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Advanced Blur/Focus problem in images? How to easily fix it on the P3 Advanced

Discussion in 'Phantom 3 Help' started by Malakai, Mar 27, 2016.

  1. Malakai

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    Hey all, I had a friend ask if I could take a look at his phantom 3 advanced focus issues and it appears the left side of the images look soft, more so at the bottom left. Sure, after a bit of post processing I could reduce the issue, especially after taking the images in raw but for me this just wasn't good enough. As his aircraft is out of warranty I offered to see if we could fix the issue.

    Please note, if you still have a valid warranty then send it back, following this will invalidate your warranty. However, If you follow it correctly then there is no way to tell if it has been performed other than getting nice sharp images.

    Tools required:
    Torx 6 driver
    Phillips P000 screwdriver
    Small flat head screwdriver

    First, determine where your focus issue is, in this case it was effecting the left side but the bottom left being worse. I have seen some people having an issue with the right side. You can fix it all the same. If its heavily out of focus this might not work.

    Put the aircraft facing you and tilt it back to rest on the rear rotor arms with the gimbal facing forward.
    Rotate the camera so the back is facing you and carefully remove the four torx screws. Try not to gnarl them up with the wrong sized torx bit. They should be a little tight to undo the first time as there is a little thread locker on them.
    Once you have them out the back cover will pull off easily, just lift from the side. This exposes the back of the sensor board.
    Here there are four screws as shown below.
    To do this, slightly undo the four screws holding the board down and using the flat head in the gap in between the board and the casing turn gently to adjust the position of the board slightly.
    As our focus issue is on the left side of the sensor we need to move the sensor a tiny bit in relation to the direction of sharp focus. In the images, the sharper areas are more center and right side of the image. Suggesting the sensor needs to be moved slightly to the right and up a fraction to bring the center of the circle of focus into the middle of the sensor.
    Gently tighten the screws back down. DO NOT OVER TIGHTEN. Just pinch them back up to stop the board moving again.
    Now take some pictures, check the focusing and adjust again if necessary.
    Remember to move the board very very tiny amounts as the sensor is small and tiny movements will make a huge difference.
    Once you have the screws finger tight and the image nice and sharp put the back cover back on.
    Tighten the torx screws up finger tight then pinch them off a tiny bit. DO NOT OVER TIGHTEN.
    The previous thread locker should hold up just fine.
    I have included a few images showing the before and after of doing this and total time to fix was about twenty minutes. It took longer to view the images to check the focus than it did to fix.

    [​IMG]
    The positions pointed out for the screws are in relation to the sensor.
    Top left before:
    [​IMG]
    Top left after:
    [​IMG]

    Center left before:
    [​IMG]
    Center left after:
    [​IMG]

    Bottom left before:
    [​IMG]
    Bottom left after:
    [​IMG]
    100% left before:
    [​IMG]
    100% left after:
    [​IMG]

    100% Image before:
    [​IMG]
    100% Image after:
    [​IMG]

    A short video test appears a little sharper too but its hardly noticeable, it could be because we pulled the focus back into the center of the image.

    Hope this helps you guys out.
     
    Oso, Trinimon, Tim harris and 6 others like this.
  2. With The Birds

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    Very informative and nicely explained, thank you!

    Just goes to further explain why we have the inconsistencies we see in produxts that should al perform equally and to a known standard out of the box. Near enough tends to be good enough when assembly is performed without specualist knowledge or skill.. Rather than just buy in the IP and components perhaps DJI should have done a deal to source assembled pre tested caneras from sony, panasonic, gopro even. It seems this is an issue of improper calibration when assembled or poor engineering where the board isnt precisely located.
     
  3. Malakai

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    After doing this fix and seeing video of the rest of the lens assembly I can see how this issue can occur. The lens is separate from the sensor board.
    Normally the mount for the lens would be attached directly to the sensor board and perfectly aligned with the center of the sensor. This lens then screws into the mount and being perfectly centred it only requires focus adjustment by screwing it in or out.
    In the case of the phantom the lens assembly is screwed to the body and the sensor board screws onto the back of it meaning either the lens or sensor could be assembled out of line.
    I would suggest that at quality control it may be showing as in line but while in transit from the factory any heavy movement or vibration could introduce a tiny amount of movement producing the issue we are seeing.
     
  4. mdowney58

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    In this picture I am seeing some vertical highlights, that give the appearance of a picture being taken from behind a window, like a refection.
    I can mostly see them on the right side, where the grass and plants are.
    What is causing that?

    Sent from my SM-N910V using Tapatalk
     
  5. With The Birds

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    Dirty greasy thumb print.
     
