Let's talk about PreAF

[SoCalLeicanator]

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OK, so after searching the forum.  I can't find what people seem to concur is the best setting for this.  

The manual says it helps performance.  However, it completely crippled a 28mm APO SL lens I purchased used from mpb.

Is this the nature of preAF or does the lens have to go back?  

Thanks!

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[jaapv]

I must admit you have lost me here. If you half-press the shutter button the camera locks focus. Who is “ people “ ? 

[SrMi]

I assume OP means Pre Focus:

When the function is active, the camera carries out a continuous depth mapping in realtime before the actual focusing. That allows a pre-identification of possible focus points in a scene. It speeds up the autofocus function significantly.

I did not find that option useful and kept it off. It uses more power when on.

What do you mean by crippled 28mm? What camera and what firmware?

[SoCalLeicanator]

1 hour ago, jaapv said:

I must admit you have lost me here. If you half-press the shutter button the camera locks focus. Who is “ people “ ? 

This is relates to my prior post.  I fear I have a bum used 28 f2 APO and was told in that thread to turn off the "PreAF" setting.

 

Here is PreAF in the manual

https://www.manualslib.com/manual/1941693/Leica-Sl2.html?page=108

 

I didn't do this until after the event I had been anticipating for great photos passed with about 70% missed shots (for real). 

 

In the AF focus settings under profile, there is a "PreAF" on or off mode.  If it's on, the camera is constantly hunting for a focus point and this is reflected in chattering coming from the lens itself as it hunts for focus.  My issue was that I could not lock focus period.  I have 10 more days to return the lens so need to make sure that this is a keeper or get it back to mpb. 

 

So, if the lens should work AOK with PreAF on, it goes back.  IF this setting is one that should be left always anyways, I'll give it one more shot.

Thanks 

 

 

[SoCalLeicanator]

15 minutes ago, SrMi said:

I assume OP means Pre Focus:

When the function is active, the camera carries out a continuous depth mapping in realtime before the actual focusing. That allows a pre-identification of possible focus points in a scene. It speeds up the autofocus function significantly.

I did not find that option useful and kept it off. It uses more power when on.

What do you mean by crippled 28mm? What camera and what firmware?

Yes, that's right.  It was a "like new" 28mm f2APO, with an SL2-S with the next to most recent firmware.

 

[jaapv]

2 hours ago, SoCalLeicanator said:

Yes, that's right.  It was a "like new" 28mm f2APO, with an SL2-S with the next to most recent firmware.

 

Ah-permanent focus mapping. Not something I would ever use. It probably eats battery power as well. 

[Chuck Albertson]

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1 hour ago, SoCalLeicanator said:

This is relates to my prior post.  I fear I have a bum used 28 f2 APO and was told in that thread to turn off the "PreAF" setting.

 

Here is PreAF in the manual

https://www.manualslib.com/manual/1941693/Leica-Sl2.html?page=108

 

The Pre-focus discussion is the same in both, but if you're shooting the SL2-S, you ought to go to the Leica support website and download the manual for it, instead of using a SL2 manual. The Leica manual probably tracks recent firmware changes more closely than a third-party site does.

[Mak67]

Pre-AF make focus a lot faster when you need to change focus from close up to Infinity to close up... It register a "Map" of all focusing point in the scene, then just adjust quickly by memory, it eats a lot of batterie (as do 120 frame rate viewfinder) and i think that why many people complaintes about the Sl2 batteries life.

But, same as you i discovered the fonction when i had my first Apo (35) and didn't notice it before with Slzooms nor sigma Lens ..

Not sure it is a fonction that works with all lenses ?

 

 

 

[LocalHero1953]

This is a confusing OP, thread title, and thread, with most people commenting on the usefulness of Pre-AF rather than the behaviour of the lens.

As far as I know the Apo-Summicron 28mm SL lens should work with all functions of the SL2 and SL2-S. Download the manuals for both your camera and your lens, and check that they have no limitations on using your lens with your body.

