Next weekend I plan to do aerial photography with a Canon XH-A1.

I have a few questions. But first I'll explain the camera setup and how I will control the camera.

SETUP
1) I've welded a steel, U-shaped bracket that cradles my XH-A1.
The bracket attaches to the tripod screw, and it straps to the handle.
2) The steel bracket will be attached to the wing struts of a Piper Cub plane. The camera will be 8-feet out on the wing (well beyond the propeller). I'm confident the camera is secure and will be OK in 90 mile-per-hour winds. The pilot has approved the setup.
3) I have a remote control with an 8-foot cable: record/pause/zoom/focus. I will control the camera from inside the cab.
4) I have a portable DVD player with an 8-foot cable. This is my monitor inside the airplane. The camera's LCD will be closed.
5) The front-facing microphone will be covered with a plastic bag and duct taped to prevent damage from force of wind.
6) The plane has four hours of gas. I have an 8-hour battery in the XH-A1.

QUESTIONS
1) Should I use the image stabilizer? I'm leaning towards yes. This is a small airplane (fabric construction). I don't know if the wing vibrates.
2) Should I trust auto-focus, or leave the camera set on infinity? I'm leaning to setting at infinity. If the image is constantly moving, then the camera may have a difficult time acquiring edges to focus on. Right?
3) Shutter speed recommendation? What will look natural? What setting would you use?

Is there anything I'm forgettingg? Helpful suggestions would be appreciated. I only get one shot at this.

Hi Eric,

1. Yes, you'll want OIS on in this case, to dampen any vibration transmitted through the mount.

2. If the lens is left at full wide focal length, then the AF should suffice. What are you using for a remote control, specifically? The Canon ZR-2000 wired remote controller allows you to remotely toggle between AF and MF, giving you the best of both worlds.

3. Depends on the selected frame rate and how bright the day is, and what kind of look you want. Default shutter speeds are 1/60 in 60i, 1/30 in 30F and 1/48 in 24F. Shoot in Tv (shutter priority) mode and the camcorder will keep the shutter speed locked where you want it and it will find the proper exposure automatically.

Yes, I have the Canon ZR-2000 wired remote controller.
If the camera goes to 'sleep' during a period of inactivity, then I hope I can wake it up with my ZR-2000. But I haven't tested that yet.

The ground will (hopefully) be at least 100 feet away when filming.
So I'll focus on infinity with a fairly wide-angle lens setting.

As for shutter speed ... I have more experience with still photography.
I wouldn't shoot stills from an airplane at less than 1/125th of a second.
Does the same rule apply to video? Yes, I'll use image stabalization.
I expect mid-day sun and plenty of light. I'll set ND to 1/6, and I'm thinking
about a shutter speed around 1/125 to 1/500. Comments?

If the camera goes to 'sleep' during a period of inactivity...Just disable that function.

Menu > Customize > Custom Function > C.Fn1 > Tune > Item 16 (Power Save) > Option 2 (Off) > Apply

Eric
See Chris's post reply item 3.
SLR Shutter speeds on your camcorder will result in a staccato movement on your movie. Choose your frame rate and stick with default.

Trev

The Piper Cub structure as I recall it is quite "live" in terms of vibration from its 4 cylinder engine at higher power settings but it has been a long while so my recollections may be faulty.

Try to avoid engine RPM settings which co-incide with or phase in and out of multiples or divisors of your camera's selected frame rate This gets a bit complex to calculate with 60fps and 24fps and pull-down and all the permutations and maybe too much fuss about nothing in any event.

Don't ride your pilot on this unless he is exceptionally experienced as he has enough workload to deal with and performance envelopes may be compromised if too much deviation from familiar power settings is involved.

Slightly richer mixture settings may smooth the engine vibration a little but again don't ride the pilot on this for the same safety reasons plus potential for plug fouling.

Structural compliance in the plastic casework of the AI will be a hidden enemy. This can be partially offset by having a generous baseplate to cover as much of the bottom of the camera as possible plus the added security over the handle you have already mentioned.

If it is possible to add tightly wedged dense foam in around the camera body inside of the "U" section and tape it in, this might be worhwhile as it will furthur dampen case compliance and dampen any vibration in the "U" section itself, keep cold air out, conferring some thermal insulation against the possibility of dewing after descent.

Highspeed tape or gaffer tape with the free ends facing downwind wrapped around the foam and frame might also help retain the camera in event of a tripod bolt working loose. Whilst a loosened bolt might not let the camera go, the camera may move about in the airflow and destroy itself otherwise.

Tape over the tape cassette door to prevent airflow into the enclosure and possible dewing when you come down from higher altitudes and colder air temps. Jets of airflow might also interfere with the tape transport.

Finally, the method you use to fasten the "U" section to the airframe. - Is this a clamping device around tubular sections near the wing to strut junction or does it fit to existing bolted fasteners.

