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Kinovea - Forums → Cameras and hardware → Basic High Speed Video Camera Considerations & Cameras
Could someone clarify the Aperture Priority AE and Shutter Priority AE settings ?
If I understand correctly, the "Shutter Speed Priority AE" would let you set the shutter speed manually and then the camera would set the aperture automatically based on ambiant light. I think all the Casio EX-ZR* series have these settings. That would allow one to set the shutter speed manually on the newer models?
That's correct about shutter priority. Probably more important of the two variables in most coaching situations as dictates a great deal of the image quality and it is limited by available light.
The depth of field would then vary as the aperature automatically varied which wouldn't have a great influence if looking at action at a single point or in a perpendicular plane but could conceivably do if working with a subject of variable distance as a fast shutter speed would dictate a wide aperature which would in turn dictate a smaller distance between the near point and far point of acceptable focus. Often not an issue if your autofocus works or as I think most video cameras have small maximum aperatures compared to DSLRs so have a wide depth of field - if you can get enough light in to see it...
But the settings are not always available when in video mode…
Full MANUAL Exposure Control vs Shutter Priority AUTO?
I have been a strong advocate for full MANUAL exposure control for high speed video where the shutter speed, aperture and ISO are set. I am not sure of the relative performance of Shutter Priority (AUTO) or the current availability of high speed video cameras (>60p fps) with Shutter Priority (AUTO). I hope that I have not steered someone away from a capable HSV camera that has Shutter Priority but no full MANUAL control, (hopefully, to be determined soon……).
Shutter Priority mode is an AUTO exposure mode that allows the shutter speed to be selected by the photographer and the camera’s AUTO exposure control to select other settings in order to get a video of the desired brightness. If Shutter Priority (AUTO) is available for video or high speed video modes then it should allow faster shutter speeds that produce smaller motion blur.
Aperture Priority mode sets the aperture and the camera AUTO adjusts the shutter speed. Motion blur would be unknown, probably rarely desirable for video motion studies.
Mode descriptions for a SLR camera: Full MANUAL, Full AUTO, Shutter Priority (AUTO), Aperture Priority (AUTO)
http://imaging.nikon.com/history/basics/04/06.htm
http://en.wikipedia.org/wiki/Exposure_%28photography%29
See discussion of lighting issues for using full Manual.
http://www.picturecorrect.com/tips/aper … nual-mode/
Exposure Compensation (‘EV’) adds or subtracts exposure when in AUTO modes.
http://imaging.nikon.com/history/basics/04/07.htm
I believe that the proper use of the term ‘Exposure’ should relate to the actual number of photons collected by the sensor. Both aperture and shutter speed affect the number of photons collected. In addition, after photons are collected and converted to electrons in the sensor, amplification of the sensor output (controlled by the ISO setting) also affects the brightness of the video. In Internet usage, the term ‘Exposure’ may not be consistently used with the idea of separating exposure (in photons) and ISO amplification (resulting output electrons).
See “best answer” reply
http://answers.yahoo.com/question/index … 308AA1q6Ti
My Casio FH100 in AUTO modes (S, A) uses both exposure and ISO together to adjust video brightness. ‘EV’ compensation is available in AUTO modes. In full MANUAL mode (M) ISO still can be left on an “AUTO” but the videos are very dark for some reason. ?
Again, I’d advise anyone interested in high speed video to get a full MANUAL exposure control camera. Unfortunately, I don’t know of any affordable HSV cameras with full MANUAL in 2012 that are now being manufactured. An AUTO exposure control HSV camera with Shutter Priority might do as well regarding shutter speed with somewhat less flexibility regarding video brightness (?). Full AUTO will select an unknown shutter speed that will likely vary with light level.
Which HSV cameras have Shutter Priority? I’m not able to say what features the many models of AUTO control high speed video cameras have and don’t have.
