Leica X Vario: Functional Issues - Autofocus (Introduction)

Archive

While I like my Leica X Vario, it also has a number of functional issues or, in my opinion, deficits that need improvement. I list and discuss these on this and on related pages. Hopefully, most of the issues can be resolved in the future (a few were resolved with firmware update version 1.1)...

This page introduces the issue of autofocus (AF) errors, which are discussed controversially in the Leica camera forums. On another page, I examine autofocus (AF) issues in real world photos (my 2013 photos). One a third page, I discuss test photos that I took to produce AF errors in order to identify potential conditions and causes for these errors. Other functional issues are dealt with on page Functional Issues.

Note: The AF issues discussed here refer to the case that the camera signaled a correct focus (green rectangle(s)). The case that the camera cannot find focus and indicates this with a red rectangle is another matter. This may occur, for example, because there are no contours in the focus field. Some remarks on this can be found on page Autofocus Characteristics.

Update: Some users who installed the firmware update version 1.1 posted that they found an improvement in autofocus speed and accuracy whereas others denied this (including me). Since Leica did not mention in the comments on the update, I simply assume that nothing has happened in this area. This is supported by the fact, I still encounter AF issues from time to time after having installed the update. But the photographer is still the same - and he may be the reason for the AF issues (as some X Vario users who never had AF issues insist on...).

Note: There is an older version of this page, on which I proposed slightly different reasons for the causes of the AF issues. I provide the link to it for reference purposes only.

Introduction to Autofocus Issues

There were heated debates about the autofocus (AF) behavior of the Leica X Vario in the forums and sometimes they still re-emerge. The final word has not yet been spoken in this issue. Fact is that there are users who experience(d) AF issues with the X Vario, while there are others who did/do not. The reasons for these different experiences are still unknown. Finally, there are also users who received a replacement camera and some reported that they no longer have any AF issues (see the thread originally started by VETTRAN in the l-camera-forum). I will discuss all this further below.

It is also important to note that these issues refer to cases, in which the camera confirmed focus (using green rectangle(s)) - otherwise one would try again...

The initial testers always praised the Leica X Vario's AF accuracy (not so much its speed - although Leica does so), except for low light conditions, which is not a surprise for a contract detect AF. Maybe they just repeated what everybody would expect...

My Experiences in Short...

From the beginning that I own the Leica X Vario, a few of my photos, usually taken with 11-point AF and sometimes also with 1-point AF, are - for unknown reasons - completely out of focus. The focus errors seem to occur unpredictably. I am a hobby photographer and do not protocol the settings and/or my behavior. So I have primarily the - sometimes very fuzzy - photos to guess what went wrong and ask, "Was it my or the camera's fault?"

The focus mode is one indicator that can help in answering this question. If the focus was set manually, a blurred photo is obviously my fault. If one of the AF modes was set, both me and the camera can have their share in the issue. Since I discovered the Leica-specific Exif focus mode tag (independently of ExifTool that also lists it now), I can sort out those photos where the error clearly was on my side.

Now to the remaining photos, taken with one of the three AF modes: 11-point AF, 1-point-AF, and spot AF. A closer look at the photos often reveals that the focus is set to a near-by distance. There are also blurred shots without any foreground, so that I cannot tell for sure whether the distance was set too close. Luckily, since I discovered the Leica-specific Exif distance tag, I am able to check what distance the camera set automatically (or better, what distance it listed in the Exif data):

Usually, I find that the camera set a distance of around one meter or even less, confirming the visual impression.
There are also cases, in which the camera sets a too close distance, but it is beyond 1 m.
Finally, I found that, in rare cases, the camera states in the Exif data that it set the distance to infinity, but the image is rather blurred (for an explanation see below).