Clamping metal-to-metal or metal-to-painted metal may set up surface or crush-deformation stress risers to fail much later down the track. Despite your pilot's assurances, I would be inclined to enquire with a licenced airframe engineer.

It would be a pity to inadvertantly damage one of these delightful aircraft. As I am sure you are already well aware, safety first and everything else is a bonus.

I'm assuming you've got FAA or CAA clearance for your mount. You're not allowed to bolt mount anything onto an aircraft without their approval.

Sounds like they're just taking their chances that an incident will not occur. Approval for their installation would be expensive to obtain if they are not using a camera mount with an STC for the aircraft model being used.

I hope we get to see some of the footage!

If you want to try deshaking the footage in post a faster shutter speed helps. Without it the motion leaves odd trails behind when the footage is stabilized.

FAA inspection/approval is required unless this is an experimental aircraft.

You could kill people if this thing shakes loose.

You may also want a rain cover to protect from insects and debris. I have had my camera hanging out the sunroof of a car doing 100mph down a runway chasing an aircraft (experimental ornithopter in Toronto) and the lens got Covered in gooshy insects... great footage, though a dragonfly might even crack your lens :P

Since US is the land of lawsuits it might be a good idea to secure it well. As to putting up a camera through the sunroof at 100 mph there might be similar considerations. If you did that on the German Autobahn I guess they'd throw you in jail on the spot.

Looking forward to some footage samples.

A locust leg, speared 5mm into your elbow at 130km/h is not a fun accessory to your day either. I guess there was always a reason not to drive on a stinking hot day with the window down, elbow on door for cool breeze rolling past.

Thanks for all your comments about mounting to the plane:
1) I'm bracketing to the airplane at a location where the pilot usually mounts his snowshoes or rifle. We'll be flying over unpopulated areas.
2) I'm using brackets that do not not crush the plane's tubing.
3) The bolts I'm using are drilled-through and a wire will be threaded through the hole to prevent the nut from coming loose or backing out (this includes the tripod mounting hole).

Great suggestions for dampening the camera even more with foam rubber.
Yes, I'll provide a photo of the camera bracket and footage after the flight. I'll summarize the setup and the precautions taken in one final post.

yes I understand the concept of safety wiring - in fact I made the instructional vid used by the FAA. As long as you understand that without FAA inspection/approval what you are doing is illegal - sounds like you are good to go.

Will the camera be in some sort of box? 100 mile an hour winds are going to push particulate into every nook and cranny.

I would definitely advise not orienting the cam in the direction of travel - backwards would be best - but even an oblique angle will keep the lens clean for a lot longer. Using a filter will make any dirt on the lens a lot more noticeable. Using a lenshood/mattebox would help with contrast but I doubt it would hold up to wind shear without major mods.

best of luck

From my experience shooting aerials with the XHA1, you definitely want the image stabilization OFF. Footage with it on is very "jumpy". It holds for half a second then leaps off to a different place.

Forget the plane.
Get one of these.
Or use a helmet cam inputting to a deck,

You have me curious what your filming like that.

Eric,

We've been experimenting with something like you are describing. Currently testing a strut mounted rig.

As I expect is the case with any aerial video, vibration and movements are the the biggest challenges. Out of the box, this particular system was very secure (and reinforced further by us) but as a result offered little isolation from the air frame.

Obviously the A1 with it's far superior manual control offers numerous advantages over the little Optura X1 we were using, but I'm not quite ready to hang an AI out there yet. [g]

One thing we're looking at was mentioned here:


Bob: If it is possible to add tightly wedged dense foam in around the camera body inside of the "U" section and tape it in, this might be worthwhile as it will further dampen case ...


We have some things to try, but if anyone has any sources for such material please post here.

I've been doing photography and aerial photography for years, but the video is relatively new. Much of the advice I've received is seemingly contradictory and I think simply the result of applying "normal" video principals to aerial video without actually having the benefit of first hand experience. Perhaps what appears as different advice is even more attributable to the fact that I'm still learning this stuff and don't fully understand the points being made.

For example:


Chris: 1. Yes, you'll want OIS on in this case, to dampen any vibration transmitted through the mount.

Chuck: From my experience shooting aerials with the XHA1, you definitely want the image stabilization OFF.


I've seen many discussions about IS for aerial stills-- from both "use it" and "lose it" perspectives. Personally, I can see little to no difference between the two.

Shutter speed:
Like yourself, I had to rethink my understanding of shutter speed to understand how it applies to video. Here too, there seems to be a difference of opinion: (?)


Trevor:
SLR Shutter speeds on your camcorder will result in a staccato movement on your movie. Choose your frame rate and stick with default.

Bob: If you want to try deshaking the footage in post a faster shutter speed helps. Without it the motion leaves odd trails behind when the footage is stabilized.


Perhaps both of the above are true? I definitely see the staccato movement Trevor refers to. Need to do some more experimenting obviously.