  6. Malakai

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    Yeah, you are right, its reflections from my window, it was raining heavily on and off outside and as i had the back of the camera I had to take them through the window while I was fixing the focus issue. I posted this fix after I did this because I thought it might help others. If I had had more time to plan I would have done the test shots outside.
     
    pomonabill220 and mdowney58 like this.
  7. With The Birds

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    I think this thread will help a LOT of people.... Did you have a play with moving the lens assembly (winding in and out)? I am tempted to try.
     
  8. mdowney58

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    AHA! Thanks, that explains it!

    Sent from my SM-N910V using Tapatalk
     
  9. Malakai

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    Nah, to move the lens assembly the sensor board would need to be removed and the lens removed from the body to be able to crack the glue off the lens thread in order to rotate to focus.
    Thinking logically, they must set the focus on the lenses before they are installed into the camera body and before the sensor is placed over the lens as the lens is glued at the correct focal length. This would help in a mass production environment as then they can bang them out quickly.
    Any that get returned to DJI I guess will just get swapped out with a new gimbal in the hopes that its aligned enough for the customer. I would hazard a guess that 90% of the ones out there are slightly out of alignment but not enough that the customer notices. Easy enough fix though if its only just out of focus at the edges. If its uniformly out of focus that would be the lens needing adjustment.

    If anyone else tries this please let us know. I would like to know if it has helped you.
     
  10. Trackman1

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    Absolutely brilliant work.

    Any thoughts on using feeler gauges in the gap?
     
  11. With The Birds

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    Good idea re feeler gauges.

    Preference would be cnc machined mounting bosses with bushes on the mounting screws for the sensor board. Engineer the thing so even with unsiilled assembly it comes off the line within tollerance.
     
  12. Malakai

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    they wouldnt be of use. its fractions of a mm movement. i guess a digital micrometer might work if it can measure within 0.001 of a mm


    Sent from my iPhone using PhantomPilots mobile app
     
  13. Malakai

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    If i had got more time with this fix i would have measured everything with extremely detailed analysis on the alignment, board movement and how best to correct it to get the sharpest focus.
    Fortunately I got lucky with my phantom being aligned correctly.


    Sent from my iPhone using PhantomPilots mobile app
     
  14. Mako79

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    Thanks @Malakai.
    I'll be doing this tonight :)
     
    StevenQX likes this.
  15. Trackman1

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    Malakai. Was the circuit board tight to the metal ridge before you adjusted? Or was there a small gap
    already? The reason I ask is the p3 you worked on had soft focus on the left side.
    Mine is the opposite with good focus on the left and soft on the right.
    That means I would have to adjust in the opposite direction from you.
    If there is no gap to begin with. I could not adjust.

    Is my thinking correct on this?
     
  16. Malakai

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    There was already a tiny gap. First we nudged the board left, opening the gap but then i realised it would be inverted due to the optics. We nudged it back and forth taking shots to check the focus each time then downloading the image to the iPad and viewing in photos, zooming in to check the focus. It really was a very tiny movement that effected the focus because the sensor is tiny and the edges of the circle of focus are quite tight at the edges.
     
  17. Malakai

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    Let us know how you got on
     
  18. Mako79

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    Not good... I think it made it worse. I will take her out for a flight today and see if there is any improvements.

    You are on the money on the focus/blur issue though. There is too much room for error in the way the lens is mounted to the board. Its a piss-poor design as micro-millimetres can affect the performance of the camera. DJI needs to treat each camera with precision or review the manufacturing process.
     
  19. StevenQX

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    Thanks for the report, let us know the follow.

    In the case it's worst i think it worth to try to adjust directly from the lens as shown in the video that explain how to replace the p3 lens...
     
  20. Malakai

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    Check you tightened the four screws that hold the sensor board on back down. If they are really loose it will be well out of focus, even a tiny amount as you know now.
    When I was adjusting the focus, i got the board centered so it was even focus all round then worked on the tightness of the screws. By this i mean tighten them down literally till they just touch against the board. no tighter. Take a test shot and if its out of focus turn each one in a tiny bit and repeat until its all in focus. The reason being the board will compress slightly when you do those four screws up and it will push it into the circle of focus. The thick rubber backing on the back plate will help stop any further movement of the sensor board if your sensor board screws are a tiny bit loose.
    As for the video where someone swaps the lens out. If you want to go that route be very careful. First during the process your sensor will be exposed, if you are not careful and you scratch it while taking out the lens its borked. New gimbal will be required. There is no fixing it. When you get your lens out and crack the sealant you will need to adjust the whole lens assembly for focus, seal it again, then realign your sensor. If you do. Take your time. Be methodical and careful. Grab a rocket blower to clean out the lens and barrel before you put it back together and really be careful with your sensor.
    :) good luck