Sensor Speed & Motion Blur. What are they?? Let's Discuss it!
May 13, 2018 09:29:47 #
Notorious T.O.D. wrote:
I shoot a lot of trains doing 50-70mph and drag cars doing up to 200+mph in an 1/8th mile. I can shoot a car doing 175mph a lot easier from the stands than standing trackside. Especially if I am trying to get a full side shot... I attribute this in part to the fact that the objects speed moving through the sensor view is slower the farther off parallel to the sensor it is... So it is distance, angle and how much you are filling the sensor's view with the subject in my experience...
Even though the drag car is moving faster than the train, its angular velocity is less because it's further away. That makes panning with the camera easier.
May 13, 2018 10:06:16 #
SharpShooter wrote:
Here are 2 new pics. both shot at ss 1600, iso 160... (show quote)
It looks like your tests are going well. I wonder if the difference would be even more apparent with a faster shutter speed. If you do more photos maybe try 1/4000 second or even faster than that.
I'm wondering about the 50 megapixel image and the 18 megapixel image. Was the 18 megapixel image taken with a cropped sensor camera? If that's the case, there wouldn't be that much difference in the pixel pitch of the full frame 50 megapixel camera and the 18 megapixel cropped sensor camera. If the pixel pitch of the full frame and cropped sensor cameras were the same, we wouldn't be seeing any difference in the blur of the fan blades.
May 13, 2018 13:58:35 #
Yes, IMO, this is all mostly a product of magnification. As with camera shake, magnification also exacerbates motion blurring from SUBJECT movement - quite simple really - when you THINK about it - and we should not need to go into mathematics to grasp this.
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May 13, 2018 14:33:49 #
Notorious T.O.D. wrote:
I shoot a lot of trains doing 50-70mph and drag cars doing up to 200+mph in an 1/8th mile. I can shoot a car doing 175mph a lot easier from the stands than standing trackside. Especially if I am trying to get a full side shot... I attribute this in part to the fact that the objects speed moving through the sensor view is slower the farther off parallel to the sensor it is... So it is distance, angle and how much you are filling the sensor's view with the subject in my experience...
Todd, pretty much anybody that shoots very fast moving sports has the same problems, especially if shooting tight!
And at trackside is what I described as shooting a fast moving jet from a quarter mile away. As I said if you are right on top of a slower moving subject it may be a much more difficult shot than a fast moving subject at a far distance, especially if you are panning, thus rendering the subject motionless. But you have learned what to do to get those shots, or at least improve your odds of getting those shot. Thanks
SS
May 13, 2018 15:26:13 #
imagemeister wrote:
Yes, IMO, this is all mostly a product of magnification. As with camera shake, magnification also exacerbates motion blurring from SUBJECT movement - quite simple really - when you THINK about it - and we should not need to go into mathematics to grasp this.
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Meister, mathamatics would certainly bring out the unquestionable truth, at least for those that are capable of understanding it.
I’m not so sure that magnification has much to do with it, or at least it’s not that simple to me.
Magnification certainly comes into play but once the frame has been filled, is, I think, where sensor speed takes over, whether it’s macro, gels or wide angle. It won’t matter if we call it angular velocity or something else, the has to be movement involved for sensor speed to take place.
Yes, camera shake could compound it but camera shake is evident at very slow speeds usually because of a lack of light which is why shake comes into play.
And we all know that camera shake is minimized by keepin the ss above 2x the length of the lens.
But magnification by itself, once the entire frame is filled is no different than filling the frame using a wide angle lens in what I’ll call negative magnification.
My point was entirely that the faster a subject traverses the pixels on the sensor, the more subject we are to motion blur, and a higher pixel density on the same size sensor will compound the problem. I just hope I’m being clear enough! Thanks
SS
May 13, 2018 15:34:19 #
May 13, 2018 15:39:05 #
SharpShooter wrote:
But magnification by itself, once the entire frame is filled is no different than filling the frame using a wide angle lens in what I’ll call negative magnification.
My point was entirely that the faster a subject traverses the pixels on the sensor, the more subject we are to motion blur, and a higher pixel density on the same size sensor will compound the problem. I just hope I’m being clear enough! Thanks
SS
But magnification by itself, once the entire frame is filled is no different than filling the frame using a wide angle lens in what I’ll call negative magnification.
My point was entirely that the faster a subject traverses the pixels on the sensor, the more subject we are to motion blur, and a higher pixel density on the same size sensor will compound the problem. I just hope I’m being clear enough! Thanks
SS
I AGREE with all you are saying basically, just trying to present the main reason for it.....
Magnification is the main factor that makes the relative speed of the subject transverse more pixels in a given time - just as it does with camera shake.
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May 13, 2018 16:24:27 #
Maybe adding something far away many shoot would add to this discussion...and experiments if people want to take it that far... The Moon...
Best,
Todd Ferguson
Best,
Todd Ferguson
May 13, 2018 16:44:06 #
I attempted to look up sensor speed on google to acquaint myself with the meaning of the term prior to reading your post. I could not find anything related to sensor speed. Thus, I'm reluctant to anything more than write a reply asking for you to provide a source for information regarding this elusive subject of sensor speed.