Some questions:

• Which camera is it? It sounds like it may be the SL2-S, but your OP does not say.
• Is this your camera that you have owned for some time, or did you buy it with the lens from the same owner?
• Have you updated your camera to the latest firmware?
• Does your camera work, with or without Pre-AF, with other L-mount lenses?
• When you first mounted the lens on your camera, did it work with Pre-AF switched off?
• Does your lens work now when you have Pre-AF switched off?
• What do you mean by "crippled"? Does your camera recognise the lens? Can you take correctly exposed photos with it, even if AF is not working?

With this information you might get better advice here!

[Jean-Michel]

16 hours ago, SoCalLeicanator said:

In the AF focus settings under profile, there is a "PreAF" on or off mode.  If it's on, the camera is constantly hunting for a focus point and this is reflected in chattering coming from the lens itself as it hunts for focus.  My issue was that I could not lock focus period.  I have 10 more days to return the lens so need to make sure that this is a keeper or get it back to mpb. 

 

So, if the lens should work AOK with PreAF on, it goes back.  IF this setting is one that should be left always anyways, I'll give it one more shot.

Thanks 

 

 

The pre-focus function does not make the lens focus, it does not make the lens 'hunt for focus'. Your lens should work equally well with the pre-focus function ON or OFF.

[Hanno]

From the manual as FYI and to support @Jean-Michel ’s post in what the pre Focus function does.

I have it off to preserve battery.

 

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Edited April 25, 2023 by Hanno

[Jean-Michel]

2 hours ago, Hanno said:

From the manual as FYI and to support @Jean-Michel ’s post in what the pre Focus function does.

I have it off to preserve battery.

 

In my car, I keep it ON, and carry extra batteries, usually I do not need more than one fully charged battery for a day, but do always carry a second battery(I have 3, not cheap, but worth it)

[SoCalLeicanator]

11 hours ago, LocalHero1953 said:

This is a confusing OP, thread title, and thread, with most people commenting on the usefulness of Pre-AF rather than the behaviour of the lens.

As far as I know the Apo-Summicron 28mm SL lens should work with all functions of the SL2 and SL2-S. Download the manuals for both your camera and your lens, and check that they have no limitations on using your lens with your body.

Some questions:

• Which camera is it? It sounds like it may be the SL2-S, but your OP does not say.
• Is this your camera that you have owned for some time, or did you buy it with the lens from the same owner?
• Have you updated your camera to the latest firmware?
• Does your camera work, with or without Pre-AF, with other L-mount lenses?
• When you first mounted the lens on your camera, did it work with Pre-AF switched off?
• Does your lens work now when you have Pre-AF switched off?
• What do you mean by "crippled"? Does your camera recognise the lens? Can you take correctly exposed photos with it, even if AF is not working?

With this information you might get better advice here!

First, apologies for two threads and any confusion this may have caused.  My first post was "Help, did I get a defective 28mm f2 APO?!".  My second was "Is Prefocus useful? Not useful?  Does it negatively impact performance?"

It is an Sl2-s (reporter) purchased new with Firmware 5.0.  Have not upgraded to 5.1 The lens firware was listed as 3.1.

It works  flawlessly with the Sigma 35 1.4 DG DN, 24-70 2.8 Art and Lumix 50 1.8

I didn't turn the Pre Focus off until later.  For the event I was photographing, the cameras was in face detect mode, the "children and animal" profile and AF-S.  The focus bombed >50% of the time even including stationary objects.  I experimented with AF-C and that only made the problem worse (especially with stationary objects)  The exposure seems fine, but it was that mid day SoCal sun that is tricky regardless. 

With Pre-AF off, it seems to be fine, but I haven't taken it out in real world conditions yet.  I'll see if I can later today.  I guess I was just surprised because in all of my systems (leica example being the CL with the Summilix 35 1.4 and Summicron 23 f2), I screwed on a new lens and it would work immediately without any drama   The Sigmas and Lumix worked from the get go (and still do, I checked) so was perplexed that the house brand would let me down. 

