Best choice for Sony Full Frame Macro: Sony 90mm vs Sigma 105mm

I'm currently using the A7C + 28-60 kit lens + CMC-1.  It works well if you can get very close to the subject, but in many cases, the subject is positioned in a recess, preventing the shot.

For dedicated macro dives, I'm considering adding a macro lens + port to my kit to enable a longer working distance.

Does anyone have experience with both the Sony 90mm and Sigma 105mm macro lenses?

Thanks.

The sigma 105mm focuses by extending the barrel, this means two things first being that the mass of the moving parts is high so focus tends to be slow.   IF lenses move small elements internally and for shorter distances so focus quicker.    Second it means that wet diopters won't work well, they rely on being close to the front element of the lens and this only occurs at closest focus.  In addition the Sigma is put into manual focus by push/pull of the focus ring so switching to MF may be a problem in a housing.

As fa as sharpness goes both lenses have been tested by DXO here and Sony seems significantly better:  https://www.dxomark.com/Lenses/Compare/Side-by-side/Sony-FE-90mm-F28-Macro-G-OSS-on-Sony-A7R-II-versus-Sigma-105mm-F28-EX-DG-OS-HSM-Macro-Sony-on-Sony-SLT-Alpha-99-II__1517_1035_987_1120

Hi Chris,

I should have been more explicit.  I was referring to the 

Sigma 105mm f/2.8 DG DN Macro Art Lens for Sony E

I think that's a different lens than the DXOMark link you sent, no?

yes, different lens, the art series are well regarded lenses.  Found one site that has tested both lenses:

https://www.lenstip.com/595.4-Lens_review-Sigma_A_105_mm_f_2.8_DG_DN_Macro_Image_resolution.html

https://www.lenstip.com/561.4-Lens_review-Sony_FE_90_mm_f_2.8_Macro_G_OSS_Image_resolution.html

at f11 the performance is pretty much equal. I doubt you'd go wrong with either lens out of that pair.  There is probably a slight reach advantage for small critters and diopters will give more magnification with longer focal lengths.  Both are said to be slow AF, though the Sigma seems slightly faster - jump into the reviews to see what they say about AF, there's an index table at the bottom of the page.

Thanks, Chris.

If my calculations are accurate, the Sigma would have an additional 1cm working distance.

I also noticed that the Sigma does not have image stabilization.  Not sure if this is required, or if the Sony 90mm image stabilization works in conjunction with the A7C image stabilization.

I use back button focus.  If the autofocus can get close, i can fine tune by moving the camera in and out.  I wonder how the reported autofocus compares to the Oly EM-1 II + 60mm

While I think the Sigma Art 105 is on the same image quality level the auto focus is not. Even the Sigma CEO said the lens is slow to AF when the lens was released and was targeted more at macro shooters using a tripod and manual focus along with focus stacking.

Currently the Sony 90mm macro is the highest rated macro lens buy a good bit reviewed by DXO marks. The Sigma 105 art for Sony has not been reviewed by DXO at this time.