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01-09-2014, 08:11 PM   #1
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K-3 birds: playing with & testing AFC

I do not track wildlife, birds, or any of that sort of action. Photos I may be taking will probably be editorial, travel, and street. I'm a newbie in all of the above subjects.

However, I thought I will get out of my comfort zone, take K-3 out this morning, and track bird in flight for the first time to play. The lens I've used is the 18-135mm WR that came with K-3. So, this is the closest I can get. It was around 8am. So, light has only started to come out. But, for the most part light level is still quite low (hence may have a few motion blur on a few of them), except the sky.

Please forgive the jumpiness of the images. I was just waving the camera around, in some cases going reverse to the bird .

Also, please excuse the blown highlights and lousy post processing in a lot of these images and evaluate the AFC performance only. I'm lazy and just created a Photoshop action to take care of it instead of individually which would take forever.

I think it did reasonably well, though probably none of them are poster worthy . All the images were taken handheld, AFC with high bursts. ISO 100 & f/5.6 @ 135mm. Varying shutter speeds from 1/400 to 1/1000. These are complete bursts. Not one image omitted. Please excuse the lengthy images. Most test sequences I have seen while researching K-3 were short. So, I thought I will post a longer one. The file setting I have used is JPG S. So, buffer write time was reasonable. Raw might take longer.

Hopefully, this serves as a test sample (either good or bad) for the performance of K-3 AFC for people researching into getting or upgrading to a K-3.

Admins & moderators: I assume the number of images are ok since they are external links. If not, please feel free to edit / remove / move them to appropriate location. Thanks.

Bird Sequence A (everything in this sequence came out well). If the images doesn't appear to be in sequence, it's because I moved my camera around to force the bird back into the center point of the frame . Also, these are truly from the same burst since I shot a single still between each sequences to separate them; no chance of getting confused.













































Bird Sequence B

The last frame is bad probably because I thought that's enough spraying for the day and my head is also twisted about 90 degree right and 85 degree up .


























Last edited by penmar; 01-09-2014 at 08:20 PM.
01-09-2014, 08:40 PM   #2
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Did you have auto focus linked to the shutter release button (i.e. default setting) or AF button only?
01-09-2014, 09:02 PM   #3
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QuoteOriginally posted by calsan Quote
Did you have auto focus linked to the shutter release button (i.e. default setting) or AF button only?
I imagine it was the default setting? All I did was change to AFC, then, shutter to H continuous, then focus point to Auto. What is the AF button only mode? I have to admit, I just started looking at the manual . May be I'm not doing it the right way? If you don't mind would you explain a little bit. Thanks.
01-09-2014, 09:24 PM - 1 Like   #4
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By default, the camera auto focuses when you push the shutter button.

In order to get bird in flight shots with my K-7, I have to turn this behaviour off, which is in the custom settings, something like 'link AF to shutter release".

The reason being, that AF can't keep up with the bird and will miss focus on some background trees or try and focus on the sky. To auto focus, you then press the AF button, the rest of the time you're in manual focus.

Make any sense? :-)

01-09-2014, 09:28 PM   #5
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Example - not best shot, but shows why there's a need to have AF only when you want it. AF would have focused on the closer branches, not the cockatoo landing in the background.
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01-09-2014, 10:33 PM   #6
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QuoteOriginally posted by twitch Quote
AF Hold setting? I think by default it is off which would explain that last frame.
Thanks. I got that's what it does now. I have seen that setting in the Custom menu pages. Never quite got it before.

QuoteOriginally posted by calsan Quote
By default, the camera auto focuses when you push the shutter button.

In order to get bird in flight shots with my K-7, I have to turn this behaviour off, which is in the custom settings, something like 'link AF to shutter release".

The reason being, that AF can't keep up with the bird and will miss focus on some background trees or try and focus on the sky. To auto focus, you then press the AF button, the rest of the time you're in manual focus.

Make any sense? :-)
Thank you for the explanation. That makes perfect sense now. That's what that AF button was for. To be honest, those two buttons AF & A-EL at the right hand corner, I haven't exactly played with . I will look at the manual read a bit more.

Also, there is an AF Hold Status in custom menu with off, low, medium, and high, which probably is what twitch was referring to. It is off by default. I can probably try again with different setting.

Note to self: better finish reading the manual
01-10-2014, 12:11 AM   #7
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The K-3 seems a huge improvement over previous cameras if you can track a bird just by "waving the camera in the general direction" of the bird (no offence!). I can get BIFs with my K-7 and 55-300, but it took a lot of practice - maybe 6 months to get pretty good, where I could get 1 or 2 in focus shots each time. Certainly not a whole sequence in focus.
01-10-2014, 10:07 AM - 1 Like   #8
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QuoteOriginally posted by twitch Quote
AF Hold setting? I think by default it is off which would explain that last frame.
Twitch. Thank you for this. After setting AF Hold to High, I'm getting better results.

