So what causes this ?

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Was messing about yesterday at a track day with the camera and I've got a recurring problem that I'm not quite sure how to solve..

Here is an example:
f11 @ 1/100th

(click for bigger sizes)

So what causes part of the car to be sharp and part to be soft ? Doesn't always happen but I don't know what I'm doing to cause it.
The lens is the canon 55-250, granted its not going to be the fastest lens in the world but I do get some stuff from it I'm happy with.

A friend suggested it could be depth of field - we were looking at another shot that was at f5, but I've looked through and a wide aperture doesn't seem to be a common theme, so I think I can rule that out ?

Quite happy to believe its dodgy panning skills/technique - if so how do improve ?

typically shoot with AI Focus, continuous shot, at or around 1/100th..

TIA.
 
I would say that it is likely that the rear end of the car was moving about a little more than the front and so caused extra blur making it softer. Has the car just come around a corner or something? Maybe the back end was still a little loose.

I'm sure someone with a little more knowledge of shooting cars will be along shortly.
 
pretty sure that one was taken in the gp loop at brands, along the straight, but as the car is heading away from me, the back is closer than the front, wonder if that has an impact..

heres another, f22 @ 1/60th if your eyes are as bad as mine you'll need to look at the large size :lol:



and its not the lens either, 24-105L, f16 @ 1/100th
 
Shutter speed seems to be ok, looking at the picture excellent shot btw.

what camera are you using, can you select multiple focus points, it may be the camera was focusing on one point only

just a thought as I have no idea about motorsport photography :)



Kind Regards

Rob 80386
 
Well looking at the full size one you have focus to far back looking inside the car and it is sharper then the body of the car. Also the front is sharper and as the car is on a slight angel this confirms the focus point with inside the car.
What focus point did you have one? You can see it with your software and it will show you.
 
thanks for the comments rob.

focus points, should of mentioned, fixed on centre point. camera is a 450D.

I think the effect works sometimes, gives a sense of movement, its just I'd like to be able to choose to do it or not, rather than it being the luck of the draw :)

Chaz : you mean the canon software ? I'll have a look, I normally use LR.
 
yes I have done it before when checking a lens you can see the red dots. Will check how I did it might have been zoombrowser not sure
Just checked and you can see it in Zoombrowser open it in is own window and there is a tool at the top click on it and you will see the focus square and the one in red is the one
 
hmm just had a look with "zoom browser ex" and I'm not sure its accurate, I think all its doing is overlaying which focus point was in use (centre) over the image. For example in the first picture it claims the focus point was just below the window, in between the logo of the sun and the door shut.
The second (yellow porsche) is on the window, immediately in front of drivers head, just above his white sleeve.
 
this is what I get on mine when looking it shows where you focused By the way I not know why this duck got a grey bill?
4162204261_6e6a6e73cf_o.jpg
 
Here's your problem...

4162196577_61717be263_o.jpg


You can see that the single centre AF point woukd have been on a bit of blank black paintwork. No AF system can fuction without some detail or contrast within the AF area.

The other thing is you say your were using A1 Focus? A1 Focus is a complete waste of time, I don't know why Canon insist on using it. A1 focus starts off as Single Shot AF but if it detects movement it switches to continous focus and is meant to analyse and predict the direction/speed of movement. It sounds impressive, but in practise it's completely pants - have nothing to do with it.

Use A1 Servo which will continually autofocus all the time, and try to get the AF square over some detail in the car which has enough detail for the AF system to lock onto
 
I have to agree with what CT has said.:thumbs:
 
thanks all, especially CT.

I read somewhere that it was AI Servo that was the problematic one, not AI Focus, must of got confused.. not difficult!

Just had a quick play and can hear/see AI Servo tends to re-focus alot more, which will obviously help.

just need to go and play now !
 
