how wide?
- Thread starter fletch5
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sportysnaps
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- martin
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i have the answer i just dont get the question?
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- Bob
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Cut and pasted from a thread I started a while back....maybe it'll help you sort this out.
Bob
This may be obvious to some but maybe not to everybody........
Going on a shoot and need to know what focal length is required?
How far away will you be from your subject....Distance
How wide is your subject (frame).................Width
What size is my sensor...............................Sensor
The focal length required will be obtained by using the following equation;
(Distance / Width) x sensor size = required focal length
************************************************** ******************************************
Example 1.....you're going to shoot motor sport. You expect to be 45 metres from the track and want to get close-ups of the cars.....a 5 metre frame width (car + a little bit of background)...and you're using a Canon crop body.
Your required lens would be....(45 / 5) x 22.5mm = 202.5mm
************************************************** ******************************************
Example 2.....you're out to catch a bluetit. You expect to be 4 metres from the birdie and want a 15cm frame width.
Your required focal length would be...(4 / 0.15) x 22.5 = 600mm
(if you expect to be 20 metres from the bird...I suggest that you stay home and work on a money making scheme to fund your 3000mm lens requirement!)
************************************************** ******************************************
If you're using a full frame camera then substitute 35.8mm in place of the 22.5mm in the above equations.
Bob
This may be obvious to some but maybe not to everybody........
Going on a shoot and need to know what focal length is required?
How far away will you be from your subject....Distance
How wide is your subject (frame).................Width
What size is my sensor...............................Sensor
The focal length required will be obtained by using the following equation;
(Distance / Width) x sensor size = required focal length
************************************************** ******************************************
Example 1.....you're going to shoot motor sport. You expect to be 45 metres from the track and want to get close-ups of the cars.....a 5 metre frame width (car + a little bit of background)...and you're using a Canon crop body.
Your required lens would be....(45 / 5) x 22.5mm = 202.5mm
************************************************** ******************************************
Example 2.....you're out to catch a bluetit. You expect to be 4 metres from the birdie and want a 15cm frame width.
Your required focal length would be...(4 / 0.15) x 22.5 = 600mm
(if you expect to be 20 metres from the bird...I suggest that you stay home and work on a money making scheme to fund your 3000mm lens requirement!)
************************************************** ******************************************
If you're using a full frame camera then substitute 35.8mm in place of the 22.5mm in the above equations.