Battle of the 43mm Lenses - Leica vs Pentax

John Riley compares the Leica Q3's 43mm lens with the SMC Pentax-FA 43mm f/1.9, both lenses designed to match the same view as the human eye. John provides test charts for both lenses, sample photos and his verdict.

Posted: 09/03/2025 - 17:01

Handling and Features
Performance
Verdict
Ratings

Here's a brave concept, pitting the original SMC Pentax-FA 43mm f/1.9 lens against the new Leica APO Summicron 43mm f/2 as found on the £5900 Leica Q3 43 fixed lens camera. It might seem a bit of a David vs Goliath task with the Leica lens bristling with aspherical elements (7 in total) and the camera it is fitted to sporting a very unsporting 60MP. The humble Pentax 43mm Limited in its day was lauded as the first real redesign of the "standard" lens for decades, outclassing the Zeiss Planar. Interestingly, it was so well regarded that small numbers of Leica fit versions were produced. So there is a rationale for looking at this now, even if the pixel count and the price levels are so far apart. Armed with the 60MP Leica Q3 43 with APO Summicron 43mm f/2 Asph lens and the 36MP Pentax K-1 with SMC Pentax-FA 43mm f/1.9 Limited lens, let battle commence.

Handling and Features

The initial impression is of two lenses of totally different styles but which are both extremely well made. When the lenscap is removed, the Pentax is by far the most impressive as the flock lined metal cap slides smoothly into place, as slick a piece of manufacture as anybody would wish for. The Leica cap is bigger, brasher and tricky to align properly. It is also only partially flock lined.

The Pentax is a tiny lens by modern standards, just 155g or 165g with the discrete metal hood screwed into place. The Leica does have a dedicated hood, but this was not provided with the review lens. It was previously tested on the original Q3 and found to be somewhat tight in fit.

We haven't looked into why 43mm yet, as most standard lenses are 50mm or even 55mm. Historically this is because such lenses were easier to manufacture when technical capability was not so high as it is today. Very fast lenses were also inclined to be longer, some even 58mm. 43mm is actually the diagonal measurement of the 35mm full frame and it is deemed that this is the required focal length to give the same view as that of the human eye.

The Pentax has a couple of wins there so far, and probably a third win when we look at the quality of the engravings. The Pentax finish and paint fill of the engravings is both delicate and accurate and part of what makes their range of Limited lenses stand out.

As we heft the two cameras into action, the Leica wins hands down on weight and bulk, not because the Pentax lens is large or heavy but because by the time it is fitted to a K-1 full frame body it is weighing in at a substantial 1170g, compared to the Leica at 772g. Despite any weight considerations, I do not use camera straps, preferring to carry a camera in the right hand to have it ready when needed. It is also a benefit when reviewing as product shots look tidier without a strap. The Leica comes with a beautiful leather strap attached, but the way it is fitted makes temporarily removing it a virtually impossible task seemingly intended to destroy fingernails.

The Pentax is scoring well so far, and continues to do so when we bring the cameras into action as the handling is like chalk and cheese. It is of course a personal thing, but the Leica I find clunky in terms of ergonomics when compared with the slick efficiency of the Pentax layout. Handling is another point for Pentax, but it's not a home run yet and we shall see whether or not the performance tests bring a sharp come-uppance in favour of the legendary Leica quality.

SMC Pentax-F 50mm f/1.7 Performance

Imatest graphs tell the story, and in terms of bald measurements then the Leica is the one in the ascendent. Basically, if you want ultra-high sharpness from infinity to the closest focus then it's Leica. There is of course a discrepancy in pixel dimensions, so the 60MP results give far higher figures than the 36MP ones. What it tells us is that the Leica lens is outsanding centrally and to be fair the Pentax is not too far behind, being excellent. The edges are the difference, but seemingly especially close up. The Leica is excellent at the edges, the Pentax only fair to good, but this is at test chart distances and the Pentax delivers nicely sharp edge-to-edge images at more normal distances out in the field.

