SharpShooter Loc: NorCal

I've been seeing a lot of questions lately about shutter speed and related motion blur.
A lot of what we read is about hand holding longer, heavier lenses but this is not so much about that, though camera motion compounds sensor speed.
And by SENSOR SPEED I don't mean ISO either.
I'm talking about the time/speed it takes a subject to travel across the camera's sensor, thus I'm calling it "sensor speed".
I'll give an example we see here a lot.
Every Blue Angels performance we hear, "this jet was going 1000 mph and look how SHARP it is".
Yet with the same exact settings a bicycle going at 25 mph a few feet in front of us has motion blur!
WHY???
The difference is that a plane at 1000 mph and a 1/4 mile away doesn't even come close to filling the frame and is but a small part of the sensor and might take 2 to 3 seconds to traverse the sensor, effectively giving it a very slow sensor speed. And the longer the lens the more sensor speed it creates.
Yet the bike is only a few feet away and fills the entire frame/sensor and any given part of it might cross the sensor in a fraction of a second giving it a much higher sensor speed than the jet thus creating more blur.
The more pixels traversed in the same amount of time the more likely there is to be motion blur.
And as has been brought up several times is that high mp cameras have smaller pixels thus exacerbating sensor speed and motion blur.
I'm hoping my image of the fan can help explain this.
Obviously the rpm is the same in the center of the fan as the outer edges but the fan blade tip speed is MUCH greater thus increasing the sensor speed while the center appears still. That's why we increase the shutter speed to try and control the number of pixels traversed by the fan's blade edge and mitigating the sensor speed.
So lets dive into this. Those that know can help those that don't to understand the mechanics of motion blur.
This is not scientific but anybody that wants to make it so can feel free to take us there and provide image samples or data. I'm not here enough to moderate this so I'm putting it out there and will check in when I can. Feel free to carry on with out me!! LoL
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All exif intact. ss1600, f8, iso 1600

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Bozsik Loc: Orangevale, California

I think this should help many understand a subject that seems to elude them. The same thing happens when you pan with the subject, you are able to use a much slower shuetter speed because the subject is in the same location on the sensor during the exposure.

CHG_CANON Loc: the Windy City

We've enjoyed more than a month free of these 'discussion' posts from other member ... and now you want to restart them?

CO

I've read about how data is off loaded from a digital camera sensor. I remember reading about how off loading data from a full frame sensor quickly was more challenging because of the greater distance across the sensor. The data was collected off to one side of the sensor. Some of the data had to travel further. The off loading speeds are probably so fast now that it's irrelevant.

I'm not sure if the examples you're citing have anything to do with sensor speed. The angular velocity of the fan blade is the same at the hub and blade tips. The great circumference at the blade tips give it greater surface speed.

DaveO Loc: Northeast CT

Good info for contemplation!

Linda From Maine Loc: Yakima, Washington

"The more pixels traversed in the same amount of time the more likely there is to be motion blur."
The visual in the opening about distant objects taking up much less space on the sensor seemed a clear and easy example when talking about motion blur. But then member CO mentioned angular velocity and surface speed re the fan photo, and if you start looking up stuff like that you can run into circumference speed too

How about another relative speed difference in the same frame: a fast moving crop duster. I got the body fairly sharp at 1/1000 second even though the plane nearly fills the frame, but the much smaller propellers show motion blur. I'm told that some movement in propellers is desirable in order to emphasize that the plane is not just hanging up there in space.

A humble conclusion: achieving or avoiding subject motion blur requires a great deal of study and practice! Just as with depth of field, color saturation, the position and intensity of light, perspective - among many other considerations - blur can be controlled and used to achieve a photographer's goal.

Kmgw9v Loc: Miami, Florida

I 'll devote my weekend to contemplation about the information in this thread.

CO

That's an excellent photo. You got the motion blur of the propeller just right. You could probably sell it to the crop duster company for their advertising.

CO

Say we photograph the jet traveling at 1,000 miles per hour from the 1/4 mile distance with an extreme high resolution camera. We then heavily crop the photo so the jet fills the frame. Wouldn't the motion blur be the same as if we had photographed the jet from a much closer distance?

LoneRangeFinder Loc: Left field

Thanks. I’m spending mine imagiining how all of that lint in my dryer could have ended up in my navel.

CHG_CANON Loc: the Windy City

No.

Consider simple math and a sensor that is 10-pixels wide by 10px high, total resolution = 100 pixels. Your far away plane might cover a 2x2 square within the larger 10x10 frame. If you crop to just the plane, it's still only 2x2. Data containing the plane impacts just 4 pixels in this simplified example (2x2)

Now bring the plane closer to the sensor where maybe the image covers 8x6 within the larger 10x10 sensor. You'd have 48-pixels with image data related to the plane. If you have a fast shutter and no camera movement, the plane at 48-pixels will seem a lot sharper in this hypothetical 48-pixel resolution than the 4-pixel crop.

Now ramp-up to a EOS 5Ds with a 50.6MP sensor (8688 x 5792). There are way more pixels in the same 36x24mm sensor area. Now subject motion causes subject details to cross over more pixels at a faster rate, potentially resulting in blur and a loss of pixel-level sharpness as compared to the same subject at the same speed and distance from a lower-resolution sensor. Users of "high" MP bodies such as Nikon's D8xx cameras and Canon's 5Ds/5DsR cameras have found that fast-moving subjects may require faster shutter speeds to avoid pixel-level motion blur. In addition to subject motion, camera motion from hand-holding or even the mirror-slap can negatively impact the image quality of high MP sensors, regardless of the speed of the subject.

SharpShooter Loc: NorCal

Yes, my goal is always disrupt everybody's life for as long as possible....., happy reading!!!
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SharpShooter Loc: NorCal

CO, I'm not sure Sensor Speed is the right term either but it seemed to fit. I realize that in camera manufacturing that term might be applied to something different. Maybe someone has a more correct term? Thanks!!!
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SharpShooter Loc: NorCal

Lone, you just need to put your wife on the problem.
I complained to mine about the same problem and she simply called the Pentagon and ordered up a Navel Blockade....., problem gone ever since!!! LoL
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SharpShooter Loc: NorCal

Canon, I was thinking last night what I might get a chance to do this morning.
I'm gonna take a pic of the same fan but using two different cameras. one camera has 18mp and the other 50mp. If everything else is the same, will we see more motion blur from the 50mp sensor???
Thanks for taking the time to present that example!!
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