Sigma SD9 First Outing - Images Advice

[PaulSands]

Let's forget about my trials with this on it's first trip out and get down to the nitty gritty.
Firstly what can I do to get more of the picture in the following link into sharper focus (all images have not been resized in an attempt to retain the clarity)
The portion foward of the cockpit seems sharp enough but moving back gets fuzzier
settings f.80 1/250s 84mm ISO200
http://paulsands.org/sitebuildercont...s/IMG00280.jpg

Secondly was it purely down to shutter speed that the first of the following tww images was more consistently sharper?
settings f8 1/180s 80mm ISO200
http://paulsands.org/sitebuildercont...s/IMG00315.jpg
settings f8 1/250s 70mm ISO200
http://paulsands.org/sitebuildercont...s/IMG00317.jpg

And how about this..moving towards me at speed what can I do to sharpen but maintain the image of a moving object
settings f8 1/350s 210mm ISO200
http://paulsands.org/sitebuildercont...s/IMG00310.jpg

[andy_b]

Awesome shots

[PaulSands]

noooooooooooooooo you should say they are pants and tell me how to make them better
thanks though

[kdr]

weather looks a bit grim. i would have gone 400 or even 800. head on shot there appears no point of focus...maybe camera shake. i would have put it up to 500th anyway.

your panning shots are fine...nothing more wrong than missing the key point of focus. theres sharpness on the car, but not on the helmet.

[Rocktracer]

Seriously there excellent!! wish mine could be that good!!

[Damon]

Superb pics!

[Rocktracer]

have you any of the 85 tyrell that was used in Exchange and mart competition. Ussually driven by Tim Matthews?

[vwpilot]

I think what you are seeing are just physics involved here.

The reason your second shot is more in focus is because it is more directly at a 90 degree angle to you than the others.

Here is what happens. When an object is moving at you and you are panning in a 3/4 type shot, different parts of the car are moving differnt speeds in relation to the camera. As you are panning, the front corner away from you is moving in a different direction/plane in relation to the camera as the front close corner and the rear corner etc. Because of this when you are shooting with a slower shutter (which is what you want to maintain blur in the wheels etc) this slight difference of speeds/directions of the differnet parts of the car will cause some parts of the car to be sharp while others blurred. This is very common.

In this picture http://www.motorsportsimaging.com/Pr...s/DSC_3913.htm you can see that the front is a little blurred as is the rear. That is because the lens is pointed at the door and the rest of the car is rotating around the door in relation to the camera. The front is moving away as the rear is getting closer to the camera. At a slow shutter this causes them to blur.

The closer the car is to a 90 degree angle and the car is all in a steady position in regards to the plane and distance from the camera, more will be in focus. This is what happened in your second shot and why it seems more sharp than the others.

Dont be afraid of this slight blurring though. As long as the focal point of the car, usually the front or driver, is in focus, some slight blurring of the other parts proves to the viewer its in motion and gives it some style.

I think your shots look fine and I would not be put off by the slight blur you are seeing.

[blackfalcon]

nice shots, especially the pans.
i think if you shot the head on shot at 500 more of the car would be in focus. It's very difficult to get head on shots in focus at slow shutter speeds. Try tracking the car for a split second to give the autofocus the chance to lock on.
If you can choose focus points, use the one where all points are selected for head on shots.

[Dave Brand]

Aha, you've discovered depth of field!

Focus on a given point & anything within a certain distance either side of that point will be in focus; the total distance in which objects are in focus in known as depth of field. DoF depends on two factors: focal length & aperture.

The longer the focal length, the smaller the DoF, the smaller the aperture the bigger the DoF. Obviously, to get the shots you want, you can't reduce focal length; stopping down will give you more DoF, but you'll have to use slower shutter speeds to compensate.....you pays your money & you takes your choice!

[Aysedasi]

I'm not giving any advice, quite frankly. I think they're terrific shots that I would have been well chuffed to have taken.....

