sl 21mm apo

[jplomley]

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3 hours ago, jiggyb21 said:

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. 

Yes, Sigma are that good. Has anyone tried the 28-45/1.8 DG DN Art lens? Wonder how that compares to the 28-35-50 APO Summicrons?  Alongside the 35/1.2 II, I would love to see a 28/1.2 for a fantastic 28-35-50 trio....

Edited July 25 by jplomley

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[Olaf_ZG]

Laundry on the 2s

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[o2mpx]

Anyone has insights b/t the APO21mm vs the SEM 21mm f3.4 M lens at mid aperture for landscapes?

If not shooting wide open but at mid apertures, which is the closest to APO21mm performance? In an earlier post the Sigma 20mm f1.4 seems to get the nod, others?

Considering the APO21mm but the weight and bulk always a holdback factor. With mid aperture landscapes, have been using the SEM 21 f3.4 with the SL3; actually don’t own any L mount lenses as the SL3 has been a body for M lenses only. 

Edited September 3 by o2mpx

[Photoworks]

6 hours ago, o2mpx said:

Anyone has insights b/t the APO21mm vs the SEM 21mm f3.4 M lens at mid aperture for landscapes?

If not shooting wide open but at mid apertures, which is the closest to APO21mm performance? In an earlier post the Sigma 20mm f1.4 seems to get the nod, others?

Considering the APO21mm but the weight and bulk always a holdback factor. With mid aperture landscapes, have been using the SEM 21 f3.4 with the SL3; actually don’t own any L mount lenses as the SL3 has been a body for M lenses only. 

I stopped using the SEM 21 on the SL3, since so many other lenses are doing a much better job.  I am using the 14-24 lens
The SEM21 is a good lens if you have an M camera, but would not get it for the SL

[o2mpx]

3 minutes ago, Photoworks said:

I stopped using the SEM 21 on the SL3, since so many other lenses are doing a much better job.  I am using the 14-24 lens
The SEM21 is a good lens if you have an M camera, but would not get it for the SL

Fair points. 

The red dot forum video has a good compare of the APO 21 vs the SEM 21 at 5.6 and as expected much better corner detail from the former. Another forum member @flashhad commented on the Fred Miranda site that he owned both and give the edge to the APO if money was not an issue, and the Sigma is the next best. 

Unfortunately the Sigma is 140g heavier, taller and has a 82mm filter thread va 67mm in the APO; so presumably despite the weight and bulk, the APO remains the IQ leader with acceptable size/bulk from the super wide club for the SL3. 

[o2mpx]

1 hour ago, o2mpx said:Unfortunately the Sigma is 140g heavier, taller and has a 82mm filter thread va 67mm in the APO; so presumably despite the weight and bulk, the APO remains the IQ leader with acceptable size/bulk from the super wide club for the SL3. 

Sorry, meant to say despite the Sigma being 140g lighter, but taller and larger. 

[Ken Abrahams]

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I have both 21 SEM and Super Apo Summicron SL 21. The SEM has been one of my favourite and most utilised lens. I use the 21 SEM on my M10M and SL2S and sometimes the SL3S but rarely on the SL3. My observations from post processing indicate the results of the SL3/21 SEM combination is not as good as the smaller sensor sized cameras.

I could not sell the 21 SEM. I specifically use the lens for walk around lens because of its ability for Street Photography. I can shoot "on the go" by zone focussing and its size and weight make it the perfect lens, in conjunction with 28 Summilux M, 35 Summilux M and 35 Summicron M. The Vario Elmarit 14-24 SL is also a great lens but not ideal for street photography. The AF function and wider angle adds another dimension to urban landscapes, abstract and architectural genre.

Ken 

Edited September 4 by Ken Abrahams
sentence

[Stuart Richardson]

1 hour ago, o2mpx said:

Fair points. 

