Leica X Vario: Lens

The Lens | A Few Technical Data | A Collection of Opinions on the Lens | Lens not Retractable | "Rattling" Noises - What They Reveal | In-Camera Correction of Lens Deficits | Additional References

On this page, I would like to discuss one the specific characteristics that lead me to buy the Leica X Vario, namely the lens. It is often the most prominent argument in favor of the Leica X Vario camera. Elsewhere, I mention that some users maintain that the X Vario's lens equals in quality - or is even better - than some genuine Leica M-mount lenses. In this vein, some users state that the X Vario is like a Leica M with four prime lenses: 28 mm, 35 mm, 50 mm, 70 mm - and in between. This makes up for a much more compact and lighter package than having to carry with you a Leica M with four primes... Leica also maintains that the X Vario's lens satisfies 90% of the "normal" shooting needs. On this page, I will investigate what reviewers and the available test results say, and I will also cover some lens specifics.

 

The Lens

The Leica X Vario features a fixed lens, a Leica Vario-Elmar 28 –70 mm f/3.5 – 6.4 ASPH. (35 mm equivalent; 18 – 46 mm real; 9 lenses in 8 groups, 2 aspherical lenses), with a zoom range of 2.5x, or the equivalence of four "classic" prime lenses: 28 mm, 35 mm, 50 mm, 70 mm. It features a distance ring and a zoom ring. The first seems to be "by wire" but feels like a mechanical ring, the second seems to be purely mechanical. While there are distance marks on the lens, it regrettably lacks depth of field indicators (as there are on old mechanical zoom lenses). See my pages about hyperfocal distances and depth of field tables for more information on this.

Figure 1: The "pure" Leica X Vario - front view

Figure 2: Leica X Vario seen from above showing the lens with two rings for setting distance and focal length - and the lens hood

The lens has a 43 mm filter thread for attaching filtera and close-up lenses. ´There you can also attach a lens hood, which you can either from Leica (see Figure 2), which is fairly expensive (90 EUR in Germany), or you buy a look-alike, which costs about one third of it (35 EUR). Leica praises the lens hood, but it does not really help, whenever you shoot against the sun. But it seems to protect the lens against rain and keeps you from touching the front lens...

I often confuse the distance ring with the zoom ring (and vice versa). A design with different surfaces for both rings would help avoid confusing them, but probably designers would find this ugly... There is a small difference in diameter between the distance and the zoom ring. But to feel it you have to move your fingers over both rings...

Find more technical information about the lens below.

 

A Few Technical Data

Data Leica X Vario (Type 107) Comment
Lens Leica Vario-Elmar 18-46 mm f/3.5-6.4 ASPH. (corresponds to 28-70 mm in 35 mm format)

9 lenses in 8 groups, 2 aspherical lenses

For focusing, only one movable element is used. This is meant to speed up focusing.
Zoom Optical zoom: 2.5x The zoom range includes four "classic" primes: 28mm, 35mm, 50mm, and 70mm (equivalent).
Filter diameter 43mm Some filters seem to cause vignetting.
Aperture range From f/3.5 to f/16 (at 28 mm) / f/6.4 to f/16 (at 70 mm) in 1/3 EV increments The X Vario lens is particularly slow at the tele end.
Distance setting range 30 cm/1 ft (at 70 mm focal length) to infinity; otherwise starts at 40 cm

Lens designer Peter Karbe states 20 cm as shortest distance in an interview.

You can use close-up lenses for achieving higher magnification (+5 = 0.4, +10 = 0.5).

Smallest object field Manual: 27 cm x 18 cm at a distance of 30cm and a focal length of 46 mm (70 mm equivalent)); approx. 12 cm x 8 cm according to own tests (same data) Magnification: 0.2 for no lens, 0.4 for +5 lens, ca. 0.5 (1:2) for +10 lens

Maximum Aperture Versus Focal Length

Focal Length
Equivalent
28 35 50 70
Actual 18 23 33 46
Maximum f-Number 3.5 4.5 5.1 6.4

Actually, some data suggests that the maximum aperture for 23/35 mm should be f/4, but the camera insists on f/4.5...

Sharpness Data

Jim Fisher (PC Magazine) used Imatest to check the sharpness of the X Vario's zoom lens. Below is a tabular overview of his results:

Focal Length
Equivalent
28 35 50 70
Actual
18 23 32 46
Mimimum f-Number 3.5 4.5 5.1 6.4
Lines - Center 1,774 --- 1,978 2,043
Lines - Edges 1,441 --- just below 1,800 1,900
Stopped down to f/5.6 Lines - Center 1,869 --- --- ---
Lines - Edges 1,500 --- --- ---
Stopped down to f/8 Lines --- --- about the same about the same

The lower resolution in the corners may, at least in part, be caused by electronic (software-based) distortion correction. Because pixels in the corners of the frame are "stretched" to correct for the distortion, there is, according to Imaging Resource, some loss of resolution in the corners.

