SIGMA MOUNT CONVERTER MC-21 for the L Mount system by SIGMA UK camera ambassador Paul Monaghan

SIGMA MOUNT CONVERTER MC-21 for the L Mount system by SIGMA UK camera ambassador Paul Monaghan

With the camera market evolving from single lens reflex to mirrorless designs it can be a worrying time for photographers not knowing if their equipment will become obsolete. Especially as over the years we have invested and built a collection of lenses that are designed to work on a specific system.


However, the shift to mirrorless cameras with the shorter mount to sensor distance design has also enabled SIGMA to create a high-quality adapter called the SIGMA MC-21 MOUNT CONVERTER which enables photographers to continue to use their favourite SIGMA glass. Such an adapter allows photographers to use their current lens collection on the new L mount camera bodies that will be introduced from the Panasonic, Leica and SIGMA alliance.


The SIGMA MC-21 comes in either a Canon EF to L mount or Sigma SA to L mount fitting. Both are designed specifically for SIGMA lenses to be used on the new L mount camera which opens the creative options for the use of your SIGMA lens. Other photographers have published tests using other manufacturer lenses with a varying degree of success but that is not the intended use of the SIGMA MC-21, therefore, it will not be discussed in this article.

Inside the box of the SIGMA MC-21 are the tools you need to attach/detach the tripod socket including a hex key, fixing screws and screwdriver. It is recommended to use the hex key to avoid damage as other tools may tighten excessively.


The build quality is exactly on trend and what you expect from a Sigma Global Vision product; it feels solid and looks like a finely crafted device. The rear of the adaptor has a rubber seal and the SA version includes one on the front. The inside is covered with a black felt material to help reduce internal reflections.

Unlike the SIGMA MOUNT CONVERTER MC-11, there is no USB port on the side. The SIGMA MC-21 comes preloaded with the data needed to drive the current Sigma Global Vision lenses while new release lenses will come with the data needed to work with the MC-21. It means no firmware updates of the MC-21 will be required to use those new lenses. In addition, the MC-21 also supports correction functions of camera such as peripheral illumination, chromatic aberration of magnification, and distortion.


Using the MC-21 is as easy as attaching it to the camera and then attach your lens and your good to go. The compatibility of the lens is instantly visible on the LED light on the side of the unit. It flashes green if everything is good, orange if the lens needs a firmware update and no flashing means the lens isn’t compatible.


There are two L mount camera bodies that currently support the MC-21; the Panasonic Lumix S1 and Panasonic S1R but they come with the following limitations that might affect your shooting style depending on your subject.
• Only AF-S works in Autofocus Mode. AF-C cannot be selected.
• The Auto continuous operation cannot be used during video shooting.
• Touch AF cannot be used.
• With lenses incorporating MO (Manual Override), operation in manual mode is possible only after focusing. MF guide is not available.
• The image stabilization function inside the camera body and the lens cannot be used simultaneously.
• Please ensure one of these is selected.
• The AF Function Button and the Focus Pre-set Button incorporated on some lenses cannot be used.

I recently had the honour of testing the Lumix S1R thanks to Panasonic UK and would like to share my experience with using this combination.

AF-S vs. AF-C

The camera could only be used in the AF-S mode as the AF-C mode was not available and was greyed out in the menu option. Although this did not cause a problem for me as the AF-S mode is very accurate even in low light especially when using a fast aperture lens. This used in combination with the human/animal eye detect feature made it very easy to nail focus even when using a very shallow depth of field lens such as the SIGMA 105mm F1.4 DG HSM | Art lens.


With the AF-S mode the camera can still detect people, faces and animals even if they are out of focus however I’ll admit that it would be convenient if we could utilise the AF-C mode to track as it would make some types of shooting much easier. Sadly this lack of AF-C also applies when using Video mode which might be more of an issue depending on how you shoot.


