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Archive 2008 · Motorsport OOF - What's Going On Here?
  
 
msalvetti
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p.1 #1 · p.1 #1 · Motorsport OOF - What's Going On Here?


I believe this is relevant to this board, as I think my problem is either related to panning technique or car dynamics.

These were shot at ALMS Northeast GP at Lime Rock last week, although I've seen this before as well.

What seems strange to me is that sometimes I can get the entire car in focus, front to back. But other times only the front is sharp and the back is very blurry.

I don't think it's a DOF issue, as the DOF is dozens of feet at these settings, even with the varying f-stops and focal lengths. All are shot with my 40D and 70-200L non-IS, all focus points (but it also happens using just the center).

This one is pretty sharp throughout. ISO200, 160mm, 1/200 sec, f/13
http://msalvetti.smugmug.com/photos/335306972_xUdSm-L.jpg
And this one is just sharp in the front. ISO200, 130mm, 1/200 sec, f/11
http://msalvetti.smugmug.com/photos/335307189_yoXBk-L.jpg
Sharp. ISO200, 170mm, 1/200, f/13
http://msalvetti.smugmug.com/photos/335309863_TLzpG-L.jpg
Fuzzy in back. ISO200, 120mm, 1/200, f/13
http://msalvetti.smugmug.com/photos/335307319_zsFxg-L.jpg

So what's going on? Is it normal, maybe the car is bouncing a little? Am I doing something wrong? Just happens depending on where the camera grabs focus? Or just the way it is?

Thanks!

Mark

Edited on Jul 22, 2008 at 01:50 AM



Jul 22, 2008 at 01:49 AM
Terry D
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p.1 #2 · p.1 #2 · Motorsport OOF - What's Going On Here?


I don't think that it is anything that you or the camera or the lens, for that matter are doing. Is this on a curve or straight? Could the back end be coming around under acceleration a little? And if it is in the same spot on the track there could be a little dip there that is bouncing the back end up or down.

Truthfully... it doesn't bother me. The shots are of a very high quality...nice panning control. Some action shots just don't look right stopped dead still... we know they are going like a bat outa hell... so a little motion blur helps sell that reality. I'll take 1 and 3 over 2 any day.

Nice work.

Terry

Edited on Jul 22, 2008 at 02:38 AM



Jul 22, 2008 at 02:37 AM
fdldb
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p.1 #3 · p.1 #3 · Motorsport OOF - What's Going On Here?


I also have that on my pictures from time to time, so I believe that this is the way it is.

-
Frederic

Edited on Jul 22, 2008 at 09:10 AM



Jul 22, 2008 at 09:10 AM
markcapilitan
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p.1 #4 · p.1 #4 · Motorsport OOF - What's Going On Here?


It's your panning technique. Work on it...but it hard to always nail the whole car sharp, when shooting at an angle.


Jul 22, 2008 at 09:22 AM
msalvetti
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p.1 #5 · p.1 #5 · Motorsport OOF - What's Going On Here?


Thanks guys. Didn't mean to disappear after posting - I fell asleep.

These were shot after the Esses. No longer a curve, but the cars are approaching at an angle, and that may have something to do with it as Mark and Terry suggest. The first and the third photos were taken only 13 seconds apart, the second about 5 minutes later from the same spot (I think).

Then again, the last one is moving more left to right than the first three, and it's blurred too.

Oh well, sounds like that's the way it is sometimes. I didn't see any other shots posted from this race; I'll put up some better one's when I get a chance.

Mark



Jul 22, 2008 at 10:06 AM
PierreB
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p.1 #6 · p.1 #6 · Motorsport OOF - What's Going On Here?


I can see why the OOF tail wing might bother you but there is nothing wrong with these IMO. Panning a target moving at those speeds is tough and the keeper rate is very low.


Jul 22, 2008 at 10:10 AM
Tony Brown
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p.1 #7 · p.1 #7 · Motorsport OOF - What's Going On Here?


you have to remember to pan at the same rate and angle in which the subject is moving......and at 1/200 you HAVE to be in sync.


Jul 22, 2008 at 01:04 PM
philwillmedia
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p.1 #8 · p.1 #8 · Motorsport OOF - What's Going On Here?


I shoot plenty of motorsport and these look fine to me.
Unless you are at ground level and taking the photo when the car is directly in front, you usually wont get all of the car pin sharp when panning.
It's hard for me to explain simply but it's got to do with angles and distance from the "film plane" of the different parts of the car during the exposure time.
Maybe someone else with some idea of physics can jump in here and explain it better than me.
Mark, have a look at my website www.freewebs.com/philwillmedia/apps/photos and you might have a better idea of what to expect.
You can also try www.catchfencephotos.com.au
Regards
Phil



Jul 22, 2008 at 02:07 PM
gman1339
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p.1 #9 · p.1 #9 · Motorsport OOF - What's Going On Here?


