sl 21mm apo

[Mak67]

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Hi, 

Considering this lens to extend my apo series, but didn't see so many neutral review about it.

Does anyone has experience comparing it to the SL16-35@21mm this lens is my reference lens for ultrawide, used it for years and have a pretty good knowledge of how it works and render. 

 

But appreciate also experiences comparing it against sigma 20/2, sigma 20/1.4, sigma 14-24, Panasonic 16-35 as i've also owned and test thoses lenses against the SL16-35.

 

Use case: architecture/interior architecture @5,6-8

Chromatique aberration and sharpness is probably not as good as the 35apo, but should be good enough.

My main concern, is corner resolution, field curvature and coma. 

Real life expériences appreciated

Thanks,

 

 

 

 

 

 

 

 

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[dynaerik]

Maybe you saw it already but I find this video from Reddotforum very helpful. Comparing the SL 21, SL 14-24mm, SL 16-35mm, Wide-Angle-Tri-Elmar 16-18-21mm, and Super-Elmar-M 21mm f/3.4.

 

 

[albireo_double]

In my experience, the SL 21 Apo is better than the 16-35 shot at the 21mm focal length. Sharper, more contrast, less distortion. I would say comparable to the 35 SL Apo. I also use it for architecture (old factories, urbex etc) - the first image on my website  was shot with the 21 SL Apo and is very close to straight out of camera. Not sure how much of the perfection comes from the embedded profile in the processing software (Capture One in my case) but I find the 21 SL Apo astonishingly good. It is my "go to" lens every time I need to be quick in and out of somewhere where it might be risky to work with a Phase One XT on a tripod.

[Eoin]

I have used many 21s on various systems over my lifetime, both in primes and within zoom ranges.
Unfortunately, I don’t have the SL 16-35 or any zooms for the SL system, I prefer prime shooting.

But as a purely subjective opinion, the Super APO Summicron-SL 21mm is the absolute best 21 I’ve ever had the pleasure of using… period.
I think it will exceed your expectations in every respect to the criteria you listed. You need to get your hands on a demo, that will make the answer very apparent.

[Ken Abrahams]

Initially I didnt like the 16-35 and thought it too clinical or that something Leica was missing. I couldn't put my finger on it but - it's a very fine lens indeed. One can keep "looking in" further and further into the image with this lens. Very sharp in a different way which like the Apo SL 21, leaves itself open to layers of processing and something special. I have the 21 Apo and in the short time of using this lens its lived up to everyone of its praises. I use the 21 a lot, now with the Super Elmar M in reserve or dedicated to lighter street work.

I wouldn't ignore the SVE SL 16-35 but its not the same as the  Apo Summicron SL 21

Best   

[Tpau17]

I have already had the opportunity to use several wide-angle lenses with the L-Mount system – the current SL21, the Sigma Art 14-24mm, the Panasonic 16-35mm, and the M21 ASPH. Unfortunately, I have never been able to use the Leica 16-35mm as a comparison lens.

Sigma Art 14-24mm – zoom excellence with one drawback - it fully justifies its ART status. Sharpness, color reproduction, and distortion correction achieve impressive values for a zoom lens. Unfortunately, it was stolen during a trip to Lapland, forcing me to look for alternatives.
Panasonic 16-35mm --
I chose the Panasonic 16-35mm as a pragmatic replacement, mainly because of the possibility of using front lens filters -- unlike the Sigma, which only accepts slide-in filters on the rear lens (e.g. from HAIDA). Despite these practical advantages, the Panasonic did not completely convince me. It lacks that certain spark, that brilliance that distinguished the Sigma -- and that's not because of the missing two millimeters at the lower end of the focal length range.
Leica M21 2.8 -- solid, but not convincing The M21 2.8 delivered respectable results, but the edge sharpness did not meet my usual standards. The 3.4 version was too expensive for me.
The SL21 clearly surpasses all my previous 21mm experiences.
It plays in the same league as the renowned SL35 APO, although it is difficult to determine an exact ranking between these two top lenses. see #3 from @albireo_double
After careful consideration, I decided on the SL21—a choice that has proven to be spot on. The image quality consistently exceeds my expectations. There is a special group for this lens on Flickr where you can find impressive sample images that demonstrate the potential of this lens.

[ImmerDraussen]

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Hi,

I own the SL 16-35 mm and the Apo 21 mm, but my focus is landscape and not architecture.

The 16-35 mm is pretty good in high contrast situations when shooting against the sun. Used for shots of the night sky there is a clearly visible coma in the edges. So if highest resolution in the corners is important for you, the zoom is not the right decision.

The Apo 21 mm is the clearly better lens in any respect. This is even visible without going to 100% magnification.

As landscape photography often means nasty conditions there are reason to use zooms to avoid lens changes and the results are pleasing.

