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Old Dec 23, 2012, 01:58 PM
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Basically you get more motion blur with lower frame rates, giving the shots a more "realistic" look. The lower the frame rate, the slower your camera needs to move. A fast pan at 24p will make people sick, whereas the same pan at 60p will make people less sick. Your shutter speed should also be at double your frame rate to match the motion blur. 24p at a 200th of a second looks like saving private ryan movie.
I've found that shooting in 60p helps a lot with vibration and the innate movement of our camera platforms. If your shooting from a tripod, that is a different story all together


Quote:
Originally Posted by SeismicCWave View Post
>>Use Frame Blending: on (Since I shot in 60p and output in 24p)<<

I know this is getting pretty far off topic but I do have a question about frame rate for digital video. I kinda get an idea about recording frame rate and I am starting to understand the bitrate idea. I know they are not the same thing.

So for some of the "better" video recording devices such as camcorder, Sony NEX series cameras, GoPro Heros etc. etc. They all claim a certain recording frame rate such as 60i, 60p, 30p, 24p etc.

Let's assume I understand the 1080 meaning 1080 pixels across the image on the wide side.

Let's also assume "i" means interlace and "p" means progressive and that is another topic.

Then those numbers such as 60, 30 and 24 simply means the number of frames per second, correct?

So for a "motion" to appear you need to "show" or "flicker" at least 16 images per second before the human eye can perceive seeing motion. It is because our human eyes can retain a latent image for 1/16th of a second.

The cinema projector play a movie at 24 frames per second. That's why they call 24 frames per second the "cinema" rate.

The higher end camera claims to record up to 60 frames per second which is great. Now when I do, iMovie cannot interpret my AVHCD when I record at 60p. So I use something called Clip Wrap to convert it to 30 frames per second.

My question with this long description is that what is the difference in playback between 30 frames per second and 24 frames per second. It seems like such a small difference. So why not just play back at 30 frames per second instead of using 24 fps? Is there an advantage to using 24fps?

It was so much simpler back in the film days.
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Old Dec 23, 2012, 01:59 PM
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Quote:
Originally Posted by SeismicCWave View Post
>>Use Frame Blending: on (Since I shot in 60p and output in 24p)<<

I know this is getting pretty far off topic but I do have a question about frame rate for digital video. I kinda get an idea about recording frame rate and I am starting to understand the bitrate idea. I know they are not the same thing.

So for some of the "better" video recording devices such as camcorder, Sony NEX series cameras, GoPro Heros etc. etc. They all claim a certain recording frame rate such as 60i, 60p, 30p, 24p etc.

Let's assume I understand the 1080 meaning 1080 pixels across the image on the wide side.

Let's also assume "i" means interlace and "p" means progressive and that is another topic.

Then those numbers such as 60, 30 and 24 simply means the number of frames per second, correct?

So for a "motion" to appear you need to "show" or "flicker" at least 16 images per second before the human eye can perceive seeing motion. It is because our human eyes can retain a latent image for 1/16th of a second.

The cinema projector play a movie at 24 frames per second. That's why they call 24 frames per second the "cinema" rate.

The higher end camera claims to record up to 60 frames per second which is great. Now when I do, iMovie cannot interpret my AVHCD when I record at 60p. So I use something called Clip Wrap to convert it to 30 frames per second.

My question with this long description is that what is the difference in playback between 30 frames per second and 24 frames per second. It seems like such a small difference. So why not just play back at 30 frames per second instead of using 24 fps? Is there an advantage to using 24fps?

It was so much simpler back in the film days.
I really think it's just for that "cinema" feel. I also think that since your bitrate will be the same, there may be a bit more detail at 24p vs. 30p, but I am not sure on that.

That being said, the Hobbit was played at 48fps, so maybe this lower frame rate thing is going away.
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Old Dec 23, 2012, 02:49 PM
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Originally Posted by MauiNate View Post
Basically you get more motion blur with lower frame rates, giving the shots a more "realistic" look. The lower the frame rate, the slower your camera needs to move. A fast pan at 24p will make people sick, whereas the same pan at 60p will make people less sick. Your shutter speed should also be at double your frame rate to match the motion blur. 24p at a 200th of a second looks like saving private ryan movie.
I've found that shooting in 60p helps a lot with vibration and the innate movement of our camera platforms. If your shooting from a tripod, that is a different story all together
Thanks, that's what I thought but some of these new digital video thing is counter intuitive for me.
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Old Dec 23, 2012, 02:52 PM
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Originally Posted by jcmonty View Post
I really think it's just for that "cinema" feel. I also think that since your bitrate will be the same, there may be a bit more detail at 24p vs. 30p, but I am not sure on that.