I put up some small thumbnail video of one of our first tests. Just send email to diffbeat AT gmail.com and the link will be in the "vacation message".

Pretty crude, but one small step.

Tim, thanks. Yes, I also noticed the contradictory opinions in this thread RE: image stabilization and shutter speed. I plan to use IS on, and 1/60 shutter, but I'll summarize all my settings in a final post along with a clip.

Also ... I plan to point the camera downward so the horizon isn't in the center. The terrain is my interest, and I don't want too much sky in the image influencing the exposure. I'm not sure what my downward angle will be (perhaps 15-20 degrees). I want a little sky, but not much.

I would definitely use the OS; it helps a lot with that type of vibration.

I don't think anyone is invalid in their comments. All answers address specific issues.

Perhaps a look at things point-by-point. view these comments with a jaundiced eye as I am no expert.



THE AIRCRAFT.


Engine and related airframe vibration, a consequence of extracting power from a piston engine. Frequencies at level cruise assuming engine rpm of 2250, may be in the ballpark of :-

2250 divided by 60 for Hz for crank cycles and out-of-balance on prop.

4500 divided by 60 for Hz for two bladed prop and slipstream buffet on wheels, struts, inner wing, fuselage and tail surfaces. This is a hairy beast to assess as there is the tiime taken for the airflow to travel down the fuselage.

What hits the wheels and struts will be most evident and also co-incident and is the source of much of the signature sound of a particular aircraft type as it passes overhead.

1125 divided by 60 for Hz for variations in the power cycle due to stronger cylinder versus weaker cylinder.

There may be multiples of these induced in the airframe but good design attempts to eliminate them.

Close to the outboard strut to wing junction, this might be expected to appear as a tiny combined vertical and twisting movement across the image plane at the tripod mount, amplified by resonances in the camcorder structure which will convert them to angular deviations off the optical centre axis.

Provided the vibrational frequencies do not co-incide with or phase in and out through head drum rpm or camera frame rates, I would not expect much of a problem. Issues will likely manifest as pixellation dropouts (drum rpm or tape transport) and periodic line doubling artifact in interlace footage.


Airframe compliance.

All airframes bend and twist, all a part of the natural dynamics of flight. A camera mounted in a fixed upper position on a wingtip, viewing across to the other wingtip, would likely observe small bending movements of the wings during turbulence penetratration or heavy pitch movements, a desireable view if not re-assuring to nervous fliers.


Airframe movement.

The direction an aircraft is pointed constantly changes with control inputs and turbluence, all part of the natural dynamics of flight.


THE CAMERA.

Modern small consumer video camcorders tend to be structurally comprised of molded plastic casework with metal re-inforcements added where needed. They tend to have flex or compliance built-in.

This can confer some impact protection but can come at expense of movements of the optical axis relative to the baseplate area.

This compliance may permit rapid periodic movements of the optical axis relative to the baseplate if the camera structure moves in harmony with eingine vibrations.

The lens area of the camera represents a relatively heavy resistive mass and the tripod mounting point sits well behind it and well beyond its centre axis, therefore bending of the camera structure between the mount and the lens body can be expected.

The imager chip can be expected to be firmly attached relative to the lens focal plane but bending deviation of the lens centre axis relative to the optical centre of the imager chip is not uncommon. This causes the image to move laterally on the imager.

Lenses, especially zooms, contain moving groups of elements within. Rapid vibrations can be expected to move them. This might be destructive over time.


INTERACTIONS BETWEEN CAMERA AND AIRFRAME.

There is a phenonema known as flutter which can destructively affect an aircraft. This is defined as the ability of a particular part of the airframe being able to move and extract energy from the passing airflow.

In normal R & D, this is vigorously tested for and eliminated as far as is possible.

The camera represents an object which does not pass smoothly through the airflow. It is possible for the combination of the camera mass, its alteration of airflow over the aircraft and flex within the camera structure itself or the effects of its mass in causing flex of a part of the airframe, to extract destructive erergy from the passing airflow especially if the camera becomes partially loosened by mechanical vibration.

Locking wires do not necessary confer protection. They can prevent a fastener from coming off but cannot maintain tension if the structures are altered by vibrational wear on contact surfaces. Plastic is a poor performer in this respect.

The onset of destrructive movement would be rapid with little or no warning.


RELEVENCE OF SUGGESTIONS.

Engine and related airframe vibration. - Optical image stablisation cannot respond in time. Digital image stabilisation is unlikely to. Camera shutter speed set higher is unlikely to assist.

Solutions - mount camera firmly with lens area of camera supported. Set lens field-of-view to its widest.

Airframe compliance. - Optical image stabilisation and digital image stablisation cannot respond in time. Additionally, much of the movement can be expected to be a minute rollling movement which image stablisation is not intended to deal with.