CAMERA SPECS. – It is often not clear in the specs, as listed, whether the spec applies only to the camera’s still photography or also to all video modes. For any camera that you are considering, it is necessary to double check the specs. The user’s manuals can be downloaded. Check with people who own the camera.
CASIO EX ZR300. The Casio Ex ZR300 does not support Shutter Priority in high speed video mode based on the following.
http://forums.dpreview.com/forums/post/42191777
According to the Casio Ex ZR300 user’s manual that I downloaded, “Note”, on page 69 -
"The A, S and M recording modes are not supported when shooting a movie, or when using the "Prerecord (Movie)" and "For Youtube" BEST SHOT scenes. In these cases, the recording mode is always Auto."
PDF: http://support.casio.com/pdf/001/EXZR30 … 0619_E.pdf
There are other similar dpreview threads that discuss the Casio ZR100 and ZR200. The new ZR1000 does not yet have a user's manual available on the Casio support website.
There are Youtube videos comparing cameras or discussing HSV and shutters.
ZR200- No Shutter Priority or full MANUAL shutter speed control.
http://www.youtube.com/watch?v=TwC4sK89d68
ZR100- Review & Comparison to the FH100, at 2:50 he is saying that the ZR100 does not have Shutter Priority to set the shutter speed.
http://www.youtube.com/watch?v=SNut_kshlYM
To see if a camera is capable of small motion blur one approach is to search on Youtube ‘golf swing & camera model’ etc. and look for motion blur from the side view of a golf swing. There is no way to know if the camera was operated to minimize motion blur.
ZR200 - Motion blur.
http://www.youtube.com/watch?v=TWZ6MsKt5sw
Thanks for all the valuable info 
Another set of experiments would be to compile a list of the typical shutter speeds required for an acceptable image, for each sport.
For example, considering a golf swing rotating at x°/s, filmed at a standard distance, what is an average shutter speeds from which the blur start to vanish.
In this video of a football kick, they start to have good results as low as 1/300. But this will probably be too slow for golf or baseball swings. On bike, we could have various values depending on RPM. Even just having order of magnitudes and relative values would be interesting.
As you pointed, the object displacement during a single image is equal to the velocity of the object divided by shutter speed. If we know the typical speed of a given sport, we can start to compile some values.
Then it would be interesting to convert these values into number of pixel smeared for a typical camera distance. It would help setting up tracking.
Thanks for all the valuable info
Another set of experiments would be to compile a list of the typical shutter speeds required for an acceptable image, for each sport. #1
For example, considering a golf swing rotating at x°/s, filmed at a standard distance, what is an average shutter speeds from which the blur start to vanish. #2
In this video of a football kick, they start to have good results as low as 1/300. But this will probably be too slow for golf or baseball swings. On bike, we could have various values depending on RPM. Even just having order of magnitudes and relative values would be interesting.
As you pointed, the object displacement during a single image is equal to the velocity of the object divided by (correct to - multiplied by) shutter speed. If we know the typical speed of a given sport, we can start to compile some values. #2
Then it would be interesting to convert these values into number of pixel smeared for a typical camera distance. It would help setting up tracking. #3
#1 Each sport has motion velocities up to some maximum velocity. For example, since a baseball pitcher can throw a ball at 100 MPH (161 Km/hr, 44.7 m/sec), the maximum finger velocity is probably about 100 MPH. Is the baseball pitching velocity the highest for a body part in athletics? Sports implements such as rackets and golf clubs would exceed the maximum velocity of the fastest body parts. The maximum ball velocities are usually known and could be used for an estimate of maximum velocity for some sports. Estimate & plot over a range of parameters, every 1 m/s or 10 m/s?
Added 7/8/2013 - Fastest sports hits -
http://www.guinnessworldrecords.com/med … its-V2.jpg
#2 Geometric Perspective Considerations for Motion Blur -
The object will move V x t during the exposure time, where V is object velocity, a 3D vector, and t is equal to the exposure time.
Objects Moving Mostly Across & Up & Down in the Frame.