That being said, the Hobbit was played at 48fps, so maybe this lower frame rate thing is going away.
Well I am sure the old time silent movies were probably at 16 fps. That's why we can see the flicker. I think for the cinema the frame rate may be a budget constraint. It may be very expensive to go from 24p to 30p or as you mentioned 48p. With the movies being filmed more and more digitally maybe the frame rate will go up also.
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Old Dec 23, 2012, 03:18 PM
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Nate covered it pretty well, it is a complicated combination of frame rates, shutter speeds, bitrates, lighting, and what is being filmed that all add up to the final look. One thing I will say is that you will pretty much always want to shoot progressive for the best quality, and at the highest bitrate you can. Interlaced footage can look fine, but it will show some ugly side effects of it being interlaced. So any camera that tries to make a big deal of it shooting a 60i frame rate annoys me, it is no more useful than a digital zoom (you know what 60i actually is? 30p).

Hansen, the frame rate that a camera can capture doesn't directly impact the quality of the video so much as the look of the video. Having different frame rates just gives you more options to choose from that could be beneficial depending on what you are shooting. To me one of the more important factors when it comes to the video quality a camera can capture is the bitrate. This statement is a bit simplified but think of it this way, the higher the bit rate, the higher the quality / more detail will be captured. This actually gets even more complicated depending on the codec that is being used as well, but if you were to simply ask me what one differentiation would I look at, it would be the bitrate a camera captured at (of course you and I know I never only look at one factor!). Next would be the quality of the optics, then quality of the sensor (in general, bigger sensors are better with less noise), and then everything else kind of falls into the category of "does it help me do my job better", such as OIS and manual controls.

The difference between 24fps and 30fps is slight but when you get used to it you can tell a difference. They exist because cinema adopted 24fps while broadcast adopted 30fps. The difference between 24p/30p and 60p is more noticable, there is much more being captured in the same period of time so you don't miss fractions of a second in the action. It is a little hard to explain but visually the difference is that 24p looks smoother and what most would consider natural, while 30p (to a lesser extent) / 60p looks a little more harsh and slightly unrealistic (though some of that depends on how it is shot), almost kind of sterile compared to 24p. For most normal filming I use 24p, sometimes 30p if I might want to do a slight "dreamy" kind of slow motion to the clips (or if it is for broadcast). For action I normally use 60p since I usually plan on slowing it down in post, and even if I don't plan to slow it down 60p should still capture the high speed action that is happening better. That's not to say all action needs to be done at 60p though.

The main thing I think about with regards to shutter speed is motion blur. With video you expect movement to have some blur to it, a small amount for slower movement and a higher amount for faster movement. For most normal types of filming the general rule of thumb is to use a 180* shutter, which means use a shutter speed that is twice that of your frame rate. But I don't believe that is always the best way to go about it (maybe it's because I come from a photography background). No matter what frame rate I'm shooting, if I want to have a natural amount of blur I will shoot at around 1/50th or 1/60th of a second. If I want less blur I will shoot at 1/125th, and if I'm shooting something high speed and want to capture a lot of detail with very little to no blur I will shoot at 1/250th or faster. In general the faster the action is, the higher I will set my frame rate as well...but not always, such as when I know I won't be doing slow motion, in which case shooting at 24p is fine.

Bitrates can kind of be equated to compression settings for still images. When shooting the higher the bitrate is the more data there will be captured, or when it comes to outputting videos the higher the bitrate the more detail will be retained (like using lower compression). This applies no matter what size your video is, so if you were to export the same video at 1920x1080 and 720x360, using a constant 5Mbps, the file sizes would probably be similar but the 1920x1080 video would have less detail / show more compression like artifacts. I actually just re-cut the video from yesterday with a few new clips and also decided to output it at 1280x720 and 12Mbps to increase it's quality while trying to keep the file size reasonable, which took it from a 219mb file yesterday (at 1920x1080) up to a 305mb file today (at 1280x720).

