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07-29-2013, 05:38 PM   #16
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QuoteOriginally posted by Class A Quote
For sure the AF system is on fire with this trick.
Thanks a lot Uluru, for making me a constant AF-C shooter again.
I just gave this a try and every single time the AF-C shot was sharper than the AF-S shot.
Thank you too for starting this thread.
Mind you, this works to improve the performance of screw drive lenses.
More sophisticated DA* lenses with motors built in are different beasts — but I wouldn't mind someone trying the same with them.

07-29-2013, 07:49 PM   #17
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QuoteOriginally posted by Uluru Quote
This is probably well known, but I have discovered it by testing myself. And it works well on K-7.
By keeping the focus in AF-C constantly, two quick AF checks in a row — made by slightly moving the focus point targeted at the same distance but on slightly different vertical or horizontal position — improve the AF accuracy to that distance substantially, at all apertures and using all my lenses (DA zooms and DA Ltd primes). It's almost like simulating an another array of AF points which aren't there.
It takes a fraction of a second to do it routinely, but the results are great. No more misses or miscalculated distances which cause OoF pictures and is especially good for static subjects — something that usually asks for AF-S, but actually AF-C works better.

Again, if you know this already, just ignore it.
Do you mean by keeping your finger on the shutter button while moving the focus point ?
If that's so, I don't understand why this would help the accuracy of the AF ???

I seldom use AF-C ... because it has never helped much at all, especially for moving "targets".

JP
07-30-2013, 01:06 AM   #18
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QuoteOriginally posted by jpzk Quote
Do you mean by keeping your finger on the shutter button while moving the focus point ?
If that's so, I don't understand why this would help the accuracy of the AF ???

I seldom use AF-C ... because it has never helped much at all, especially for moving "targets".

JP
I think he meant keep the camera in AF-C. Then just focus, and then focus one more time to check.
07-30-2013, 06:00 AM   #19
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QuoteOriginally posted by Uluru Quote
This is probably well known, but I have discovered it by testing myself. And it works well on K-7.
By keeping the focus in AF-C constantly, two quick AF checks in a row — made by slightly moving the focus point targeted at the same distance but on slightly different vertical or horizontal position — improve the AF accuracy to that distance substantially, at all apertures and using all my lenses (DA zooms and DA Ltd primes). It's almost like simulating an another array of AF points which aren't there.
It takes a fraction of a second to do it routinely, but the results are great. No more misses or miscalculated distances which cause OoF pictures and is especially good for static subjects — something that usually asks for AF-S, but actually AF-C works better.

Again, if you know this already, just ignore it.
Very interesting... never heard about this before. Anyone know why or how this works?

07-30-2013, 07:17 AM   #20
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QuoteOriginally posted by IchabodCrane Quote
Anyone know why or how this works?
Well, it works by re-checking the focus. In my testing, the camera sometimes doesn't actually refocus, probably because it locked focus properly the first time.
07-30-2013, 07:18 AM   #21
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QuoteOriginally posted by Giklab Quote
I think he meant keep the camera in AF-C. Then just focus, and then focus one more time to check.
QuoteOriginally posted by IchabodCrane Quote
Very interesting... never heard about this before. Anyone know why or how this works?
I think the OP will answer that.
I am still unsure about this because once you have the camera in AF-C it does "constantly" (read; continuously) try to focus, so by focusing again will not really have any effect I think.

We shall see.

JP
07-30-2013, 08:11 AM   #22
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QuoteOriginally posted by IchabodCrane Quote
Very interesting... never heard about this before. Anyone know why or how this works?
I can only speculate, but I guess there are several aspects to it:

1. engaging both vertical and horizontal sensors of a cross type sensor.
2. covering multiple subregions of the focus target, avoiding false locking on something that is near in the 2D space, but in a different distance.
3. forcing the AF system to correct even the most minute deviation that it would have otherwise let slip.
4. adjusting focus till the very last moment, as opposed to locking a once obtained focus that becomes invalidated after a small camera move.

Points 1. - 3. should be achievable with repeatedly requiring re-focus using AF-S as well.
Point 4 depends on AF-C being chosen.

Again, I'm just speculating, but incidentally, I've been using the same technique with my K100D. I had it set to AF-C and when I wanted to obtain focus, I didn't just press the OK button to focus once only, but multiple times, allowing the lens to make micro-adjustments, until it stopped adjusting. At the same time, I moved the focus "point" a bit over the target to make sure that the camera agrees with me about what the target is as opposed to locking on to something else. This worked great, and I'm very happy to see that this strategy continuous to work with the K-5 II.