If the object velocity is mostly up and down or across the camera frame the motion blur will be equal to about V x t. Many sports motions occur mostly in one plane and that plane is often made perpendicular to the camera viewing direction. Examples are, side views of running, walking, golf, bicycling, etc.
Objects Also Moving Toward or Away From the Camera
If, however, the object velocity also has components toward or away from the camera then the apparent motion blur will be less than V x t. Examples of complex 3D sports motions are: tennis strokes, baseball pitches, baseball batting, shot putting, etc.
Also, golf swings when viewed from behind have considerable motion toward and away from the camera. Golfers often view their swings from behind because the motion blur for their fastest shutter speed is much less than when viewed from the side. As an extreme example of an object traveling toward the camera, a bullet traveling directly toward a camera only increases in size and does not smear. This view is routinely used in ballistics research (the camera views the bullet through an expendable mirror placed on or near the trajectory).
For future projects and set-ups keep the perspective issue in mind but for this analysis estimate motion blur as V x t.
#3 Motion Blur and Pixels
Let's say that the horizontal linear field of view of a camera, W, is 10 meters. Let's say that the sensor has 1000 elemental detectors, Nh, in the horizontal direction and assume that the camera can resolve 1/1000 of the horizontal linear FOV. Then each pixel would resolve
W / Nh = 1 cm.
Where
W - Camera's linear horizontal field of view.
Nh - Number of sensor detectors in the horizontal direction
If we estimate motion blur to be V x t then the motion blur would be equal to one pixel when
V x t = W / Nh
It would be equal to n pixels when
V x t = n(W/Nh)
The number of pixels covered by the motion blur is
n = V x t / (W/Nh)
Where
V - object velocity (across linear field of view) __ Estimate by user or plot over range of parameters, every 10 M/s, etc.
t - Camera exposure time (shutter speed) __ t is unknown and variable for each AUTO exposure control camera. Measure t by viewing an object with known velocity and illumination conditions? How does it vary? This camera issue is problematic with AUTO control of the shutter speed...........
W - Camera's horizontal linear field of view. __ Cover athlete or action area and 5-10% extra on each border.
Nh - Number of sensor detectors in the horizontal direction __ Available in camera specs.
To estimate the number of pixels that the motion blur will smear across:
1) Estimate the highest velocity in the athletic motion. The highest possible velocity of any body part in all athletics is estimated as 50 m/sec. (Corrections?) More typical athletic body part velocities might be 10 m/sec. Assume parameters 50 m/s and 10 m/s.
2) W depends on camera set up FOV, for example, assume 5 meters.
3) Nh is the number of detectors across the camera's sensor, for example estimate 1000.
4) t is exposure time, unknown for AUTO control cameras. Assume parameters 1/100, 1/1000 and 1/10,000 sec.
Once the camera and experimental set up are determined - W & Nh are known - it is easy to make n estimates by using n = V x t / (W/Nh) and making reasonable estimates for V and t.
For maximum body part speed of 50 m/s & exposure time of 1/100 sec then
n = V x t / (W/Nh)
n= (50 m/s x 1/100 sec)/ (5 m/1000)
n = 100 pixels
Another example - body part speed 10 m/sec & exposure time of 1/1000 sec then
n = (10 m/s x 1/1000 / (5 m / 1000)
n = 2 pixels
There is probably some clever way to display this information for all values and parameters but I don't see how. An Excel spread sheet?
[Or, A high speed video camera such as the Casio FH100 can set shutter speed to 1/10,000 sec - more than adequate to eliminate athletic motion blur and set the frame rate to 240 fps (captures a frame every 23 cm for a 200 Km/Hr object).]
Low Cost High Speed Video Cameras Capable of Tennis Stroke & Other Athletic Motion Analysis.
The high performance, high speed video cameras, such as the Casio EX FH100, with full manual exposure control, as discussed above, are not currently in production in 2013. They are worth it, but are now expensive and difficult to find.
How about much lower priced cameras with automatic exposure control?
