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Everybody’s a Photographer

drone aerial photography concept
Because there's a bit of Spielberg in all of us

Aerial photography

Camera mounts & gimbals

How can such a simple device play a critical role? Well, having a super stable quadcopter without a good camera mount is analogous to a good camera with lousy lenses. Premium video can be easily compromised by a wobbly camera mount with sluggish controls, often a consequence of substandard material, hardware and design. To select an appropriate camera mount, first determine how many axis needs to be auto-compensated by gyros and/or accessed on your transmitter. For single-axis camera mount (e.g. Gaui G-210705 & HM-UFO-MX400-Z-32), look for a rigid structure to carry the camera. Since single-axis gimbals are sometimes used on smaller quadcopters, minimizing weight is often a contributing factor in reducing structure. As for 2 and 3 axis camera mounts, there are two basic designs. The lighter simpler pivot design on a quadcopter can be very effective in turning out quality video without too much fuss. Strategically placed servos drive the structure to pivots on 2 or 3 axis. Pay special attention to the both the material and the joints used to establish a structure that can retain its shape while holding and moving the weight of a small to medium size camera. Flush bearing is an integral part of the pivot design (ALA3CM01) and so are high quality metal gear servos of the appropriate size, speed and torque. Pivot gimbals improvised with hinges (Helibest) results in uneven movement and will eventually fail prematurely. For heavier cameras, you might want to consider the track mount gimbals using a combination of tracks and pivots. The track mount gimbals can be quite heavy which can affect both payload and performance. You will need at least a very powerful hexacopter or octocopter.

The size of and dimension of your camera can greatly affect you choice for gimbals. First make sure the camera will fit in the gimbals with the proper alignment of mounting holes and hardware. As with helicopter, quadcopter and multi-rotors, center of gravity on a camera mount is also key consideration. When a servo attempts to move both the gimbals structure and the camera, the combined center of gravity will need to be close to the pivot point. If the center of gravity is too far off, the servo will strain to lift and offset the difference. Forcing servos to lift unnecessary weight will cause undesirable jerky movements and reduce the life span of both the servo gears and motor. A versatile camera mounts for your quadcopter can usually be adjusted to accommodate a variety of camera configurations. Before attaching your gimbal to the base of a quadcopter, first test the center of gravity with the camera that you are using. Whether if you are using a one-axis camera mount vs a 2-3 axis, the procedure is the same. By holding the gimbal near each pivot point you can see if the camera is tipping towards a certain direction. You should move the camera in the opposite direction on the mounting plate until you achieve the best balance.

Video stability

Because a quadcopter is a moving platform that can tilt, roll or pan, it’s often difficult to consistently stabilize a subject in your frame. Fortunately, many of the more advanced camera mounts can automatically compensate for a quadcopter’s movements. Continuous signals from onboard attitude sensor or 3-axis gyro in combination with your transmitter input effectively instruct the servo(s) on the camera mount where to point. This compensation significantly stabilizes the image. As with each apparatus, there are limitations as to how fast the servos can move. So the stability of the quadcopter is paramount in provide quality footage that you can later utilize. Even with the best camera mount, you will still see some residual motion which can be filtered out by utilizing a video stabilizing software such as Mercalli which is a very practical software tool for the average videographer or photographer.

On the other hand even the quickest multi-axis camera mounts and the smartest stabilizing software cannot neutralize excessive video vibrations. These critical elements must be addressed at several different levels. The root of most vibration problems starts from the quadcopter’s rotors with well balance motors and propellers producing less vibrations. Some motors are dynamically balanced at the factory such as brushless motors use on the Turbo Ace X830 & Matrix. Similar to balancing a tire, each motor is spun at high speed and small amount of material is added to a few selected edges of the motor drum until the rotation is completely smooth. As for propellers, a similar procedure can be used to balance them with an inexpensive blade-balancing tool. Propellers are usually quality controlled but not factory balanced so end users need to complete this process to reduce vibrations for each individual propeller. Finally, even with properly balanced motors and propellers, there will still be some residual vibrations. The last line of defense is to isolate the vibration from the camera mount. For heavier cameras & gimbals, look for a more substantial vibration dampening system. Inadequately matched dampening features sometimes weaken a gimbal’s foundation, and the extra layer of components becomes counterproductive.