Panning at an angle can be tough at those speeds. I would think the 40D focus tracking also shares some of the blame here. Here's one from last weekend at Mid Ohio...

1/200 sec f/10

http://www.sprowlsstudios.com/web/_DSC0734.jpg



Jul 22, 2008 at 02:11 PM
ftemoto
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p.1 #10 · p.1 #10 · Motorsport OOF - What's Going On Here?


I do a lot of slow speed panning for mx, and what you see a lot in the extreme there and may be experiencing here is that in motorsports there often is more than one axis of motion and you cannot pan for all of them. If the car is brake or acceleration drifting, you'll see part out of focus because it's moving on a different axis from the pan and you're shooting a slow enough speed that it will pick up that motion as blur.

I actually like the effect as long as some critical element of the subject remains sharp, but you have to be at peace with the fact that you're going to burn a lot of frames to get the image that really grabs you (a peace easier in a digital world).

It's possible that it's a DOF issue, but that seems remote because generally (at least for me) you're going to be pretty stopped down to get the daylight low shutter speeds you're looking for to pan.




Edited by ftemoto on Jul 23, 2008 at 03:10 AM GMT

Edited on Jul 22, 2008 at 07:10 PM



Jul 22, 2008 at 02:34 PM
 

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philwillmedia
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p.1 #11 · p.1 #11 · Motorsport OOF - What's Going On Here?


Thanks ftemoto,
Thats exactly what I was trying to get at - axis of motion etc
Regards
Phil



Jul 22, 2008 at 04:07 PM
msalvetti
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p.1 #12 · p.1 #12 · Motorsport OOF - What's Going On Here?


Thanks everyone. The axis of motion bit was what I was getting at when I mentioned car dynamics as a possible reason in my initial post.

Phil, thanks for the link to your website. Some great shots there. Thankfully the Grid Girls gallery is tack sharp.

I'm pretty sure I've seen the same phenomenon even in John Thawley's work; I just thought it was worth discussing to see if I could better understand WHY.

Here in the Boston area Lime Rock is really the only convenient road course. I get two, maybe three events a year (Grand Am in May, ALMS in July, Vintage on Labor Day). Usually I only do ALMS and vintage, so not many opportunities to practice, or work on more creative type shots. Recent motorsports galleries are here:
http://msalvetti.smugmug.com/Sports/90579

At least I think I'm improving slowly over the last three years.

Thanks again,

Mark



Jul 22, 2008 at 04:28 PM
pappawheely
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p.1 #13 · p.1 #13 · Motorsport OOF - What's Going On Here?


Here are some more extreme examples. In the first shot the truck is moving through the corner over bumps and slightly pitching the rear end out. Only the door area is in focus as that was the area I was following with the camera. The front and rear are moving with the door area being the axis of rotation. The second shot has movement in several directions so some areas are sharp but most is not. It is not focus, it is motion blur.
Image 262217 not found



Image 262218 not found




Edited on Jul 22, 2008 at 06:17 PM



Jul 22, 2008 at 06:16 PM
DustinFinn
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p.1 #14 · p.1 #14 · Motorsport OOF - What's Going On Here?


During the exposure, the car is moving as you are moving the camera to pan.
Even at your 1/200th of shutter, the car has moved.

In long exposures the effect is more dramatic.

http://www.dustinfinn.com/gallery/Posted_2008/2008.06.07_162900_Cosmo_WatkinsGlen_DP_SoD_DCF_1756_web.jpg

1DMK2n, 70-200@125mm, F/18, 1/50th, ISO-100

I think JohnT had the best explanation, but I cannot find it.

Edited on Jul 22, 2008 at 07:34 PM



Jul 22, 2008 at 07:33 PM
sav0320
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p.1 #15 · p.1 #15 · Motorsport OOF - What's Going On Here?


At an angle, different parts of the car are moving at different velocities relative to the camera. This causes some parts to be sharp, some to be blurred. Go slightly higher on the shutter, you'll maintain wheel blur but you can experiment with getting the whole car in focus.


Jul 22, 2008 at 07:46 PM
gman1339
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p.1 #16 · p.1 #16 · Motorsport OOF - What's Going On Here?


Where is JohnT? I saw he posted his weekend work on his site. I didn't notice any of it posted here on FM. He must be enroute to another track.


Jul 22, 2008 at 07:46 PM
WLSchnee
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p.1 #17 · p.1 #17 · Motorsport OOF - What's Going On Here?


