T Low Light AF Performance

[barjohn]

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As many know, I have the T with the zoom lens. I have now ordered and will shortly receive the 23mm f2 lens. I have found the zoom's AF performance in moderately low light to be extremely slow and in low to very low light it will not AF at all. Additionally, what one sees on the LCD/EVF is that for a brief fraction of a second as one presses the shutter to the ½ press position one sees a bright image which immediately turns very dark as it tries to focus.

 

Those that have both lenses, have you seen the same thing with the faster lens? Have you seen a significant improvement in low light AF with the f2 lens or are you seeing the same behavior?

 

Another thing I have noticed is that in low light, if you chose to use flash, you must switch from aperture priority to shutter priority to set the shutter speed but then you have no way to adjust aperture. Program mode is unusable with flash as you can't get the camera to change anything but ISO once flash is up. Maybe I am doing something wrong. If so please enlighten me.

[thighslapper]

23/2 seems quite responsive and accurate even at iso 3200 wide open and at 1/30 sec.....

 

certainly a lot better than the T and XV zooms at their widest ......

 

Not investigated flash except as in-fill so can't help.

 

As Leica's implementation of flash is universally abysmal I have no great expectations ....

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[colonel]

Brighter lenses will always focus better as there is more light.

I have found the T zoom focuses well in low light, you just need to search for an area of contrast

Rgds

[Guest]

Hi John,

 

I have both lenses. I just took side-by-side shots with both lenses in pretty low light (1/15, f/3.9, @ 1600 ISO w/ zoom@ 24mm; 1/25, f/2, 1600 ISO w/ 23mm).

 

They seem pretty even to me, speed and noise wise (with zoom at ~23mm). The zoom seems to be just a tad faster to grab focus at 18mm believe it or not. The zoom focus may have less of a distance (or fewer elements) to move/travel (this is just a hunch). Both grabbed focus on a spot of sufficient contrast and otherwise hunted where contrast was low.

 

EVF was a bit brighter with the 23mm lens. The camera seems to exhibit less of that dimming problem with the 23mm than what you observed with the zoom.

 

What is noticeably different is the bokeh between the 2 lenses (that's explaining the obvious, no?).

 

Both are great lenses! The T is a more formidable low light camera with that 23mm lens.

 

Hope this is helpful.

[barjohn]

Perhaps I should add one more aspect to clarify the issue. Yes, if you have a high contrast subject the zoom will focus in low light; however, people's faces don't seem to provide that kind of contrast and that is where I am seeing the biggest problem in lower light situations. In light where at ISO 800 the zoom at 18mm wide open requires a shutter speed of 1/2 to 1/8, try and focus on a face quickly using AF.

[Joe Lazio]

As many know, I have the T with the zoom lens. I have now ordered and will shortly receive the 23mm f2 lens. I have found the zoom's AF performance in moderately low light to be extremely slow and in low to very low light it will not AF at all. Additionally, what one sees on the LCD/EVF is that for a brief fraction of a second as one presses the shutter to the ½ press position one sees a bright image which immediately turns very dark as it tries to focus.

 

Those that have both lenses, have you seen the same thing with the faster lens? Have you seen a significant improvement in low light AF with the f2 lens or are you seeing the same behavior?

 

Another thing I have noticed is that in low light, if you chose to use flash, you must switch from aperture priority to shutter priority to set the shutter speed but then you have no way to adjust aperture. Program mode is unusable with flash as you can't get the camera to change anything but ISO once flash is up. Maybe I am doing something wrong. If so please enlighten me.

 

The leica T is a camera with too many problems and one of them is focus in low light. I have it with the Vario Elmar and I stopped using it waiting for a firmware update. I received yesterday the wrist strap, silicon white. I find it very fragile and I fear for the camera.; to make matters worse I read on the web that rubber wristbands for watch perform poorly and silicon are even worse.

 

Wear too many years as an amateur photographer and I've used dozens of different digital cameras; the only answer is that my Leica T is different. In my humble opinion the T is a camera prematurely offered for sale. Leica wide .Sorry for my bad English

[Guest]

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Perhaps I should add one more aspect to clarify the issue. Yes, if you have a high contrast subject the zoom will focus in low light; however, people's faces don't seem to provide that kind of contrast and that is where I am seeing the biggest problem in lower light situations. In light where at ISO 800 the zoom at 18mm wide open requires a shutter speed of 1/2 to 1/8, try and focus on a face quickly using AF.

 

With limited contrast to aim for, the 23mm behaves pretty much the same way in super low light, I am sorry to say.

[barjohn]

Joe,

 

It is apparent that leica must have rushed the camera to market as the firmware clearly exhibits signs of immaturity. The delivery rate is probably also related to the fact that things were rushed. There are numerous small glitches, some more annoying than others, that need to be fixed but the major annoyance is the AF performance. Since the readout for the sensor is supposedly twice as fast for the T as it was for the XV (the reason the XV EVF could not be upgraded to the VF4), AF performance should have seen a significant improvement. In fact, it hasn't and in my opinion it is slower and worse in low light with one shining exception...it is more consistently accurate in indicating when it has focus lock. After 3 cameras, X1, X2 and XV all suffering from slow AF and complaints on this and other forums you would think it would be the one thing Leica would be sure to fix on the T, especially given its high price and the high price for its AF lenses. If Leica thought the majority of buyers would buy it to use M glass and MF, they failed to provide much of an assist and should have built in a range finder for focusing. In hopes that Leica will address many of these issues in the next firmware iteration, I will post my comprehensive list a little later and hope that much of the list is addressed.

[colonel]

I fail to recognise the picture painted of the T's focus.

Firstly it is recognisably faster then:

XV, x-pro1 and RX1

Secondly it is very accurate.

Thirdly I am used to using PDAF cameras in low light and searching for contrast and the T is hardly different. I get very few hunts and no more then my A7 or Df. Actually I find it a bit of a myth that phase detect is perfect in low light. In my experience it can also hunt and it's never as accurate as PDAF.

 

The T is not state of the art PDAF like the A6000 is, but it's hardly a limiting factor of the camera.

[barjohn]

There are numerous CDAF only cameras that easily out perform the T's AF, both in good light and low light. Obviously with static subjects the AF performance is fine and even in low light one can look for a high contrast subject within the plane of focus in order to obtain focus. The T works very well in this environment up to a point. There is a point where the light level is too low for the T to find sufficient contrast and it cannot find AF. That point is higher than other cameras I have used. Whether they have traded off some accuracy error in order to achieve the lower level I can't say but the A7r is one example that comes to mind.

 

Having now done a few preliminary tests with the 23mm f2 lens, I can say it will find focus a little better than the zoom in low light and can achieve focus where the zoom cannot. I haven't conducted any normal light tests yet.

 

In my testing with the zoom lens it did not focus as fast as the XV but was more accurate. I realize that there are those on this forum that still claim that there is no problem with the Xv's AF accuracy but far too many users have reported it and the data proof is in the EXIF for anyone that cares to take the time and effort to understand the EXIF data. I have not observed this type of error on the T.

 

I disagree that the AF is not a limiting factor. With even normally moving subjects, such as subjects engaged in conversation, it is hit & miss as to whether you will obtain focus lock before the subject moves out of the plane of focus, especially at the wider end of the lens where DOF is shallowest. In indoor environments, one is frequently shooting wide open to keep ISO levels lower and shutter speed higher so the lag does impact the ability to capture the moment. With a doubling of the readout speed from the sensor there should have been and maybe still will be, much faster AF than the XV.