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View Full Version : 1.6 X focal length=min shutter speed


bl4scott
20th of September 2008 (Sat), 09:48
I understand this but why is this so??? What is the benefit? If you are shooting for ambient light, then most of the time you are breaking this rule.

Just wondering...

Blessings,

Brian

gasrocks
20th of September 2008 (Sat), 10:02
I guess I do not understand what the question is.

ImRaptor
20th of September 2008 (Sat), 10:13
The benefit is to avoid blur from camera shake.
Its not so much a rule, but a rule of thumb.

SkipD
20th of September 2008 (Sat), 10:23
The rule-of-thumb is the thread title divided into one.

1 / (focal length) is the formula accepted for 35mm film cameras, and

1 / (focal length * 1.6) is the equivalent formula for APS-C cameras.

The rule-of-thumb, Brian, provides the slowest shutter speed that the average photographer should use when hand-holding a camera to avoid camera-shake blur. Some photographers can hand-hold slower shutter speeds just fine while others require a faster shutter speed. Technique and the individual photographer play important parts in the results, of course.

JeffreyG
20th of September 2008 (Sat), 10:26
Faster shutter speed = less blur from camera motion and less blur from subject motion.

Subject motion varies by subject speed, but handholding (camera motion) is going to be a factor of focal length and photographer steadiness.

The old focal length rule works for most people shooting images they intend to print at about 8x10. If you plan to print bigger or view at 100% on a monitor then you may see some motion blur at speeds almost twice as fast.

For 4x6 prints you might be able to handhold much slower.

Also keep in mind that photographer streadiness and technique are factors.

John_B
20th of September 2008 (Sat), 10:54
bl4scott,
I believe its so because us photographers have hearts and we breath too. Yea and those things keep beating and filling up and emptying while holding the camera! Good thing too...

Honestly the heart beating along with other things like us breathing affect a camera movement when holding it in our hands. The slower shutter speeds usually show this. The longer the lens the more it can be seen thus the faster shutter speed is recommended. As each person is different (we all don't have the same size heard and lungs) its used as a general majority use suggestion. That is why some can shoot slower and some need to shoot faster.

bl4scott
20th of September 2008 (Sat), 16:18
awesome guys!!!

Thanks for the description. Totally makes sense. I figured it was something like that.

Brian