General High Speed Video Cameras with Automatic Exposure Control. To video tennis strokes, low priced, high speed video (> 60 fps) cameras are available. The currently available cameras all have automatic exposure control (AEC). The shutter speed selected by the camera's automatic exposure control might not be optimized to minimize motion blur. In other words, you often get too much motion blur with automatic exposure control cameras. The amount of motion blur from these cameras is not predictable from available information but can always be measured in tests.
Canon Powershot ELPH 110 HS/ IXUS 125 Tests. I purchased a low priced Canon Powershot 110 HS / IXUS 125 camera in order to test it for tennis stroke analysis. It does 240 fps at a reduced resolution of 320 X 240.
The automatic exposure control selects the shutter speed based on the light received from the scene. The specs list the fastest shutter speed as 1/2000 sec, but it is not known if that shutter speed is reached for high speed video mode. Unfortunately, predicting the shutter speed that this camera's AEC might select is not possible without testing.
To test for shutter speed/ motion blur in direct sunlight -
1) Observed the motion blur on a rotating disc.
2) Observed the motion blur on the tennis ball and racket of a tennis serve.
I found that a very important setting for minimizing motion blur was the zoom setting on the lens. The widest angle zoom aperture setting has the fastest f#, probably 2.7. The wide angle zoom produces very small motion blur in direct sunlight - see videos below. The telephoto aperture setting is probably f# 5.9 and produces significant motion blur - see videos below. In fact, the telephoto videos below show that the motion blur from the ball streak is roughly equal to the distance that the ball travels between frames. This implies that the shutter speeds for the telephoto videos was very slow, roughly equal to the time between frames, 1/240 sec. For these video tests, it might also have been important for the AEC that more skylight was accepted by the wide angle field of view than by the telephoto field of view. See note below on light metering.
To attempt single frame advance on Vimeo press the play-pause control as fast as possible. The video image quality after compression on Vimeo is not as good as viewing directly on my computer or on the camera's display.
Widest angle zoom setting - small motion blur
https://vimeo.com/74060780
https://vimeo.com/74060778
https://vimeo.com/74060705
Most telephoto zoom setting - considerable motion blur
https://vimeo.com/74060777
https://vimeo.com/74060779
These tests were under direct sunlight to get a fast shutter. With less light the motion blur will increase. See also other Canon high speed video tests of tennis serves and also a rotating disc test to show Jello Effect distortion and shutter speed.
This camera cost $119, refurbished, with free shipping on sale from Canon. The one I received was in like new condition.
http://shop.usa.canon.com/shop/en/catal … efurbished
The Canon 110 HS camera is capable of showing the fastest parts of the tennis serve with small motion blur using the wide angle zoom setting and under favorable lighting conditions. Other Canon Powershot cameras with high speed video might work in the same way. ? Other low cost cameras with high speed video might also produce small motion blur with wide angle lens settings and in direct sunlight. ?
Test your camera under similar conditions and reply with some videos to show its smallest motion blur.
To minimize motion blur - video in direct sunlight with the widest angle zoom setting. Also, have a bright background, include some sky (but not the sun) in the field of view.
Note: The Canon Powershot 110 HS in high speed video mode uses Canon 'Evaluative' light metering to view the full scene for its automatic exposure control. Here is a general link on Canon Evaluative light metering. It is not very clear or useful and may not apply to the Powershot 110 HS / IXUS 125.
http://www.cyberscholar.com/canon/camer … nu=mod_on1
I have to thank Chas Tennis for introducing me to this forum, he found me on a golf forum where I had started a discussion on the best camera for golf practice. It does seem to me that this forum has a much higher technical level of knowledge than any of the others I have been on. My issue is from the standpoint of a n R & D designer of high performance cameras and my background in designing same for the law enforcement world and military world. Now, in 2014, technology has reached the point where a very high performance camera such as 1.3 megapixel at 1000 IPS ( images per second) with a global shutter can be made as a mobile unit with internal storage and battery power. Such a camera can now be designed to be sold at about £1,500 - is there a market?
