I was wondering.....

Hello all,
The other day I was shooting with a 70-300 mm lens and had my camera on Tv mode. To avoid blurred pictures, I set the shutter speed at 320 - you know, the "never shoot at a slower shutter speed than the focal length of the lens" rule- but then I started thinking: if I am using a canon 60D, which has a 1.6x magnification,shouldn'​t I set the shutter speed no lower than 500 since the magnification makes the 300 mm a 480 mm?
I thank you in advance for your thoughts and advice.

Yes. You are using the correct thought process here. Crop sensors magnify the effects of a lens so you must compensate.

I don't agree. The magnification factor has no bearing in this case. The suggestion of not shooting slower than 1/focal length is simply to provide a fast enough shutter speed to avoid blur because of the size and weight of the lens. In this case, the magnification factor doesn't come into play.

gv0861 wrote in post #15515153
Hello all,
The other day I was shooting with a 70-300 mm lens and had my camera on Tv mode. To avoid blurred pictures, I set the shutter speed at 320 - you know, the "never shoot at a slower shutter speed than the focal length of the lens" rule- but then I started thinking: if I am using a canon 60D, which has a 1.6x magnification,shouldn'​t I set the shutter speed no lower than 500 since the magnification makes the 300 mm a 480 mm?
I thank you in advance for your thoughts and advice.

In a nutshell, yes. You do have to adjust for the effect of the format size. So if the '1/focal length' rule works for you when you use a 35mm camera, you should adjust by 1.6 for a 1.6X format camera.

Sometimes people get confused by this, but the best way to get your head around it is to take the comparison to a logical extreme. Think of one of these superzoom digital cameras with a 40X zoom lens and a telephoto range of '600mm effective focal length'.

The superzoom camera has a teeny little sensor and the real focal length is probably something like 70mm on the long end. So what do you think, absent image stabilization should you be able to handhold this superzoom at 1/80, or would 1/640 be more likely?

The reason you have to adjust for the format is due to the degree of enlargement. The smaller the sensor, the more you enlarge it going to a display. This enlarges defects like blur.

flyinlow007 wrote in post #15515180
I don't agree. The magnification factor has no bearing in this case. The suggestion of not shooting slower than 1/focal length is simply to provide a fast enough shutter speed to avoid blur because of the size and weight of the lens. In this case, the magnification factor doesn't come into play.

More zoom is more zoom though. If you have a smaller field of view due to sensor size then all movements will be magnified. So yes you should keep in mind that a crop sensor will magnify any hand movements compared to a FF sensor.
I do some astronomical photography and it is a definite factor when deciding how long of a shutter speed to use based on the rotation of the Earth. You can get away with a longer SS with FF compared to a crop. Of course it matters. A crop will magnify the Earths rotation compared to a FF using the same FL lens.

flyinlow007 wrote in post #15515180
I don't agree. The magnification factor has no bearing in this case. The suggestion of not shooting slower than 1/focal length is simply to provide a fast enough shutter speed to avoid blur because of the size and weight of the lens. In this case, the magnification factor doesn't come into play.

I don't agree with your don't agree. So let's agree to disagree.

Let's say you are shooting with 70-300 on full frame - on 70 you must be at 1/70, and at 300 you must have 1/300 right? But it's the same lens!
Also, I think it's safe to say that if you could go even further in effective focal lenght, it will increase even further - and that's what you do buy mounting in on a extender or an adapter.

Also, it's just a rule of thumb - it greatly depends on other factors as well.

flyinlow007 wrote in post #15515180
I don't agree. The magnification factor has no bearing in this case.

This is incorrect.

Assuming that the (1/focal length) rule of thumb works for a photographer when using a 35mm format camera (film or "full-frame" DSLR), then the rule should be modified to (1/focal length X "crop factor") for smaller format cameras.

The reason is simple. Given a lens of X focal length and a lens motion of Y, the same blur would appear on the sensor of a "FF" format camera and on the sensor of an APS-C format camera. Now the difference comes into play. In order to make an 8"x12" print from the "FF" camera, the in-camera image (24mm by 36mm) needs to be enlarged 8.47 times to fill the print. To make a similar 8"x12" print from the APS-C camera, the in-camera image (14.9mm by 22.3mm) needs to be enlarged 13.67 times to fill the print. Thus, the identical blurs on the two in-camera images become different sizes on the prints. The image of the blur from the smaller format camera will be larger in the print. Thus, a faster shutter speed is recommended for the smaller format camera to make the in-camera blur due to camera/lens motion smaller.

One must realize that the "rule of thumb" for shutter speed is based on the "average" photographer. Some photographers will need faster shutter speeds to hide camera/motion movement blur and others can use slower shutter speeds.

Just curious, what were you shooting? I think that has more to factor than certain "rules"

EightEleven wrote in post #15515246
Just curious, what were you shooting? I think that has more to factor than certain "rules"

Not if it isn't moving, it doesn't.

JeffreyG wrote in post #15515251
Not if it isn't moving, it doesn't.

Exactly!

EightEleven wrote in post #15515246
Just curious, what were you shooting? I think that has more to factor than certain "rules"

First of all, thanks everyone for your advice. It is greatly appreciated.
I was shooting a bird standing on a branch, so it was more or less a static subject.