The red dot forum video has a good compare of the APO 21 vs the SEM 21 at 5.6 and as expected much better corner detail from the former. Another forum member @flashhad commented on the Fred Miranda site that he owned both and give the edge to the APO if money was not an issue, and the Sigma is the next best. 

Unfortunately the Sigma is 140g heavier, taller and has a 82mm filter thread va 67mm in the APO; so presumably despite the weight and bulk, the APO remains the IQ leader with acceptable size/bulk from the super wide club for the SL3. 

I compared the SEM to the 550 dollar Sigma 24mm 3.5 and the Sigma was substantially better over most of the frame. The SEM was slightly sharper in the very center. L mount primes are just better than M lenses in my experience. I have a lot of M lenses, including APOs, and the APO Summicrons and even the zooms (24-90) are often better than the M versions...often it is not a subtle difference. And I mean better than they are on M bodies as well. The M lenses are great for size, but when it comes to image quality, the L mount lenses are the way to go. 

Edited September 4 by Stuart Richardson

[beewee]

I can’t speak for the 21 SEM because I don’t own one but I can say that, at 96 MP and equivalent apertures, the Sigma 14-24 is on par with the SL 16-35 at far distances but the APO 28 has significantly more resolution in the corners at 96 MP multi shot on the SL2-S compared to the other. I haven’t done similar testing on my APO 21 but my general impression is that the APO 21 is also going to out perform the zooms.

As a general rule of thumb, coming from Peter Karbe himself, non-APO TL and SL lenses were designed to resolve at minimum 60lp/mm across the frame with at least 50% contrast which would look ‘sharp’ to the eye at ~60MP. Whereas modern but non-APO M lenses were designed to resolve at minimum 40lp/mm across the frame with at least 50% contrast which would look ‘sharp’ to the eye at ~24MP. APO SL lenses can resolve in excess of 100 lp/mm across the frame with at least 50% contrast and are designed for sensors with 100-200MP of resolution in mind.

Edited September 4 by beewee

[beewee]

3 minutes ago, Stuart Richardson said:

I compared the SEM to the 550 dollar Sigma 24mm 3.5 and the Sigma was substantially better over most of the frame.

The Sigma 24/3.5 is a crazy good performer especially when stopped down to f/5.6. My copy was sharp to the very corners when I tested with 96MP multi shot on the SL2-S.

[Stuart Richardson]

I shoot it along with the APO Summicrons and have no complaints. It is one of the best deals I have ever had in lenses. It is not quite at their level, but it is great...substantially better than the 45mm Sigma and 35mm f2 contemporary lenses that I also tried from Sigma. Not quite as good as the 105mm 2.8, however, which truly is on par with the APO Summicrons. 

[Ken Abrahams]

On further inspection of different cameras using the 21 SEM shows degradation of image file in shadow detail. The image appears with pin head sized white dots extensively in deepest shadow areas. The same applies whether using denoise or not. The artefacts do not appear in the SL2, SL2S or M10M ( still looking for these artefacts on SL3S files but would think they would not be apparent.)

The artefacts are quite predominant on the SL3 however.

Edited September 4 by Ken Abrahams
sp

[Photoworks]

The 21 SEM and 18mm have been a benefit of very little distortion. When they came out, Leica commented that you can shoot on location Portraits with very little distortion

[Stuart Richardson]

On 9/4/2025 at 3:50 AM, Ken Abrahams said:

On further inspection of different cameras using the 21 SEM shows degradation of image file in shadow detail. The image appears with pin head sized white dots extensively in deepest shadow areas. The same applies whether using denoise or not. The artefacts do not appear in the SL2, SL2S or M10M ( still looking for these artefacts on SL3S files but would think they would not be apparent.)

The artefacts are quite predominant on the SL3 however.

Pin sized white dots are usually hot pixels…or dead, mapped out pixels. They are usually invisible when the exposure is sufficient, but on long exposure, high iso or lifted shadows, they can become visible. It should not have anything to do with the lens. I think Capture One has a setting to get rid of them. You might find they are improved with enhanced details in lightroom (which does a better bayer conversion), but I am not sure. 

