As you know, Sigma recently launched a new 105mm F2.8 DG DN MACRO Art lens.
I watched these reviews and was shocked by the image performance of the new Sigma lens. 
I am considering selling a Sony lens that has been purchased for less than a month and buying a new Sigma 105mm lens.
I bought a Sony lens only for camera scanning purposes.
So AF speed or OSS is not an important factor for me… 
I’d not jump ships so quickly, just because of someone posting something on youtube…
A lens can work miracles on one camera body and look bad on an other. Also, lenses are put together from many parts which can/will introduce sample variations. The same holds true for cameras and attaching a lens to a camera can make variations add up or cancel each other out. Moreover, differences can come up depending on distance, aperture settings etc. Most lens tests are not made at macro distances, so the results you get at different distances might be different too - or not.
If you want to spend more money for a lens that might be better than what you already have, I’d propose to get the new lens first and see if it really tops your current lens. You can then always return the “bad” lens after your tests.
I agree with your opinion and thank you.
I am not an early adopter. Anyway, I did several tests with the a7R IV and a 90mm macro lens, and for 4x5 films, I had to take two shots to get comparable results to Hasselblad/Imacon sacnner. But I still think Hasselblad/Imacon captures more fine detail and I’m thinking that the new Sigma 105mm lens will completely fill this detail and gap.
Phew… 
After long thoughts and research, I ordered a Sigma 105mm f/2.8 DG DN Macro Art lens.
It is essential for me to capture my 4x5 films in the highest quality, but before I started the scan, sigma lenses came out and I had to check its performance.
I scanned the 35mm lens test target(created by Charles Sleicher) with each lens.
Sony had better f/8 than f/5.6, Sigma had better f/5.6 than f/8.
So these images are compared at f/8(Sony) and f/5.6(Sigma) respectively.
Now I’ll scan my 4x5 films and compare again, then I’ll decide which lens to keep. 
– Sony a7R IV, Tru Vue Museum Glass.
According to your images above, it looks like the Sigma resolves a tad better than the Sony.
Nevertheless you’ll shoot negatives 4 inches high with something that is less than ONE inch high. I’d try to compare stitched shots too - at least for the wow-shots you’ll want to print XL. Stitching could be difficult though, depending on how much distortion and vignetting the lens has at the settings used for capture.
I just compared the 1x3 multiple-shot 4x5 scan images, and Sigma again produced a little sharper image.
This is the small improvement I wanted for the Sony 90mm lens.
However, there is no lens profile for Sigma 105mm lens in Lightroom or ACR.
Sigma lenses have slightly noticeable pincushion distortion and vignetting.
Now, I’m going to create a lens profile with Adobe Lens Profile Creator.
I made a new profile for Sigma 105mm lens with Adobe Lens Profile Creator program.
Before merging multiple shots with Merge to Panorama in Lightroom/ACR, the lens profile should be ready for better results.
I’m puzzled why, if you are looking for a dedicated lens for scanning you are using a lens dedicated for photography? Macro lenses suffer from barrel/pin cushion distortion (as you have found) and more importantly, chromatic aberrations.
Before buying, may I suggest you look at dedicated scanner lenses such as those from Minolta, Nikon, Scitex, Schneider, etc. These have extremely high resolution and a perfectly flat field with near zero aberration of any kind and knock spots off any macro lens at sometimes a fraction of the cost.
@Belinda, are you thinking of something like shown here (dig into the menu for more)
https://www.closeuphotography.com/
Yes, exactly.
It’s a great site by the way - my go-to for lens information.
My short list depending on budget would be:
Sigma Art 70mm f/2.8 DG Macro Lens
Minolta DiMAGE Elite 5400 Scanner Lens
Nikon Scanner-Nikkor ED 100mm Scanner Lens
Schneider Kreuznach Macro Varon CAS 85mm f/4.5
Nikon Printing-Nikkor 105mm f/2.8A or any often other Printing Nikkors by Rayfact.
The Minolta Dimage 5400 scanner lens (see the tests!) was my choice based on cost/benefit ratio. Although it looks insignificant to put it mildly, it’s outstanding and relatively cheap. It behaves like a super-achromat and makes my other macro lenses look very sad by comparison.
I just saw your post.
Since I shoot with a large format camera, I only need a lens for film scanning.
I am satisfied with the scan quality of the Sony a7R IV camera, the Sigma 105mm F2.8 DG DN Macro Art lens, and the height adjustable micrometers.
This combination produces images equal to or better than my Hasselblad Flextight X1 scanner.
Anyway, thanks for your information.
You have an impressive set up. Can I ask what the components are?
Sorry, what components are you talking about? 
The whole rig! The column, stage plate, etc. Looks 100%.
● Camera stand: Beseler 45V-XL enlarger. I attached the ProMediaGear PX8 8" Arca-type double dovetail plate to the two 1/4-20 screw holes on the focusing track of this enlarger. And for the C1 cube, I put the RRS Mini-clamp package on this plate.
● Camera rotation device: Arca-Swiss C1 cube with RRS TH-DVTL-55 dovetail plate, ROGETI CAP-GZA geared panning head.
● Light source: RaLeno PLV-S192 LED video light panel and Perspex Spectrum Opal 1TL2 Acrylic Plastic Sheet (3mm).
(I have a Kaiser Slimite Plano 5000K 10.5x15.5" LED lightbox, but I no longer use it for this purpose after purchasing RaLeno.
Brightness uniformity is not good, dark, and touch buttons are inconvenient)
● Light source moving device: SGB15-4-LOCK slide block x 4, SGR15 550mm Linear Guide Rail x 2.
● Light source leveling device: LZ60 Z-Axis Manual Linear Stage x 4.
● Tru Vue 8x10 museum glass x 2.
● Jingyan TLL-90S digital level.
Thank you. A brilliant set-up. I feel an upgrade coming on…
I started with a 50mm Sigma ART with extension tubes and got reasonable results with 6x6 but not with 35mm as one can’t frame enough of the negative. Then I bot an older Canon NON USM 100mm macro; that lens is useless with sloppy focus; the euphemism is soft. Now I have a 70mm Sigma ART Macro and it is spectacular with both 35mm & 6x6. One cannot be too careful with levelling the negative and sensor planes. Almost more important than really fine focus.These Sigma Art lenses are absolutely tack sharp!
I tested the 70 f/2.8 Sigma Macro ART and the 90 Sony. Have not used the 105 Sigma, but I hear it’s also excellent.
The Sony, for double the price, is NOT better.
I agree with the first three in Belinda’s lens list above. I’ll add the older Sigma macros (50 and 70 EX DG Macro in many mounts) to the list, and the 55 f/2.8 Micro Nikkor AI.
Hi there 
What‘s the reason for choosing the Sigma 105mm over the 70mm f2.8 Art? I am currently thinking about getting one of these two for my 35mm scanning. Thank you!
Haven’t looked for it, but I’d get the one with published MTF diagrams. Manufacturers like to brag about the good lenses they make - and nice MTF is better than sales text.
I’d opt for non-extending designs for practical reasons mostly.
