Safe Shutter Speed

[T_O_M]

With the 10D & 300D having a effective focal length 1.6x do you have to adjust you shutter speed to suit? With film photography a minimum safe hand held shutter speed was 1/focal length. EG 300mm lens (no IS) would be 1/350 sec, with a 10D 300mm would be 480mm so do you have to adjust yor safe shutter speed to 1/500 sec? I do not own a digital SLR and I am looking at getting a 10D or a 300D when I have saved enough cash. I do own a EOS 300V and a PowerShot A70 which gets me by for now.

[henkbos]

The focal lenght of the lens doesn't change because of the size of the CCD. Therfore the calculation should be done on 300mm.

[Roger_Cavanagh]

Don't agree with Henk here. The rule of thumb about minimum handheld shutter speeds should be adjusted to take into account the smaller sensor.

To get the same size print, 10D images have to be enlarged more than 35mm film so any camera shake becomes more noticeable. Hence, you must decrease shutter times to compensate.

Of course, it's only a rule of thumb and some people will have steadier hands than other and you must have good technique. It's also a rule based on viewing 10x8 prints and not 3000x2000 pixels images on a 21 inch monitor with your nose 6 inches from the screen. :)

Also you can use technology to help by buying IS lens. This will give you an extra 2 stops or more. For a 300mm lens:

1/(300*1.6) = 1/480 => 1/500 sec shutter speed

With IS, this reduces to 1/125 sec.

Regards,

[RichardtheSane]

I suppose at the end of the day it depends on wether you will be printing them or not. In practice both Henkbos and Roger are correct.
The theory behind the optics etc suggests that henk is correct as the camera shake would be no different on a smaller snesor as it would be on a large sensor/film.
However if you don't have a steady hand (I am fortunate, I do) then Roger is spot on, as any increase in magnification for printing would bring out even the slightest camera shake.

Do whatever suits your needs, and remember unless you need a slower shutter speed for creativity then aim as high as you can :)