Any comments on using the M 21mm Summilux on an SL body?

[Ken Abrahams]

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1 hour ago, Photon42 said:

The Miami crew did compare wides from L-mount, but also in comparison to the WATE and the 21SE. The M lenses turned out to be surprisingly good.

Especially the WATE 

[Elliot Harper]

Sorry if this topic has been brought up before, but SL21 APO is my first Leica SL lens, so I don't know if it's normal or not.

I understand the camera/lens, when it's on, it makes some kind of hissing sound. Probably it's because IBIS is working.

Also, I heard the lens makes intermittent "click" sound when the camera is set to AFs, and it's moved around. Probably because the camera wants to adjust the focus? I assume it is because when I set the camera to be MF, this sound is gone.

However, I have two questions:

1. Why are this IBIS hissing sound and the lens focusing "clicking" sound much more profound on APO SL 21mm lens than the other SL lens, for example Sigma 35 DG DN f/2 ? On this Sigma lens, the sound is so fainted that I have to attach my ear to the camera in order to hear it.

2. Why does the camera have to keep adjusting focus even when it's set to AFs and shutter button is not pressed/half-pressed? And again this sound is more profound on Leica SL lens than on Sigma lenses?

I am not running on the latest firmware yet, currently on 2.0.0. But I assume this observation is irrelevant to firmware anyway.

Edited Thursday at 06:13 PM by Elliot Harper

[helged]

1 hour ago, Elliot Harper said:

Sorry if this topic has been brought up before, but SL21 APO is my first Leica SL lens, so I don't know if it's normal or not.

I understand the camera/lens, when it's on, it makes some kind of hissing sound. Probably it's because IBIS is working.

Also, I heard the lens makes intermittent "click" sound when the camera is set to AFs, and it's moved around. Probably because the camera wants to adjust the focus? I assume it is because when I set the camera to be MF, this sound is gone.

However, I have two questions:

1. Why are this IBIS hissing sound and the lens focusing "clicking" sound much more profound on APO SL 21mm lens than the other SL lens, for example Sigma 35 DG DN f/2 ? On this Sigma lens, the sound is so fainted that I have to attach my ear to the camera in order to hear it.

2. Why does the camera have to keep adjusting focus even when it's set to AFs and shutter button is not pressed/half-pressed? And again this sound is more profound on Leica SL lens than on Sigma lenses?

I am not running on the latest firmware yet, currently on 2.0.0. But I assume this observation is irrelevant to firmware anyway.

Have you the menu system's pre-focus mode activated? If so, the camera will focus continuously.

[Elliot Harper]

1 hour ago, helged said:

Have you the menu system's pre-focus mode activated? If so, the camera will focus continuously.

Yeah you are right. It’s pre focus.

I never used this function or I didn’t even notice its existence and didn’t hear the clicking sound mainly because the other SL lens are so small and making very fainting sound I can hardly hear

[Stuart Richardson]

On 10/9/2025 at 9:42 PM, Elliot Harper said:

Yeah you are right. It’s pre focus.

I never used this function or I didn’t even notice its existence and didn’t hear the clicking sound mainly because the other SL lens are so small and making very fainting sound I can hardly hear

Yeah, when I got my SL2 at first, I was really unhappy with this behavior and noise until I figured out it was something that could be turned off. It seems like such a un-Leica-like behavior, I am surprised was enabled by default. It churns through the battery, makes noise and is generally pointless other than to shave a few microseconds from your af time. Even then, it doesn't really work that well. In my use, if I had the camera at my shoulder, prefocus would have chosen a point on the ground, so when I lifted the camera to my eye it would be out of focus for a moment. With it off, it just stays at the last place I focused (usually in the distance), so it is much more likely to be in correct focus. 

Edited Saturday at 09:52 AM by Stuart Richardson

[jaapv]

On 10/4/2025 at 11:53 AM, Stuart Richardson said:

In my experience, the L mount versions of the 21 and 24/25mm lenses are just a lot better. I am talking sharpness and freedom from aberration,  not “character”. I don’t find much use in character in super wides for my own work. I just want them evenly sharp and without chromatic aberrations. The one wide M lens I have found to be excellent on the SL2 is the new Voigtlander 28mm APO Lanthar. That one does superbly well. 