Further Investigations - Preliminary Conclusions

Since I could not find any indication that Leica will ever solve the X Vario's AF issues, and being frustrated by the spurious inexplicable AF errors of my camera, I decided to do some investigations into this matter on my own. I did not believe that I would find the technical causes for the errors, but I hoped to find conditions under which they occur, and, more importantly, to be able to produce such errors to prove that they do exist (even though I may have to take tens or hundreds of photos - or just AF measurements). You can find my investigations on the following pages:

Preliminary Conclusions for Real World Photos

Overall, my "collection" of real world photos with AF issues (and similar ones that are OK) does not point to a fundamental difference between 11-point and 1-point AF with respect to AF errors. In some cases, 11-point AF may have been distracted by foreground objects, but I tried to exclude such examples from my collection (I included a few samples where foreground objects were at the periphery and therefore, should not be considered by 11-point AF). I also found examples, where 1-point AF may have been distracted by peripheral foreground objects, although this shouldn't have been the case, either.

All in all, except for the few "infinity errors" (for an explanation see below), there seems to be one common pattern in the AF errors that I encountered: The camera unpredictably focuses too closely, never too far (while sending a "green" focus confirmation). "Infinity errors" may point to a different issue or to a related issue, both is possible.

Preliminary Conclusions for Spot and 1-Point AF (Test Photos)

Taking together barjohn's and my results, evidence enough has been collected to conclude that on certain occasions - and for unknown reasons - spot AF and 1-point AF signal to have found focus but completely miss the target (typically the camera sets a distance of about half a meter in such cases).

The picture may be somewhat different for different focal lengths and perhaps lighting conditions, but the fact of wrong focus confirmation coupled with a completely "off" distance setting exists at all focal lengths. In my opinion, both issues - incorrect focus confirmation and missed focus - go together. But note Ricoh's statement in the GR manual that wrong focus confirmations can happen under certain conditions.

Tripod tests show that AF errors happen when a tripod is used as well. But the camera's distance settings are much more consistent than when the camera is used hand-held.

I did not look more closely at "near misses" when using spot and 1-point AF, particularly because I mostly used 11-point AF at the beginning. But a re-test suggests that such "milder" focus errors may occur in these focus modes as well - and in the same unpredictable manner. At least, spot AF may tend to make "slight" AF errors, setting the distance to about 2 m, although the object is farther away. This may be the case under better lighting conditions, but at the moment this is just a speculation.

Preliminary Conclusions for 11-Point AF (Test Photos)

When 11-point AF fails (but indicates to have found correct focus), the camera typically sets a distance of about a meter. Thus, the photos do not look as blurred as in the case of focus errors for spot AF and 1-point AF. Here, the problem is that such errors are much harder to detect in the viewfinder (on the fly....). You only find them when you inspect your photos at home, but then it's usually too late...

11-point focus errors seem to occur more rarely than the drastic focus errors for spot and 1-point AF. Nevertheless, they occur - unpredictably - and may ruin valuable photos (which led me to take each photo at least twice...).

The Infinity Issue

There are rare cases, in which the photo is completely blurred* as if the camera had selected a nearby focus point (according to visual inspection), but the Exif data lists a distance of infinity (65535). Here, we have the issue that the Exif data does not correspond the the camera's actual distance setting (infinity would be the correct distance). This may either be a related or separate issue. I re-discovered it just recently, that is, in March 2015. So, it is still there...

*) Note that there many be similar photos in a set of photos, where the camera lists the same distance (infinity) - and these photos are sharp (as they should be).

Others' Experiences

barjohn and Others...

One of the Leica X Vario users who experienced and reported similar AF issues is barjohn. He documented them in several threads in the l-camera-forum. In 2014, I looked at his older samples that he had provided on Dropbox once again and also at the new ones that he published in January 2014. The old samples all use spot AF, the new ones, too, apart from the first one, which uses 1-point AF and which is the only one in focus. For all of his photos, he reports to have had a "green" focus confirmation. Moreover, barjohn published out-of-focus photos that were also taken with 1-point and spot AF. Regrettably, I cannot find out which photos used which type of AF...

There were more X Vario users who reported AF issues, such as VETTRAN, Gobdulm, wda, and others. See, for example the thread originally started by VETTRAN in the l-camera-forum that includes VETTRAN's, Gobdulm's, and wda's postings, as well as some recent postings and statements on this issue. By the way, VETTRAN's camera was replaced by Leica, and he had no AF issues since.