--Bob
--Bob
SharpShooter wrote:
I've been seeing a lot of questions lately about s... (show quote)
May 13, 2018 17:04:51 #
geezer7
Loc: Michigan
The issue is the angular speed of the image across the sensor. This is defined as the speed of the object being photographed divided by the distance from the camera to the object. Normally the units would be meters per second, meters and radians. Actually feet and feet per second would also work!
May 13, 2018 21:56:01 #
rmalarz wrote:
I attempted to look up sensor speed on google to acquaint myself with the meaning of the term prior to reading your post. I could not find anything related to sensor speed. Thus, I'm reluctant to anything more than write a reply asking for you to provide a source for information regarding this elusive subject of sensor speed.
--Bob
--Bob
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".
Bob, the above from my initial post in an attempt to describe it. I don't have any idea what it's officially called but Sensor Speed seems a bit descriptive but I just made the term up, though I'm sure there is an official term. I'll bet sensor designers have a term for it!?
My goal was not to name it but if we can, it's about TIME the Hog is on the CUTTING edge!!! LoL
What's important is that those that are here discussing it all know what we are talking about and can help those that don't know to understand it.
Bob, I did not look it up thus I do not have any supporting materials. I'm sure there is a white paper somewhere! Maybe as Lamiaceae suggested, Angular Speed/Velocity may be the appropriate terms but I did not look those up. Maybe we should standardize it until we come up with the official term!?
Thanks for the input.
SS
May 14, 2018 00:00:41 #
The photosites on a sensor react to light and they create an extremely small electrical signal as light strikes them. The setting of ISO amplifies this electrical signal that the photosites collect as the light strikes them. This either creates a gain or it can retard the intensity of the electrical signal. Adding gain creates the impression of noise in the image.
The speed of light is 186,000 miles per second. Thus the light striking the photosites is for all practical purposes instantaneous. It is the duration that the shutter is open that allows the light striking the sensors photosites to electrically conduct. The longer the shutter is open, the more the light signal changes from photosite to photosite and it is the change of that electrical signal that creates a blur as evident in time lapse photography.
The speed of light is 186,000 miles per second. Thus the light striking the photosites is for all practical purposes instantaneous. It is the duration that the shutter is open that allows the light striking the sensors photosites to electrically conduct. The longer the shutter is open, the more the light signal changes from photosite to photosite and it is the change of that electrical signal that creates a blur as evident in time lapse photography.
May 14, 2018 01:43:44 #
SharpShooter wrote:
b I'm talking about the time/speed it takes a sub... (show quote)
Your test photos were done to illustrate how motion is being recorded by different sensors. One photo was taken with a 50 megapixel camera. The other photo was taken with an 18 megapixel camera. The megapixel count of the two cameras is not really telling us anything. The full frame 36 megapixel Nikon D810 and the 16 megapixel cropped sensor Nikon D7000 have almost exactly the same pixel pitch. The test photos probably would have looked the same. Wouldn't the pixel pitch come into play?
May 14, 2018 03:22:44 #
CO wrote:
Your test photos were done to illustrate how motion is being recorded by different sensors. One photo was taken with a 50 megapixel camera. The other photo was taken with an 18 megapixel camera. The megapixel count of the two cameras is not really telling us anything. The full frame 36 megapixel Nikon D810 and the 16 megapixel cropped sensor Nikon D7000 have almost exactly the same pixel pitch. The test photos probably would have looked the same. Wouldn't the pixel pitch come into play?
CO, here's what I think. I think it was you way back there that asked if one was FF and the other Crop, thus having approximate equal Pixel Densities/pitches. You theorized they would look the same(or someone did)!?
I failed to label my pics but both are FF.
Now, back to what I think. I think that if one was FF and one was crop, they would probably look the same as long as the pixels are the came size, even though the fan would take longer to travers the FF sensor but it's crossing the pixels themselves at the same rate, which is what you were saying.
In my samples the pixels are definitely not the same size so pixel pitch is definitely at play.
In your sample, the fan speed is constant so travels quicker through the crop sensor because it's smaller but traverses the pixels themselves at the same speed.
And to look the same visually the DoF has to not interfere with the outer edges of the image because on the FF the outer edges of the image would give the illusion of more blur. At least that's how I'm seeing it would be too!
Thanks for posting the samples!!!
SS
May 14, 2018 07:09:38 #
What is your definition of time lapse photography? My definition is a number of frames shot over a period of time. A simple example would be one frame per day each day for a year. The exposure of the shot, duration of light hitting the sensor, is a totally separate issue. Maybe the blur you believe you are seeing is because the individual frames are usually presented as a film or video rapidly displaying the individual frames in sequence.
I am not seeing how time lapse relates to this discussion and blur.
Best,
Todd Ferguson
I am not seeing how time lapse relates to this discussion and blur.
Best,
Todd Ferguson
sippyjug104 wrote:
The photosites on a sensor react to light and they... (show quote)
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