There seems to be hundreds of domestic cameras and mobile telephones that can do 240 IPS at about 640 X 480 and very low cost, but with rolling shutters. I could create one with 640 X 480 @ 300 IPS and with a global shutter that would have to sell round the £400 mark. The question then arises if just another 60 IPS and a global shutter is worth the extra money over a mobile telephone where the camera is virtually free?
For the tennis world I could create a dual lens/dual sensor camera that would cover 180 degrees ( 90 degrees per lens ) and then stitch the two video streams together. In my thinking this camera could be a fixture in a tennis court on a wall at about the net position and be battery or mains powered and use terabytes of storage and WiFi. But is there a potential market?
Lee Tracey
dvrdigital@gmail.com
UK
It is a niche market for sure. Whether the niche is large enough to sustain a business is a tough question.
Also noteworthy are the alleged specs of the upcoming GoPro Hero 4 : 4K @ 30fps, 1080p @ 120fps, 720p @ 240fps… In a consumer ranged price. I think it has a rolling shutter though, and untweakable shutter speed, so whether it's suitable depends on the final application.
Somewhat related to wide angle view, I've also noted this currently live Kickstarter project of a 360° cam in the affordable zone. I don't know if they can pull it off.
Hi Joan:
I will try to locate the pitch on Kickstarter for the 360 degree cam. I am a bit suspicious though as 360 is not technically difficult or even NRE costly. The simple approach is to make a mechanical 360 mirror and point a normal lens camera upwards into it. Also two fisheye lenses and dewarping will do the job.
My feeling is that regardless of the resolution a rate of 240 will not cut the mustard and it needs to be at least 1000 - is there a business there? You are right: a tough question!
Lee Tracey
I'm actually cautious with the very high framerates for now. During some experiments I have found that there seems to be "time noise", with the framerate variating around its nominal value. The higher the framerate, the higher the error. When digitizing coordinates, this is aggravated by the reduced resolution.
As the frame interval is used to compute the velocity of tracked objects, time bias on high framerate videos have a massive impact and introduce larger errors than for lower framerates. At 1000fps a 1/10px digitization error can be catastrophic for acceleration measurement, so if the frame time itself is not exact…
I haven't found much literature on the subject yet (contrary to spatial distortions), but I intend to explore the subject more when time permits. The time bias introduced by the rolling shutter is another time distortion I would like to experiment with.
Do you know how the framerate fidelity is assessed at the manufacturer level ?
Even the simplest experiments where I would film a high resolution stopwatch displaying miliseconds is not trivial to implement as these sort of stopwatches are not so common.
In addition to this, the things we see at 1000fps that we don't see at 300fps are probably for different analysis contexts. For evaluating limbs or implement movement in the context of sport technique, 300fps might be sufficient. Medical applications or "ball" analysis might benefit from higher framerates.
Here is a video of a close-up of a golf club head impacting a ball by a golfer trying to get the most out of her Casio Ex FH25 camera.
http://www.youtube.com/watch?v=hzNQMhyuXd0
The frame rate was 240 fps and the shutter speed was 1/10,000 sec.
Still picture with club in place.
Here is the closest frame to impact
I believe that the shape of the ball has been distorted by Jello Effect distortion.
Golf Swing - I believe that the Casio Ex FH25 will do an excellent job of showing the body and golf club during the golf swing with small motion blur. There is Jello Effect distortion but it is probably similar to what I measured for my Casio Ex FH100 camera.
https://vimeo.com/user6237669/videos/page:6/sort:date
It is usually small, predictable and correctable if you were interested in the highest accuracy. I believe this applies to most of my tennis videos but not all. On closeups of the tennis ball, I see JE distortion similar to that of the golf ball frame above.