Just User Error?

So I am not alone with encountering AF issues, although many Leica X Vario users report in forums that they don't have any. Some of the latter attributed the issues to the users, not the camera. That's definitely a "killer argument" and, in my opinion, unfair and most probably wrong. But I am no longer willing to quarrel with these X Vario owners in the forums.

I will discuss this argument in my current speculations on the AF issues below.

Potential Explanations for AF Issues

The following issues/explanations for AF issues have been proposed in the Leica forums:

AF makes more errors with spot AF or 1-point AF than with 11-point AF
Possible explanation: The area to evaluate the focus is smaller und thus, it is more difficult for the camera to find the correct focus.
Initially, I could not confirm this finding. When I had problems with 1-point AF due to low contrast, the camera showed a red rectangle. But in the meantime, I have found cases in which the camera sent a green confirmation, but the focus was completely off (see my investigations).
Focus goes beyond infinity
I was able to decipher undocumented Exif fields for focus mode and distance. From investigating the distance Exif data, I cannot confirm this finding. I found that typically the focus is too close (about 1 m or even less...)
Since focusing is performed using a step motor, focus may be slightly off, because the steps are too large.
Hopefully the steps are small enough and do not cause any focusing problems, particularly considering the not so fast lens. Nevertheless, when inspecting Exif distance data, it is evident that only certain values appear, which might be an indication of the steps. But the focus errors that I usually find are so big that this argument does not apply.
Furthermore, the following argument was put forward in the l-camera-forum: Other cameras, including expensive studio DSLRs also exhibit focus errors from time to time. Thus, the X Vario's focus errors are quite "normal."
My simple answer to this that I am willing to believe that any camera makes focus errors. But I have encountered more errors with my Leica X Vario than I was used to from my previous (much less expensive) cameras.
Only recently, I hit on a posting by barjohn, where he had investigated that AF measurements take place when the lens is stopped down. He argues that because of the large depth-of-field, the camera may have difficulties in determining the correct focus and sometimes guesses (wrong)...

All in all, none of these arguments can be accepted as a satisfying explanation for the AF issues that I have experienced and that other users reported.

What Ricoh Has to Say...

In the Ricoh GR manual I found the following statement (p. 33; mode dial set to "auto shooting" mode):

"The camera cannot focus or a subject may not be in focus even if focus frames are displayed in green in the following cases.

Objects that lack contrast (the sky, a white wall, the hood of a car, etc.)
Flat objects with only horizontal lines
Fast-moving objects
Objects that are poorly lit
Objects with bright reflections or backlighting
Flickering objects, such as fluorescent lights
Point light sources (light bulbs, spotlights, or LEDs)

If the camera is unable to focus, lock focus on another object at the same distance from the camera as your subject, then recompose the photograph and take the picture."

There is no mentioning of this issue in the sections for advanced photographing, where the focus modes are discussed in detail. Most probably, the above-mentioned statements apply there as well...

Transferring this information to the Leica X Vario, it may well be that there are inherent technical restrictions to autofocus that caused wrong "green" focus confirmations under certain conditions.

What Can I Do Now?

Perhaps, Leica will resolve the X Vario's AF issues one day in a firmware or hardware update - perhaps it will not... Particularly in the latter case, one might ask what one can do to reduce the number of AF errors.

During the first months of ownership, I encountered many more AF errors that I do now. I attribute this to a number of measures that I took - or changes in my shooting habits. One reason is that I now use the 11-point AF less often, another one is that I set automatic review to "Zoom" so that I can check sharpness more easily after I took a photo. In extreme cases, you can already see in the viewfinder or on the LCD screen that a photo will be blurred, but this requires that you take a little time for a closer look at the preview...