For rapid repetiion, high camera shutter speeds are unlikely to assist. For slower movements such as wing flex in across the wing views, a higher camera shutter speed will assist apparent image clarity.

Solutions - mount camera firmly with lens of camera supported. Set lens fied-of-view to its widest.

Airframe movement. - These motions are normally fairly slow and limited. They are a natural to the flight experience and should be faithfully reproduced, epsecially if part of the airframe is in the shot.

When the aircraft is maintained on a constant heading and the view directly forward or rearward, optical and digital image stablisation will most definitely help, but during course or attitudinal changes, a periodic stutter of the image will be introduced whiich will not be desirable.

A higher shutter speed will assist apparent image clarity but may cause an undesirable stutter effect at corners where human peripheral image motion blur might normally be apparent.

I would favour the higher shutter speed, say 1/100th to 1/150th sec but no higher unless a sharply defined strobe effect on the propeller blades is wanted.

If the view is directly to the side, optical image stabilisation may be beneficial but digital image stabilisation may cause stutter in the image.

Solutions - If the airframe is to be in shot, optical and digital image stabilisation should be off, as unnatural movements of the visible airframe may be introduced if it is a very insignificant part of the image. At worst however it will appear as if the camera has been hand-held.

If no portion of the airframe is to be in the shot and direction of view is to be forward or rearward, then image stabilisation may be benefical.

Set lens field-of-view to its widest.



ADDITIONAL NOTES.

Rolling shutter. - If the cam is a CMOS imager type, the rolling shutter issue will become evident in the propellor disk or any shadows it casts.

at very low altitudes, say 100ft, image shear in the lower portion of the forwards and rearwards views may occur and downward views of the flight shadow on the passing terrain may be unusable.

Automatic exposure controls. - If automatic exposure controls are chosen, set the response times to their slowest to avoid the camera attempting to rapidly hunt for best exposure levels whilst the propellor shadow falls across the lens.

Lens controls. Select manual focus. My personal preference is to cycle the zoom all the way to the tele and then back to the wide view, to cycle the manual focus to close-up then back to infinity. Hopefully this locates the moving lens groups into positions hard against end-stops where maybe a bit of grease will dampen movements due to high-frequency vibration.


Finally, except for aviators and the techically inclined, in-flight and ground-to-air vision without humans interacting becomes very boring.

What effect would there be by using a fast shutter speed then slowing the video down by 50% or so in the editor.

Unless there were action in the frame, wouldn't this help to smooth the vibration in the video and also eliminate the jerky look from a fast shutter? I don't know, just asking.

Also, when they shoot from one plane to another doing aerobatics, how is the camera held... just handheld by someone sitting in an open cockpit?

For the technical interest of those who take cameras into the air, a short clip derived from experiments with a compact home-made stabiliser, a sort of much shortened version of a steadicam. There was no float in the lateral twisting plane only in yaw and pitch movements.

www.brightcove.com/channel.jsp?channel=570698206

Hey Eric. No one has answered your question about shutter speed yet. No, it's not the same as photo. The normal shutter speed for video is double that of your frame rate. So, if you're shooting in 24f, then a normal shutter speed will be 1/48. It won't be blurry, video is much different than taking stills. If you're shooting 60i, then shoot 1/120. 24f will look more like film and 60i will look much more like video.

Wondering what would be an example of an application where high shutter speed in video (in excess of the ratio above) would be utilized?

Obviously with still photography high shutter speeds are used to either freeze moving subjects or to allow for a wider aperture and a desired depth of field effect.

Wondering what would be an example of an application where high shutter speed in video (in excess of the ratio above) would be utilized?

Obviously with still photography high shutter speeds are used to either freeze moving subjects or to allow for a wider aperture and a desired depth of field effect.

It's been called the gladiator effect. Essentially if you have a super fast shutter speed it will make all the motion overly crisp and give you the "gladiator effect". There is no motion blur. So, fight scenes, action scenes, intense emotional scenes could all use this effect when appropriate. Be careful though, its getting a little cliche.

As a pilot and user of the A-1 airborne, I would suggest flying your shoot either early in the morning or late in the afternoon when the wind is more likely to be calm. If you fly and video any other time while the air is bumpy, you will be wasting your time. This camera does not like to be moved. I have used 24fps with a 48 shutter speed with good results. Props spin and don't show any stoppage. As far as hanging your pride and joy outside an airplane, I never would except in a closed container of some sort. Get your pilot friend to take you up and try to hold the cam outside the cockpit and get a feel for the slipstream at the speeds you intend to fly. I bet that you will call this off after you sample the forces that your camera is about to be subjected to. You may prove me wrong and if you make the attempt, I surely hope that I am.