[PaulSands]

Does the colour of the car you are shooting have any effect on anything...I had extreme difficulty getting a shot of the number 11 Lotus 11 from the BRDC race and was wondering if the silver bodywork was a factor...I know the BRM in the FORCE race must've been longer than every other car cos I couldn't get it in frame

[G_Ilott]

The colour of the car will affect your shutter speed and / or aperture depending on the shooting mode you're using. A very light (e.g. white) car will cause underexposure whereas a darker car will cause overexposure. Depending on how clever your camera's metering system is, it will over and underexpose to different amounts. The problem with cars, of course, is they are many different colours and tones, with reflections being a headache also.

You will gradually learn what your camera will do in certain circumstances and you will then use the exposure compensation feature of the camera to rectify any under/ overexposure.

A way of avoiding this is to operate in manual mode, taking a reading from a mid-toned object (grass) or a 'grey card' obtainable from Jessops, or by using a handheld lightmeter to take an ambient light reading.

To take perfectly exposed shots of motorsport, you want to measure the light falling onto the track, NOT the light reflected back by the car and track (which is what your camera does), and then use this reading to set aperture and shutter speed manually. The problem with this is changing light levels dictated by the weather. A cloud passing in front of the sun can alter your exposures by a stop (e.g. 1/500 to 1/250) making the settings you've dialled in incorrect at that moment. Therefore you have to be aware of changing conditions.

I hope that's what you meant by "difficulty getting a shot"...

[PaulSands]

Thats perfect thanks...so I need to add a light meter to the list
I did actually forget to take my manual with me at the weekend so that I could at least check things out during the quiter moments (be a bit naff standing trackside looking stuff up wouldnt it )

[vwpilot]

You dont need to rush out and get a light meter, especially with digital.

I shoot manual all the time because I dont want the color of the car, or headlights affecting the exposure. But I will take a reading off of a nice grassy area or something that has a wide range of colors in it so that camera can get a good reading not off of one color. Use a metering mode like Matrix, or evaluative or whatever Sigma calls thiers. Try not to use center weighed or spot unless you are taking the reading just off a bunch of grass or something.

The other thing is that you are shooting digital. This makes metering even easier. Take a reading and set your exposure. Take a test shot of the area you will be shooting or the first car that comes by whatever. Then use your histogram on the camera to evaluae whether the exposure is set properly. The histogram will tell you if you have too much light or dark in the shot and you can then adjust that way. I rely way more on this now than I do my light meter. My light meter gets me in the vicinity of the proper exposure and its fine tuned with the histogram.

Lastly, another issue you might be having since you talk about things out of focus is that your auto focus system works with contrast. So if you are just trying to focus on the side of a silver car with no other writing, numbers or contrasting colors, your camera will have a much harder time locking focus. This is why when I use af I try to lock onto a sponsor logo, number plate, stripe or something like that. If you just hit a solid color area the camera will not track properly.

If you find this an issue you will need to turn off af and go to manual and pre focus where you are going to shoot the shot.

[G_Ilott]

I didn't mean to give the impression you need a lightmeter.

[vwpilot]

I didnt think you did, but paul said he was going to add it to his list. I know he has a smiley, but just thought I would give some other options.

[PaulSands]

I wont then
Waiting for deilvery of my Compact Flash reader today to get Sunday's Cadwell batch uploaded (one of the problems I have with this particular camera is the apparent inability to upload direct to PC) I combined manual settings and auto so hopefully some different results were achieved.

[PaulSands]

second outing here http://www.paulsands.org/cadmg.htm
I'm trying to get it right for Spa in a couple of weeks...my 400mm lens arrived today too AND Sigma have agreed to rush a replacement to me in an effort to sort out the issues I've been having.
Acid test could be Donington on Sunday..I have benchmark 35mm images from the first F3 round I can compare to

[G_Ilott]

What 400 lens? The 135-400? Or the 80-400 stabilised? Or the 400 macro?

[PaulSands]

135-400 APO