Home L-Mount Alliance Dreams of Summertime: Leica’s APO-Summicron-SL 28 f/2 ASPH

Dreams of Summertime: Leica’s APO-Summicron-SL 28 f/2 ASPH


I had a copy of this lens for testing during late July and early August 2020, the gap between the springtime lockdown and the autumn upsurge of the Coronavirus.

When I get ready to write a report, the first thing I do is to go through the images taken with the camera / lens and make some basic picks to give me ideas about what to write.

In this instance, the pictures seemed like a glimpse into another world, the world of Cornish beaches and moorland in summer sunshine (actually, it rains much of the time, but that isn’t what the pictures say).

A lot of the pictures in the attached gallery were shot wide open, which adds to the dreamlike feeling surrounding them.

Blue and Yellow
Leica SL2 with APO Summicron SL 1:2/28   1/2000 f4.5 ISO 100

On the other hand, social distancing was definitely the order of the day, so people pictures are few and far between

So here is a short report to celebrate the release of the new APO Summicron SL 28mm f/2 ASPH

The 28mm is the 5th lens in the APO SL Summicron lineup. There will be more wide-angle lenses released during the next year or so, while the 35, 50, 75 and 90 have already been released.

All Summer Long
Leica SL2 with APO Summicron SL 1:2/28   1/1000 f8 ISO 100

The lens

As expected, the APO-Summicron-SL 28 f/2 ASPH is exactly the same form factor as the previous APO Summicrons (and the future ones as well). The optical design varies between the lenses: in this case it is 13 elements in 10 groups, with three aspherical lenses and six aspherical surfaces. Eight of the elements are made with anomalous partial dispersion glass, which helps to completely remove any colour fringing.

The minimum focus distance is 0.24 metres, allowing a magnification of 0.2x (as the other SL Summicrons).

The lens weighs in at a little over 700gm (without lens hood), not light perhaps, but it balances perfectly on the SL2 (and the SL2-S) and is fine for a full day’s shooting.

Leica SL2 with APO Summicron SL 1:2/28   1/8000 f2 ISO 100

Manual focus is ‘focus by wire’, but using an innovative system with a magnetic focusing ring, this changes its polarity when the ring is turned. By default, this causes an acceleration if the rotational speed is faster. However, with the SL2 and SL2-s you can now make the focus action linear and decide between focus throws from 90-360 deg in a number of steps.

The lens uses the same ‘Dual Syncro Drive’ motor as the other SL Summicrons and shares their excellent autofocus performance (fast enough and very accurate).

Leica SL2 with APO Summicron SL 1:2/28   1/800 f7.1 ISO 100

APO lenses, contrast and depth of field

The almost zero aberrations (especially chromatic aberrations) in the new Summicron SL lenses means a big increase in contrast where the image is in focus. As you move away from the point of perfect focus the contrast drops sharply.

This means that the transition between ‘sharp’ and ‘bokeh’ is defined more quickly and results in smoother out of focus areas than in conventional lenses. I have a diagram drawn for me by Peter Karbe in my notebook, but here is the graph from the Leica website comparing the APO Summicron SL 75 with the Summilux M 75.

The result of this is not just that the 75 APO SL is sharper (it certainly is), but that it has apparently the same DOF as the 75 Summilux-M. The MTF figures for the 50 APO are even better, and so the effect is even more visible.

So we have a series of modestly sized autofocus lenses for the L mount which perform better than their aspherical competitors and without any depth-of-field disadvantage. Of course, they gather less light, but that isn’t often a problem with modern sensors.

Bottle Green Dawn
Leica M10r Noctilux f1.2   1/350 f4.8 ISO 100

MTF curves

Whilst the MTF values for the 28 APO are not quite as jaw dropping as those of its 35mm sibling, they are still outstanding, In real terms there is no penalty shooting the 28 APO at f/2 and little shooting at 0.5 metre.

Image quality

It’s all very well talking figures (sorry), and I’m always a little wary of proselytising about the ‘Leica Look’ (it would be easier if I could actually define it). Like the other SL Summicrons, I just love the results this lens produces; many of the images in the attached gallery were shot at wide aperture (often at f/2) and there seems to be a real glow about them. This isn’t evident just at base ISO where you might expect it, but right up to ISO 6400 and beyond.

