[Zygonyx]

OK, i tried it again thoroughly with the lens, both on my K-3 (FW 1.21) and K-S1 (FW 1.01) : the results are the same with both bodies, but actually a bit different from what i wrote in my last post, and i am sorry for that.


Case 1- lever switched on green "AF" position : each time you press on one of the 4 barrel buttons, the autofocus is activated and is set in the same way as when you press the body's shutter button. So you can effectively have a problem if you press those buttons by mistake. But this is no more than an extended AF function.


Case 2 - lever switched on "AF preset" position : this allows you to memorise any focus distance you wish, or to change the last previously memorised position, in pressing also the rugged "preset" button. As far as i remember, there is no "default" focus position, so if you don't activate first the rugged button, nothing happens with the 4 barel buttons in this position (this would however have to be confirmed with a new lens). In case you are pressing at the same time the body's shutter button and one of the 4 lens barrel buttons, the priority is given to the barrel buttons.


Case 3 - lever switched on "AF cancel" position : there is no MF functionning, unless you also switch the quick-shift/MF lever to MF position on the lens, or the MF lever of your body : so the 4 barrel buttons are desactivated, and AF is done normally by pressing on the body's shutter button (or rear AF button). So basically, this is what you are looking for, and doesn't need any FW evolution imho.

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Last edited by Zygonyx; 07-17-2015 at 10:04 PM.

[Cannikin]

Case 3 - lever switched on "AF cancel" position : there is no MF functionning, unless you also switch the quick-shift/MF lever to MF position on the lens, or the MF lever of your body : so the 4 barrel buttons are desactivated, and AF is done normally by pressing on the body's shutter button (or rear AF button). So basically, this is what you are looking for, and doesn't need any FW evolution imho.

Zygonyx, I appreciate your trying to help here, but the lens does not function as you describe. With the camera switch on AF, the lens on AF Cancel mode and QFS/A or QFS/M, while holding down any of the lens buttons neither the AF button on the camera nor half pressing the shutter button will activate AF. In addition, any AF operations that were going on when the button was pressed are immediately halted.

It even says very clearly in the manual: "Temporarily cancels autofocus operation on the camera side." See my scan of the manual in my previous post.

[Zygonyx]

Yes, i didn't say anything else : the "temporarily" is in fact all the time you maintain the lever in the position 3.
But i actually do not agree with what can be meant by "camera side" : with my two bodies, AF is operating whilst case 3.
"AF cancel" position should in fact be named "lens AF button cancel".
Are you sure your lens isn't bugged ?
Or if its mine, that's for the best

[Cannikin]

Yes, i didn't say anything else : the "temporarily" is in fact all the time you maintain the lever in the position 3.
But i actually do not agree with what can be meant in "camera side".
Are you sure your lens isn't bugged ?

No, my lens functions exactly like the manual says it should, and not as you say.

Do exactly these steps:

1. Put the lens cap on to force the lens to hunt so you can clearly see the focusing scale move through the whole range instead of stopping at focus lock. Any AF button will make it go back and forth and the AF assist light will go on if you have it enabled.

2. Put the lens in "AF Cancel" mode, AF mode to "QFS/A" or "QFS/M". Camera body switch to "AF" (AF.S/C/A should not matter).

3. Press and hold the AF button on the camera for several seconds. The lens will attempt to autofocus and hunt back and forth.

4. Half-press and hold the shutter button (assuming you have it set to autofocus) for several seconds. The lens will attempt to autofocus and hunt back and forth.

Now two tests to demonstrate what happens when you accidentally press one of the lens buttons while trying to AF normally with the camera buttons:

Test A
Press and hold any of the AF buttons on the lens. The "AF" button on the camera will now do nothing. Half-pressing the shutter button will meter but will not autofocus. Release the button on the lens. The camera AF buttons will now activate AF normally.

In this scenario, accidentally pressing the lens button means AF functionality is completely disabled and will not activate as long as the button is pressed.

Test B
Press and hold either the AF button on the lens or half-press the shutter. The lens will hunt back and forth. While it is hunting, press any of the AF buttons on the lens. Autofocus will immediately stop. Continue holding the button on the camera and release the button on the lens. Autofocus will immediately resume.

In this scenario, accidentally pressing the lens button will interrupt any AF you had going on when it was pressed.


The desired solution: a mode where accidentally pressing the lens buttons does nothing, and the AF buttons on the camera body function normally.

With the switch set to "AF", the lens buttons will activate AF.
With the switch set to "Preset" the lens buttons will make the lens go to the preset focus distance.
With the switch set to "AF Cancel" the lens buttons do as I described above.