Here’s what you see when using the face/eye detect on the Lumix S1R when used in combination of the SIGMA MOUNT CONVERTER MC-21:



Touch AF via the LCD screen cannot be used even when it is enabled in the camera menu. This also applies to controlling the camera via the WIFI tethering app and to video shooting but thankfully the USB tethering works fine via the LUMIX tether software. I believe the reason why has more to do with the lack of AF-C. In AF-S mode the rear LCD screen is used to simply allow you to quickly change your focus point. You can enable the camera to automatically take a photo after touching the rear LCD and in this case, it will focus just before capturing the image. You can enable this in the touch tab menu or if you press the shutter button on the camera or WIFI app. It would be nice if there was an option to enable AF while in AF-S without taking the shot as you can do in the LUMIX tether software.


The cameras focus bracketing mode was a feature I had wanted to try and use with the SIGMA MC-21 combination but this was also disabled. I had hoped to try it with capturing some MACRO images and would love if this becomes available at a later date.

Lenses incorporating MO (Manual Override)

With lenses incorporating MO operation, manual mode is possible only after focusing. This is not an issue with most of SIGMA’s Contemporary or Art lens series that I have been using but would be for the SIGMA Sports series lenses.


AF Function Button / Focus Pre-set Button / MF Guide

The AF Function Button and the Focus Pre-set Button incorporated on some lenses cannot be used but this doesn’t appear to a huge issue. Nor is the fact that the MF guide is not available. Neither is a big issue for me personally as it’s only used to show the focus distance in meters or feet. Although it would be a handy feature for video shooters doing focus pulls. Other focus aid features such as focus peaking or picture in picture zoom work fine.

Image Stabilization Function

The image stabilization function inside the camera body and the lens cannot be used simultaneously and only one can be selected. I tested this fact when I used the Lumix S1R + MC-21 + SIGMA 18-300mm F3.5-6.3 DC MACRO OS HSM | Contemporary lens at the Glasgow and District Sunday Football Championship cup game. I disabled the IBIS in the camera and used the lens own stabilization instead to capture some decent results.



So while there are some feature limitations they aren’t large enough to prevent you from using the combination without success. My style of photography is mostly portraiture, products or landscape images and the SIGMA MC-21 worked perfectly for me in these situations. I especially enjoy using it in combination with the SIGMA 105mm F1.4 DG HSM | Art  lens along with the camera’s eye detect feature. It allows me to take fantastic portraits such as this one of my wife Catherine.


For landscape images I’ve combined it with the SIGMA 12-24mm F4 DG HSM | Art lens for images such as this of St Mary’s Parish Church in Kirkintilloch.


Then for my macro or product images, I’ve used the SIGMA MC-21 in combination with the SIGMA 70mm F2.8 DG MACRO | Art lens.


Using it for event/sports photography when I combined it with the SIGMA 50-100mm F1.8 DC HSM | Art lens required a different approach then I was accustom. The limitation of the AF-C did affect me when shooting the football match which I shared earlier in the article. I normally use the AF-C setting on my SONY using the SIGMA MOUNT CONVERTER MC-11 SE mount to track subjects and wait for the right moment. Using AF-S caused me to feel that I was reactive to action after it happened, therefore, I struggled to adjust and eventually shifted to manual focus. This also enabled focus peaking and picture in picture zoom plus the high-quality 120hz EVF was actually a rather enjoyable experience.


I feel the SIGMA MOUNT CONVERTER MC-21 is a great investment for people who want to use an L mount camera system such as the Panasonic Lumix S1 or S1R and still want to use their loved SIGMA lenses. It allows the opportunity to use a current lens you already own plus provide the options of using new lenses that would be available in the future. We’ve seen how the SIGMA MOUNT CONVERTER MC-11 SE mount performance and features have improved over time, excelling to the point of it performing as though you were using a native lens.   I’m hopeful that the same will happen with the SIGMA MC-21 and interested to see how the system will evolve so that more features are unlocked for the user.

You can see more images created by SCA Paul Monaghan on one of the following links:



Featured product: SIGMA MOUNT CONVERTER MC-21