I also think it is a bit of a misnomer that 24p gives a "cinema" feel, it's more complicated than that. It is just one of many different factors that go into creating more of a cinema look to footage. As for 48p, I haven't seen The Hobbit yet but don't think that frame rate will be replacing any others in the near future. It's just another tool that can be used to create a different look, which may or may not be what you want for any given shot.
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Old Dec 23, 2012, 03:20 PM
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Quote:
Originally Posted by SeismicCWave View Post
Well I am sure the old time silent movies were probably at 16 fps. That's why we can see the flicker. I think for the cinema the frame rate may be a budget constraint. It may be very expensive to go from 24p to 30p or as you mentioned 48p. With the movies being filmed more and more digitally maybe the frame rate will go up also.
Old silent movies have flicker because they are variable frame rate...they vary based on the skills of the guy cranking the handle!

(ok, that may not be the only reason...)
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Old Dec 23, 2012, 03:24 PM
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Also, remember that with the nex cameras, 24p and 60p have the same bitrate. Meaning that in 60p you are actually getting half the bitrate per frame of 24p because you are capturing twice as much information So the 24p is more detailed, but you need very smooth, slow motion to make it look right.
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Old Dec 23, 2012, 03:27 PM
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Originally Posted by MauiNate View Post
Also, remember that with the nex cameras, 24p and 60p have the same bitrate. Meaning that in 60p you are actually getting half the bitrate per frame of 24p because you are capturing twice as much information So the 24p is more detailed, but you need very smooth, slow motion to make it look right.
Yup, like I said, it's complicated.
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Old Dec 23, 2012, 03:28 PM
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Originally Posted by mattchase View Post
Nate covered it pretty well, it is a complicated combination of frame rates, shutter speeds, bitrates, lighting, and what is being filmed that all add up to the final look. One thing I will say is that you will pretty much always want to shoot progressive for the best quality, and at the highest bitrate you can. Interlaced footage can look fine, but it will show some ugly side effects of it being interlaced. So any camera that tries to make a big deal of it shooting a 60i frame rate annoys me, it is no more useful than a digital zoom (you know what 60i actually is? 30p).

Hansen, the frame rate that a camera can capture doesn't directly impact the quality of the video so much as the look of the video. Having different frame rates just gives you more options to choose from that could be beneficial depending on what you are shooting. To me one of the more important factors when it comes to the video quality a camera can capture is the bitrate. This statement is a bit simplified but think of it this way, the higher the bit rate, the higher the quality / more detail will be captured. This actually gets even more complicated depending on the codec that is being used as well, but if you were to simply ask me what one differentiation would I look at, it would be the bitrate a camera captured at (of course you and I know I never only look at one factor!). Next would be the quality of the optics, then quality of the sensor (in general, bigger sensors are better with less noise), and then everything else kind of falls into the category of "does it help me do my job better", such as OIS and manual controls.

The difference between 24fps and 30fps is slight but when you get used to it you can tell a difference. They exist because cinema adopted 24fps while broadcast adopted 30fps. The difference between 24p/30p and 60p is more noticable, there is much more being captured in the same period of time so you don't miss fractions of a second in the action. It is a little hard to explain but visually the difference is that 24p looks smoother and what most would consider natural, while 30p (to a lesser extent) / 60p looks a little more harsh and slightly unrealistic (though some of that depends on how it is shot), almost kind of sterile compared to 24p. For most normal filming I use 24p, sometimes 30p if I might want to do a slight "dreamy" kind of slow motion to the clips (or if it is for broadcast). For action I normally use 60p since I usually plan on slowing it down in post, and even if I don't plan to slow it down 60p should still capture the high speed action that is happening better. That's not to say all action needs to be done at 60p though.

The main thing I think about with regards to shutter speed is motion blur. With video you expect movement to have some blur to it, a small amount for slower movement and a higher amount for faster movement. For most normal types of filming the general rule of thumb is to use a 180* shutter, which means use a shutter speed that is twice that of your frame rate. But I don't believe that is always the best way to go about it (maybe it's because I come from a photography background). No matter what frame rate I'm shooting, if I want to have a natural amount of blur I will shoot at around 1/50th or 1/60th of a second. If I want less blur I will shoot at 1/125th, and if I'm shooting something high speed and want to capture a lot of detail with very little to no blur I will shoot at 1/250th or faster. In general the faster the action is, the higher I will set my frame rate as well...but not always, such as when I know I won't be doing slow motion, in which case shooting at 24p is fine.

