whats happening in this motorsport panning shot

<p>Just need a bit of explanation hope you can help.<br>

I just started taking motorsport photographs and after much practice I am starting to get the hang of panning smoothly combined with experimenting with exposures and shutter speeds. I realise this takes alot of practice.<br>

I am using a 5d Mark 2 combined with a 70-200 2.8L IS and 24-105 F4L IS.<br>

I have read the pros and cons about using the IS on these lenses and currently use mode 2 on the 70-200 and switch the IS off on the 24-104.<br>

Most panning shots I now tend to get are spot on, this is a result of experimentation dependant on the car speed and alot of patience, the example below I am happy with. (I would like to know if you agree).</p>

<p><a href="http://dc14.4shared.com/download/105072192/b7813f3d/IMG_3014.jpg">Infocus Hi Res Jpg</a> (1.8meg)<br>

However I do get the odd shot as below which has me asking questions as to why the rear area of the car is in perfect sharpness but the front seems to have a blur effect, as the whole car is travelling at the same speed. I presume that if i pan correctly and manage to get a sharp focus on one part of the car, all should be in focus? You will notice that 'cams' sticker towards the rear is perfect but the front of the car is a mess and very blurry.<br>

Is this the IS system or something else? I also realise I am no exactly on a 90 degree angle to the car, but surely its possible to take a pin sharp image of a car at this angle, panned at the correct speed.<br>

I noticed that increasing the Fstop to F11 helps with getting more of the car in focus, but just wanted to know what the explanation is or is there a better technique.<br>

<img src="file:///F:/Real%20Deal/PHOTOS/26th%20April%202009/Lightroom%20Burned%20Exports/IMG_3019.jpg" alt="" /><br>

<a href="http://dc14.4shared.com/download/105069915/54edf9f/IMG_3019.jpg">Problem Hi Res Jpg</a> (1.3meg)<br>

All my other badly panned shots the car is ALL blurry nothng is sharp.<br>

I use the common technique of manaul focusing on an area of the track and pan and shoot that that exact spot, so it cant be the AI servo.<br>

Advice would be greatly appreciated or some better examples of shots your have taken yourself.<br>

My last answer is... it could be the 5dmark2, I hear about problems with the AF on this new model, I wonder if anybody else is experiencing the same thing.</p>

<p> </p><div></div>

<p>Well as you are at an angle to the car's path, the front of the car is approaching you at a faster rate than the rear. In other words your pan speed to get a sharp image of the front has to be faster than your pan speed for the rear of the car. You are between a brick and a hard place.</p>

<p>Why use manual focus? Try using the center focus point, AI Servo (for fast moving objects) and a high shutter speed (over 250th) to freeze the car. Also try Shutter Priority, until you get the shot you want and then go to manual and/or play with the fstop. Thats why they make the fancy computers in these cameras! You SHOULD get more keepers like this. Also maybe a monopod? Good luck</p>

<p>I can't remember if the 5D's shutter is horizontal, and whether it travels right/left or left/right, but sometimes you can get focus problems like you illustrated--especially when using a slow shutter speed and large f/stop. I've had some success photographing auto races using slow shutter speed but smaller f/stops. You're on the right "track".</p>

What aperture are you using?

 

Possibly, the focus was on the front of the car at the beginning of the shot, but as the car is coming closer, the front moved out of the focus area, leaving the front to be OOF for most of the exposure.

<p>Thanks for your comments so far. This exposure was at f5, 1/125, iso 100 at 55mm. I can understand what you mean about focus on the front of the car at the begining of the shot, but surley at the distance was taking it at (25metres) and at 55mm the DOF between the front and the rear of the car wouldnt be that great would it? Like I said later in the day i started using F11 this made the shots much sharper from bonnet to tail, but not perfect. would love to see a similar angled motorsport shot in focus so i can note the exposure.</p>

<p>cheers</p>

<p>Is there a bump on the track at that spot? Notice the angle of the streaks in the hotspots near the headlights. Compare that to the angle of blur you got from the smooth panning motion. They're about 15% off. It appears the front end of the car is moving up during the exposure.</p>