The upgrade trap for hobby sized quadcopters

In general, camera and gimbal payloads exert too much stress on smaller quadcopters, the main cause of deteriorated video stability and shorter flight time. Rampant problems call for an ever increasing amount of remedies. From carbon propellers that exert too much force on stock motors to larger motors that exert to much force on weaker frames, solutions often lead to new problems. Misinformation and exaggerated upgrade claims from factories, vendors and overzealous “end user” reviews often leads to unrealistic expectations. The rule of thumb is don’t expect miracles if you combine several upgrades on hobby sized quadcopters.

Typical CX-20 Auto Pathfinder quadcopter upgrades start with a set of stiff carbon fibre propellers (around $60), a good brushless gimbal for a Hero 3+ (around $250 + installation) the Hero 3+ itself (around $350). Oh let’s not forget to add the telemetry and video transmitter to the payload (around $200). Then for extra measure, why not double the battery to get more flight time (another $50). Most hobby quadcopters similar to the size of the CX-20 Auto Pathfinder will be overloaded at this point. The controls will be sluggish. The flight time has only increased from 20 to 30 minutes. Once you look at the resulting video, reality sets in. Perhaps the online video that you are desperately trying to replicate took 20 takes on a perfect windless day.

Go big or go home

In the world of quadcopter there is no substitute for size and power. The stock propellers that come with a quadcopter is a very good indicator of the quadcopter's capacity to carry a payload because you are not forcing small stock motors to drive larger after-market propellers. If the plan is to stick with a small camera without an auto-stabilized gimbal, a minimum of 200mm propellers will suffice. Flight time will be approximately 10 to 20 minutes with a camera onboard. If you try to maxout the flight time like the ones on YouTube, you risk damaging expensive batteries. When you use higher capacity batteries on a small quadcopter, you are trading performance and video stability for marginal flight time gains. If you go overboard with a huge battery, the flight time will actually decrease. For most videographers, an ideal setup is a compact camera mounted on an auto-stabilized gimbal (camera mount) with video transmitter for live video feed. Video stability and flight time with this larger payload requires a big quadcopters with 300mm propellers for about 10 to 15 minutes of flight time depending on the size and weight of the battery that you are willing to implement. Going bigger with 400mm + propellers will yield 30 to 45 minutes of awesome stability.

Structural strength, payload and stability

At this juncture, you are well aware of the importance of payload. So, please be warned that differentiating between flying weight and total weight with and without battery is very different. Payload, battery sized, flight time, stability and performance are all inter-related. A chart may be very misleading because you won’t have the stability and performance factor that is critical to a secured flight with expensive equipment on board. Always go on the safe side when specking your equipment for payload. If a quadcopter is able to pull 1kg, which may mean that the quadcopter will barely get off the ground with 1kg. What if you add a larger heavier battery or if the battery gets weaker after 2 minutes?

Another often overlooked factor, structural strength, will significantly affect the ability to carry heavier camera equipment such as DSLR cameras. Most quadcopters has the payload capacity to carry 1kg but lack to structural integrity to sustain the weight without flexing. Flexing which causes a dangling and bouncing effect is detrimental to both video stability and flight stability. Especially when dealing with a larger wingspans on a hexacopter or an octocopter you need to make sure the overall structure is sufficient to suspend the payload in addition to the carrying capacity of the multirotor helicotper.  Look for a well braced super structure which will sustain the addition weight without sagging the center hub where the weight will be attached. Hexacopters and octocopers which are integrated mainly from carbon tubes are generally results in a weak central hub and arms that are too and thin for the wingspan. Although DSLR cameras are getting smaller and lighter, you are still encouraged to acquire the most powerful quadcopter, hexacopter or octocopter you can afford with special consideration for adequate payload and structure to address proper performance.

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