If directly compared against the SL Apo‘s any zoom will loose.
 

 

 

[beewee]

I have the SL16-35, 24-90, 90-280, 21 APO, 28 APO, Sigma 14/1.4, 14-24, and 24/3.5.

A couple years ago, I did some controlled testing (Gordon Laine @ Camera Labs review Brighton Pier style) at all marked focal lengths and at all whole stop aperture increments on my L-mount lenses with the SL2-S in multi-shot mode. Unfortunately, the 21 APO and 14/1.4 didn’t exist at the time.

The general conclusion of the test was that the SL zooms and the Sigma 14-24 all performed similarly which actually gave me a huge amount of respect for Sigma. Seeing the results myself, it is no surprise why Leica decided to rehouse Sigma zooms, perhaps with some minor customizations and tweaks for the SL versions.

The other striking conclusion was that the 28 APO was head and shoulders more performant than all the others lenses, especially out into the corners. There’s simply no contest for which lenses performed best for corner sharpness. I haven’t repeated the test with the 21 APO but based on normal use so far, my general impression is that it is on par or very close to the 28 APO performance.

Edited July 20 by beewee

[Tpau17]

vor einer Stunde schrieb beewee:

especially out into the corners.

I can confirm this with the SL21 – compared to the Leica M21, the Sigma 14-24 (and the Leica 14-24 based on it, where further optical optimizations are unlikely, not workmanship and materials). The Panasonic 16-35 also failed to impress me here, even though it is an S-Pro lens.

 

[Virob]

Here are my notes comparing Leica 21APO vs Sigma 20/2 and Panasonic 16-35 at 21

Center

f2.0 small amount of chromatic aberrations with 21 APO, Sigma has more and is less sharp with lower contrast.

f2.8 chromatic aberrations mostly gone with 21 APO, slight improvement in sharpness and contrast. Sigma chromatic aberrations reduced, but still more than 21 APO at F2.0. increase in sharpness and contrast but not as sharp as 21 APO at 2.0

f4.0 Chromatic aberrations gone. No real change in sharpness or contrast in 21 APO. Sigma, chromatic aberrations mostly gone. Sharpness and contrast still not up to level of 21 APO at 2.0. Panasonic less sharp and lower contrast than Leica or Sigma, but no chromatic aberrations.

f5.6 Slight loss of sharpness and contrast for 21 APO. No real change with Sigma, sharpness about the same as 21APO, but lower contrast. No real change with the Panasonic which is still less sharp with lower contrast..

Corner

f2.0 21 APO looking very good, much sharper than Sigma

F2.8 21 APO bump in sharpness. it is about as sharp as the the 21 APO at 2.0 in the centre! slight increase in Sigma but still way behind 21 APO at 2.0

F4.0 21 APO slight bump in contrast, slight increase in Sigma but still way behind 21 APO at 2.0, Panasonic slightly better that Sigma in terms of sharpness, but very bad fringing

F5.6 21 APO no real change, Sigma improves again but still behind 21 APO at 2.0, Panasonic improves also and is better than Sigma but still very bad fringing

F8.0 21 APO slight loss in sharpness, Sigma no change, still behind 21 APO at 2.0, Panasonic slight loss, still very bad fringing

[BillCB]

This is a non-scientific response. I'm a nature and landscape photographer. 

I have owned several systems including Canon, Sony, Hasselblad and most recently Phase One. The Leica APO 21 is simple the best of it's kind I have ever used - hands down. IMHO it has no competition.

[jplomley]

Pick any of the APO L Summicrons and you will not be disappointed.....I have the 21-35-75 combo and have zero complaints.....looking to add the 28 APO at some point....

[Tpau17]

vor 16 Stunden schrieb Virob:

No real change with the Panasonic which is still less sharp with lower contrast..
Panasonic slightly better that Sigma in terms of sharpness, but very bad fringing

Thank you very much for testing the different lenses. Your reviews have helped me to finally put my own experiences into words. I couldn't have put it so precisely myself – probably because I never had all three lenses at hand at the same time (see my #6 here) 

[helged]

20 hours ago, jplomley said:

Pick any of the APO L Summicrons and you will not be disappointed.....I have the 21-35-75 combo and have zero complaints.....looking to add the 28 APO at some point....

Havung SL21, 35, 75 and 90: Don't forget the SL50Lux... Yes, it's large and it's heavy. But the rendering wide open is beautiful (in my eyes), and stopped down a little, it is optically at APO-level. In additiin, near new/hardly used second-hand SL50Lux can be found at a reasonable cost.

[jplomley]

4 hours ago, helged said:

Havung SL21, 35, 75 and 90: Don't forget the SL50Lux... Yes, it's large and it's heavy. But the rendering wide open is beautiful (in my eyes), and stopped down a little, it is optically at APO-level. In additiin, near new/hardly used second-hand SL50Lux can be found at a reasonable cost.

