[munce]

hi chings,

I am using 500D with 18-55 at the moment.

I have heard of safe shutter speed, which is equal to 1/focal length x 1.6.

Eg at 55mm, the safe shutter speed should be 1/(55x1.6) = 1/88 s

Is that correct?

Now the question is if I am not at 18 or 55 end, but somewhere in the middle, how can I tell which focal length I am currently using? I don't think the focal length is shown in the viewfinder, right?

THANKS

[h0001244]

Of course you don't find the focal length on the viewfinder...... it's imprinted on the lens instead........for more precise, you can check the focal length in exif file.

[卍明仔卍]

應該吾使x1.6
另外你枝鏡好似有is 所以可以除番吾知係咪四

第二條: 吾使咁認真. 大約就ok..

[pkpartner]

安全快門有好多因素既 1/焦距 係概念嚟未必啱
例如: 我24mm 1/4都有機會中 (condition:食飽 二-三中一)
而300mm 1/300 都震 hahaha
自己嘗試搵下個安全位 糾正下姿勢,跑下步舉下鐵都有幫助

[h0001244]

<<<I have heard of safe shutter speed, which is equal to 1/focal length x 1.6.>>>

It was recommended long ago for 135 film system the safe shutter speed is faster than 1/focal length .
When it developed to aps-c, there's no absolute answer for whether we shall multiple x1.6 on the focal length. But if you consider the DC camera, 5mm is (28mm equivalent in FF). I don't think we can get steady shoot easily with 1/5 second. So I tends to multiple the factor x1.6 on aps-c camera.

<<<Eg at 55mm, the safe shutter speed should be 1/(55x1.6) = 1/88 s
Is that correct?>>>
Correct in theory but could be wrong in practical ! ! ! ! depends on your camera holding skills (posture), depends on whether you are on the bus, depends on whether the object is moving quickly, depends on wind.........
It is only some kind of reference for photographers, not absolute.

[munce]

卍明仔卍,


I remember someone in this forum said has to multiply the crop factor, not sure whether this is true.

[munce]

h0001244,

In that case, if I wanna to use M mode, say I use f/4, ISO 200 (assume day time), then what shutter speed should I use?

I always use Av mode, and now want to explore M mode.

THANKS

[snoopybee]

The safety shutter speed is just a guide. If you have steady hands / posture, you can adjust it accordingly.

For the equation 1/F. Think about it seriously, under even lighting condition, with the same aperture and shutter speed settings, would you think using 18mm or 55mm be affecting the exposure by much?

The reason for having 1/F is because for longer focal length, the lenses would be relatively heavier and more susceptible for shaky hands.

[h0001244]

<<<In that case, if I wanna to use M mode, say I use f/4, ISO 200 (assume day time), then what shutter speed should I use? >>>

There is no absolute answer but there is some recommendation. You can spend some time and take a look at the film packing in supermarket. There is some recommendation for you. Or you have exposure meter in your camera, why don't you make use of it.

[Obi-Wan]

My dc has a zoom 5.9-29mm
but the 35mm equivalent angle of view is 25-125mm
the safety shutter speed for the 5.9mm wide is 1/25 s, NOT 1/5.9 s
similarly the safe shutter speed for apsc 55mm is 1/88 s, not 1/55 because the 55mm lens on apsc camera has an angle of view as a 88mm lens

[reflexboy]

You wanted to prove something obi wan？Wanted to prove something other than the concept of safety shutter speed huh??? I think you should have the answer by now!

[SleepingIII]

对于安全快门，我没有听说过一个通用的，准确的定义。所以，讨论是否要乘以转换系数，我认为是没有意义的。