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X5 - how to get the most out of it

Discussion in 'Zenmuse X5' started by Aeoutsider, Jan 18, 2016.

  1. Aeoutsider

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    Original Thread
    DJI Forum|X5-how to get the most out of it

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    The X5 brings the Inspire 1 further into the world of professional photography, where you can no longer point and shoot. With this additional power there are now more ways to create a terrible image than a good one so you need to know what you're working with.

    This is frustrating because when you spend a lot of money you expect all your results will be superior but this isn’t the case. You will take many shots that look horrible compared to the X3, making some people feel they received defective cameras.

    The most significant improvement is interchangable superior lenses. A better lens gives you much more power which does allow for much much better results, but just as it’s relatively easy to drive a car but impossible for most of us to drive a 747, you need to know how to wield the new power or you will crash and burn.

    The X3 is pretty easy to use as you just point it in the right direction and as long as the image isn’t grossly over or underexposed you are going to get a decent image This is because three of the main adjustable components, focal length, focus and aperture, are fixed.

    So what are focal lengths? Easiest way to understand them is how “zoomed in” or “zoomed out” the lens is. Measured in millimetres, it determines the field of view the lens sees. Wide lenses, such as the X3, show a great deal in the frame where long lenses are quite tight.

    The focal length also determines the character of the image. Wide lenses create an almost bending quality where you feel like you are close to an object but can somehow see more than you would expect. Long lenses are the opposite, they feel more intimate and straight, making you feel like your subject is the only thing in the world. This goes far beyond what is physically shown in the frame, it affects how you perceive it as well.

    Another thing different focal lengths affect is depth of field, which is basically how much of the image is in focus. With a shallow depth of field your subject will be in focus but everything in front or behind it will be increasingly out of focus. The longer your lens, the shallower the depth of field. Take the X3 for instance. It has a very wide focal length which makes everything sharp, regardless of where it is in the frame and is so wide it completely removes the requirement to focus at all. But with the X5, longer focal lengths will require much more attention to these aspects, as focus will become a very real issue.

    So choosing the right focal length for a shot and shooting conditions (single or dual control) is crucial.

    While speaking of depth of field, the second aspect the X5 allows for is variable aperture. Aperture refers to the iris of the lens itself. This works the same way as your eye. If there is too much light the iris of your eye will close, and in low light it opens very wide. But light isn’t the only thing the aperture controls, it also affects depth of field. When you open the aperture by reducing the number (f/1.7) it also reduces the depth of field. When you close the aperture (f/8 or f/16) it expands the depth of field, sometimes to infinity. Think of squinting your eyes to make things clearer, it’s the exact same thing.


    Okay, so we’re getting there. Focal length determines how tight or wide the image is, along with adding character, and aperture controls how much light comes in, and both affect depth of field, which is how much of your image is in focus. So let’s review and add it to what we already know.


    Shutter speed is of course how many times per second the shutter opens and closes per second. This is another way to control light but the shutter has a big effect on the final image. Put the shutter to high and you will get a stuttered effect where every frame is ultra sharp. A high shutter will also exaggerate rolling shutter known as the jello effect. Too slow a shutter will give a lot of motion blur and aesthetically look like cheap video. In feature films, the shutter speed of choice is exactly double the frame rate. This is known as a 180° shutter as film cameras used a shutter that was literally measured in the circular degrees the shutter obstructed.

    So if you are shooting 24 frames per second the shutter speed would be 48.

    With the X3, since we couldn’t control aperture, it’s fixed at f/2.8, if you were already at 100IS) (lowest light sensitivity) the only other way to control light without changing the shutter was to add ND filters. The ND filters act like sunglasses and reduce the light, allowing you to get the shutter close to the correct number.

    But with the X5 we can now control the aperture, so we can just raise it up to balance the shutter. So instead of f/2.8 we can raise it f/16 or even f/22 depending on the lens. But as you read above, this will also affect your depth of field so you need to be careful you are getting the right effect. It might be that you are shooting on a bright day but still want a shallow depth of field. In this case you would still put an ND filter on, set the shutter to double your frame rate, and set the aperture to a low number like f/2.8 or f/1.7.

    So as you can start to see, your perfect image is a well thought out combination of all these things.

