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Trying to Understand the Vision Plus Camera

Discussion in 'Phantom 2 Vision + Discussion' started by RedRyderMedia, May 26, 2014.

  1. RedRyderMedia

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    My interest in the P2V+ is to use it as a video camera. I'm less interested in the still photos and don't fly it unless I'm recording video. Therefore, I'm interested in understanding the camera and how it functions. The User Manual isn't very complete, so I've assembled what I THINK I know about the camera. Please let me know if I've got any of it wrong.

    I understand the P2V+ camera has a sensor cropped to a maximum resolution in large still photo mode of 4384X3288. The sensor is then further cropped to achieve two additional aspect ratios, but the horizontal pixel count always remains the same. There is no picture quality improvement by going to the larger files sizes, just a larger image in height with the width always remaining the same. I can see why someone would take still photos in L to achieve the largest image, or S to achieve a 16X9 aspect ratio to incorporate into HD video without cropping, but any M mode advantage escapes me.

    In video mode, the sensor is further cropped to achieve different resolutions and FOV options, but always at the same 16X9 aspect ratios (except VGA mode). The 720P allows for a higher frame rate presumably because it's processing fewer pixels. Unfortunately, the 720P uses only the Medium FOV and the prop guards (and props) show too often in this mode. So unless I'm flying slow with no wind or flying downwind/backwards, I don't like the 720P too often to use it as my everyday mode. That leaves 1080P (can't imagine why anyone today would shoot 1080I) with two (not three like the User Manual says) Medium, and Narrow FOV. The Medium FOV is the same as the default FOV in 720 mode. So essentially, there is one FOV option for all modes, except for the Narrow FOV available only on any of the 1080 modes.

    So it seems really, there are only four useful video modes. 1080P Medium and Narrow FOV at 30fps, and 720P Medium FOV at either 30 or 60fps. For me, that really leaves only one mode, 1080P Narrow at 30fps. If the wind is blowing, the prop guards show even in the 1080P Narrow, so either fly backwards into the wind, or no prop guards. Regardless of image quality, this shows the real limitations of this camera compared to the GoPro with a wider assortment of video options.

    The 1080P Narrow works best for me because I don't see the props and there is very little fisheye distortion because you're only using the very center portion of the lens. I'm happy with that video when the camera is pointing straight ahead. There seems to be a slight curve to the horizon, but very acceptable. The curve of the horizon is worse with the camera pointed slightly downward, but everything seems fine once you get the horizon line above the FOV.

    The lens aperture and focus is fixed, so exposure control is primarily achieved by varying the exposure time. Exposure time 'control' is achieved either by changing the gain on the sensor by changing the ISO, or by shifting the exposure manually up or down from the standard setting. Higher 400 ISO increases gain and shortens the shutter time, and 100 ISO lengthens the shutter time. Shifting the exposure darkens or lightens the image. The higher ISO setting (more sensor gain) will result in more noise in the image. One other alternative for exposure time 'control' is to add a neutral density filter to reduce the available light resulting in lengthened exposure times.

    Is there anything else useful I can learn about the capabilities of this camera? Thanks for reading my TL explanation and for any help.
     
  2. Mal_PV2_Ireland

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    Get rid of your prop guards.
     
  3. RedRyderMedia

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    Yes, but sometimes it's important to use them.
     
  4. rgc2005

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    No audio support. The engine sounds almost always give away the cause of a crash or hard landing.
    DJI needs to extend the legs at least an inch to protect the camera.
    Also for rookie pilots like myself the Prop Guards are very important.
     
  5. malacca

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    This post summarizes the limitations of the camera very well. Even without prop guards, the propellers can sometimes be seen.

    Having the narrow frame of view in 720p for 60fps shooting and very little fisheye would be outstanding. I would probably shoot in that mode almost all of the time. I can't think of a reason this could not be enabled extremely easily by DJI.

    The different photo sizes are quite strange - simply different aspect ratios. I suppose having the super-tall Large photo could be useful for later cropping, but it was a strange decision to make the different 'sizes' really be different aspect ratios. Oh well.
     
  6. Zycor

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    If I am not mistaken, the three different resolutions of the still photo represent different aspects used in printing, ie 4:3, 3:2 and 16:9. But I always take the pictures in the largest size and crop down to what I need
     
  7. doug86

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    Well done. I learned a bunch reading your post.

    Perhaps a Phantom 3 with full GoPro controls is next?

    And the P3V+2, which will have zoom capability, adjustable tilt speed, and 1080x60fps?
     
  8. RedRyderMedia

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    Thanks, I'm pleased you found it helpful. I know it helped me focus in on how to best use the capabilities of the camera.
     
  9. RedRyderMedia

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    +1
     
  10. Dirty Bird

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    Not really. What's really important is to use your head and be in control of the aircraft at all times. I ordered a set with my Vision+, but they have never been out of the box.
     
  11. BlackTracer

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    Great post redrider. I too learned a lot from your summary.

    I do have a question. I could swear with my P2V that changing the video FOV also changed the stills FOV. But changing the FOV on my plus doesn't seem to affect the stills FOV at all. Does it?
     
  12. RedRyderMedia

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    I can't speak to the Vision because I don't have any experience, but on the Vision Plus, the still and video FOV are totally independent. Actually, there isn't even any overlap. None of the still FOV are the same as the video. The aspect ratios overlap, but not the FOV.
     
  13. D_Tshudy

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    It's posts like this that make me appreciate this board more every day. Thanks OP.
     
  14. RedRyderMedia

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    The jury is still out for me on the prop guards. I've flown with and without them. They've saved me a couple of props, but I think they shorten flight times. I haven't noticed any control differences, but I think everyone feels a little better when little kids are around it.
     
  15. Zycor

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    I have been studying the camera more and took the bird outside today and put it on a table and did a sample of 1080p at both FOV settings. I tried setting all the settings to a fixed setting instead of auto, 100iso, WB to daylight, exposure +. 03 I think. Well, in my test, the wide 110 FOV looked much better quality. I would like to see if maybe a few others can try this. I am at a loss at exactly how the get a wider FOV unless they are sampling 2x the area of 1080p and downsizing the picture back to 1080p. I am assuming that the narrow FOV is just the exact center of the sensor. When I get back home I will post my samples, I also need to test the software extender beta from FPVFlyer as I just got back in town last night. Any ideas or thoughts?
     
  16. RedRyderMedia

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    That's what I assume they're doing. For the medium, they're sampling that portion of the sensor equal to 110 degrees (however many pixels that is) and then converting that to 1920.
     
  17. Zycor

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    I wished we had access to the codes they use to send that info to the camera, I would presume the camera is capable of more with the right software, granted not a whole lot more, overall the camera and video is somewhat of a disapointment
     
  18. fastsmiles

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    Be sure and read
    viewtopic.php?f=27&t=16388

    Prop guards might be the cause of several crashes that occur due to turbulent air beneath the quad and loss of control. It makes sense that prop guards would make the effect worse.
     
  19. Zycor

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    I think more than anything the ability to turn up the recorded video bitrate, its not much higher than low side youtube quality to begin with, edit it once and you just have lost a lot of quality, you can work around some of the other things with the camera, lighting, angles recorded, etc, but bitrate no control over.
     
  20. DrJoe

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    Gotta say, having 60 fps in 1080p like a go pro would be great. At 30 fops, I can't get great turns without choppiness unless it's a dead calm and I'm really babying the Phantom. With 720 P and 60 fps, I get very smooth video and the ability to edit in slo-mo, but give up a bit of quality.