I am torn because I purchased the Sigma 50/1.2 DG DN not expecting all that much for the price....needless to say I was blown away to the point I have not considered the Lux, or the 50mm APO....f/1.2 rendering is simply epic on this lens, and stopped down it is so close to the APO performance it is difficult to see the difference in actual prints following work-up.  My only concern (slight) is the weather sealing. I do enjoy photographing in inclement weather, and here the Leica lenses are top-drawer. I have shot in downpours and in wickedly brutal winter storms and the SL2 with APO Summicrons are un-phased. I like the level of confidence this camera and these lenses instill under these shooting conditions. I don't need to worry about the gear which allows me to just focus on the capturing process. Now, please develop a 135 APO and 100 Macro APO and a couple of T/S lenses. I have zero doubts Leica can do this and the demand is there, especially for the APO Macro

Edited July 22 by jplomley

[helged]

9 hours ago, jplomley said:

I am torn because I purchased the Sigma 50/1.2 DG DN not expecting all that much for the price....needless to say I was blown away to the point I have not considered the Lux, or the 50mm APO....f/1.2 rendering is simply epic on this lens, and stopped down it is so close to the APO performance it is difficult to see the difference in actual prints following work-up.  My only concern (slight) is the weather sealing. I do enjoy photographing in inclement weather, and here the Leica lenses are top-drawer. I have shot in downpours and in wickedly brutal winter storms and the SL2 with APO Summicrons are un-phased. I like the level of confidence this camera and these lenses instill under these shooting conditions. I don't need to worry about the gear which allows me to just focus on the capturing process. Now, please develop a 135 APO and 100 Macro APO and a couple of T/S lenses. I have zero doubts Leica can do this and the demand is there, especially for the APO Macro

Yes, lot's of praise for the Sigma f1.2! Havn't used it, want's to do, one day (and isn't Sigma coming with smaller f1.2 lenses, as well?).

[Tpau17]

vor 8 Stunden schrieb helged:

and isn't Sigma coming with smaller f1.2 lenses, as well?)

I've heard that the 35/1.2-Art should be available in a smaller Gen2-Version this year.

 

[jplomley]

On 7/23/2025 at 2:34 AM, Tpau17 said:

I've heard that the 35/1.2-Art should be available in a smaller Gen2-Version this year.

 

Indeed, and even though I have the 35 APO, I will still have a look at the Sigma 35/1.2 for that unique rendering with buttery smooth backgrounds, something the 35 APO does not offer. I would not say the bokeh is overly nervous on the 35 APO, but it is not smooth like my 50/1.2.......so I have high hopes for the 35/1.2

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Hallo,

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[Tpau17]

vor 2 Stunden schrieb jplomley:

Indeed, and even though I have the 35 APO, I will still have a look at the Sigma 35/1.2 for that unique rendering with buttery smooth backgrounds, something the 35 APO does not offer. I would not say the bokeh is overly nervous on the 35 APO, but it is not smooth like my 50/1.2.......so I have high hopes for the 35/1.2

I have the 35/1.2 Sigma (Gen1 🙂 ) and it really is an exceptional lens – but at 1090 g / 1 kilogram -> it's really heavy compared to my M-35 Summilux....

[jiggyb21]

I own the Sigma 1.4 ART (I have a really good copy) and do landscape and astro photography. I have always been happy with it. I purchased the 21 APO based on the incredible praise it receives all over the internet. The first thing I did when I received the lens was perform tons of daytime side by side, controlled tests with my SL3 at 60mp. I had my wife scramble all the file names and hide the exif data and I spent a good 30 minutes studying the photos and taking notes. I wanted to be sure I didn’t let the hype influence my eyes.  
 

My conclusion was shocking. When it came to the overall image, I preferred the Sigma image over and over again. Somewhere in the neighborhood of 75-80% of the time. Color between the two was identical. Zooming in to 200%, sharpness was consistently better on the Sigma everywhere but in ONE of the most extreme corners (centering issue with the Sigma I assume). Upon closer inspection, the Leica had a little less distortion, but the Sigma is 1mm wider so that allows for total correction while maintaining the same overall field of view. I could go on and on about how blown away I was by the results but suffice it to say, I made $5000 that day by boxing the Leica lens back up and returning it. I would imagine if I were shooting people or events maybe the results would be different. Maybe some of that Leica magic would shine through. Instead I was shooting brick walls, fences, trees and bookshelves and in those more clinical scenarios, the Sigma won. And I paid $800 for it. 
 

Edit- just to say, I don’t think I had a bad Leica copy or anything. My conclusion is that the Sigma is just that good. 

Edited July 25 by jiggyb21