 

A Collection of Opinions on the Lens

Leica

Let me start with what Leica itself has to say about the lens, particularly in combination with an APS-C sensor:

Maike Harberts, Product Manager for the Leica X System (from David Farkas, Red dot forum):

Actually, "paper is patient," as we say in German. The Ricoh GXR A16 camera unit was the first combination of an APS-C sensor with a (much more) compact camera, "compact" may not be quite the right characterization of the X Vario, and a maximum aperture of f/3.5 is not well known for creating photos with stunning plasticity... Nevertheless, some of my photos taken with the X Vario indeed show what Leica claims...

Peter Karbe designed the X Vario's lens. In The Leica Camera Blog, he talks about the design goals for the lens and also about the constraints. Here are some excerpts from the interview with Karbe (from The Leica Camera Blog: A Look through the Elmar-Vario Lens):

By the way, in this interview, Karbe speaks of a minimum distance of 20 cm at the long end and 30 cm at the wide end. The manual, however, speaks of 30 cm and 40 cm - and reality is closer to this. This would have made a noticeable difference for close-up shots - so reality is a little disappointing...

Others

Here are a number of statements about the lens from some other sources:

 

Lens not Retractable

Many compact digital cameras, like my wife's Ricoh CX4, have a retractable lens, which makes them compact and easy to put in a pocket. The main disadvantage of such a design is that it is delicate (the CX4 has a "wobbly" lens) and also that it is susceptible to dust (we had this issue already with my wife's CX).

My GXR Ricoh A16 camera unit has a different lens design, because it has an APS-C sensor. The lens is already fairly long so that it is definitely not "pocketable." It extends a little bit when turned on at the wide end (24mm equiv.), and extends more and more towards the long end, reaching nearly twice the initial length at a focal length of 85 mm (equiv.). Since there is only one moving part, I expect the design not to be susceptible to dust.

The Leica X Vario lens does not extend when the camera is turned on. It is shortest at a focal length of a little more than 50mm (equiv.), extends a little bit when turned to wide angle, and extends a little bit less when turned to tele. Since this lens also has a non-retractable design, it should not be susceptible to dust as well. Time will tell whether this is indeed the case.

Figure 3: The non-retractable lens design does not make the Leica X Vario "pocketable"...

On the other hand, both the Leica X Vario and the Ricoh GXR A16 cannot be easily put in a trouser or shirt pocket. This is the price to pay for an APS-C sensor camera with a zoom lens.

 

Lens Noises - What They Reveal

First of all, all the lens noises described here are OK - there is nothing wrong with the camera. In the following, I list the "usual" noises that the lens makes and provide explanations what they reveal.

Viewfinder Image Brightness

If the camera is turned "on" and you do nothing except for pointing the lens to different targets, you can here a "rattling" noise. It is created by the iris blades (or aperture blades - or by the shutter, because it is a leaf shutter...) that move to adapt the brightness of the viewfinder image. You can see the blades move when you look at the lens while moving the camera.

When you look through the viewfinder and move the camera, you can observe how the image gets lighter or darker, depending on the target. This happens rather smoothly, sometimes, however, with a slight delay. All this suggests that there is an electronic gain control involved.

People with very good eyes might even recognize that DOF changes. However, I am not able to recognize this...

Focus

When the camera is turned "off," you hear only mechanical noise when you turn the focus ring. When the camera is "on" and you move the focus ring (manual focus) you can hear the "working" of the step motor, which moves one small lens element. I put the lens cap on the camera when checking this so that there is no confusion with the first noise. In autofocus mode, you can hear the step motor work, when you half-press the shutter button for setting distance and exposure.

All these observations confirm that the X Vario lens uses a "fly-by-wire" mechanism for focusing, even though it may feel as if focusing were mechanical.

Zoom

According to colonel/harold1968, the Leica X Vario's zoom works purely mechanical. An indication of this is the fact that the lens changes its length (a little) already when you zoom while the camera is turned "off." However, when I turn the camera "on," put the lens cap on the lens to avoid confusion with other "noise sources", there is more to hear than when the camera is "off." It sounds like something is being moved when the camera is "on," sometimes even with a little delay. At the end of the zoom movement, you can also hear the "rattling" noise of the iris blade, because the camera adjusts aperture for the viewfinder after zooming.

Only lens designer Peter Karbe knows what exactly is happening...