Best of luck,

Don

Just to explain a little further about shutter speeds and this only applies if doing image stabilization in post, if your camera is mounted on gyros you can ignore this.
If the plane / camera makes any unwanted movement that you'd like to remove and there's plenty of good software to do this ranging in price from free upwards then the standard shutter speed will impart a blur to the image in direction of travel. This in the original footage appears normal and at slow frame rates helps mask the perceived stutter, faster shutter speeds expose the stutter from shooting a low number of frames per second. At times fast shutter speeds and films low fps are used deliberately to impart a certain 'feel' to the footage. This isn't the intent here though.

Consider a simple unwanted vertical oscillation of the aircraft, could be from buffeting or rotor wash in a helicopter. Camera moves up and down, each frame will have matching up and down blur. Fine so far.

Now we use our stabilization software to remove the vertical movement. Unfortunately each frame still has the blur and watching the sequence of frames as per normal we see a blur trail that moves up and down. Shooting with a faster shutter speed will avoid this problem but at say 24fps certainly create stuttery footage if there's fast motion involved. However it all depends on what you're shooting here. If it's dog fights between two planes then you probably don't want to remove any of the unwanted camera movement anyway, you'd endup with a pretty unnatural look to the shot, your audience knows if the camera is in a fighter plane being flung around the sky it's not going to be a silky smooth ride. But if you're shooting aerial landscapes then usually the wanted motion of the camera is quite low and the impact of faster shutter speeds become less relevant.

In my seat of my pants, Z1 out the window of a Longranger, shooting at 100th of a second 50i there's no sign of stutter. I was shooting as wide as I could and we were at 500' so in the shots of us approaching the city motion is very slow, the 180deg turn over the bridge and Opera House are also pretty slow. When I did try to get tighter shots of places of interest the footage just became useless anyway although very fast shutter speeds might have allowed me to extract some stills however it was a very overcast day and there just wasn't enough light to really push the shutter speed up to 1/1000th.

Dear Eric,

You'll have no problem with airframe harmonics. If your wing and struts are vibrating noticeably you got much bigger problems than shaky video. The folks who warned of legal/FAA liability were right on the money. You make a modification to an airframe, which is what you're doing, the aircraft's insurance underwriters will have a field day if anything would happen. In fact, they'll have a field day if something happens that isn't remotely related to mounting the camera to the airframe. Lot's of people do it, but you should know the risks and so should the pilot/owner. I spend about 300 hours a year shooting from everything form helicopters to F-16's, still and video.

My guess is you're going to proceed with your shoot and hope you've covered everything. I understand. Just make very sure your camera mount doesn't compromise the aircraft structure or control cables. In the Cub the aileron cables run up the trailing edge of the rear of the rear streamlined strut. Your camera should be mounted as close to a hard attach point as possible, meaning where the struts attach to the fuselage (unlikely that will get the perspective you need) or the top attach point at the wing. While aircraft structures are over built, you can't assume that hanging a 5 lb camera plus mount, placing a 60 to 100 mph wind against it's profile and then pulling G's, changes the equation considerably. With a fairly mild dive and pull it's fairly easy to put 2 G's on the airframe. That means your camera and mount weight doubles, plus wind force, so you've got 12 to 18 lbs hanging on that streamlined strut. One possible solution to some of your weight problem is use an HV-20 instead.

I hope this helps, sure don't want to be the bearer of bad news, but I've done all this 50 to 60 times annually for the last 26 years. A fun adventure can turn into a tragedy in the blink of an eye.

Sincerely,

Jim Wilson
www.Jimwilsonphotography.com

Last weekend I mounted a Canon XH-A1 to an aircraft and went flight seeing. Please, no more FAA comments (re: external load permit).

There is a jerkyness problem with the video. Maybe someone can tell me the exact cause.

See this URL for a four-minute, small frame, edited version (Flash video).
The jerkyness is reduced since this is a small-screen version.
http://www.ericmuehling.com/video/aerial_shorts.html

See this full-size 10-second video that shows the image jerkyness problem.
Video compression is not causing the jerkyness (compression masks it a bit).
Can anyone tell me how to solve the jerkyness problem?
http://www.ericmuehling.com/video/bluffs_short.html

First, I read all of your comments before taking these aerials. Thank you.
All of your comments helped. Sometimes I had to choose between
different opinions, but they all helped.

POSITIVE RESULTS
Safe trip. Interesting footage. No dropped frames. No damage to my precious Canon XH-A1. The footage was generally well-exposed and in focus.

-- The camera's downward angle was perfect (1/8 sky, 7/8 ground) and exactly what I wanted. The horizon on the footage was level when the airplane was straight and level.
-- Shutter speed (Tv 1/100) seemed just right.
-- It drizzled once, but the rain drops on the haze filter dried without leaving a residue. Thanks to Alaska's clean mountain air.

ROOM TO IMPROVE
I'm dissatisfied with the jerkyness of the images. Not professional. It looks like the image 'jumps' (and when it jumps it blurs) about once every 1/2 second. Note: see the dead mosquito near end of the video on the haze filter. Even dead, its silhouette moves slightly. I think this is an OIS issue.

