KronTalk
Chronos => Chronos User Discussion => Topic started by: SlowEng on May 04, 2023, 11:21:51 AM
-
Hi,
I'm very new to high-speed camera usage. I need to record a spherical projectile coming from an air gun (BB gun to be precise) at around 92 m/s and hitting a 3D-printed model about 1.4 m away. The camera I have at my disposal is Chronos 2.1 HD. I've already made some tests but there are 2 problems:
1. The recording is too dark, even with the shutter slider set to max. There should be enough light on the scene since I'm using a large professional lamp. Are there any settings that I should check?
2. With 1000 fps (1920x1080 resolution) the bullet is not even visible in the recording, I can only see the debris after impact. Thus, I tried with 14 825 fps (1280x96) but then the image changed to a narrow bar and only this region was recorded. How can I fix it? Also, with this frame rate, the bullet is visible when traveling through the air but it's still very fast and hard to notice. Is it even possible to capture such a velocity using this camera? What settings would you recommend for my case?
-
Hi, Can you provide any Further Detail on the Light Source you are using, also on what Lens you are using (Especially Lens Settings)?
.
Regards Resolution, there is not much to be done about that, if you want / need more Frames Per Second to capture Faster Events, you Resolution gets lower, that is just how Highspeed-Cameras generally work.
-
Hi, Can you provide any Further Detail on the Light Source you are using, also on what Lens you are using (Especially Lens Settings)?
.
Regards Resolution, there is not much to be done about that, if you want / need more Frames Per Second to capture Faster Events, you Resolution gets lower, that is just how Highspeed-Cameras generally work.
Thank you for the reply. Unfortunately, I won't have access to the light source until the actual experiment since it's in the lab. I can provide the data regarding the lens though. It's Nikon AF Nikkor 85mm f/1.8D with HN-23 hood. I only adjust its focus on the target.
So, when it comes to the resolution, those highest frame rates will always be just very narrow bars? There's no way to stretch them somehow? I don't need very good image quality, I just want to capture the whole target in such a way that all the objects (including the structure of the target, debris and bullet) are distinguishable and the recording can be used for research purposes.
-
what Aperture Setting did you use on the Lens?
Regards the Light, can you at least provide any Further Info on it? Like Type of Light? is it a big Tungsten Light for Filmmaking, LED, HMI, ect. / size or rough Power of the Fixture?
.
And yes, High Framerates will generally Crop your Frame to a much smaller Area, and for very High Settings its usually going to be a very Shallow, Wide Frame.
-
I attached a picture showing the current settings of the lens.
The light is in the form of a large wide rectangular lamp (likely LED) on a tripod. Like this (horizontal version): https://m.media-amazon.com/images/I/71Cg-A0vSGL._AC_UF894,1000_QL80_.jpg It provides bright white light which should be enough to illuminate the scene. The normal room light was also on when I was recording. I've also tried using a lamp similar to this one: https://www.toolstation.com/luceco-110v-single-head-tripod-work-light/p88271 but it wasn't powerful enough.
-
Yeah, in that Case, its probably just way too little Light.
That Lamp you Linked has 22Watt of Power, which is close to nothing for Trying to Light a highspeed Shot of the Full Flight Path of a Projectile.
you need ideally at least 10 to 100 times More Light than that Lamp Provides for a High Quality Shot (not kidding, 200 to 2000 Watt of LED Lights! ).
.
Your best bet is Likely to either Get your Test Setup to Somewhere on the Outside where it can Safely be done and you can get Direct Sunlight, or somehow use a Window and use a Big as Possible Reflector or Mirror to Redirect the Sunlight inside.
If both of those are not Possible, you most Likely need to Seriously Upgrade your Light to Shoot Highspeed Footage of Projectiles.
Something like 200W LED output Power would be the Absolute Minimum i would Recommend, if its your Only Light Source (Normal Room Lights are usually hardly noticeable for stuff like this, because they are so dim), better if you can Get your Hands on More than that.
If your Background is somewhat Similar to your Projectile in Brightness and / or color, try using your Light as a Backlight / Rimlight so you at least get a Clear outline, even if the Majority of the Frame is Very dark.
-
It seems to be much more powerful than the linked one, only the style/shape is similar. I will try to figure out the exact model of that lamp.
By the way, it might be a stupid question but I'm really inexperienced in such tests - my projectile can be silver or coppery and the target is light orange. Should I use white or black background? Which one will be better for filming? I would choose the white one but I've heard an opinion that black might be better.
-
A lot of it comes Down to Preference and the Actual Situation.
I Personally like Black / very Dark Backgrounds more, cause they usually Tend to look cleaner, and Overexposing can be quite Problematic with the Chronos (which can be Tricky to balance with Very Bright Backgrounds).