 

In-Camera Correction of Lens Deficits

All lens designs are a compromise between different requirements and therefore have certain deficits - the X Vario's lens is no exception to this rule. In an The Leica Camera Blog interview A Look through the Elmar-Vario Lens, lens designer Peter Karbe states:

Above, I cited "the five things" Leica "really strived to achieve with this lens" - here they are again:

So, there must be a downside of or a secret behind the lens design, but where is it? One downside is that the lens is fairly slow. Karbe comments on it, and many users did so, too - I do not want to join this discussion here. Another one is the fairly small zoom range of about 1:2.5 (18 mm to 46 mm). But what about the typical lens characteristics that are checked in camera tests? In such tests, the Vario-Elmar shows fairly low distortion, very little chromatic aberration, and little vignetting (see the comments on Chasseuer d'Image's findings below). But there is a secret behind these excellent values: They are the result of in-camera corrections performed in software. The newer Leica T does the same, and in the respective forums a controversial debate arose. Some users were deeply disappointed by this strategy, while others did not bother. Obviously, software corrections are common practice these days and have been implemented by Fuji, Sony, Canon, Nikon, and other manufacturers.

Distortion

Distortion correction may be easiest to recognize. But since it is already applied to JPG images and also performed automatically in Adobe Lightroom, you need a tool that can display DNG files without any correction applied. The following thread in the l-camera forum discusses distortion correction and shows a sample scene (the second sample does not have distortion correction): XVario lens distortion. Another example of distortion without correction (at 28 mm equiv.) can be found at the top of Erwin Puts's second part of the Leica X Vario review.

Chasseuer d'Image (No. 357, October 2013) finds a barrel distortion of about 0.3% at 18 mm; beyond 32 mm distortion decreases to 0.1-0.2% at 46 mm (also barrel distortion). They regard this amount of distortion as "in practice, invisible in the images." These values must, however, be electronically corrected ones.

Jim Fisher from PC Magazine finds much higher, probably uncorrected, distortion values: "Distortion was modest, but present; at its best it's about 1.2 percent, and only 2 percent at its worst."

Imaging Resource (Leica X Vario Review - Lens Quality - Summaries) summarizes that there is "low geometric distortion from the X-Vario's 18-46mm fixed lens in JPEGs, though strong distortion at wide angle in uncorrected raw files."

Details: For JPEGs, the lens produces only about 0.2 percent barrel distortion at wide angle (18 mm), which is much less than average and hardly noticeable in its images. Distortion at 46 mm is even lower at about 0.1 percent, and is also barrel-type instead of the usual pincushion (confirms the results of Chasseuer d'Image).

The authors converted raw files of the same test shots with dcraw, which does not correct for distortion. The actual barrel distortion at 18 mm that they found was quite high at about 2.3%, while barrel distortion at telephoto remained the same at about 0.1%.

Chromatic Aberration, Corner Softness

Chasseuer d'Image (No. 357, October 2013) asks "which aberration?" and concedes that it is difficult to decide whether aberration is corrected optically or electronically - but at least it is "quasi absent."

Imaging Resource (Leica X Vario Review - Lens Quality - Summaries) summarizes:

Details: Chromatic aberration in the corners is low at wide angle, and just a little higher at telephoto in JPEGs. ... As usual, color fringing gradually reduces in brightness and width as it approaches the center of the image, where it is almost non-existent. When stopped down to f/8, ... chromatic aberration is a bit lower.

Luminous Landscape: ..., no CA that I can see, sharp in the corners ...

Vignetting (Corner Shading)

Chasseuer d'Image (No. 357, October 2013) finds a decrease of 2/3 EV at the edges for f/3.5 and f/4 at the wide end (18 mm). For other focal lengths, the decrease is below 1/3 EV, which means that it is more or less invisible.

Imaging Resource (Leica X Vario Review - Lens Quality - Summaries) writes about Vignetting: Some minor corner shading ("vignetting") is also noticeable from the difference in brightness of the center versus corner crops above, and it appears the camera is applying some shading correction. When stopped down to f/8, ... vignetting (corner shading) also improves, but overcorrection at telephoto is still detectable.

Corner Softness

Imaging Resource (Leica X Vario Review - Lens Quality - Summaries) summarizes that corner sharpness is "very good to excellent sharpness in the corners."

Details: The Leica X Vario's 18-46mm lens produces slightly soft corners at wide angle when wide-open at f/3.5, and much of the softness is likely due to the strong distortion correction. Corner performance is very symmetrical (all four corners show similar sharpness), and the center is quite sharp (though sharpening halos are quite evident). Corners are sharper at full telephoto when wide-open, with excellent sharpness across the frame. When stopped down to f/8, corner sharpness improves just slightly.

These results are in line what Jim Fisher (PC Magazine) found (see above).

 

Additional References

Below, I list some more references to lens tests and other lens-related stuff :

 

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14.02.2016