Auto exposure resulted in some extreme, fast changes when the
sun reflected off water, or when the amount of blue sky in the frame increased, or when glacier snow showed up in the image. The next time I'll set the response times (automatic exposure controls) to their slowest to avoid the camera attempting to rapidly hunt for best exposure levels.
I may even shoot in manual mode, although I hate having to ride exposure all the time.

PHYSICAL SETUP
-- Canon XH-A1 in a steel bracket. Canon ZR-2000 wired remote controller. -- Sony DVD player (as a monitor).
-- Foam rubber (1/4 inch) provided some insulation from vibration between camera/bracket.
-- Blue painters' masking tape covered all gaps and slots on the XH-A1 (to avoid air impacting the tape drive mechanism). The blue tape is easy to remove. The microphone was wrapped with a plastic baggie (to avoid air impact damage).
-- Covering everything (camera and bracket) ... duct tape.

XH-A1 SETTINGS
-- Tv (shutter at 1/100 second)
-- Manual focus (set at infinity most of the time)
-- Optical Image Stabilizer on
-- ND 1/6
-- Power Save option off
-- A1 filter

PROBLEMS
There appears to be a jerky frame about every 1/2 second.
Having a fuzzed-out frame is very consistent throughout the three-hour trip. I am guessing at the cause:
-- Engine/prop vibration. Note, the pilot and I experimented with different RPMs during flight and we minimized this issue. But it never went away. It's possible prop vibrational frequencies created harmonics in the wing, or in my camera bracket.
-- Optical image stabilization was constantly trying to correct the image motion (when no correction was needed). Proof of this is the mosquito*that hit the A1 haze filter near the end of the flight. The dead mosquito moves around as a result of the OIS.

WHAT I WISH I HAD DONE ...
Turn off Optical Image Stabilizer.

The Sony DVD player (my monitor) battery lasted three hours. The flight was slightly longer. I forgot to bring the 12-volt adapter that could have powered the DVD player.

-- Reminder to self: Do most of the low flying near the end of the trip. Mosquitos*fly low.
-- Next time: OIS off.
-- Next time: Manual exposure (on a sunny day the ground exposure doesn't change that much).

Was the jerkiness possibly caused by the OIS?

My bet would also be on the optical image stabilisation and that in combination with the higher frequency motion induced by airframe vibration and the highly textured subject in motion through almost the entire frame area, that it is unable to do its job properly.

There may also be a rolling shutter issue but it is near impossible to assess this on my computer on downloaded material.

The once per half-second period, (15-frame GOP??) suggests that the OIS over-corrections, if they are happening, are also, along with the movement of a higly detailed and textured subject through almost the entire frame, - possibly too much for the HDV codec to deal with and that resolution is being thrown out for maintaining frame rate and that even this is getting compromised by the data load.

My mext move would be, fit a wide-angle adaptor on front to slow the motion through the frame and of course OIS selected "off" all also to reduce data change between frames and if this doesn't work, bring a little more sky into the shot, just a little, to reduce the data change between frames.

I would also set the video gain to manual and 0db as this on auto, may also add some data load when sensor noise is amplified.

Looks good so keep trying.

Seeing your footage so far, I can well understand why you want this to work - magnificent.

I would be curious to see what it looked like slowed down 50%. If you shot at 100, then 50 would be close to normal. It wouldn't help the jerkiness, I suppose, but I think it may help the overall vibration and movement.

In case you can't re-shoot the flight and have to use this footage, you might try the new smoothcam filter of Final Cut Pro 6 (if you edit on a mac). It works usually very well, although it takes some time to analyse the footage.
If you are going to use it, remember that it analyses the entire clip, disregarding the in an out point, so capture just a small clip to test.

On reflection, bringing the shutter speed back to 1/50th or 1/60th sec might assist. Motion blur might soften the fastest moving portion of the image in the lower part of the image frame and the slower moving portions in the upper part of the image frame might be enabled to stay sharp.

I would not mind being in that aircraft with you to solve this thing. That country below looks magic.

I think your mount should not need any mods except for safety and endurance. If there is airframe movement as I expect there is, nothing short of a mount system which totally isolates the camera will make it any better.

The only extra thing I might be tempted to do would be to add more support for the camera very firmly in a compressed foam cushion surrounding the front end of the lens enclosure.

This support would need to be rigidly attached to the main mount and also be firmly cushioned against the camera body sides. This is intended to eliminate the possibilty of the camcorder lens enclosure flexing relative to the main section of the camera body and moving the image laterally on the sensor.

A wide angle lens on front of the camera if available as an accessory should help slow the movement down, assist sharpness and maybe help with any data overload of the codec.

To eliminate the HDV codec as an issue, try a test shooting MiniDV at SD if this option is available in your camera. If the problem is still there in MiniDV SD, then there is another goose to chase.

