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07/18/2007 01:36:27 AM · #1 |
hi everyone,
is there a way to have a great depth of field with a telephoto lens , i mean i want to take an image with the foreground & background in focus with the telephoto lens..is this possible ? |
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07/18/2007 01:42:00 AM · #2 |
As far as I know, just raise the F/stop number, the higher the number - ie the smaller the aperture - the wider the DOF.
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07/18/2007 02:03:03 AM · #3 |
edward80, i had the same thought so i set up the tripod and took some pictures at differnt f stops.
 F2.8
 F5
 F8
 F16
 F32
All that was changed between these shots was the f stop.
Bob |
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07/18/2007 06:54:51 AM · #4 |
| thanks a lot bob .. that was very helpful |
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07/18/2007 06:56:34 AM · #5 |
| Just to be accurate so you aren't asking again later, something else had to change in those shots besides aperture or they'd be getting increasingly dark. You will need to lower your shutter speed as you raise the F number. |
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07/18/2007 07:02:49 AM · #6 |
Edward,
It's also worth bearing in mind that since with a telephoto the DOF is always relatively limited, even at smaller apertures, it becomes very important WHERE you focus. With a telephoto, I much prefer using manual focus wherever possible.
here's the rule of thumb: when speaking of DOF, approximately 1/3 of it extends in front of the plane of focus and 2/3 behind it. In other words, if you have 6 inches of DOF, 2 inches are in front and 4 inches behind the plane of focus. If you have 30 feet of DOF, 10 feet are in front and 20 feet behind the plane of focus.
It pays huge dividends to be very particular about where you place that plane of focus in telephoto shots, and in macro shots (which the coins above are) for that matter. When/if you use autofocus, you need to carefully select which autofocus point you will use, or practice the "half-push" of the shutter button which can be programmed to lock in your focus prior to reframing your subject and making the exposure.
All in all, I much prefer manual focus when I use telephoto, though it's not always practical on fast moving things like birds flying by.
R.
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07/18/2007 07:25:32 AM · #7 |
thanks routerguy666 & Bear_Music
i currently do all my shooting with manual focus thats because when using autofocus it doesn't focus where i want it to..
last week i took a picture of a helicopter while its flying & i managed to freeze the blades ,all i remember i had a fast shutter speed but don't remember other settings,now i can't shoot a flying bird :(
but thatnks a lot guys am learning much from you.. |
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07/18/2007 09:10:02 AM · #8 |
Originally posted by Bear_Music:
here's the rule of thumb: when speaking of DOF, approximately 1/3 of it extends in front of the plane of focus and 2/3 behind it. In other words, if you have 6 inches of DOF, 2 inches are in front and 4 inches behind the plane of focus. If you have 30 feet of DOF, 10 feet are in front and 20 feet behind the plane of focus. |
IIRC, that is true for some cameras and lenses (cross type sensors and lenses that are f/2.8 or better?). I seem to remember that the AF system is less picky with other lenses and that the focus point may be anywhere within the DOF. (or did I say that backwards?)
Will a consumer lens (say an f/4-5.6) or even an f/4 lens have a less accurate focus than an f/2.8 lens when used with a non-cross type AF sensor? (becasue the DOF is less, and the AF sensor can pick out the middle of the DOF better?) |
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