Suggestions

In the following, I would like to make a few suggestions based on my own experiences. They may also help other photographers to reduce the number of AF errors (if they should have any...):

Use 1-point AF (or spot AF if needed) instead of 11-point AF, particularly when there are objects in the foreground, whereas the target objects are further away.
Reason: 11-point AF seems to be easily distracted by objects in the foreground, even if they are in the periphery (even 1-point AF seems to exhibit such a tendency...).
Use face detection AF if you are taking photos of people instead of 11-point AF.
Reason: Face detection prevents foreground objects to interfere. If there are no faces, it's just 11-point AF...
Note: I did not yet test this proposal, it's just theory...
Use 11-point AF for uniformly colored objects, not 1-point AF or spot AF.
Reason: 11-point AF has a larger target area and therefore is more likely to find a suitable focus target.
Set the distance manually to infinity when there are a lot of objects in the foreground and you use a wider focal length (for longer focal lengths you have to be more careful with the distance setting...).
Reason: This prevents objects in the foreground to interfere (for details, see here).
Set the distance manually (either using the viewfinder/LCD screen or the lens' distance scale) when the scene might be confusing for the AF system.
Reason: This prevents other objects from catching the focus (for details, see here).
Use the the "Zoom" setting for automatic review.
Reason: The magnification allows you to evaluate "after a photo has been taken," whether the photo is sharp (for details, see here).
Caveats: (1) I often do not wait long for until the magnified section to appear, (2) the "central" object may not be at the center and therefore its sharpness cannot be judged.

Caveat

Often AF errors occur when there is little time to think, you take photos of people, or the location is unclear (like in a boat). In such a situation you would, of course, prefer just to take photos and not think of technical issues or check focus and exposure. I am well aware that, for such situations, my suggestions may not help a lot...

My Speculations (or Analysis)...

Finally, it's time to speculate about the causes of the X Vario's AF issues, or non-issues. On the one hand, there have been, in addition to my own AF issues, several reports on AF issues with the Leica X Vario in the Leica forums - including the one started by VETTRAN, mentioned above. Other users, however, have never experienced such issues. So the question is still, why some cameras show these issues, whereas other users' cameras do not. In my opinion, there are three potential causes for the X Vario's AF issues: (1) firmware bug, (2) user error, and (3) hardware problem (or a combination of the three).

Based on my experiences and investigations, others' experiences, reports and opinions, and an attempt to "think logically," I will try an "analysis" of the issue.

Ad1: Firmware Bug?

Initially, I thought that the AF issues might primarily be caused by a firmware bug. Obviously, firmware update 1.1 did not address AF issues: Leica does not mention to have done so, and my updated camera still shows spurious AF errors. And there are also arguments that the issue is not caused by firmware, or not by firmware bugs alone:

Some users reported that after their camera had been replaced by Leica, the AF issues did not re-appear (see the thread started by VETTRAN). Since there was no change in firmware (apart from an incident with barjohn, see below), there must be other reasons, why the AF worked flawlessly after the camera exchange.
Secondly, in the case of a firmware bug, I would expect that most of the X Vario samples would exhibit AF issues, not just a few.

Ad 2: User Error?

The second item above is countered by some X Vario users who blame the photographers who experienced issues, not the camera. They argue that there is simply a minority of X Vario users who are not able to handle their cameras correctly.

I agree that it may very much depend on the users' shooting behavior whether the AF errors will surface or not. And changes in AF mode and other settings and in my shooting behavior improved indeed the "signal-to-noise" ratio for me. But, in my opinion, there are two arguments that contradict this hypothesis as being the "primary cause" for the X Vario's AF issues:

The already mentioned improvements after exchanging the camera
My observation that within more or less identical series of photos, some photos are focused correctly, while others are blurred (there are, of course minor differences in the section and sometimes in the "technical" data).

Ad 1: I know only of one incident, where the camera did not work correctly after being sent to Leica because of AF issues. barjohn reported that his camera was repaired (not exchanged) by Leica and received a new firmware of "unknown" origin, but the issues remained. barjohn reported:

I did send the camera in to Leica NJ, as suggested, and it took a month to have it repaired. I was told they replaced the lens assembly and AF module. I received back the repaired XV with the strange firmware number. The camera is on its way back to Leica as the same AF problem still exists.