Good luck. Don't forget to try a polariser when flying over some water with fish and reefs in it. You'll need to rehearse that handheld in the cabin and perhaps make notes as to time, direction of travel.

gentlemen, this has been a fantastic thread.

i had some relevant experiences a few weeks ago w/ a dissimilar camera (1-chip Optura 50) but my jockeying around with mount, shutter speed and OIS may be useful:
I had to mount the optura to a diesel Kubota ATV ( a farm vehicle with full cabin, roll bars, windshield etc-- a tiny 'jeep' essentially). I used the same mount i had used previously to mount my XL-1 to cars and motorcycles-- from my moto experience i upped the shutter speed to as high as 1/2000, and the harmonics of the damned diesel engine simply played hell with the camera whether OIS enabled or not. I did tests of all shutter speeds from 1/60 to the upper end, no difference. To clarify: the quite solid Optura footage never showed a physical/mechanical tape dropout (ie the transport mechanism never glitched) , but the chip/imager could not cope with the harmonics of the diesel engine-- i can correlate the vibration with engine RPM using the on-board soundtrack; you can clearly see the imager stuttering in various power bands of the Kubota's motor.

Again, I know the cams are different, and the OIS parameters/performance of an Optura vs an A1 are likely significantly different, but i can't help but think that resonance from engine is always going to be a factor in any set-up that is'nt mechanically optimized for vibe isolation. And the relative wind speeds you're trying to work in are going to certainly exacerbate things.

My dad flies an Aztec and we've talked at length about shooting possibilities from it-- it's not a Cub, of course, and his Aztec has a plexi'd camera port up in the front wheel well, which makes cam mounting just an internal mount issue.

For an external solution I'm wondering if the smallest underwater camera housing available-- mounted to the Cub's strut-- might make life easier on you. You've already sussed out the remote-operation/monitoring thing so maybe that's an alternative?

Just my observations that we cannot expect OIS or full-wide lens settings to replicate dedicated (and spendy) aero-mounts when such severe operating vibration/wind-resistance harmonics are going to be present

Good luck, mang!

MRP

That is good footage for the first go around Eric. I have had my A1 out the window of a Cessna 182 using an adapted tripod (we took the front passenger seat out and taped up the window to the wing.) Twice we went up to shoot and twice I got some very bizarre vibrations from the engine for most of the footage. I noticed that the vibrations correlate to the rpm of the engine. I noticed more blurriness when using OIS (with my experience). I also figured the vibrations were transfering from the floor to the tripod, which I could help fix by placing the tripod on some hi-tech foam. I shot all manual- 24p Shutter at 48 with no filters (hood off). Yes, 80-90 Mph winds are tough to handle, but there are times the plane can slow down enough for it to be tolerable for the camera and my arm. In your situation where water and bugs are around, protect the camera in some way without creating too much wind resistance. Also, make sure to take the hood off of the lens. That will lessen wind vibrations.
My guess on your trouble with vibration is that the camera needs to come in more on the wing. It might be less shaky that way. Even if the prop is in the way, you can experiment with shutter to avoid the prop. Better yet, could you mount the camera under the airplane?
For strait down shots, I was thinking you could modify the plane to have a small window in the floor of it. Is this possible without disaster? I thought that would be nice for those kinds of shots.
Keep up the good work! I think your first round is quite nice considering all of the hurdles involved.

Oh, and to help in post, I have had good results using the new smooth cam feature in FCP6. You may want to experiment with that. It will crop your image but sometimes it does quite well in bumpy situations.

Michael, GREAT idea about the underwater housing.
Some of my preparation time was spent taping the
openings and seems of the XH-A1 so high speed wind
would not impact the camera's internal tape drive.

I spoke to the pilot today. The next time we do this we
will spend the first 1/2 hour or so flying at various
engine RPMs as I observe image jitter. We'll find the
engine RPM that produces the least jitter and fly with
that (providing it's a speed that will keep us airborne).

Hows the progress? If it goes well before next april do you think you would be able to help me with this?
http://dvinfo.net/conf/showthread.php?t=103450
I am also using a canon A1 so footage would easily integrate with my film....thanks

I don't intend to fly again until next spring (2008).
So there won't be any more to report until then.

I have concluded that most of the vibration problem
was due to the engine rpm, and on this light airplane
the engine vibration transfered easily through the wing
strut to the camera. Air turbulence was also a factor.
The fabric wing on this small airplane was simply
too bouncy to mount the camera.

The next time I plan to mount the camera on the
airplane's floats in hopes that location vibrates less.

I'm also considering another mount. I'm looking for
8-inch diameter PVC pipe. I plan to cut it 2-foot long
and slice it twice length-wise.

Next, I'll wrap the XH-A1 in foam packing and
close the PVC clamshell around the camera, then
wrap the pipe with duct tape.