And yes the manual is downloaded both to my phone and computer and gets consulted frequently. 

Edited April 25, 2023 by SoCalLeicanator

[Stuart Richardson]

I do not have the 28, but I have the 35, 50 and 90-280, as well as some Sigma lenses. None have had any notable trouble in achieving focus. I rarely (if never) use AFc. I turned off pre af as soon as I got the camera, because I do not like the camera randomly focusing as I try to compose. It seems that the SL series cameras are at their best with pre af off, and AFs, not iAF or AFc. I would suggest trying just using it with AFs, and seeing how it goes. But either way, it sounds like your 28mm may need another look by a technician.

[Hanno]

25 minutes ago, Stuart Richardson said:

 not iAF 

As a side comment, the SL2 works incredibly well for portraiture when in iAF coupled with Eye/Face/Body Detection. You can even select which of the 2 eyes to focus on. 

For non portraiture AF, I would use indeed AFs with Field/Spot as the subject of focus' contrast warrants.

[LocalHero1953]

3 hours ago, Stuart Richardson said:

I do not have the 28, but I have the 35, 50 and 90-280, as well as some Sigma lenses. None have had any notable trouble in achieving focus. I rarely (if never) use AFc. I turned off pre af as soon as I got the camera, because I do not like the camera randomly focusing as I try to compose. It seems that the SL series cameras are at their best with pre af off, and AFs, not iAF or AFc. I would suggest trying just using it with AFs, and seeing how it goes. But either way, it sounds like your 28mm may need another look by a technician.

I was about to reply, but this post says what I was going to say! I don't use Pre-AF, for the same reasons, but do use iAF with Face Recognition, which picks and chooses between AFs and AFc depending on what it sees. In a crowded scene you have to work hard with the joystick to pick the person you want, but it is good enough for my purposes.

 

[LocalHero1953]

3 hours ago, SoCalLeicanator said:

First, apologies for two threads and any confusion this may have caused.  My first post was "Help, did I get a defective 28mm f2 APO?!".  My second was "Is Prefocus useful? Not useful?  Does it negatively impact performance?"

It is an Sl2-s (reporter) purchased new with Firmware 5.0.  Have not upgraded to 5.1 The lens firware was listed as 3.1.

It works  flawlessly with the Sigma 35 1.4 DG DN, 24-70 2.8 Art and Lumix 50 1.8

I didn't turn the Pre Focus off until later.  For the event I was photographing, the cameras was in face detect mode, the "children and animal" profile and AF-S.  The focus bombed >50% of the time even including stationary objects.  I experimented with AF-C and that only made the problem worse (especially with stationary objects)  The exposure seems fine, but it was that mid day SoCal sun that is tricky regardless. 

With Pre-AF off, it seems to be fine, but I haven't taken it out in real world conditions yet.  I'll see if I can later today.  I guess I was just surprised because in all of my systems (leica example being the CL with the Summilix 35 1.4 and Summicron 23 f2), I screwed on a new lens and it would work immediately without any drama   The Sigmas and Lumix worked from the get go (and still do, I checked) so was perplexed that the house brand would let me down. 

And yes the manual is downloaded both to my phone and computer and gets consulted frequently. 

Thanks for the details. You don't say if the 28mm is working in any way at all. Is it just not focusing reliably? Or is it just dead?

[SoCalLeicanator]

1 minute ago, LocalHero1953 said:

Thanks for the details. You don't say if the 28mm is working in any way at all. Is it just not focusing reliably? Or is it just dead?

It's missing focus left and right.  I like to make photo calendars and this even would have been fecund for me had I been able to nail more shots.

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[SoCalLeicanator]

OK so took out yesterday and the same thing.  The focus box will turn green indicating locked focus and every 3rd to 5th shot when I depress the shutter the lens will front and back focus for three seconds before returning where it was.  I contacted mpb and will be getting a refund.  Thanks for everyone's help.