QuoteOriginally posted by calsan Quote
The K-3 seems a huge improvement over previous cameras if you can track a bird just by "waving the camera in the general direction" of the bird (no offence!). I can get BIFs with my K-7 and 55-300, but it took a lot of practice - maybe 6 months to get pretty good, where I could get 1 or 2 in focus shots each time. Certainly not a whole sequence in focus.
Yes. K-3 is great. None taken. Well, I did have to work hard by keeping the bird in the frame . Even that seems pretty hard for a newbie like me . Today, with the AF Hold setting changed, I got better tracking result as shown here.

Bird sequence C (last 3 frames were omitted because that's where I went "where did it go?" due to the zoom's narrow FOV; there's nothing there, but, the rest are all here).































01-10-2014, 03:15 PM - 1 Like   #9
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The AF Hold setting ignores momentary interruptions. I believe it was first introduced in the K-5II. Penmar, your bird-among-the-leaves is a good example of its effectiveness. What level did you set the hold to?

What needs to be determined is what negative consequence its use has. How does it affect the AF lock on an object coming towards you (radial motion) where there are constant changes in distance? Does the AF still update for this, but ignore greater momentary changes like another bird flying across the frame (tangential motion) closer than your intended subject? Or does the AF, with AF Hold applied, become laggy or jumpy when attempting to track radial motion?

I'm hoping to determine that by shooting Long Jump head on. I've started, but only one session so far due to weather and illness:
https://www.pentaxforums.com/forums/172-pentax-k-3/247135-initial-k-3-af-testing.html

Here are similar AF tests I performed on a K-5 to show you what I'm aiming to do:
https://www.pentaxforums.com/forums/172-pentax-k-3/241586-my-k-3-af-experienc...ml#post2583770

Note: the examples in the 3 links mentioned in the the message above will take some time to load due to the number of images in that thread.

Dan.

Last edited by dosdan; 01-10-2014 at 04:28 PM.
01-11-2014, 08:31 AM   #10
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QuoteOriginally posted by dosdan Quote
What level did you set the hold to?
AF Hold is set to High.

QuoteQuote:
What needs to be determined is what negative consequence its use has. How does it affect the AF lock on an object coming towards you (radial motion) where there are constant changes in distance? Does the AF still update for this, but ignore greater momentary changes like another bird flying across the frame (tangential motion) closer than your intended subject? Or does the AF, with AF Hold applied, become laggy or jumpy when attempting to track radial motion? ... show you what I'm aiming to do
Hmm. Since I haven't started using AF lock at all (haven't gotten to that part in the manual yet), I have no idea at all . But, I may be able to test at a swimming class, although compared to long jump, it might be an easier test.
01-11-2014, 01:27 PM   #11
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QuoteOriginally posted by penmar Quote
.
Hmm. Since I haven't started using AF lock at all (haven't gotten to that part in the manual yet), I have no idea at all .

There isn't an "AF lock" control per se. The AF Hold affects the way the AF system maintains the lock on the subject when dealing with interruptions.

The fact you had AF Hold on High explains why you were able to get so many frames of the bird amongst the leaves without the AF moving from the bird.

A simple experiment you can try. I used wind chimes moving in the breeze. In AF.C move to about 2m from the chimes. The actual distance will depend on how far the chimes are swinging. You want them to stay roughly within the extent of the camera's active AF points array. As the camera's AF is following the chimes (you have your eye to the OVF and have either the shutter half-pressed or the AF button pressed - depending on how you've configured the camera) move you extended left arm, with fingers bent parallel to the front of the camera, at a medium pace across the front of the lens i.e you interrupt the camera's view of the subject. Without AF Hold, the camera will immediately try and refocus on to your fingers, but even with AF Hold set to Low, it will tolerate a short duration interruption. And with AF Hold set to High, the interruption can be quite long.

Swimming may be difficult. It may be the perfect test of AF Hold or it may fail miserably unless you use Centre-point AF. The reason is the great distraction from all the ripples and flying water spray and droplets. (This is for the in-the-water part. The off-the-blocks leap is more straightforward.)

BTW, here is a link to competitive swimming shots I took almost 2 years ago when my son was 10. It was taken with a K-5 & DA 55-200/F4-5.8.

https://plus.google.com/photos/110304554160411023759/albums/5710741706163115841

Dan.
01-12-2014, 11:44 AM   #12
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QuoteOriginally posted by dosdan Quote

A simple experiment you can try . . . .

BTW, here is a link to competitive swimming shots I took almost 2 years ago when my son was 10. It was taken with a K-5 & DA 55-200/F4-5.8.
Dan. Great idea on wind-chime. That I can probably find and try. Will definitely do that. Great swimming shots. Thanks for the tips.
01-12-2014, 06:24 PM   #13
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I'm amazed that the K-3 will track a bird through branches. That's incredible. Penmar's photos above are the best example of the new auto focus system I've seen anywhere. Thanks. Now you need to buy a 300mm lens and give that a go!
01-13-2014, 08:45 PM   #14
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Thanks. Glad you find my camera test useful. You're welcome. For 300mm, I will probably wait till I get a few primes first since most photos I will be taking are street, travel, low light, and editorial type images. Probably best for me to space out buying additional lenses to preserve the peace & quiet at home .
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