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10-16-2015, 04:54 AM   #1
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Will manual exposure increase AF speed

Just curious if using manual exposure with the K-3 to shoot birds in flight will increase AF speed using AF.C? One less thing for the computer to do if the sky is fairly clear. Thanks.

10-16-2015, 06:36 AM   #2
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I doubt it very much .... Metering won't be any significant strain, there's no moving parts. In any case, with an aperture coupled lens, even in manual meter mode, the circuits still take the readings and display the EV bar for reference.


There are far more significant things to do with the autofocus technology in the lens and the power of the camera for screw -drive, the focus throw of the lens and it's resistances ... These plus the contrasts in the scene are going to be way more important than metering on impacting focus speed.
10-16-2015, 06:41 AM   #3
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QuoteOriginally posted by mcgregni Quote
I doubt it very much .... Metering won't be any significant strain, there's no moving parts. In any case, with an aperture coupled lens, even in manual meter mode, the circuits still take the readings and display the EV bar for reference.
Thanks for the information and insight. Just wishful thinking on my part. Birds in flight are probably my most difficult things to capture. I seem to have less success than the people I shoot with and their skill level is about the same as mine. I'll just have to practice with the AF settings and see what works best for me.
10-16-2015, 10:56 AM   #4
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It's not my field at all, I'm sure I'd struggle a lot. Most of the experts I've heard writing about it tend to use either Av or Tav for exposure control, and exposure compensation to manage brightness. I think manual mode might be considered a little fiddly for aerial action. Switching to centre point focus only is also a traditional approach to strengthening accuracy on moving objects in a very large sky space. Hope you enjoy the practising and your hit rate increases. .

10-17-2015, 07:09 AM   #5
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QuoteOriginally posted by RockvilleBob Quote
Just curious if using manual exposure with the K-3 to shoot birds in flight will increase AF speed using AF.C? One less thing for the computer to do if the sky is fairly clear. Thanks.
Though it's unlikely to physically increase the camera's focusing speed, what it will do is eliminate the camera's response to changing light as you pan across the scene. Setting the exposure manually beforehand ensures the camera isn't wildly changing values to accommodate changing backgrounds. Setting the camera to spot exposure, taking a reading off a similar bird or object, then switching to manual gives you a constant to work from.

---------- Post added 10-17-15 at 07:15 AM ----------

QuoteOriginally posted by RockvilleBob Quote
Thanks for the information and insight. Just wishful thinking on my part. Birds in flight are probably my most difficult things to capture. I seem to have less success than the people I shoot with and their skill level is about the same as mine. I'll just have to practice with the AF settings and see what works best for me.
BIFs are the most difficult thing for just about everybody. So much going on with all that movement. We work so hard in normal shooting situations to keep the camera as still as possible then, when shooting BiFs, we're moving the camera! It's amazing it can be done at all.

What is the nature of your "less success"? Fewer captures in the frame? Bird out of focus? If you'd like to share that, along with the settings you're using, we might be able to decipher the problem here.
10-17-2015, 11:42 AM   #6
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QuoteOriginally posted by Kath Quote
Though it's unlikely to physically increase the camera's focusing speed, what it will do is eliminate the camera's response to changing light as you pan across the scene. Setting the exposure manually beforehand ensures the camera isn't wildly changing values to accommodate changing backgrounds. Setting the camera to spot exposure, taking a reading off a similar bird or object, then switching to manual gives you a constant to work from.

---------- Post added 10-17-15 at 07:15 AM ----------



BIFs are the most difficult thing for just about everybody. So much going on with all that movement. We work so hard in normal shooting situations to keep the camera as still as possible then, when shooting BiFs, we're moving the camera! It's amazing it can be done at all.

What is the nature of your "less success"? Fewer captures in the frame? Bird out of focus? If you'd like to share that, along with the settings you're using, we might be able to decipher the problem here.
Thanks for offering some advice
My problem is poor focus/low hit rates:

I have the camera set to AF.c using SEL Small - nine points with the center point selected.

Camera settings:
16 - 1st frame action in af.c is set to 3- Focus Priority
17 Action in AF.c continuous shooting is set to 1 - focus priority
18 Hold AF Status is set to 2 - Low

I use back button focus
10-17-2015, 11:48 AM   #7
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I've noticed with my K-3 that holding the rear AF button in AF.C doesn't slow down the AF but it does slow down the frame rate some using my DA* lenses. I didn't notice any difference using a rented Sigma 150-500 Bigmos. Just my $0.02.
10-17-2015, 12:06 PM   #8
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My next outing I will need to concentrate on keeping the back button depressed. I think I do but I also release it periodically to refocus. I just have to make sure I am depressing the shutter button when I also have the back button depressed and the subject focused.

10-17-2015, 01:45 PM   #9
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May I ask what lens you are using?

Your settings look ok but I would recommend testing SEL M and turn off hold aswell.

---------- Post added 10-17-15 at 10:54 PM ----------

Also make sure the AF is tack sharp when testing on a static subject in the same environment. Some days I won't get a sharp image due to environmental issues like pockets of warm or cold air between me and the bird or moon or whatever. Or I am in a camoflaged building (do not know the name in english) and the air is warmer inside then the air will go out where I put my lens out and cause vibrations in the air making it impossible to get a sharp image.
10-17-2015, 02:22 PM   #10
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QuoteOriginally posted by RockvilleBob Quote
My next outing I will need to concentrate on keeping the back button depressed. I think I do but I also release it periodically to refocus. I just have to make sure I am depressing the shutter button when I also have the back button depressed and the subject focused.
Well, that's a big one. If back-button focusing is newish to you, muscle memory may not be fully developed yet. Which is to say, you may indeed be letting go as the bird is moving. I think one of the best - and hardest - things to do on outings is to practice doing one thing really well (such as BBFg, or panning, or...). It's hard because we want to get some great photographs, not "waste" a beautiful day practicing and messing up.

Of course, there are many other possible variables. If you're doing hand-helds, is your panning technique solid? If tripod-mounted, we still have issues of shutter speed and DOF. I shoot a way faster shutter than I think I should, if I can get enough light to do that. And stopping down as far as possible (trying for f/8 or 9) will give you some wiggle room re: what's in focus.

You didn't mention what lens you're using, but if it's slower focusing, the camera may not be able to keep up with the movement of the subject in and out of the focal plane.
10-17-2015, 02:26 PM   #11
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QuoteOriginally posted by Tjompen1968 Quote
May I ask what lens you are using?

Your settings look ok but I would recommend testing SEL M and turn off hold aswell.

---------- Post added 10-17-15 at 10:54 PM ----------

Also make sure the AF is tack sharp when testing on a static subject in the same environment. Some days I won't get a sharp image due to environmental issues like pockets of warm or cold air between me and the bird or moon or whatever. Or I am in a camoflaged building (do not know the name in english) and the air is warmer inside then the air will go out where I put my lens out and cause vibrations in the air making it impossible to get a sharp image.
Thanks for the insight - yes I will need to try SEL M. Pentax real does a poor job with explaining the AF.C system and how best to use the options but I have gotten some great tips from you and others on the forum. Thanks for taking the time to share your thoughts.
10-17-2015, 02:33 PM   #12
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Highly recommended:

Pentax K-3 e-book
10-17-2015, 03:05 PM   #13
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QuoteOriginally posted by Kath Quote
Highly recommended:

Pentax K-3 e-book
Thanks - I just got it. Significantly better than the Pentax paltry manual. I did have it for my K-5, in that case the Pentax manual was about as good. However for the K-3 Pentax made a leap forward with the camera and fell off the cliff with the manual.
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