mount not for FE-Mount.

rjlittlefield
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by rjlittlefield »

chris_ma wrote:it's in the youtube video I've linked in the first message:
https://www.youtube.com/watch?v=zoMLAvZ9Wbw
Thanks for the link. Yes, good lens diagrams at 11:29.

What I see in front of the aperture is that with their old lens, there's a strong negative group that moves backward with respect to the aperture at close focus, where with the new lens, there's a moderate positive group that moves forward with respect to the aperture at close focus. I expect that both lenses will have the entrance pupil moving backward at close focus, but I can't tell which one will move more.

I don't see anything in either design to make me particularly worried. Experience will have the final word, of course.

--Rik

ray_parkhurst
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by ray_parkhurst »

I rarely get excited about regular lenses, but this one has me very interested. I need to review the references but this may be something I end up purchasing when I get my next camera.

Ichthyophthirius
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Re: Sigma 105mm F2.8 DG DN MACRO Art

Post by Ichthyophthirius »

That was a delightful presentation. Thanks for the link!

I can also believe the increase in macro lens sales in Europe during lockdown that he talked about. Certainly confirms my own observations.

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