Ad 2: Here, the photographer (me) obviously behaved (more or less) the same during a series of shots and got "mixed" results. In the case of a "pure" user error, all the photos in a series should be blurred.

Ad 3: Hardware Problem?

So, after evaluating the AF issues once again, I speculated that there may be hardware reasons for the AF issues that some users encountered. There are mainly two arguments that, in my opinion, support this hypothesis (and above I also listed arguments that contradict the other two hypotheses):

Infinity errors, where the camera lists a distance in the Exif data that differs from the actually set distance
AF issues ended after Leica replaced the camera (no firmware change).

Both items suggest to me that there might be a spurious mechanical issue, such as mechanical tolerances, that (1) leads to a difference between listed and actual distance setting, and (2) can be dealt with by exchanging the camera without changing the firmware. Maybe it's simply the single moving lens element in the optics that serves for focusing, which may get stuck sometimes (this is just my speculation...).

But there is still one argument that makes me doubt the "hardware" hypothesis:

There are too many misfocused photos, where the camera reported the distance correctly in the Exif data, with "correctly" meaning that the camera reported the distance that it had set - not that that the distance was correct.

I assume that the camera measures the distance, reports it in the Exif data, and finally commands the step motor to set the distance. In the case of "infinity" errors, there would indeed be a hardware failure because the camera did not set what it reported. But I do not know the camera's and lens' inner working, it might as well be the other way round...

Conclusions

I have come full-circle (or "back to field one") now. For each of the three hypotheses, I could find arguments and counter-arguments. In science, counter-arguments are more important when it comes to accepting a hypothesis. So, I can throw a dice now. In the end, it is not my job to find the reasons for the AF issues, it is Leica's job, even if the final verdict would be "user error."

Finally, there might be a "conceptual" or "design" problem with the X Vario's AF: As barjohn found out, AF measures distance while the lens is stopped down, which makes it harder for the camera to find the correct focus because of the larger depth-of-field. But maybe that other cameras do just the same...

Afterword

With my previous digital cameras, I often took more than one shot of a motive, because I was unsure about the correct exposure, but never because of focusing issues (except for macro shots). With the Leica X Vario, I often take more than one shot not because of the exposure (sometimes, I do...), but because of the focusing. Whenever I take only one shot, often enough, the focus is off... Of course, there are also a lot of "operator's errors" involved, but I am learning and use manual focus to avoid some of the pitfalls (which may also introduce new errors because I forgot that I had set manual focus...). Nonetheless, there are, to my taste, far too many occasions left, where I have to blame the camera. In the l-camera-forum, some posters insisted that the users have to adapt to the camera's behavior. This reminds me of related discussions with developers in my profession as a usability engineer. There are also usability people who maintain that it is always the system that is to blame, not the users. I tend to a middle position...

Some people like barjohn, whom I know for his impatience, moved over to other cameras soon (among others, to the Leica T for a while...). Perhaps, I will follow him one day when I do not see any reaction from Leica (as was the case with my two attempts to contact them via e-mail). At the moment, however, this is not my intention and I am still patient and optimistic.

References

Ricoh: Ricoh GR manual (p. 33)
l-camera-forum: www.l-camera-forum.com
- AF Unreliability (thread started by VETTRAN): www.l-camera-forum.com/leica-forum/leica-x/336456-x-vario-af-unreliability.html)
- X Vario AF Issues Follow Up (thread started by barjohn): www.l-camera-forum.com/leica-forum/leica-x/318745-x-vario-af-issues-follow-up.html • Start posting by barjohn: www.l-camera-forum.com/leica-forum/leica-x/318745-x-vario-af-issues-follow-up.html#post2616427
- X Vario AF Issues (thread started by barjohn): www.l-camera-forum.com/leica-forum/leica-x/300386-x-vario-af-issues.html
- Issues with New X Vario (thread started by VETTRAN): www.l-camera-forum.com/leica-forum/leica-x/297113-issues-new-x-vario.html • Posting on AF measurements with stopped down lens by barjohn: www.l-camera-forum.com/leica-forum/leica-x/300386-x-vario-af-issues.html#post2509109