P.S.: If posters don't mind, I'll collate the various contributions in my first post, of course attributing the respective contributor (pointing to their post).
07-30-2013, 08:23 AM   #23
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To check focus accuracy I keep my K-5 and Q quick zoom setting at x8.
This way, when camera shows the instant review display I can click the rear wheel once and instantly get a near 100% crop.
I use this to verify that the shot is in focus, especially when doing manual focus.

07-30-2013, 09:36 AM   #24
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QuoteOriginally posted by Class A Quote
Exposure Lock in Manual Mode
This one is the one I use the most. Broading the common saying "exposure is always locked in manual mode". Pitty it doesn´t lock ISO value too.

QuoteOriginally posted by Class A Quote
Focus Priority on Demand
Another way to see this is setting the AF button to disable AF. So when pressing only the shutter release you get focus priority. When pressing AF button while half pressing the shutter release you activate release priority.

Exposure Compensation in Manual mode
QuoteOriginally posted by Fogel70 Quote
Another favorite feature is the green button in manual mode, where you can select to use it as semi-automatic P, Tv or Av mode. And this combined with EC and spot metering make it very easy to set exposure in difficult lighting situations.
As Fogel said, it is really convinient when ocassionally (or not) using the green button, the calculated exposure will take EC into account.

I will add:
OK button: Play mode and Histogram
When reviewing images, if youvé set your histogram to show up when in play mode with the info button (pressed 2 times) you can turn it off with the OK button. Press info and it shows up again.
07-30-2013, 09:43 AM   #25
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QuoteOriginally posted by crewl1 Quote
To check focus accuracy I keep my K-5 and Q quick zoom setting at x8.
This way, when camera shows the instant review display I can click the rear wheel once and instantly get a near 100% crop.
I use this to verify that the shot is in focus, especially when doing manual focus.
This is fast only if you focused on the center of the image. That´s why I set the quick zoom to x4

QuoteOriginally posted by Class A Quote
I had my K100D in AF-C mode as well and simulated AF-S by just tapping the AF button once (one can configure the K100D's OK button to become an AF button).

I was always wondering whether I'm giving up any accuracy by doing so.
Is it safe to just be on AF-C all the time and just do a quick tap of the AF button for effectively achieving AF-S behaviour?
I remembered reading this articles, perhaps they can help, part 2 especially where he covers the "double tap autofocus" and found out the camera has already focused the best it can the first time. Perhaps, for pentax screwdriven lenses this is not true due to mechanical tolerances and a second autofocus attemp will erase the mechanical difference?
LensRentals.com - Autofocus Reality Part 1: Center-Point, Single-Shot Accuracy
LensRentals.com - Autofocus Reality Part 2: One vs. Two, Old vs. New
LensRentals.com - Autofocus Reality Part 3A: Canon Lenses
LensRentals.com - Autofocus Reality Part 3B: Canon Cameras
LensRentals.com - Autofocus Reality Part 4: Nikon Full Frame
07-30-2013, 10:31 AM   #26
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For the AF-C trick, it's something I learned on my D800 and now use on my K5s all the time.

I've actually shut off the half press shutter to activate AF and just use the rear AF button. Leave it on AF-C and hold the button down until I take the shot.

This way it's constantly correcting focus so it's nailed every time. Helps keep the focus locked. If your subject moves just a hair or the camera moves the AF corrects right away.

Also with the AF not being engaged by the shutter you can focus and re compose then not worry about accidentally triggering the AF by the shutter.



07-31-2013, 05:31 PM   #27
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Great thread so far. Useful to those of us that are recent Pentax converts. Wish I had something to contribute, but I encourage anyone who has something they find helpful to share it.

I'm mostly a "hands-on" shooter, using Av, TAv, and M, but it's very useful to know these tricks.

@Fogel70, you may have some copy/paste errors above re auto ISO, if I'm not mistaken. Right?

Anyway, keep 'em coming if you got 'em!
07-31-2013, 11:27 PM   #28
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QuoteOriginally posted by filoxophy Quote
@Fogel70, you may have some copy/paste errors above re auto ISO, if I'm not mistaken. Right?
Yes, you are right. Thanks for pointing that out.
08-02-2013, 07:49 PM   #29
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The "Disable status screen" idea for quick access to many controls is a beauty! Thanks so much for this thread.
08-03-2013, 07:31 AM   #30
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If you are using an autofocus lens that is not capable of Quick Shift manual focusing tweaks, you can still tweak your focus manually by auto focusing (AF.S) and then either:
  • flip the switch into the MF position, or
  • press the lens release button

Either action will retract the AF screw drive from the lens and allow manual focusing. The advantage of pressing the lens release button is the camera will automatically return to normal AF function when you release the button.
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