.
Then also Depends a lot on the Lights that are available to you, and how they are set up. Given you set it up like that, you can make a White Background look Dark or a Dark Background Look very Bright.
.
In the Most Cases, you just want Clear Separation between Background and the Subject you are Shooting. So given enough Light Available, you would typically tend to Light that Subject Bright enough, so its nicely end Evenly Lit (except you are Going for a more Stylistic Look, or have other Limitations).
The Background is then Kept Darker than that or Completely Blacked out, so you clearly see the Subject and nothing else.
Especially for Small (metallic) Particles, they could Catch some Reflection or be roughly the Same Brightness as a Light Colored Background, but its Generally very hard to NOT SEE THEM on a Completely Black Background, as they will usually always catch some Amount of Light.
.
Now that is of Course different if You are Shooting Black Plastics with a Black Projectile, in that Case a Light Background would in my Opinion be a much Better Choice, but that can be a bit harder to get the Lighting right on.
-
Thank you for all the tips, black background might make more sense in my case then. What about the lens settings (like aperture)? Should I change them from the current ones somehow? Apart from adjusting the focus, of course. Also, are there any important settings of the camera itself (recording/saving) that I should adjust in such conditions? Perhaps this camera is not sufficient to capture a projectile at so high velocity but it’s the only one I have at my disposal.
-
The Camera is very much Capable, but it can do nothing in a dark room (at least not for the Higher FPS Settings).
.
Imagine F1 Car in a Swamp... about like that with the Chronos if it tries to go fast but has no Light.
-
for Lens Settings, keep it as Wide open as Possible, until you got so much light, that your Image is getting too Bright. Meaning f/ 1.8 for that Lens or the Smallest Possible number for any other given Lens.
.
To get the Image Brighter, try using Gain Settings.
Start to work your way up in that order:
.
Digital Gain in steps up to 12dB (analog Gain at 0dB)
.
if still not bright enough, Increase analog Gain to 6dB, and work your way up to 18dB Digital Gain in Steps
.
If STILL not Bright enough, increase analog Gain to 12dB, and work your way up from 12db to 24dB digital Gain.
.
If still too dark, increase the Analog Gain to 18dB / 24dB, and Keep the Digital Gain at 24dB
.
the higher the Gain Settings are, the lower the Image Quality becomes, so ideally you would just have enough Light and keep the Gain at 0dB and 0dB for analog and Digital, but that is sometimes not Possible or Practical, especially for the Higher Framerates.
That way you will get an image that does not look as good, but you will usually at least see what is happening.
. For the Lens setting, given you have enough Light, closing the Aperture to an f-Number of 8 would also be Beneficial, as you get more of whats happening in Focus at once, but it also makes the Image much darker.
So, for as long as you are Struggling to get enough Light, you will need to keep it wide open, and only be able to see a very shallow Plane of Focus Sharp at once.
.
Regarding Aesthetic Lighting Advice, if you need further Advice / Information about that, let me know I will PM you some.
-
Thank you for the advice. I've figured out the name of that lamp. It's F&V Z1200VC CTD-Soft. Should it be sufficient ?
-
The Website Tells me, that is a 250W LED Panel.
Its a good Start, but you probably still would have to get the Light Fairly Close to what you are Trying to Record to get it Bright enough at 14ish kFps.
Try to to play around with the Gain a little, and see if you can get Footage with High enough Quality for Your Needs with that.
If not, i would recommend getting at least one or Two more Lights with Similar Power (or get some Help from the sun if Practical).
Can you Provide some kind of Lighting Diagram of the Setup you have with some indication of Distance between the Light and what is Being Lit, Camera Position in Relation to Subject and Light(-s), as well as an Rough Estimate of size of the Area the Frame is Covering / Subject Size? Makes quite the Difference if you are using that 250W right next to something or from 5 Meters away.
-
Just For Reference, these Two Videos where Shot at 1000fps using the Chronos 2.1 with about 2000 Watt of LED Lights:
www.youtube.com/watch?v=HDXXjpdEDfc (http://www.youtube.com/watch?v=HDXXjpdEDfc)
www.youtube.com/watch?v=dpx-hbIz8e0 (http://www.youtube.com/watch?v=dpx-hbIz8e0)
.
This Video is using about 1700 Watt of LED Lights:
www.youtube.com/watch?v=ku4Hnp8zUbI (http://www.youtube.com/watch?v=ku4Hnp8zUbI)
.
and this one is Shot in 2100fps using a Single 500 Watt LED Light, but its VERY Close, just right out of Frame with a Softbox on it:
www.youtube.com/watch?v=XW-O5Hz9VOY (http://www.youtube.com/watch?v=XW-O5Hz9VOY)
.