In none of these three modes will accidentally pressing the lens buttons do nothing, and allow the AF buttons on the camera to operate normally, unless the Preset was never set (way too late for that, and not a good solution anyway), or either the lens or camera is set to MF (obviously not what is desired).


My DIY solution: Relieve pressure from the bottom button by taping something relatively stiff, but still able to conform to the lens barrel's curvature, over it. A strip of corrugated cardboard seems to work well for me. See my post at #1214 in this thread for a picture. Wait and see if Pentax addresses this.

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Last edited by Cannikin; 07-18-2015 at 12:23 AM.

[Zygonyx]

Ok, thanks for these precisions.
I confirm, and didn't notice the lens barrel buttons had this "stopping AF" effect whilst autofocussing with the body in case 3.
I wonder why this has been implemented...
Then the lever should have been named "AF hold" and not "AF cancel".
That means using the lens without the tripod fixation brings you effectively this annoying situation.

[rawr]

In looking at the manual for the Nikon 70-200 F2.8 VR1, which has 3 focus lock buttons, this is all it says about using those buttons:

Simple!

Some Nikon cameras (eg the D810 - but not the D610) give you a range of in-camera options to control what those buttons do. But there is no option to simply disable the buttons, it seems, even with a D810.



Pentax could implement a range of options for those buttons, if it wanted to, judging by the Nikon example.

[Cannikin]

All I can imagine is that the testers for this lens all had larger hands than mine, which would put the button in the center of the palm (point of minimal pressure), rather than the heel (maximum pressure). I don't think my hands are much smaller than an average Japanese man's, though, being of East Asian descent myself.

That or they did all their testing on a tripod. I didn't even really notice the issue until I started handholding it a few days ago. Most of my testing before that was from a tripod.

Still, like I said, it should be relatively easy to allow disabling the buttons on the camera side in software, and maybe even implement more nifty features like rawr suggests. Focus Preset is actually a really useful feature on this lens. I use it to save precise infinity focus when the lens is cooled to about 60 degrees F, so I can use it for night work when the Moon isn't around to focus on.

In the meantime, my cardboard cover solution seems to be doing the trick for the most part.

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Last edited by Cannikin; 07-18-2015 at 03:17 AM.

[thibs]

All I can imagine is that the testers for this lens all had larger hands than mine, which would put the button in the center of the palm (point of minimal pressure), rather than the heel (maximum pressure). I don't think my hands are much smaller than an average Japanese man's, though, being of East Asian descent myself.

That or they did all their testing on a tripod. I didn't even really notice the issue until I started handholding it a few days ago. Most of my testing before that was from a tripod.

Still, like I said, it should be relatively easy to allow disabling the buttons on the camera side in software, and maybe even implement more nifty features like rawr suggests. Focus Preset is actually a really useful feature on this lens. I use it to save precise infinity focus when the lens is cooled to about 60 degrees F, so I can use it for night work when the Moon isn't around to focus on.

In the meantime, my cardboard cover solution seems to be doing the trick for the most part.

Kenspo, could you please forward this? Thank you.

[Mike.P®]

Ok, prepare to be impressed .... I was anyway.

[redpit]

Ok, prepare to be impressed .... I was anyway.

I'm too! This lens can make a difference! I will post some aviation photos next week too ;-)

PS: that camo Eurofighter is wonderful!

[Canada_Rockies]

Ok, prepare to be impressed .... I was anyway.

That is absolutely impressive! You do realize that you have made me have LBA big time with those shots, don't you? I'm up to nearly $4K Canadian between that lens and the K-3 II to hang from the back of it.

---------- Post added 2015-07-21 at 08:57 ----------

Ok, thanks for these precisions.
I confirm, and didn't notice the lens barrel buttons had this "stopping AF" effect whilst autofocussing with the body in case 3.
I wonder why this has been implemented...
Then the lever should have been named "AF hold" and not "AF cancel".

Those are the same functions as provided on the camera back AF button. I suspect that is where the logic came from.

[Mike.P®]

That is absolutely impressive! You do realize that you have made me have LBA big time with those shots, don't you? I'm up to nearly $4K Canadian between that lens and the K-3 II to hang from the back of it.

Must admit this was possible the only time I have missed the K-3 I sold last year, the extra mega pixels are very handy for cropping as the jets seem to get further away every year.

Here is one of my favourites from the day ... maybe the last time I will see her as from next year she will no longer be flying.

[rawr]

Ok, prepare to be impressed .... I was anyway.

Great shots!

Who owns the FA-18, BTW. I don't recognise the roundels.

[redpit]

@rawr its Finnish

[rawr]

its Finnish

Aha. Thanks.

What a great airshow, to see such a variety of military planes.