Understanding F stops

[vecsri]

I was sat twiddling with the knobs and wheels on my camera when i started to wonder abotu correct use of Fstops.
I've been playing recently with them and trying to get a good idea of the correct use.
The wider the focus is the lower the fstop? But how low do you go for scenery shots?

If taking panning shots of a ttrack day, high f stop? say 2.8?

Just wondered really.

 

[Toothie]

The f stop is the apature, Which is how big the hole is in the shutter and therefore how much light is let in. The lower the number the more light you get. However, this affects the depth of field and therefore how much of the pic is in focus. The lower the number the smaller the depth of field and this means less of the pic in focus. I haven't really taken many pics of moving cars but to freeze the action you need a high shutter speed and to get motion blur you need a slow shutter speed. I would expect a f stop of 2.8 would be to small to get the whole car (or bike) in focus. Personally if there was good light on the day i would sent the camera to shutter priority, adjust this till i get results I like and let the work out the f stop.

HTH

 

[vecsri]

Cheers Toothie!
I'm going to try and get to a few track days this year to get some photos. Seeing as my track car is now in car heaven

 

[dakid]

I bought a great book recently called "Understanding Exposure" by Bryan Peterson, which is pretty good at explaining how to use apertures. It might not tell you exactly what f-stop to use, but it should give you enough information to know how to work it out

Otherwise, what Toothie said

 

[Forbiddenbiker]

If taking panning shots of a ttrack day, high f stop? say 2.8?

.

Possibly yes, but not necessarily fella. .... If your panning then the blur in the background (If that's what your after) ... is caused by your panning, not so much/if at all the shutter speed.

You'll want to freeze the car I'm guessing, so a fast shutter speed will be needed, set you camera to shutter priority (start around 1/250 possibly, move up and down depending on your steadyness and accuracy) and then see what your light meter suggests for an aperture (The variable hole in the middle of your lens... affecting the volume of light hitting the shutter) ...you may well end up at f2.8 (Open aperture, 'no stops' down on that lens) or, if you can, slightly stopped down to increase your depth of field focus. ..f4 etc.

What you don't want is the front of the car in focus and its offside out of focus, which could happen at the lower open end of the aperture range, because the dof is so much narrower than stop numbers at the higher end.

You can of course increase your iso to increase the amount of stops available to you.. moving your usable range of shutter speed and aperture stops into the gloom by increasing the sensitivity of your sensor or film.

 

[RobertP]

To see what aperture settings do, have something about 6 foot away from you with a big open space like a park in the distance behind. Then use aperture priority and take the same shot at a range of aperture settings.

Panning can take some practice. The slower the shutter speed you can use and still get the subject you are tracking sharp and in focus the more skilled you are at it. As suggested above with shutter priority you can set that speed at the level you can cope with. maybe 1/250th or faster for a beginner or 1/60th if you are good? Just guessing as I haven't done much panning.