That will provide a solid shell around the camera
to mount to. This will encase the camera in more
vibration-dampening foam than before. As you can
see, I enjoy tinkering and experimenting.

I also shoot aerial video, but mine is done from inside a Mooney at higher speeds. My initial reaction upon watching your clip was "hey that was shot from a helicopter", i.e. low-RPM engine vibration. But my next reaction was "hey that's wind vibration".

Vibration can really plague airplane owners. One of my friends is currently battling a problem where his compass vibrates so badly that the liquid inside it is frothing. Mechanics can't seem to fix it.

But you might strongly consider the possibility that it's not the engine creating the vibrations, but rather the wind. If your mount is not completely 100% rigid (and it is impossible to make it 100% rigid!) then the wind can cause a tiny amount of oscillation. In this case, the faster your airspeed, the higher the vibration frequency. The problem is that the engine speed is linked to the airspeed, so how do you know which problem to attack?

There is a trick. You might be able to differentiate wind effects from engine effects by having the pilot slow the plane down to a very slow speed, pull the nose up, and rev up the engine while keeping the speed very slow. This is typically called "flight at minimum controllable airspeed", and every pilot knows how to do it. It will change the whole dynamic so that the engine is running just as fast as normal, but the wind effect will be drastically reduced. If you find the vibration changes, then it may be the wind doing it. At the other end of the spectrum, you could have the pilot create a high airspeed, low RPM condition by pulling the power and lowering the nose to pick up speed. See what difference that makes to the vibrations.

I'm going to want to talk to you some more offline, as there aren't too many of us using the XH-A1 for aerial videography, and we might be able to share tips and experiences.

Dave Morris

Thanks for your post Dave, please discuss this topic online right here, for everyone's benefit -- much appreciated,

I've done some aerials over the years, both from small and large helicopters and small planes.The most important thing I found is the pilot. If you get a pilot who is experienced at aerial photography flying, you're halfway home already. One time I was having difficulty from a helicopter with the wind, and the pilot went way upwind and tilted over and sort of drifted back over the site, and it was nice and smooth, moving with the wind at a perfect speed.

My single most important piece of equipment for aerials is...a barf bag.

I've been thinking about using some housing with windshield (like 6.6x6.6" UV haze filter) attached with dedicated mount, and independent mount for the camera behind. That setup should absorb most wind vibrations without transfering them to camcorder. If the system is sturdy enough, optical disadvantages should be minimal, similar to adding another glass in matte box. After all, big budget pros usually keep their cameras behind some nice piece of glass.

Do you guys have any experience with using protective housings for aerial videography?

Thanks for all interesting hints!

... there aren't too many of us using the XH-A1 for aerial videography

But our numbers are growing... [g]

Not ready to hang a $3k+ cam out there yet, but still testing various systems myself. Thanks, Eric for following up and posting some footage. I see pretty much the same vibration with the aerial video I've taken to this point.

We just took ownership (pilot partner and myself) of our own Cessna 172 this past week and expect to be continuing to test options as well.

I don't think anyone would dispute that for mission critical video you really need to go the helicopter/stabilizer route. But of course that's big budget projects with clients and their deep pockets. There's a lot of us who fly & shoot who would like to develop techniques for shooting usable video without having to invest a huge chuck of change.

We bought and tested this unit on one of our experimental planes:
http://flyfbi.com/html/camera_mount.html

Kinda' fun and cool, but again, the vibration was a major drawback.

The construction of this unit and many others is clever from an engineering perspective, but surely comes up short as far as the results are concerned. Made by engineers not photographers I guess.

Haven't tried this, but hard to see how it would be much different (?):
http://www.skyeye.com/Applics.html

This is the best I found so far for remote, fixed wing footage, and I've emailed these folks with some questions. Very expensive however:

http://www.lastrefuge.co.uk/data/aerials/AerialTechniques_page9.html#exter_mount

Do you guys have any experience with using protective housings for aerial videography?



Check the websites of the manufacturers of helicopter mounts for design ideas. Although the OP is using an external load permit for his ops, I don't think they issue those in the lower 48 (perhaps someone can post a citation to the contrary). If you develop something you could work with the FAA on getting an STC for various aircraft. There's definitely a market.

I would have some serious concerns regarding the last refuge configuration or any similar other which aerodynamically loads the Cessna strut so far outward below its centreline.

Where the wooden contoured clamp goes on, there may well be a solid internal fitting which anchors the strut tube to the wing. This may well function as an anti-crush device but it is not the original design intention.

Readily apparent, is the torsional leverage the camera and remote controlled mount will have over the wing-strut attach point.

If the attach point is a pin arrangement without allowance for torsional movements in the strut tube, then torsional loadings are going to be transferred to the attach point on the wing and to the fuselage attach point as well.

A fatigue fracture at the wing-strut junction might be induced but not become manifest until long after the mount has gone soemwhere else. Failure at this attach point is not something I would like to contemplate when airborne.