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Has anyone used these ND filters yet???

Discussion in 'Inspire 1 Discussion' started by flyingclint, Mar 11, 2015.

  1. flyingclint

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    I've seen these online and also seen mention of them here on the forum (http://www.allerc.com/dji-inspire-lens-filter-kit-part-35-p-9806.html) but before I hit the purchase button I wanted to hear if anyone has used them yet and if so, are they good? What's the quality of the glass and does it affect image quality at all???

    Thoughts???

    -Clint
     
  2. johnmont250

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    those are just the stock replacement ones like what came with your inspire, no different....
     
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  3. The Editor

    The Editor Moderator
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    Yes..... And you've used them as well. They came with your Inspire ;)
     
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  4. flyingclint

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    Well, mine didn't come with any dark filters. Only the clear filter came in my I1 box, so I guess I need to order this one since I got gipt... I can't shoot in any light outside with my shutter speed even close to double my frame rate without massively blowing out my shots! I only had one filter in my kit and its just the clear glass, no darker filters.
     
  5. Richard-Inspire

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    was just about to ask about that - what is the benefit of the ND filters? Is it that a shutter speed of double the frame rate is the ideal (in which case why?) and therefore the ND is required to stop it all over exposing? What's wrong with just choosing a faster shutter speed to keep the image exposed correctly? I haven't noticed what the max shutter speed is actually - is it relatively slow?
     
  6. Quadpilot

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    In video, to prevent jittering or jello, it is recommended that shutter speed be set at twice the frame rate: when shooting in 24 fps, select 1/50th shutter speed; when shooting 30 fps, select 1/60th, etc. This will provide an amount of motion blur from frame to video frame that is pleasing to the eye. Trust me, smarter minds than you or I have figured this out. ;) Higher shutter speeds make the video look like the image is jumping from frame to frame.
    The problem comes with bright daylight, where even ISO 100 will result in an overexposed image with f/2.8 (it's a fixed aperture lens) and with the DJI provided ND filter the shutter speed for correct exposure (histogram centered) is somewhere around 1/200th sec or higher. Many have requested that DJI provide a stronger ND filter than the one provided, or have resorted to trying to find a replacement that is stronger (ND .9 or higher).
     
  7. Richard-Inspire

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    ah yes I forgot about the fixed aperature. thanks.

    I actually do a lot of photography, but wasn't aware of the effect of higher shutter speeds etc on video. next on the list to get my head around is shutter angle. Now there's a weird one (and not an issue for us in this domain fortunately).
     
  8. Quadpilot

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    There are other factors that come into play as well, such as the fact that digital sensors record a video frame by recording line after line, usually horizontally, and that when there is movement in the image, the image is distorted. This is called rolling shutter and can cause havoc with an image that records fast movement. It also can cause an effect called jello in images that have a lot of detail.

    BTW, shutter angle is still used in digital cinematography, even though it was invented for film. It's now theoretically possible to have a nearly 360 degree shutter angle; i.e., use 1/24th sec shutter speed at 24 fps to get desired motion blur for a smooth video. This results in increasing the rolling shutter effect, though. :(

    Ideally, if DJI came up with a CMOS sensor of micro 4/3rds size that had global shutter (the image recorded instantaneously) we'd all be in videographer's heaven.
     
    #8 Quadpilot, Mar 12, 2015
    Last edited: Mar 12, 2015
  9. Richard-Inspire

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    the explanation of jello is why I thought a faster shutter speed would be better - the image is scanned faster and there is less chance of movement to have taken place during the scan. That's why I thought the ND was a odd thing to have - but you learn something every day!
     
  10. Quadpilot

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    The effect of jello is that when video is played, the minute jumps between frames of detail in the image is noticeable, whereas if there is a desirable amount of motion blur (180 degree shutter) that is negated.

    Granted, vibration of the camera can also result in jello, but slower shutter speed can paradoxically result in a sharper seeming image.