Bitrates can kind of be equated to compression settings for still images. When shooting the higher the bitrate is the more data there will be captured, or when it comes to outputting videos the higher the bitrate the more detail will be retained (like using lower compression). This applies no matter what size your video is, so if you were to export the same video at 1920x1080 and 720x360, using a constant 5Mbps, the file sizes would probably be similar but the 1920x1080 video would have less detail / show more compression like artifacts. I actually just re-cut the video from yesterday with a few new clips and also decided to output it at 1280x720 and 12Mbps to increase it's quality while trying to keep the file size reasonable, which took it from a 219mb file yesterday (at 1920x1080) up to a 305mb file today (at 1280x720).

I also think it is a bit of a misnomer that 24p gives a "cinema" feel, it's more complicated than that. It is just one of many different factors that go into creating more of a cinema look to footage. As for 48p, I haven't seen The Hobbit yet but don't think that frame rate will be replacing any others in the near future. It's just another tool that can be used to create a different look, which may or may not be what you want for any given shot.

Cool, thanks for the detailed explanation. The more you know...
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Old Dec 23, 2012, 03:46 PM
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Thanks guys for the AVCHD converter suggestions, appreciated. Great info on frame rates etc.
One thing that has me confused is the shooting at 60fps and then converting it down to 30fps to get a nicer look. Im on a mac and using FCP X or iMovie. With iMovie I dont understand how to do the conversion down to 30fps. It usually tells me the frame rates dont match and the only options are the lower frame rates. What is it Im missing in this?. Cheers
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Old Dec 23, 2012, 03:48 PM
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Originally Posted by mattchase View Post
Nate covered it pretty well, it is a complicated combination of frame rates, shutter speeds, bitrates, lighting, and what is being filmed that all add up to the final look. One thing I will say is that you will pretty much always want to shoot progressive for the best quality, and at the highest bitrate you can. Interlaced footage can look fine, but it will show some ugly side effects of it being interlaced. So any camera that tries to make a big deal of it shooting a 60i frame rate annoys me, it is no more useful than a digital zoom (you know what 60i actually is? 30p).........

...........I also think it is a bit of a misnomer that 24p gives a "cinema" feel, it's more complicated than that. It is just one of many different factors that go into creating more of a cinema look to footage. As for 48p, I haven't seen The Hobbit yet but don't think that frame rate will be replacing any others in the near future. It's just another tool that can be used to create a different look, which may or may not be what you want for any given shot.
Whoa Matt! That's a lot of very good information. I am saving it to read over again and again. I am pretty much a still image photographer all my life. I only dabbled in movies with a 16mm Bolex and now a bit in digital videos.
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Old Dec 23, 2012, 06:52 PM
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Originally Posted by sdaudet View Post
Hello
I need help i build a rusty camera mount but i would like be sure about the solder on the potentiometer
Some body could say me where is the positif and the negatif on the rusty potentiometer
It is the red in midle. And invert the black and white if it turn in the wrong ?
Thanks a lot
Sorry, but my first answer to this was wrong. I don't know what I was thinking, but here's the corrected answer (and I edited the original post).

The original servo pot has three wires, almost certainly in a row. The center wire from the original pot goes to the center connection on the external pot. The outer two wires go to the other two connections on the pot, and it's essentially trial and error. If it doesn't work correctly, reverse the two outer wires on the pot.

I should have just referenced one of Hansen's earlier answers to the question, since it would have been correct

Rusty
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Old Dec 24, 2012, 11:57 PM
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The latest tinkering:

I just fitted one of those black square plastic pot that was from the inside of a servo to the tilt axis on the camera gimbal. Once the glue dries I will take some pictures to show you. It saves a few grams.
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Old Dec 25, 2012, 12:07 AM
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Finally finished and tested the gimbal:

hitec 7940th x2, HoverFly Pro as controller.

I had a short flight at night with a GH2, but I will generally be flying with a T2i. I probably sized it larger than most. First flight looked good, but I need to tune the reaction a bit.

Overall, really impressed with this design. Way to go Hansen and rusty!
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Old Dec 25, 2012, 01:07 AM
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>>hitec 7940th x2, HoverFly Pro as controller.<<

I really want to hear your impression on the 7940.

>>I had a short flight at night with a GH2, but I will generally be flying with a T2i. I probably sized it larger than most. First flight looked good, but I need to tune the reaction a bit.<<

Wow you do have one of the larger size built so far. I really want to know how you like the 7940's on the gimbal with a heavier load than many of us.

Nice work!!
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