Golf Ball Impact - But for the next level of studying golf - ball impact - the Jello Effect distortion seriously distorts the ball and club interaction. I don't know how much research has been done on the impact of the golf club head and the ball. I don't believe that it is routinely done for golf instruction. Unfortunately, I doubt that many golf instructors or golfers will pursue this level of detail. I'm sure the details of impact are very important in determining the ball's flight .......
240 fps for Tennis Strokes - Before, During and After Racket-Ball Impact - For tennis, 240 fps captures a frame every 4.2 milliseconds. The tennis ball is on the strings for an estimated 3-5 milliseconds. Typically I see, as you would expect, one frame with the ball in contact with the strings or very close to the strings. At 240 fps it is informative to show a frame before impact, impact and a frame after impact. Racket motion is considerable between frames at 240 fps. Recently, we have been trying to correlate the racket positions before, during and after impact with the type of serve - kick, slice, flat or topspin.
Composite pictures for high speed videos by Anatoly Antipin.
240 fps does a great job showing how a high level server's racket is moving for a kick and slice serve. For the kick serve the racket is rising. For the slice the racket is going across with much less rising. These are preliminary results.
(Players verbally describe what they think is happening on these serves. I can't get a clear picture from the verbal descriptions.)
Golf Ball Impact - But for the next level of studying golf - ball impact - the Jello Effect distortion seriously distorts the ball and club interaction. I don't know how much research has been done on the impact of the golf club head and the ball. I don't believe that it is routinely done for golf instruction. Unfortunately, I doubt that many golf instructors or golfers will pursue this level of detail. I'm sure the details of impact are very important in determining the ball's flight .......
Regarding Golf, the folks at Quintic commercialize a dedicated rig for putting analysis. A small high speed industrial camera attached to a platform with additional flood lighting (link to software page). I have no expertise whatsoever in Golf mechanics. I don't know if it could be used for the full speed swing, they probably tried but they don't market it this way. In any event, it means there is indeed interest and research done in the club/ball impact, and not only at the "fundamental research" level.
UPDATE - As of 3/3/2015 I have not been able to find information on the high speed video capabilities of this camera. I do not know if the coordination of several cameras with WiFi applies to high speed video mode.
UPDATE - As of 6/24/2015 - I have not found whether this camera has manual exposure control or the shutter speeds. ?? From viewing videos of a wine glass breaking and others, I do now believe that the multi-camera high speed video operation applies to up to 7 cameras.
If you learn anything please provide some links.
Casio Ex 100Pro
Just heard today about a new camera - researching it now especially the mention that it might have manual exposure control and a very fast shutter.
http://www.dpreview.com/forums/post/54968131
http://petapixel.com/2014/12/18/casio-s … d-capture/
Youtube, coordination of several cameras -
https://www.youtube.com/watch?v=wrhJjkpgBDM
Hi everybody and a happy 2014 Xmas. I am fascinated to discover that the 1000 IPS ( images per second ) issue has surfaced again. You may remember me as the UK based development engineer who had a plan to design a low cost domestic 1000 ips camera. After so much negative feedback that at over $300 nobody would buy it and after other adverse comments I shelved the idea. Now I see Casio want $870 for their latest edition and a chap named Gerald Rowan has raised some $120,000 on Kickstarter to produce a version to sell for about $500, though elsewhere I found it priced at over $1,000. To see the whole detail put Gerald Rowan into Google and then select the Kickstarter reference.
My personal opinion is that Rowan has got the conception fairly right at 840 ips at 640 X 480 but his execution looks a total mess.
If I were to start on this again I would make a 4K camera that was everything MOM wanted to video the family but a camera that without additional equipment could go diving to about 40 metres and also switch quickly to about 1,600 ips at 640 X 480 so that the sporting members of the family could record their daredevil exploits and also golf practice shots. The price would be about $600 - but customers would need only one camera and not a GOPro and a 1000.
Having dropped the camera idea for the present I am working on a range of HEVC /SNVR 4K video recorders.
Kinovea - Forums → Cameras and hardware → Basic High Speed Video Camera Considerations & Cameras