[ImmerDraussen]

I had a similar issue with files shot with an SL2 (the camera was a heavily used model during a Leica training with a lot of hot pixels). The hot pixel could not be removed with denoising or the hot pixel tool. I used C1. The funny thing was that the wrong pixel have not been visible at the 100% view. The pixel became visible somewhere around 60% magnification.

I had a long chat with the Capture One support. First they could not believe this, because they could not see it on their screen with my files. Finally I sent screenshots to show the effect. At the end the answer was that C1 takes some short cuts to increase the development speed of the raw files (i.e. denoising is not executed at low magnifications). 

Some files processed in LR had no issues

 

[Ken Abrahams]

10 hours ago, Stuart Richardson said:

Pin sized white dots are usually hot pixels…or dead, mapped out pixels. They are usually invisible when the exposure is sufficient, but on long exposure, high iso or lifted shadows, they can become visible. It should not have anything to do with the lens. I think Capture One has a setting to get rid of them. You might find they are improved with enhanced details in lightroom (which does a better bayer conversion), but I am not sure. 

Thanks Stuart, not sure they are pixel related. They don’t seem to be uniform in size and looks more like degradation of file processing, as you say mostly in the shadows. I know it’s reasonable to see them in heavy shadow areas especially when pushing the image, I use dust and scratches filter to remove them if I can’t reduce their visibility through other adjustments first .

it can happen with any sensor however it happens more so with the SL3 and 21 SEM compared to smaller sensor sizes of the SL3S and SL2S

 

 

[Ken Abrahams]

On 9/5/2025 at 8:07 PM, Stuart Richardson said:

Pin sized white dots are usually hot pixels…or dead,

Thanks Stuart I believe we are talking about the same things re hot pixels and what I am referring to artefacts created by excessive processing. Devil of a things to show up. Dead pixels are usually the full size of the pixel I thought. I have a line of them on my M Monochrom going the full width of the frame. I haven't been able to recreate them on the SL3 Sensor so it's just a result of pushing the file too much. At least one can know the limits of the different files and why I like the SL2S in this regard.

Ken  

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Edited September 8 by Ken Abrahams

[mirrorless]

Need a bit of advice for my next lens purchase. I currently shoot with the Q3 28mm and the SL3 with the 75mm APO. Normally both cameras are with me so I look for a new FL that makes sense beside the 28mm and the 75mm. I know 21mm is sometimes a bit challenging, but I am completely sold on the pop and colors of the 21mm SL. Also it looks it's maybe the best SL APO lens in the lineup. (Street, Weddings, Vacations, Landscape, Milky Way is the plan) So actually the nominal FL of the Q3 is a bit wider and more a 25-26mm instead of 28mm and I wonder if this is not too close to the 21mm? On the other hand the next logical prime FL in the SL-line would be a 35mm which would be too much on the tele-side for me. As a plus point the non APO version of the 35mm is really light-weight but at the end still a 35mm and a bit too long for wide shots. I also never got warm with a 50mm and would always choose the 75mm. 14-24mm/16-35mm fall out since I am a prime-lens guy. Decisions, decisions....

21mm - 28mm (Q3) - 75mm and later on a 70-200mm F2.8 should be a nice setup incl. the 60MPIX crop-possibilities and also still portable

In my Sony times I already loved the ZEISS Loxia 21mm (Must say it was considerably lighter than the 21mm Leica) and had it a lot as a go-to lens

I wonder if anybody was in the same boat with that decision and can support me that the purchase of the 21mm SL will be the one to go... Thanks!

Edited September 21 by mirrorless

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[Eoin]

Just get the Super APO Summicron SL 21mm, job done!. Who knows, with all that resolution available you might even leave the Q3 at home and crop the 21 when needed.

The 21 SL brought a huge smile to my face first time I reviewed the images from it, 6 months later it has yet to disappoint in ANY aspect. Stunningly good lens.