Check out John Thawley's website (http://www.johnthawley.com/) and head into the race galleries. Notice that a there are photos with this same effect on his site, and he's one of the best authorities on motorsports photography around here, so if it's in his work it must be okay, right?

It's just a matter of the car moving not exactly parallel to the plane of the sensor, so if the car is rotating out of the corner or under acceleration then part of the car might appear OOF. It makes them look viciously fast when the back looks like it can't keep up with the front, IMHO.

Edited on Jul 22, 2008 at 08:23 PM



Jul 22, 2008 at 08:20 PM
maczippy
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p.1 #18 · p.1 #18 · Motorsport OOF - What's Going On Here?


Long time since I posted here but for me, I'll typically shoot all manual when I want to pan, so I'll set shutter speed and aperture based on what I'm looking for or how much of an effect I want..

[/url]

I'll have to find the EXIF info, but from my fragile memory this was 1/160@f18 (me thinks..)

Andrew



Jul 22, 2008 at 09:44 PM
John Thawley
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p.1 #19 · p.1 #19 · Motorsport OOF - What's Going On Here?


Hi Guys... and thanks to those for their kind words.

Let me see if I can break this down and keep it clear.

Someone mentioned the film plane. That is key to this discussion. ONLY that part of your subject that is absolutely parallel to the film plane (or lens face) can stay in focus... assuming you're dead-on with your panning speed.

So... if the subject is going straight in front of you... from one side to the other... that car stands a decent chance of being sharp corner to corner.

Now... as you move into a situation where the subject is coming toward you at an angle... or going away, only a slice of the subject will be parallel to your lens or film plane. The sharper the attack of the angle, the smaller the slice.

Here is why. The part of the subject that is closest to you is traveling the fastest. For instance, if you shoot a 3/4 pan of a car 100 feet away it's going to be pretty simple for your camera to catch and your pan to be decent. Why? Because your not really panning... your camera movement is minimal in order to keep up with the car. A little tougher at 60 feet. A beast at 30ft.

Think about this... a car travels by you at 30mph on a road 50 ft. away. No big deal right. What if that car came by your at 30mph 12 inches from your nose? You'd be heading for the bushes.

So, if the car is coming at you at 45 degree angle, you could draw an imaginary line from the driver's headlight to the passenger taillight. Point your camera barrel so it's looking right down that line. Now draw another imaginary line from the driver's taillight to passenger headlight. Now you have an X through the car. This is a little bit off because a car is not a square... but I think you get the picture. That second line, is basically parallel to the face of your lens of the film plane. So, we want to try and pick a spot along that imaginary line and pan with it. If we pick up by the front of the car, our panning motion is going to need to faster than a spot near the back of the car. Because the close point to us is traveling the fastest.

So... when we shoot this shot, we're going to have to make compositional trade-offs to get what we want. The more we want sharp, the higher (safer) the shutter speed will need to be. The more radical and blur we want, the slower the shutter will be. With the slower shutter the job of getting something sharp becomes much more difficult. Even side-to-side pans are difficult at slower shutters. So it only makes sense, that a 3/4 will be tougher.

If you want the nose sharp, put your camera's focal sensor near the middle of the windsheld where it meets the hood. Almost on the passenger's windshiled wiper. Remember, though... your going to have to pan at that speed and stay with that spot.

Start out a faster shutter speed. These shots are fairly forgiving and you'll still get decent blur even at 1/200th:

Example here: (EXIF is intact) Here I was going for the driver's helemt... but as you can see, at 1/200 a lot of the car held focus... quicker shutter, less time for the car to travel off plane.



This one is at 1/125 and is softer in the nose.. but for me, in this shot, the energy is still going by the viewer and I like it... especially the background.



Lastly an example at 1/40th. Here you can see things getting extreme:



What's important, though... with each of these examples, if you draw the imaginary line from where I was standing, you can visualize an X at the point of focus. So, that's your challenge... putting the X where you want it and getting your panning motion to keep the film plane parallel to that spot.

Of course, all the basic panning rules then come back into play. Smooth motion, CONTROLLED motion.... not too fast or radical... not too slow and wobbly. Find the right postion and distance from the car that allows you to pan at a speed that fits your "swing." Choose a focal length that allows you to stay in control. It's all about your SWING. Just like in stick and ball sports... you have to have your swing and it has to be consistent. Choose the right club...err... lens for the distance and go for it.

Hope that helps.

JT



Jul 24, 2008 at 04:39 AM
Raskill
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p.1 #20 · p.1 #20 · Motorsport OOF - What's Going On Here?


And thats the end of that!


Jul 24, 2008 at 04:47 AM
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