For even Higher Framerates you usually would need Much more Light than that, if Lit from the Same Position, if you want to keep the Same Level of Image Quality. Double the Framerate would in Theory need Double the the Amount of Power in Lights, 14kfps vs 1kfps would mean 14 times more Powerfull Lights...
Because that is usually not Practical, you sometimes have to get really close with your Lights, to get enough Light; like i did in that Bolex Video (was kind of just to Lazy to set up a ton of Lights for that one, so i made it work with a single one somehow).
-
Wow, I didn't know that so much light is needed for such recordings. I guess that I will have to place the lamp very close to the sample.
You would be surprised what obscene Amounts of Light are used for some of these Shots:
www.youtube.com/watch?v=A4u2xmk5Qys
-
Wow, I didn't know that so much light is needed for such recordings. I guess that I will have to place the lamp very close to the sample.
I attached a simple sketch of the view from above of my current test setup with which I got poor recordings (the sample was not used yet, shots went directly to the styrofoam block). It can be modified if needed (especially when it comes to light and camera placement). I'm not sure about the distances but the lamp was around 1.5 - 2 m away from the sample and the camera was < 1 m away from it. In the actual test, the camera should be placed perpendicular to the table (and thus also bullet trajectory). There's also an acrylic glass cover placed around the sample and the camera will be looking through it. Hopefully, it won't cause any issues with recording quality. The dimensions of the sample are around 90x90x23 mm. It will be attached to a wooden plate with aluminum profiles offsetting the sample from the plate (to see what happens after penetration). The plate will have a hole through which the bullet can pass.
The biggest issue is how to capture the proper region with the camera. It needs to include the sample (vertical rectangle of 90x23 mm size) and some area before and after it. With those narrow boxes captured at the highest frame rates, I would probably have to place the camera far away to capture everything. If I get too close, the camera with the current lens may not see or focus on the whole area of interest. Unless I'm missing something.
Edit: I removed the old post to replace the incorrect scheme - I forgot about the aluminum profiles offsetting the sample from the plate.
-
Regards getting the Whole Sample in Frame, would Mounting the Camera Vertically work for you?
The Chronos has a 1/4" Tripod Screw Hole on the Side of the Grip/ Battery, intended Mainly for Mounting it at an 90° Angle.
That way you would get an very High Frame to Capture that Sample.
Is this what you are Looking for?
.
Regards deleting the Post, you can just go to Modify Post, then Delete the Attachment and Attach a new one, no real Need to delete the whole Post.
-
Right, vertical positioning of the camera could make sense in this case. I just wonder if the bar is not too narrow. What would be the approximate optimal distance between the camera and the sample here? And the distance between the light and the sample? Should I place the light right behind the camera (once it's perpendicular to the table) or more to the side?
Yeah, I tried editing the post but I couldn't remove the old attachment and both versions were added to the post. Maybe because I was using another computer.
-
For Lighting, maybe Start with something, like i did Here for the 20kfps Shot:
forum.krontech.ca/index.php?topic=521.msg4950#msg4950
I Put one of my 300 Watt Lights Right Behind the Subject, because i needed to Close the Lens down very much, to get a Lot of Depth of Field, while also running 20kfps. This of course will make the Subject look very Dark --- Keep in mind this is an Actively Burning Sparkler / Fireworks, so in it self rather Bright Object. But it will ensure you that you will get somewhat decent Image Quality overall and you will be able to See Silhouettes, if that fits your Task; but Details in Texture or of the Surface itself Might get lost.
That should at least make it Possible to Record a bright enough image with that one Light you got.
From There you can Try to move the Light to ABOVE the Sample, shining Down on an angle from the Direction of the Air Gun, as close to the Sample as Possible without being in the Way or in Frame.
Thats Where i would probably have that Light in this Situation...?
.
Regards Framing, you can still try to start with some Less Extreme Settings like 5400fps, which will give you a much more Square Aspect Ratio. If the Lights are Set up right, you will still get a lot of Information from that Recording cause its much cleaner and better Visible, and can then decide which Part of the Frame you want to Record at the Very High Framerates if needed.
-
Just wondering, if you where able to improve your Results after all?
-
Not sure if you will see this since you haven't updated this in a month. I have filmed a lot of projectiles out of firearms. You need a lot of light like Nikon 1 said. You also need to adjust your slider (shutter angle) otherwise your projectile will be a blur. I tend to use a 10:1 ratio for muzzle velocity. If an object is moving 92 m/s that is close to 300 feet per second. I will film that at 3k frames per second then or higher.
Here is a video of a bullet moving around 800 fps. But I filmed it at 11k frames per second and 32k frames per second. I had to use a bright studio light shining directly on the muzzle to get some semblance of an image at 32 fps.
https://www.instagram.com/p/CtVnJVzNe3r/