X Vario AF Issues

[barjohn]

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Several of us have experienced inconsistent AF accuracy. The reason appears to be puzzling and unpredictable happening in bright daylight or well lit scenes. Lloyd Chanbers noted this behavior in his (paid) blog on the XV. He also states that the reason for this behavior is that the XV stops down when it auto focuses and due to the already large DOF, when stopped down even further (like in bright day light) the camera can't ascertain the actual focus point but instead makes its best guess. Frequently that guess is wrong however, sometimes, while being absolutely wrong, it is within the DOF so it produces a close but soft image.

 

The AF is hampered (in his opinion) by the fact that even wide open, at the longer end it is at f6.4 resulting in enough DOF to make it a real struggle for the camera to find the exact focus point. I plan to test this tomorrow by having the XV focus on another camera shooting video of its lens so that we can see the performance of the IRIS during AF.

[Guest]

hallo X-Vario fans and users:

 

To see AF-problem > leica XVario-review < by Erwin Puts.

Tagged: >>> Step zoom motor in the leica "XVario" vs. >>> continuously operating zoom motor in the leica "S".

 

br

 

kmhb

[mben]

Hello John,

 

I look forward for your further analysis on the XV autofocus.

 

So far, I found that "spot" af is absolutely unreliable, returning an alarming rate of "false positives". I had a chat on that with a Leica US technician, who told me that "spot" af requires much more contrast than "1 point". I made some test as directed and the failure rate dropped considerably, but I have to add that "spot" only works when inside the box there is a strong vertical monochromatic contrast edge. As a result, I am not using "spot" anymore.

 

Next up is "11 point", which in 3-D scenes is usually unable to pick the proper focus distance and makes the XV to misfocus. Two days ago I shot an entire series of pictures with "11 point" ant all of them turned out totally out of focus, i.e. with no single plane in focus across the entire frame. Unfortunately, poor rear lcd display ability concealed the fact. I am not using "11 point" anymore.

 

A short passage on "face detection": it does not work as described. The word "face" should be dropped...

 

So, for me it is "1 point" and only "1 point" af. Until Leica summons up programmers and pays for code updating (since contrast detection af is just a matter of proper coding - within the limits of lens af motor).

 

Sad to suspect that, when designing the XV, Leica either had in mind a € 600 compact (where add a € 1800 red dot and fancy box), or set XV's specs to be as distant as possible from M's specs, i.e. M lenses are fast ? Let's make a f3.5-6.4 lens; the M can shoot consecutively at each shutter press ? Let's program the XV as to have a 3 secs delay between shots (or: dumb continuous mode with 15 secs delay); M has focus peaking ? Let's say that the XV is not made for focus peaking; M allows to easily compare enlarged images ? No way the XV can do that; M has flexible auto iso ? Ok, let's limit the XV at 1/30; M has a greatly tuned dng file ? The XV dng will be so soft ... And so on.

 

Its a pity the XV has a very good (slow) lens (not as good as the GR's, but that's 28mm only), but the lens could have been at least half stop faster by slightly increasing the pupil. And if behind the (slow) lens there is a series of bottlenecks aimed at even further slowing down the camera, the very good lens is somewhat wasted.

 

The XV has a lot of potential, just needing Leica to wake up (XV sales are low) and properly re-code the camera. As it is, the XV is sadly confined at shooting static subjects, like landscapes.

 

Best,

 

Mauro

[barjohn]

I ran a test using a second camera and the XV. the second camera was set to macro focus and zoomed in on the XV lens. The two cameras were on my desk and stationary. I set the first camera to start shooting video and videoed the aperture and shutter performance on the XV as I changed focal lengths and f-stops. As the lens was stopped down, it was very clear that the XV stopped down to the shooting aperture during AF. Stopping down, as we all know, results in a greater DOF. This in turn makes it more difficult for the algorithm to find the true focus point and results in images that are slightly out of focus on occasion. Sometimes it guesses right and sometimes it doesn't. It would appear that it will do a little better in low light where the aperture is wide open than in bright light where the aperture may be stopped down considerably. The X-1 and X-2 had similar focus issues in MF making them difficult to focus until after the firmware revision that changed that behavior. Here, with the longer lens and smaller apertures it could be an even bigger problem in AF. I will test MF next to see if the behavior is consistent in MF.

[barjohn]

I have also tested MF. In MF, the aperture behaves as you would expect. It stays wide open during focusing and only stops down when the shutter is pressed and fired. Thus it is easier to obtain MF at times than AF.

[beewee]

Mauro and John,

 

Thanks for your constructive notes and insight on the problem!

[wda]

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...

So, for me it is "1 point" and only "1 point" af. ...

Best,

 

Mauro

Welcome to the forum, Mauro.

My experience is based on X1 ownership only. But I guess there are some family similarities between the first and last X cameras in the series.

 

I only ever use 1-point for focusing because of similar issues to your report. 'Face' usually settles on any recognisable object near the camera; not always what you want, even if people are in frame. Generally I find AF perfectly satisfactory in the X1 provided I stick to my settled modus operandi OR focus manually for certain subjects where AF cannot find the right target.