They may be a lot better technically than the M versions, but I'd sell my mother in law (should she still be alive) before I sold my Summilux 24 M. It is the standard super wideangle on my L cameras. 

[Stuart Richardson]

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Don't let me stop you! I am really demanding of lenses and getting sucked into all kinds of technical details. I understand how this can come across as being too focused on minor little details. But for me, it is in service of the art I am trying to make. The idea is not to obsess over details, it is to remove as many veils as possible from portraying the subject. I want people looking at the scene and the art, to be immersed in the scene. At least for me, I find that if I look at a photograph and see uneven focus, color aberrations and so on, it takes me out of the photograph, if even subconsciously, and then I am thinking more about "why does that feel unnatural", rather than about the scene. That's really what I am on about. So that is why I say things like "I don't care about character in a wide angle". It is a bit more complicated than that. But it is about finding lenses that present the world as closely as possible to how it appeared before the lens, and letting the composition and processing do the talking. I know that not everyone chooses or values this kind of process. 

[jaapv]

Have a look in the technology forum. There are a few SX24M shots there (as far as possible this way) that show a bit of the results from that lens.  All minimally processed. 

[Elliot Harper]

22 hours ago, jaapv said:

They may be a lot better technically than the M versions, but I'd sell my mother in law (should she still be alive) before I sold my Summilux 24 M. It is the standard super wideangle on my L cameras. 

I’m getting a summilux 21 M for $3000, and will try it on my SL3-S. You think summilux 21 M will be also worth more than your mother-in-law (rest her soul)?

[jaapv]

Not my focal length. I got the 24 deliberately as more versatile so more likely to be used, and use the Super Elmar 18 as a real superwide. And the Voigtlander 12. But they don't get much use, despite behaving pretty decently on SL cameras. 

[Ken Abrahams]

Good to see differing tastes with regards FL. I looked hard at the 18mm Elmar some 15 years ago, to be my second Leica lens. Hired it for a weekend and the Leica store back then took us on photo walks with a back pack full of lenses and M9’s M9M’s. It was like just good friends trying out a heap of kit around Fremantle. I still have the files. Anyway I got stuck ❤️on the 21 SEM and although it took time, I never looked back. It’s good to have a super wide in the kit. Thanks for the 12mm tip! 

[Elliot Harper]

16 hours ago, jaapv said:

Not my focal length. I got the 24 deliberately as more versatile so more likely to be used, and use the Super Elmar 18 as a real superwide. And the Voigtlander 12. But they don't get much use, despite behaving pretty decently on SL cameras. 

Versatility of 24mm means too wide but not wide enough. I prefer 28mm summilux, and think 24mm is too close to 28mm.

Edited yesterday at 01:37 AM by Elliot Harper

[Ken Abrahams]

3 hours ago, Elliot Harper said:

Versatility of 24mm means too wide but not wide enough. I prefer 28mm summilux, and think 24mm is too close to 28mm.

Sometimes a few mm of wider lens can make all the difference. Maybe not in a measurable scientific way though. I have the 28 Summilux and my choice for this lens some 10 years after buying the 21 SEM which was the predictor for buying the 28. In my mind I argued that the 21 Lens was too close in size to purchase the 24 Summilux. Money and practical sense became the final say when making the choice.  So my kit evolved in such a way like life choices and how fate plays its role. Maybe I am exaggerating a bit now but when I bought the 14-24 SL Vario Elmarit I had a different mindset and other factors steered me away from perhaps the 16-35 SL Elmar? I wanted something different. One can clearly see the pattern changing when I purchased the Super Apo SL Summicron 21 Asph when practicality was out the window. I guess want I am saying (especially to new buyers of Leica glass), to weigh up the options with lens purchases and consider the long term factors. The forum is great for a back history of lensmen making decisions in just about every which way, including changing brands, opting out of Leica glass. There are many more lens options now. My first lens was my hardest decision and I a glad I stretched myself to buy the Summicron M 35 Asph, the cheapest best quality new Leica lens available at the time. I am waffling on a bit now.     

Edited yesterday at 05:10 AM by Ken Abrahams