Yep stick to A1 servo.:):thumbs:
 
Think its worth noting that unless the car is travelling perfectly parallel to you with the slower speeds your bound to get parts of the car in focus and parts out as certain parts of the car will be travelling in a different direction to that which you are panning. The last porsche been a perfect example, you've panned the front of the car spot on but in relation to you over that period of time the back will have been at a different distance from you than the front followed, if you get what I mean? A quicker shutter will cure that but will lose the effect. Just need to compromise. Also with that last porsche you've got to apreciate that its getting closer to you so for any part of the car to remain the same size whilst you try and pan it youd have to also zoom out ever so slightly which has got to be super difficult. Id accept it how it is as its quite a nice effect anyway, Id be chuffed :thumbs:
 
CT said:
Here's your problem...

4162196577_61717be263_o.jpg


You can see that the single centre AF point woukd have been on a bit of blank black paintwork. No AF system can fuction without some detail or contrast within the AF area.
Click to expand...

That's a problem but it's not definitively the problem. I shoot a fair amount of panning with the benefit of being able to plan focus points and comp rather than resorting to central AF etc. BSMotorsport is on the money with convergence angles and relative speed.

To the OP, you can prob up your shutter speed which will reduce the effect but still achieve a sense of movement
 
Nice pan on the yellow Porsche. You have done everything possible to get the picture right, with smooth panning, action speed blur at 1/60th, and correct focus/DOF at f22.

However, there are some fundamental issues with panning which are hard to get right, namely that panning a car which is slightly off axis to you going round a corner, will always result in some part of the car being speed blurred.

The front of the car has matched the panning movement exactly, but the rear is moving differently relative to you.

It is annoying, and the only solution is to move further back so that the relative movement differences are small. Not always possible though.

Ed
 
Taken from an archive post, when I still had a couple of grey cells. :lol:

The reason that the edges of the car are showing more blur is the relative speed of the pan across the lenth of the subject. The wider the lens the more you get this. Actually, it's more to do with the closer you stand than the width of the lens but one tends to lead to the other.

It's really hard to explain (for me anyway :lol: ) but I'll try to make some sense here.

If you imagine drawing a circle with yourself at the centre and the radius being the distance to the subject, the arc you'd get in front of you represents the pan. If your subject was following this arc you would be able to prefectly match it's speed with your pan and all would be pin sharp.

When you close into the subject, the circle will get smaller and hence the arc will be tighter. (anyone still with me here?)

When you're shooting cars on track, or any subject passing across your position at a tangent, technically only one part of the subject is actually intersecting your pan (or arc) and the closer you are (or smaller your circle) the less of the subject this is.

If you use a longer lens you end up further away, the circle gets bigger and the distance between the part of the subject intersecting the arc and the parts that aren't reduces.

The bigger the gap between the arc and parts of the subject that aren't intersecting it, the larger speed differential becomes and the more blur you get.

I need a beer now. :lol:
 
dazzajl said:
Taken from an archive post, when I still had a couple of grey cells. :lol:

The reason that the edges of the car are showing more blur is the relative speed of the pan across the lenth of the subject. The wider the lens the more you get this. Actually, it's more to do with the closer you stand than the width of the lens but one tends to lead to the other.

It's really hard to explain (for me anyway :lol: ) but I'll try to make some sense here.

If you imagine drawing a circle with yourself at the centre and the radius being the distance to the subject, the arc you'd get in front of you represents the pan. If your subject was following this arc you would be able to prefectly match it's speed with your pan and all would be pin sharp.

When you close into the subject, the circle will get smaller and hence the arc will be tighter. (anyone still with me here?)

When you're shooting cars on track, or any subject passing across your position at a tangent, technically only one part of the subject is actually intersecting your pan (or arc) and the closer you are (or smaller your circle) the less of the subject this is.

If you use a longer lens you end up further away, the circle gets bigger and the distance between the part of the subject intersecting the arc and the parts that aren't reduces.

The bigger the gap between the arc and parts of the subject that aren't intersecting it, the larger speed differential becomes and the more blur you get.

I need a beer now. :lol:
Click to expand...

Good post. But it's not this in the OP's case. Lens is far too long and the viewpoint too far away for this effect.

And IMHO, neither is it focus error or a depth of field issue.

As others have said, the car is bouncing. The attitude is all wrong - rear is up. Simple as in this case. 1/100sec will not freeze that, in fact the kind of rapid up/down movement you get with a car at speed will need a very much higher shutter speed.
 
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