    Focus. Okay, focus can be a nightmare. It’s the easiest way to ruin a beautiful shot. For this reason someone just starting out is best to use the highest aperture possible to keep the iris closed. In extreme conditions with a low (open) aperture, the depth of field can be as shallow as 1/2 inch. This means if you were filming someone’s face their eyes would be sharp in focus but the tip of their nose would out of focus. Imagine trying to determine what’s in focus using an iPhone screen while your Inspire is 1/2 mile away! The challenges are massive and expect to make some big mistakes in the early days. You will quickly learn how the lens reacts and where infinity sits. But in general, the larger the screen you are using to determine focus the better.

    Finally, I just wanted to touch on the difference in sensor size. Many are surprised to hear and baffled at the concept that sensor size also affects depth of field. Crazy right? The bigger the sensor you have the shallower the depth of field. To illustrate this let’s compare sensor sizes of the X3 and X5. The X3 uses a 6.17 x 4.55mm sensor and the X5 is 3x larger, 17.3x13.00mm so you will need a much longer lens to cover the same field of view. The longer the lens the shallower the depth of field and voilà!

    Feel free to ask for clarification for any of this. Again, it's more general than X5 specific.
     
    ringolong, Highrpm955 and DrMrdalj like this.
  2. DrMrdalj

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    Great crash course :)
    Regarding the focus: please note that due its fairly small size Micro4/3 sensor behind 15mm lens, opened to f1.7, when focused at subject aprox. 15-20m away, should get you in focus everything from 7m all the way to infinity... When lens is stoped down to f5.6 and focused at 5m everything from 2m all the way to infinity should be in focus. So, due to fairly short hyperfocal distance of such sensor/lens, for all practical situations focus should not be a problem...
    To anyone who is not already familiar with "hyperfocal distance" I highly recommend to google-out that topic, as it is of great practical importance for arial photography/video.
     
  3. RaptorMan

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    One problem with stopping down with high f/#'s is that doing so will reduce effective resolution due to diffraction limiting. In fact, with a M43 camera at 16MP the point where diffraction effects begin to offset greater DOF is about f/6.3 so stopping down further than that will actually reduce effective resolution.

    So, even with the X5/X5R cameras it's often a good idea to use ND filters when it's sunny. If you're flying fairly high so that there's no near by objects there's little need to stop down much above f/4 and you won't lose much DOF even lower than that. If, OTH, you are skimming along the ground with lots of close by objects as well as far away objects then using a higher f/# is advisable, but owing to diffraction I'd not stop down much above f/11 unless absolutely necessary.

    Additionally, when the light levels are low enough that using a ND filter isn't needed it's probably a good idea to use a UV filter to protect the lens and to maintain a weight balance.

    Lastly, although we mostly setup for video and use ND filters to keep the shutter speed within 2X of the frame rate, for still images you kind of want the fastest shutter speed you can with the lowest ISO setting possible. So, as long as it's bright enough use ISO 100 with a UV filter. Also note that using a higher shutter speed is even more important when using the longer lenses like the 25mm and particularly the 45mm as the bigger the focal length the more obvious motion blur is whether caused by movement of the camera or subject.


    Brian
     
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  4. gruvpix

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    Another thing to be mindful of is the sharpness of the majority of MFT lenses is maximized between f4 and f8 and peaking at around f5.6. Any aperture value below that will introduce corner softness and aperture values above will begin to lose sharpness due to diffraction.
    Sometimes this is unavoidable as lighting and availability of filters will determine what can be accomplished but as a general rule I stick to f5.6 or f6.3 as much as possible.
     
  5. hoodlum1

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    Great stuff from people that know what they are talking about
     
  6. Luke Neumann

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    I have wondered for a while what the native ISO of this camera is? Most of the time it's not the lowest possible ISO but more in the 800 range. Where does the sensor capture the most DR? Is it ISO 100, 400, or 800?

    I am assuming there is a specific ISO value that DJI used to get the listed Dynamic Range for these cameras. I wish they would share that info.
     
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  7. dronie

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    I find that ISO200 looks better than ISO100 which seems artificial. 200 seems to be the best option for the X5.
     
  8. DrMrdalj

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    As DJI X5 seems to have much in commom with other Micro4/3 cameras I thought that some comparison and analogy whould give us an answer.
    My favorite Panasonic GH4 has native ISO400, and it is fairly flawless in range ISO100 to ISO1600 (adjusting sensivity from -2 to +2 f-stops) while ISO3200 (+3 stops in sensivity) is usable just in certain conditions... Therefore I asume that X5 has native ISO400 as well - my exepriance is that X5 is fairly usable from ISO100 to ISO1600 as well, while ISO3200 introduces significant artifacts if shooting conditions are not ideal...
    My best gues for X5 is ISO400 then...
     
