# Am I relying on SSS too much?

Started Jul 20, 2013 | Questions thread
Re: Am I relying on SSS too much?

cplunk wrote:

Allan Olesen wrote:

cplunk wrote:

TFSJake wrote:

I know the old "50mm = 1/50 shutter speed" rule of thumb, and I know it doesn't exactly apply. So I'm asking, what would be a modern day equivalent of that with SSS? I know SSS allows you (theoretically) to shoot 3-4 stops slower than without it, so is this an acceptable rule:

I figure my crop factor makes my 50mm lens behave like a 75mm lens. That would necessitate a 1/80 shutter speed, in the pre-SSS days. Now, moving it down 2 stops would be 1/20, and even further 3 stops is 1/10.

Is this the proper way of thinking? I'll admit, it's 1 in the morning and I got out of bed to post this because it was bugging me, so I may be completely off base in my thinking. If I am, could someone just give me a 2013 version of the 'focal length = shutter speed' rule of thumb?

The 50mm = 1/50 sec shutter speed is based on the "amplification" of the movement of the image on the sensor based on the distance between the lens's focal point and the sensor.

This distance does not change with a smaller sensor, it's still 50mm. And the same amount of camera movement would make the same amount of "shake" in the image.

No. It would make the same amount of shake on the sensor.

But since the sensor is smaller, the amount of shake will be larger, compared to the sensor size, and consequently more visible in the final image, compared to the same image taken with a larger sensor.

So, your taking the same amount of blur on the sensor, and expanding it for final viewing at a similar size?

I guess that does make sense.

What I'm hearing is that the 1/FL on an APS-C really means 1/effective FL, meaning 1/75 sec with a 50mm lens? In that case, three stops from 1/80 would be 1/20 and not 1/10?

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