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11-05-2014, 11:23 AM   #1
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K3 AFA Info

Can anyone explain the AFA auto function mode on the K3 as I have recently acquired K3 and find the manual to be inadequate, Also what is the optimum SD card speed for the K3

11-05-2014, 11:34 AM   #2
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I had always assumed that it detects motion, and thereby decides if it needs to continually adjust the autofocus. However, I've not really tried it much. I prefer to choose one or the other, and not leave it to the camera to choose. Others may have more experience with AF.A.

I'm very happy with the Sandisk Extreme Pro 95 MB/s card.
11-05-2014, 12:17 PM   #3
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AFA supposedly tries to determine if you should be in AFC or AFS. Personally I prefer to select on my own rather than be surprised by what the camera does.

One thing you can do to have the best of both is to set the camera up to use back button focus. Then put the camera in AFC. Hold the AF button until you get AF confirmation and let go for AFS or hold it down continuously as you track for AFC. You have to learn to use back button AF but I think that is better technique than having the shutter release tied to focusing anyway.
11-05-2014, 12:28 PM   #4
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I've never used AFA, so I cannot comment on that.

I had to purchase a new card after my SanDisk Ultra 30 MB/s card proved entirely too slow. Raw DNGs from the K-3 almost always exceed 30mb and I believe I have a few over 40mb. Review after even a single shot with the Ultra was painfully slow.

I now use a SanDisk Extreme Pro 95 MB/s card. I have no lag between photographing and review and the buffer clears relatively quickly after shooting high frames per second.

I've only used the Ultra in slot #2 once to back up RAWs when some friends had me take extra photographs at their wedding reception (they had a professional for the ceremony).

11-05-2014, 12:58 PM   #5
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I seldom use AF-A and have not been able to determine just what it does when in that mode. Usually I use AF-S

As for SD cards, a 32 GB SDHC from one of the major makers is more than adequate for most needs. Most current cards are class 10 or better for speed and 32 GB is good for 600 RAW files. If you are doing video you might want to consider the higher capacity SDXC cards, though I would warn that they have proven to be problematic for some users due to the exFAT filesystem used.

11-05-2014, 03:38 PM   #6

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QuoteOriginally posted by bhancox Quote
Can anyone explain the AFA auto function mode
Nikon and Canon DSLR's also have an AF-A mode. Like Pentax, Nikon calls it 'AF-A', Canon calls it 'AI Focus AF'. Here's how both explain it:

AI Focus AF - 'the AF system will automatically choose between One Shot AF [ie AF-S] or AI Servo AF [ie AF-C] based on whether it perceives the subject to be still or in motion'

AF-A - 'Auto-servo AF: Camera automatically selects single-servo autofocus [AF-S] if subject is stationary, continuous-servo autofocus [AF-C] if subject is moving'

The Pentax explanation in the K-3 manual is certainly the most cryptic:

AF-A: 'Switches automatically between AF-S and AF-C modes according to the subject'.

The common thread between the Pentax, Nikon and Canon explanations is that AF-A lets the camera decide if the subject is still, or in motion. If the subject is still, the camera will dynamically switch to AF-S mode. If the camera thinks the subject is in motion, the camera will dynamically switch to AF-C mode.
11-05-2014, 03:50 PM   #7
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The first time I tried using AF-A was during the reception of a wedding (non-important dancing time). The camera locked up and I had to remove the grip to get the battery out of the body. I haven't tried using it again.
11-05-2014, 05:28 PM   #8
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I think most of us rarely use the AFA setting because we do not trust it in difficult situations. I have mine set to Af-S 90% of the time and only AF-C when it is necessary to let the camera track a swift moving object. I want to control which tracking mode is used rather than let the camera decide.

11-05-2014, 05:48 PM   #9

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QuoteOriginally posted by Mikesul Quote
I want to control which tracking mode is used rather than let the camera decide.
AF-A is also very dynamic. You may find in a matter of seconds it will switch you from AF-S to AF-C, and back again, and keep doing so.

Normally I manually select AF-C and shoot that way pretty much all the time. Funnily enough, however, I have found that switching to AF-A would speed up my shooting speed (fps) sometimes. I don't know why, but it did.
11-06-2014, 06:59 PM   #10
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Currently the best card that will take advantage of the cameras speed is the Sandisk Extreme Pro at 95mbs
Second best is the Extreme Plus at 80 mbs.
Other cards in those ranges will work too, but I have found SanDisk to provide best reliability.
make sure to buy from a reputable dealer as there are lots of knockoffs on eBay and you cant be sure they are real , especially if the price is too low.

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