Leica SL2 with APO Summicron SL 1:2/28   1/800 f11 ISO 100

In common with the other lenses in the range, the 28 still shows gorgeous gentle bokeh, both in front and behind the focal plane, with a lovely roll-off between in and out of focus areas (nothing edgy). Stop down a little and the lens is very sharp, right to the corners, but still not in any way harsh. There is little or no distortion (although this is probably corrected in software). I saw almost no flare whilst testing the lens (often in tricky backlit situations) and absolutely no chromatic aberration — even in the most challenging high contrast images.

Leica SL2 with APO Summicron SL 1:2/28   1/200 f10 ISO 100


Sadly, I had this lovely lens for a short period, a period where taking pictures of people with a wide angle wasn’t really possible because of Covid.

I’m increasingly impressed with the range of SL Summicron lenses. It’s a fantastic endeavour to create a whole set of consistent primes. It makes total sense for the serious photographer to have a bag of lenses which are identical ergonomically and have a similar visual character.

Dreams of Summer II
Leica SL2 with APO Summicron SL 1:2/28   1/800 f8 ISO 100

Although I’ve only really used them for still photography, the recent firmware development of ‘fixed throw’ manual focus should make them equally popular with videographers — especially on the SL2-S.

By abandoning large aperture “bragging rights” and making the lenses f/2, Leica is able to maximise the image quality across all apertures and right out to the corners. In addition, it allows the company to make the lenses manageably small and consistent in size and weight. The apochromatic character of the lenses makes the depth of field feel like lenses a stop faster anyway, so you get the best of all possible worlds.

This lovely APO-Summicron-SL 1:2 28 ASPH is a worthy addition to the range.


Thanks as always to Emma for putting up with this malarkey (and all the related expenses!).

Thank you to Steffen Rau at Leica for providing the lens and information.

Thank you to Caryl and Dick for being companions on Gwynver beach for more years than any of us would care to remember, and thank you also to Ben (the dog) and Asher (the boy) for being my victims. Matty (the dog) needs no thanks as she is paid in treats!

Find more of Jonathan’s pictures here

Read more articles by Jonathan Slack

More on the L-Mount system


  1. Another sensational lens. I used to own the SL 35/2 and it was the most incredible lens I have ever owned for overall technical and also wonderful rendering. I purchased it as the SL 50/2 was not available. However, I prefer a 50 so I ended up letting someone else enjoy it.

    Your fine articles continue to tempt me! However, I love my truly lovely Leica 28/5.6 and it is so tiny. It is nice to have options to decide on what fits our vision as artists.

    I would love to visit you someday and snoop in your camera bag to see if a monochrom SL2 is in there so that I know what I need to save for. 😆

    I do hope that Leica will eventually bring out a SL 135 as that is a favourite focal length for me. But that is a far off dream for me as it is not forecast. But wait, Sigma has an awesome 135/1.8. We are so blessed to have the L mount alliance where we can pick from Leica, Panasonic, and Sigma camera and lens options

    Thanks for providing another fine article.

  2. I don’t go in for the SL cameras – too big for me – nor the SL lenses – ditto – but I can certainly vouch for Jono’s comment “..The apochromatic character of the lenses makes the depth of field feel like lenses a stop faster..” ..that’s absolutely the case with the M-fit 50mm f2 Apo. Gives out-of-focus results like the M-fit 50mm f1.4 ..only better; sharper, contrastier, better right out to the edges!

    (Oh, and love to Emma.. we got along like a house on fire while you were up to this malarkey..)

  3. Thanks Jonathan for a wonderful review. Just missed those Cretan images around Chora Sfakion and Loutro that often appear in your testing Leica lenses. The Cornish blues are much more muted than the Greek ones

  4. What a wonderful collection of images – I loved image two – well I got stuck looking at the wonderful sky contrasting against the beach.

    I laughed at the last image as it almost looks like Covid secure swimming – if such a thing existed.

    Thank you for the collection.

      • Hi there Mike. I’m good thanks. You won’t have seen me pacing the streets of London, since I moved back home to Cornwall almost 3 years ago. I’ve been out of the photography scene for a few years now (though I kept my Fuji xt1 and my Ricoh GR). But I’m almost getting back to the point where I fancy pulling the old cameras back out of storage! Maybe I should come up with a new photo essay for your site. I still check in on Macfilos every week and enjoy the content from afar. Keep up the good work and stay safe & well during these pesky Covid times!

        • Thanks, Treve. You would be most welcome to submit an article and I am sure readers would find your adventures fascinating. Greetings to Cornwall and stay safe!

  5. I shall never own one of these lenses, but once again enjoyed your photos which taught me a lot about 28mm focal length that I need to explore more. Thank you.


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