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03-26-2014, 09:44 PM   #16
Brooke Meyer
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These all look a little blown out. If you switch to manual exposure and acquire & track the cart with the rear AF button and single center point, I bet you could pan with a much higher ISO, like 3200 and maybe not need the flash. Start off with say 1/320 or 1/400 shutter speed. Play with your aperture to adjust. Stuff that moves parallel to tends to pan well.

The thing is, try some things. Your histogram is like the old Polaroid test shot, it will guide you.

As has been replied, the only way to get the flash that fast is HSS which reduces power and therefore distance. You may not need flash and the reflective patches will certainly blow out. Its a case of balancing ambient with flash. You can shoot with the camera in manual and the flash in P-TTL, I do it all the time at events. Here's a good free guide to flash

03-26-2014, 10:44 PM   #17
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If I pre focussed say two feet to the right of the blue #70 kart in the last photo and I hit the shutter button not on the precise spot would that be another to cause it.
03-26-2014, 11:09 PM   #18
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I think the long Tamron lens may be blocking the flash from reaching the lower-middle part of your photograph. If you're using a lens hood the effect is even worse.

Any portions of the photo that are lit mainly by ambient light will have motion blur, while those that the flash can reach will have stopped motion.


Have you cropped any of these photos, or are they exactly as they came out of the camera?
03-26-2014, 11:18 PM   #19
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photos straight from camera.

03-26-2014, 11:26 PM   #20
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Well, normally a lens that's too long would cast a rather obvious shadow, but if the ambient light level were close to the level of the flash it wouldn't be so noticeable.


The more I look the more the tilted plane of focus seems plausible - it goes from the lower right to the upper left of the photo, and also appears to tilt down at perhaps a 60 degree angle to the ground - tilting down toward the the upper right corner of the photo.
03-26-2014, 11:58 PM   #21
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I do not know the high ISO performance of the K3 bit if is we're doing this with my K5 the ISO would be pushed to at least 3200, and the lens stopped down. I don't know the tamron zoom but many of the equivalent sigmas , especially later models are a little soft wide open. Add to that the narrow DOF and you can be limited pretty fast.

As an aside, as a long time race fan, I would NEVER use a flash at a track. You do not want to blind the drivers or distract them.
03-26-2014, 11:58 PM   #22
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The track lighting down there is very poor with a lot of lighter and darker patches on the track. Would it be worthwhile to get the lens looked at by a camera repairer.

---------- Post added 03-27-2014 at 03:02 PM ----------

QuoteOriginally posted by Lowell Goudge Quote
I do not know the high ISO performance of the K3 bit if is we're doing this with my K5 the ISO would be pushed to at least 3200, and the lens stopped down. I don't know the tamron zoom but many of the equivalent sigmas , especially later models are a little soft wide open. Add to that the narrow DOF and you can be limited pretty fast.

As an aside, as a long time race fan, I would NEVER use a flash at a track. You do not want to blind the drivers or distract them.
That's why all the night photos are taken side on.

03-27-2014, 12:49 AM   #23
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Your being confused by all the different opinions,


By all means have the camera and lens checked out by a repairer, that will be 100 dollars thrown away. Theres nothing wrong with your equipment im convinced.


You have tested this lens and camera on the map shot you took, its working normally, good plane of focus, no dodgy misaligned or loose elements, the flash is illuminating the scene adequately without any shadows cast by your lens what more can you ask for.


Sort out your technique from the excellent advice already given.


Use sensible settings that are appropriate for the action shots your taking, use a focussing method the lens can operate reliably with.


Do some testing and refining of your technique until the lens focuses correctly and reliably, and this weird behaviour stops.


Only when your technique is faultless and the problem still remains should you start having a repairer look at your gear.


The excellent advice already given is use high ISO, and fast shutter speed.


Don't expect your lens to pick up and lock on focus in 1 nanosecond. You used a flash, presumably that's because it was low light. Many autofocus systems cannot lock focus in low light. Id be willing to put money on this being at the root of the issue.


Learn about the behaviour of your autofocus. Pay constant attention to the behaviour of your lens, how long it takes to stop hunting and lock focus in all lighting conditions. If your lens hunts for 5 seconds in low light before locking, how can you use it for fast action photography in low light.


Remember an autofocus system no matter how well you think you have prefocussed, will change its focus and focus anywhere it wants to unless you control it properly and use the correct autofocus settings.


Trust your gear, experiment. Take lots of rapidly moving objects outdoors in daylight, Take 100 pictures of traffic on the highway with variety of settings. Then if you do all this, youll know your gear well enough to use it with confidence.
03-28-2014, 03:28 PM   #24
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QuoteOriginally posted by Imageman Quote
You have tested this lens and camera on the map shot you took, its working normally, good plane of focus, no dodgy misaligned or loose elements, the flash is illuminating the scene adequately without any shadows cast by your lens what more can you ask for.
The map shot does not look like it has even sharpness to me. The Upper Left and Lower Right corners are clearly less sharp than the other two corners. This may indeed be a contributing factor. Take a few more shots with a map or something similar and look more closely - try to get some text or icons in each corner.


Note that these are the exact same two corners that others and I identified as being curiously in-focus (or in one case out-of-focus) in the action shots. To write this off as a coincidence makes little sense. Also notice that all these shots are wide-open at f/2.8. The effect may not be as noticeable at other apertures.


QuoteOriginally posted by Imageman Quote
Don't expect your lens to pick up and lock on focus in 1 nanosecond. You used a flash, presumably that's because it was low light. Many autofocus systems cannot lock focus in low light. Id be willing to put money on this being at the root of the issue.
How much money would you be willing to put on it? After thinking about it, I remembered just how dramatic the shadow cast by a long, overhanging lens usually is. And it's usually a wider-angle lens that shows such behavior. After realizing how silly my idea was, I tried (unsuccessfully) to back out of it gracefully. But I'm afraid your thought is just as unlikely. The AF system is obviously working quite well on the in-focus portions of the image. And it's not just some random part of the image that's in focus - it's nearly right where he'd want it with a properly functioning lens.

Last edited by DSims; 03-28-2014 at 03:54 PM.
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