Tripods, birds, and shutter speed

The rule of thumb when shooting handheld is to use a shutter speed of at least 1/focal length (assuming no image stabilization.)

First question: on a crop body such as the Canon 50D is this before or after accounting for the magnification factor? e.g. with a 300mm lens should the shutter speed be at least 1/300s or at least 1/480s?

Second question: how slow can you go with a long lens on a non-locked down tripod? I.e. the birds are not stationary and you can't take as much time as you need to frame the bird perfectly and then shoot a few seconds later with a cable release. (Ditto assume the camera is not prefocused on a feeder or obvious perch.) Assume you need to be tracking birds in the wild through the viewfinder and shooting as they move around to some extent. Have we reached the point where subject motion is going to limit the shutter speed more than camera shake? And if so, what's a typical minimum shutter speed for songbirds?

Hi Elliot We normally would include the camera magnification in the mix !!

How low can you go will vary form person to person. Without locking down you can push up on the lens barrel with your fingers and twist the camera up/right while pressing with your cheek ... takes the play out and is more stable. Do test and see how well you can do.

I like shooting a couple of test images every time I go out at low shutter speed just to see how I do and how low I can go ... one thing .. you mention cable release? For birds etc would not recommend but its just a personal opinion. For scenics etc just fine !!!

w.r.t that rule of thumb, yes, the crop factor should be considered. so it should be 1/ effective focal length.

But with practice and good technique, one can get sharp shots at 1/ focal length or even better. Of course it depends on the weight of the rig. I shoot with canon 400 f5.6L...which is a very light and well-balanced lens. I do get sharp shots at 1/400s. Couple of things I do...hold breath while clicking and push both elbows against my body. Tense the arms of course. I am trying to bring that down by one stop :-) But for some reason, even with the grip, I struggle with vertical shots. the grip of 40D is not well designed IMO.

It also helps to get a burst.....even on steady birds. One or two from a 5-6 frames burst are usually sharper than the others.

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Originally Posted by Kaustubh Deshpande

w.r.t that rule of thumb, yes, the crop factor should be considered. so it should be 1/ effective focal length.

But with practice and good technique, one can get sharp shots at 1/ focal length or even better. Of course it depends on the weight of the rig. I shoot with canon 400 f5.6L...which is a very light and well-balanced lens. I do get sharp shots at 1/400s. Couple of things I do...hold breath while clicking and push both elbows against my body. Tense the arms of course. I am trying to bring that down by one stop :-) But for some reason, even with the grip, I struggle with vertical shots. the grip of 40D is not well designed IMO.

It also helps to get a burst.....even on steady birds. One or two from a 5-6 frames burst are usually sharper than the others.

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I do not tense up my arms, in fact I try to do the complete opposite. In my view tension induces noticeable shake though of course others may experience things differently.

I'll challenge the crop factor addition to the 1/focal length guide, especially for bird photography where one tends to crop the subject anyway.

For example, suppose I photograph a bird with a 500 mm lens on a 30D and 5DII and need to crop in both images. Which rule for exposure time should I use? The 30D and 5DII have the same pixel size so would get the same number of pixels on the subject. The metric should include the pixel size, not the crop factor.
Same with other cameras. For example a 7D versus a 30D: both 1.6x crop but the 7D has pixels only 2/3 the size of the 30D, so one would need to use a faster shutter speed.

Here is a quick derivation of a metric. The 1/FL guide came about with film, and about 12 megapixels full frame (about 8-microns/pixel) more than matches the resolution of film, so a metric could be:

exposure time = (pixel size/8)/FL

So the 7D would need about half the exposure time as a 1DII.

Roger

I should mention that the guidelines go out the window with the use of IS. One can do quite long exposures with IS and get good results. I've photographed birds at 1/10 second at 1000 mm on a stopped but rocking safari vehicle. Subject movement was more of an issue than camera movement.

Roger

... but is a better starting point Roger Thanks for the info !!!

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Originally Posted by Alfred Forns

... but is a better starting point Roger Thanks for the info !!!

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Alfred, I agree. And a complex formula won't be remembered nor used. I guess people should use the 1/FL guide and make the exposure time a little faster if their camera has small pixels (e.g. 2x faster for the 7D; 1.5x faster for a 1DIV), then adjust from there depending on personal ability.

Roger

Thx Roger.

Elliote, probably more than what you want :-)...but here's a good read: http://bobatkins.com/photography/tec...ter_speed.html