  9. Casey Preston

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    I was testing last night trying to determine how to reduce the flickering in the blacks at high ISO. One thing I discovered is that the flickering is much more pronounced when white balanced for tungsten light. This makes sense since I am sure the natural white balance for the sensor is around daylight and a tungsten white balance is automatically adding quite a bit of extra gain to the blue channel.
     
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  10. x5yo

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    Doubt the gh4 native is 800, more like 200 or 400.
     
  11. DrMrdalj

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    I clearly stated that GH4 has native ISO 400... So, I can not comprehend where did you read 800?
     
  12. DrMrdalj

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    How high did you go with ISO? In which color mode did you filmed?

    Note that even with a pro camera (eg. Blackmagic Production 4K Camera) when in Log mode, it is common to have artifacts and noise in deep blacks, as every Log footage is intended to pass thru Log-to-Rec.709 process where blacks get crushed down anyway. So, in proper Log workflow these artifacts get lost in the process (I had horizontal lines and heavy noise in D-Log in black night shots, but once grading was finished everything looked smooth)
     
  13. gruvpix

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    Actually you said you assumed. Implying you didn't read that anywhere either
     
  14. andrew259

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    You should read before you write...
    He didn't. He says he assumed the x5 was 400.

    He states the gh4 was 400.
    He neither assumed it was 400 nor stated it was 800.

    Careful in making comments that are incorrect and sound a little bit rude.




    Sent from my iPhone using Tapatalk
     
  15. DrMrdalj

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    Sorry, but there are no any assumptions or guesswork about GH4 mentioned anywhere in my post - its my favorite, so I wrote what I know for sure.
    The X5 is gueswork, for which I assume ISO 400 as well.
     
  16. Casey Preston

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    I was testing at at all ISOs in "none" as I tend to avoid log at low bitrates. My tests with DJI's log indicated that it pulls the blacks up and the flickering and noise is far worse than it is with none. I expect noise on the X5. The problem with the noise is that it flickers about 5 to 10 %IRE at 3200 ISO. Because of the flickering, it can't be denoised with the software that I have. The only option is to crush the bottom 15%IRE to get rid of the flickering and the footage falls apart with that heavy of a grade in my opinion. I tried increasing the contrast on the picture profile to artificially crush the blacks before encoding, but that is not ideal either. I am hoping that DJI can either solve the flickering and turn it into the normal noise profile I am used to seeing, or I hope they change the picture profiles so that the flickering is automatically crushed as the ISO is increased.
     
  17. gruvpix

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    My apologies, misread.
     
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  18. DrMrdalj

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    I experienced similar problem, even in lower ISO when tested D-Log, but did not test it extensively while waiting for firmware updates to solve similar issues... Did you make your tests in NTSC or PAL (as far as I can recall analog and early digital days, there was reference black level in US NTSC of 7.5IRE, while PAL which I use is 0 IRE for sure)? Did you monitor your signal in studio swing (16-235) or full swing (0-255) reference?
    I am sorry that my questions are not helpfull to you, but learning what you tested will help me focus my later tests. Thanks for the answers.
     
  19. DennisR

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    I always thought the lower the better and use 100 on my X5 normally.
     
  20. DrMrdalj

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    For majority of daylight shots with X5 you will get similar result using any ISO from 100 to 800, but every camera has its native sensivity of sensor, where it produces best possible dynamic range and least noise. At native ISO of sensor, its signal does not have to be gained up or down, so you get cleanest sensor output. That does not have anything to do with overal exposure (as you can change sutter speed and iris to influence exposure as well). So, if you are trying to get widest possible range from whites to blacks with least noise in shadows your best bet is native ISO of sensor, which for X5 happens to be somewhere arround 400. If you gain down 2 stops, to ISO 100, you should get good shots with no noise but with a bit less dynamic range; if you gain up 2 stops to ISO 1600 your result will be a bit more noisy in shadows and range should suffer as well, but if you gain up full 4 stops to ISO 6400 you will see obvious noise for sure... I hope this explains and helps :)