Leica 43mm vs Pentax 43mm MTF Charts

CA (Chromatic Aberration) is centrally very well controlled with both lenses and, as befits the APO design with all those aspherical elements, the Leica maintains this performence at the edges. The Pentax shows a fair bit of edge CA, a combination of lack of complexity in the design and the edge light rays not being telecentric so hitting the sensor at a severe angle and causing fringing as a result. This does not matter so much when shooting film, but does with the design of a digital sensor. For many subjects this is not an issue, but if necessary there are always software solutions.

Leica 43mm vs Pentax 43mm Chromatic Aberration Charts

Distortion measures -0.32% barrel for Leica and just -0.17% barrel for Pentax, the difference being academic as both values are fine. Drawing is almost perfect in both cases and there should be no issues with architectural subjects and straight lines will remain straight.

Bokeh is the smoothness of the out of focus areas in an image, and here we start to look at aesthetic qualities that cannot be measured but can certainly be seen. The overall "look" of these lenses is different, sometimes very different. The Leica is critically sharp, but despite this does not go so far as to look clinical and cold. It retains smooth bokeh, even if it does not quite match the rather magical reputation of the Pentax Limited lens. Here the Pentax does have a certain something, a core of high sharpness at the centre and a variety of smoothing bokeh effects depending on the subject. This has been described as images having a "pop" or having been scattered with "pixie dust". The lenses are close though, and as this is an aesthetic call one way or the other and the characteristics are very different, it does depend on individual taste. We have a close call on bokeh, perhaps Pentax having the edge.

Leica Q3 43mm Lens Aperture Range

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SMC PENTAX-FA 43mm f/1.9 Limited Aperture Range

Both lenses can see through backlighting very well and retain detail and contrast. Again, they are different, the Leica being neutral in its resistance to flare and when artefacts are found they are minimal. The Pentax is also very flare resistant, but when artefacts are generated they have perhaps a more spectacular aesthetic to them. No doubt the new Pentax HD version will have less of this attractive effect than the classic SMC version used in this review.

Leica Q3 43mm Lens Sample Photos

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SMC PENTAX-FA 43mm f/1.9 Limited Sample Photos

Value for Money

I think we know the answer to this before we even start to check prices, but here goes.

The Leica Q3 43 is a complete package in itself, the lens being integral with the camera, priced at £5900.00

The SMC Pentax-FA 43mm f/1.9 Limited has been replaced by the HD Pentax-FA 43mm f/1.9 Limited and the new lens is priced at £629.00 - second hand SMC versions might be available, but are not overly common. Some consider the Made in Japan early versions the most desirable, and these are even thinner on the ground.

New Pentax users might need to add a full frame Pentax K-1, priced at £1899.00

This brings the Pentax cost of lens plus camera to £2528.00

Verdict

Although potentially a bit contentious, here's a selection of features and a conclusion as to whether the Leica or the Pentax might be considered winners.

On the basis of gathering as many parameters as we like, in the end it comes down to a balance between highest quality and cost and of course the law of diminishing returns. Take the price out of the equation and we have an Honourable Draw. Add the price in, and there are few of us who can happily ignore the price at these sort of levels, then Pentax has the win. Although a battle of this sort is on the face of it inevitably a battle between unequals, the serious point is that it shows us how different lenses can be in their intent as well as their price level. I have sharper overall lenses than my 43mm, but by preference I reach for the 43mm as it has other qualities that can be difficult to quantify.

Leica users can be proud of a very fine lens/camera combination. Pentax users can be gratified that the "pixie dust" still infuses its magic throughout the original 43mm Limited lens.

Ratings

Leica APO Summicron 43mm f/2 Asph - 4.5/5
A compact and highly versatile lens with outstanding performance, albeit it at a high price.

SMC Pentax-FA 43mm f/1.9 Limited - 4.5/5
A compact and highly versatile lens with superb character and that magic Pentax "look".

Members gallery photos using: smc PENTAX-FA 43mm F1.9 Limited

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