Any math junkies out there?

Discussion in 'Photography Beginners' Forum' started by dEARlEADER, May 6, 2008.

  1. dEARlEADER

    dEARlEADER TPF Noob!

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    This is what I've been trying to do:

    Take scenic pictures from a moving car and stitch them as panorama. (I've mentioned this before)

    This is my math question:

    Criteria

    -Shooting 3 frames per second
    -Focal @ 24mm
    -Focal target about 100 ft from shoot
    -a 1/3 overlap between frames will be required for stitching

    What speed should I be driving to meet the above?

    btw... anyone that can answer this should be working with NASA
     
  2. Mav

    Mav TPF Noob!

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    All you need to do is figure out the angle of view at 24mm (Google search) and then some trigonometry to get the total field that would be at 100 ft distance. Two-thirds of that field is your desired shot interval for easy overlapping. At 3 fps, you'd want to cover that two-thirds of your field of view every one-third of a second. Convert your units from feet per second to km/h (Canada, eh?) and you'll have your answer. :)

    Any reasonably alert high schooler who's taken the engineering and science related math courses (algebra, geometry, trig, etc) should be able to figure this one out. :p
     
  3. dEARlEADER

    dEARlEADER TPF Noob!

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    ya... thanks Mav.... I'm a pothead so just give me the speed....;)
     
  4. BoblyBill

    BoblyBill TPF Noob!

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    OK... here it goes.

    for a 24mm on a crop sensor, that leaves us the angle of view of a 36mm (54.4 degrees). That translates into 102.78 ft that you are viewing at your 100 ft focal target. If you wanted to cover 1/3 of the shot between each frame that would mean that you would have to take a shot every 68.52 ft. Since you can shoot 3 frames a second, you are covering 205.57 ft/s with every shot from you camera. 205.57 ft/s translates into 140.162 mph.
     
  5. dEARlEADER

    dEARlEADER TPF Noob!

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    damn.... now I need a new car....:lol:

    doesn't seem right though..... I have experimented at speeds of 80 to 110 km/h @ 3 fps and don't seem to have any overlap... I thought I was going too fast!

    What makes this task even more difficult is I am intentionally trying to get a marginal amount of blur in each frame for effect. Also when the sun is in perfect place 1 hour before sunset.

    If this result is true this save me some low light troubles. I can reduce fps(to may 1.5 per second) and throttle down the ISO a bit.

    Can anyone back up these numbers?
     
  6. Gopherkid

    Gopherkid TPF Noob!

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    With a speed that high, it sounds like it would be easier to figure out how fast you can go on the road. Set your camera manually on exposure and focus, then figure out time intervals for when you should press the shutter.
     
  7. maddermaxx

    maddermaxx TPF Noob!

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    Only issue I see is at those speeds you're going to need a fast shutter speed too, to freeze everything.

    I took a couple of BoblyBill's numbers (sorry) and I came out with ~46MPH..
     
  8. BoblyBill

    BoblyBill TPF Noob!

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    That is also what I would suggest.

    Since 140 mph converts to 224 kph if you were to go 110. kph and shoot 1.5 fps you would get the same results.
     
  9. Gopherkid

    Gopherkid TPF Noob!

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    Ok, well im a nerd and got a physics final in a week so this seems good practice. With a 54 degree viewing angle of an object 100 ft away (or 30.5m) Your camera is capable of seeing a little over 30m of the focal point at any given instant. So if you want 1/3 over lap its easy because you need to move 20 ft before taking your next snap shot. 3 fps, so 20 m in 1/3 a second give me a speed of 60.6 m/s or 218 km/hr. So yeah, with rounding error i got the same as bill. So really you should have a huge window to get your pictures in to reach your goal.

    And if you were to travel at 80km/hr you would need to press the shutter every .9 seconds to get a 1/3 over lap.

    And I would try to figure out what shutter speed you would need to kill the blur, but chances are thats going to lead me to derivatives and junk, and thats way more effort than I wanna put in to it. So just crank the shutter speed.
     
  10. Gopherkid

    Gopherkid TPF Noob!

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    Another small note, anything in front of that 100 ft focal point is going to appear to be moving alot faster than the object at 100 ft. So if getting a fast shutter speed is an issue, just aim the camera higher up and avoid taking pictures of the road in front of you. Also you need to make sure to fix the camera, probably perpendicular to the scene, and make sure it doesnt move, otherwise that will throw everything off too.
     
  11. BoblyBill

    BoblyBill TPF Noob!

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    Nerd... :D
     
  12. Gopherkid

    Gopherkid TPF Noob!

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    LOL yeah i know. And im not even that bad in my class, probably one of the more normal looking kids.
     

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