<p>As Bob Sunley says, the car is moving a) across your field of vision but also b) towards you. That means apart from its movement across the background which you can pan to correct for, it's also growing larger in the viewfinder. If you panned to follow the middle of the car you'd find both ends blurred because the car takes up a bigger portion of the frame at the end of the shot compared to the beginning. or you can keep one end in focus, and get double the blur at the other end. But not both ends at once.</p>

<p>You could (maybe) improve things if you try tracking the zoom during the exposure ... but good luck with getting that accurate!</p>

<p>You should find the effect is bigger the closer you are to the car because the closer it is to you the bigger the growth in apparent size with each foot towards you that the car moves. To put that another way, to improve things, use a longer focal length lens and move back.</p>

At f/5, it is indeed unlikely to be an OOF problem.

 

I'm with Alec on the `car getting bigger' option. Let's explore that next :-) (as for tracking the zoom: you'd need quite a high cm/octave in order to adjust zoom that precisely)

<p><a href="http://www.photo.net/photo/4615272"><img title="Going through the 'S' turn." src="http://d6d2h4gfvy8t8.cloudfront.net/4615272-sm.jpg" border="0" alt="Going through the 'S' turn." hspace="5" width="200" height="100" /></a><br>

1/50th @ f/15 ISO 100</p>

<p>nice shot geoff, I reckon the higher F stop is the key with good panning technique. Its very difficult to get a whole car in focus at an angle with a car travelling at any decent speed. I noticed even Geoffs pic is blurry at each end of the car, I am probably setting my standard too high.<br>

My 90 degree angle shots come out perfect I just dont think this is possible to take pin sharp pics at high speed at 45 degrees. Lol might have to do two shots, one high and one slow shutter speed and cheat in photoshop to get what i want.</p>

<p>Wow, I was just scanning through this forum for the first time in a while and came across this thread. Bob and Alec are pretty close, but wow, there were some pretty left field answers thrown out there. Focus, aperture, a bump on the track, or the 5D's shutter have nothing to do with this.</p>

<p>As a car is traveling across the camera, the only way for it to be 100% completely sharp is if it is traveling in a perfect circle around the photographer while the photographer pans the camera with the car. In this perfect situation, all points on the car are staying the same distance from each other because the car is not rotating from the point of view of the camera.</p>

<p>Imagine a car parked on a turntable while it is turning. You are viewing the car at first directly head on. As the car turns, you start viewing more and more of a quarter angle, then a side angle. Then it continues to rotate away from you until you see a rear angle. If you were to take a slow shutter speed exposure of this rotating car, the front and rear of the car would be blurry and the center would be sharp. If you were to follow the front of the car with the camera, the rear would be even more blurry.</p>

<p>As a car is driving on a straight road across in front of you, it is also turning in relationship to you and the camera. It starts off driving towards you, hits the middle point where it is directly in front of you with a side profile, and then drives away from you. As you pan with the car, you can only get one "part" of the car in focus as it rotates in relationship to the camera.</p>

<p>If the car is moving in such a way in which it is not "rotating" in relationship to the camera, then you can get the whole car sharp. The other way to get the whole car sharp is to speed the shutter speed up to the point where it will not pick up this rotation, but then you would get really boring photos where the cars look parked on the race track. :)</p>

<p>Here are some slower shutter speed examples which demonstrate this rotation pretty well.</p>

<p>Hope this helps explain it.</p>

<p>Aaron<br>

<a href="http://www.motorsportlens.com">Motorsport Lens</a><br>

<img src="http://www.motorsportlens.com/portfolio/gallery/images/AKupferman_0547.jpg" alt="" width="700" height="394" /><br>

<img src="http://www.motorsportlens.com/portfolio/gallery/images/AKupferman_0276.jpg" alt="" width="700" height="394" /><br>

<img src="http://www.motorsportlens.com/portfolio/gallery/images/AKupferman_0521.jpg" alt="" width="700" height="394" /></p>