Author Topic: Seeing a pellet in flight  (Read 2587 times)

WalterF

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Seeing a pellet in flight
« on: March 19, 2021, 08:18:02 PM »
I just got my Chronos 1.4 and went out to shoot exploding golf balls with my air rifle. It is tuned to shoot the pellets at 800 feet per second. I am set up a little more than right angle to the subject. I set the cameras resolution to give me a frame rate of almost 11500 frames per second. When I processed the video I had to slow down the speed to 50 percent to be able to see the pellets trajectory. I know the feet per second of the air rifle because I use it in competition and use a chronograph to check the speeds.

How are people getting clear images of the pellet going to the target? What am I doing wrong?

I included the link to the video.



https://www.youtube.com/watch?v=ashdl61T3xc

Nikon1

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Re: Seeing a pellet in flight
« Reply #1 on: March 19, 2021, 08:36:01 PM »
i dont know what lens you are using here, but there is a ton of Color Fringes going on in the image, which take away a lot of the Detail the Camera could have possibly captured here. So maybe stop down (use Smaller Apperture/ Iris Setting, this sometimes goes away or at least gets better with smaller Apperture Settings) your lens a bit or try to use a better lens.
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 Even more Important is the Lack of Seperation from the Background. Try filming the Pelet against the Sky, use some White Backdrop where you expect the Pellet to fly or use some Really bright light as a Backlight of the Pellet from the Oposite side of the Camera to give it a distinct outline (Nice Trick if you are low on light, use Heavy backlight to at least have Silhouettes clearly visible, so you sometimes can get away with an overally too dark image, while still beeing able to see whats going on). The Dark Pellet is just not very visible against the also rather Dark Grass.
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 Another thing to consider is Shutter angle and Framerate. As from the Motion blur visible and the (for gun stuff) rather low Framerate i assume you filmed this on an Cloudy day or with not too much light overall, which is understandable. But if you want slower, sharper Footage, you usually either need to up your Framerate or make your Shutterspeed / Shutter-Angle Smaller/Shorter (which will make your Frame a lot darker!). This means for some things like that you need to either add artificial Light to your Subject you are shooting or Shoot on bright and sunny days only.
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 Most general-Purpose (motion Picture Production and so on...) Highspeed-Video gets away with a lot less light (Still needs Plenty bright Environment to record anything worth showing), but especially gun stuff and Projectiles in Flight require A LOT of Light!

WalterF

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Re: Seeing a pellet in flight
« Reply #2 on: March 19, 2021, 09:11:26 PM »
Thank you, the lens I am using is the computar 12.5-75 and I had to have the aperture wide open and the gain all the way up to even get an image, it was very cloudy today. I will try to clean up the background and shoot in more favorable lighting conditions.

I was shooting around 460 something by 360 something for pixel size, this gave me the 11500 fps. If I go up more it will be more pixelated.

I will wait and try again on a sunny day, using your suggestions.

Nikon1

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Re: Seeing a pellet in flight
« Reply #3 on: March 20, 2021, 01:11:57 AM »
As far as resolution goes, for this shot you could have easily choosen an wider Aspect ratio Image, as about the lower half of the Image as of now is "dead Space", where almost nothing is happenig anyways. So if you went with half the vertical resolution and reframed the shot to only see the now top part where the pellet is flying, you wouldnt really loose any detail from that, while increasing framerate by quite a bit. For Tracking things like those in Flight, a pretty Wide image is usually more usefull anyways than an close to Square one.
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 Another Trick to make the Projectile seem to move slower, i see often used with projectile Footage is, to not shoot at an 90 Angle from the Path of flight (Of course sometimes necessary to get an good view of front and back of target...), but to get closer to the Shooters Perspective or an more shallow angle, as now the same Space in Frame covers more real World Distance the Pellet will have to travel, meaning it will be in Frame for longer (and also moves seemingly slower).
 Of course not very usefull trick, if what you are going for is the typical 90 Side angle, but still worth thinking about sometimes.
« Last Edit: March 20, 2021, 01:22:41 AM by Nikon1 »

WalterF

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Re: Seeing a pellet in flight
« Reply #4 on: March 20, 2021, 06:57:08 AM »
I tried some of the techniques you mentioned this morning on a clear bright  morning. It helped a lot. Just nor sure why I have the red band at the top.

https://www.youtube.com/watch?v=drtRe8cwoWA

Nikon1

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Re: Seeing a pellet in flight
« Reply #5 on: March 20, 2021, 07:01:57 AM »
i assume the Line is from Changing Shutter speed /angle after the Black Calibration.
 To get rid of that line, make sure to set your Gain, Resolution, Framerate and Shutter Angle first, and after all settings are done and applied, do a Black Calibration.
 This should usually get rid of that line.

CS223

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Re: Seeing a pellet in flight
« Reply #6 on: March 24, 2021, 08:23:06 AM »
Looks good for the first go at it. Remember, light, light and more light. And you can set a custom resolution as well to get the frame rate up while constraining the image area.