Aerial Photo Questions

[fslshooter]

I'm the photographer for a local minor league baseball team and the owner wants me to shoot aerial photos of the ballpark. I really do want to do the shoots for him; however, I've never shot aerial photos and I want to deliver the best possible product. Here's the deal. Between now and opening day in April 2005 they will be making major renovations to the ballpark and he wants aerial photo documentation of the progress. He'll provide the airplane and we hope to get clearance for 600 to 1,000 feet. My digital camera is a 10D and I have a 28-135, 3.5 - 5.6 IS and a 70 - 200, 2.8 L IS lens. Which of these lenses would be best for the job? Also, on opening day in April 2005, he wants a photo that he can use like a mural on the wall in his conference room. I don't know what size he needs yet but I seriously doubt that my 10D can deliver the product that he'll want. I expect I'll need film for that and I've not shot film in years. In fact the only film camera I have left is a 35 mm Canon FT QL with a 55 mm prime 1.2 lens. Will it do for the opening day wall mural photo shoot assuming he wants nothing larger than 4 feet by 6 feet or so? If so what film do you recommend. When I'm shooting the renovation progress digital photos I plan to practice with the film camera for the opening day shoot. All advice and tips will be greatly appreciated.

[steven]

For the mural photo you could do a pano photo.
That is where you take several pictures with your digital camera then use software (photoshop) to stitch them together into a single big picture.
There are several free programs that do this.

[steven]

For you lens question, I was orginally thinking how you could solve it with a little math.
You can do this, and if you want to know the formula let me know.
But thought about it and the easier way would be just to go to the ball field and get about the distance you expect to be in the air (500-1000 feet) and then just try different lenses and see which one get the whole field in view.
I think that should work.

[fslshooter]

Good ideas Steven but I don't think I'll be able to use a photomerge. I'll be shooting from a moving airplane thus I'll not be able to shoot from the same position for each part of the panorama. I'll try it though. Yes, I would like to have the formula that will help me determine which lens to use. Thanks!

[steven]

For the formula to work you have to know:
1) (AOV) The Angle of View for your lens (Canon Lenses have a PDF chart)
2) (DFS) Either the distance you are from the subject
OR
(WOS) Width you are wanting to cover with your shot.

With these two number you get

DFS = (.5 * WOS) / tan(.5 * AOV)
WOS = 2 * DFS * tan(.5 * AOV)

Now I will list my assumptions

Your subject is flat to your focal plane (camera).

Also you have two AOV for any lens, vertical and horizontal so remember the WOS will vary for your vertical and horizontal.

[Longwatcher]

You should actually have very little problem stiching the images together with a stich program given a few conditions

1. The plane must maintain altitude as best it can between pictures.

2. you need at least 10 percent overlap, but avoid more then 25%; 15% overlap between shots would be perfect. (if needed shoot as many as possible and just use the ones you need)

3. You need to shoot straight down or at the same angle each shot. This means essentially mounting the camera so the angle does not change. Small changes can be worked through, but large changes won't work without sensor, plane and terrain data you won't get from your 10D.

4. Time of day can not change significantly (meaning you have to do everything in about 30 minutes (if you were doing intelligence around 1030 and 130PM are best time, but for what you are doing just before or after noon is probably best)

The best way to accomplich this is to make a photo run. Have the pilot fly straight and level in a series of lines. If making a mosaic you want to limit your runs to no more then 5 and preferably no more then three, so that is you width. cover a little bit more of the stadium with each line. Given the 9 frame buffer and my experience with the 10D, you should be able to get about 10 shots on a run.

The really cool part is if you shoot two for one and you are at a good altitude you should get stereo pairs.

If because of the plane you may need to shoot obligue (instead of vertical (AKA Nadir)). Mounting the camera and keeping the plane level is very important if you want to stich the images. Pick calm days to fly. In this case to make a large mosaic, you need to fly the same flight line over and over, but change the angle of the camera between runs; otherwise no mosaic. [for the non-observant this is due to the fact the bottom of the image will be closer then the top of the image, so the camera needs to tilt up, but shoot from the same basic position to get the same perspective at the bottom of the second line as the top of the first.

Last note: if shooting a mosaic and given the 35mm camera format you need to shoot with as long a lens as you can get, while still covering the whole of your target in the photo run so as to minimize distortion, but within reason, just going with Photostich and photoshop, you should be able to get a nice mosaic out of your 10D. If nothing else it would be fun to try. If I can do mosaic's of live people, you should be able to do one of a non-moving stadium.

Just my experience as a former USAF Imagery Analyst

[fslshooter]

Thanks Steven - looks like I'll be using the 28-135

[fslshooter]

Thanks Tim - I'm gonna give the panogram a try. With luck we might be able to do #1 - #3. As for #4 we should be able to do every shoot within the 30 minute time frame. However, the season opener is at 1905 on 9 April 2005 so available sunlight will be poor at best and that's when I'll be shooting for the wall mural.

<you need to fly the same flight line over and over, but change the angle of the camera between runs>
I'm assuming that the line of flight should be parallel to a line between first and third base and beyond center field. Is this correct or should it be parallel to a line between second base and home plate and beyond that line?

[fslshooter]

Tim - I think there might be another problem with doing the panogram -- he wants the photo to show people in the grandstands and players on the field. Everyone will be moving about during and between photo passes therefore I'll never shoot the same scene twice even if I do manage to shoot from the same position. The grandstand and playing field will be constants (shouldn't be a problem) and fan movement might be OK. However, if we make a pass between innings, players will not be on the field. Also, if someone gets a hit during a photo pass several players will be running and in different positions from where they were during the previous pass. Won't this create a problem when I stich the images together?

[steven]

You would want to split the frames of the pano into the parts you just mentioned.
Try to get the whole field in one shot.
If that is not possible then I would go with one on each side of the diamond. Base ball action tends to be on the side the hit was to. So if you get some action it would not look too strang if one side was moving towards the ball and the other side was standing ready. Just avoid having two different actions in each shot.
To do the pano you probably want to take 2 or 3 sets so that you can pick and choose to make the best most reasonable shot.
Lots of work, hope you are getting paid well for the pano.

[fslshooter]

Steven - thanks again! I never tought of those options and I bet that'll work. BTW it should also be obvious that I've never stitched a pano together either since I called it a panogram in earlier posts - duhh. We might do the first renovation progress shoot early next week. If and when we do, I'll try to put a pano together then post an update. Jerry

[Jon]

Be sure you get a high-winged plane. With low wings, you'll have a wing in the way all the time, and forget about verticals. The pilot won't like flying one wing low for a pass either, unless he's orbiting, and that can get both of you feeling a little queasy.

Remember, when you're figuring angle of coverage for your lenses, the published charts are for 35 mm format. You'd need to re-compute for the smaller sensor of the 10D.

Does the owner want verticals or obliques? That will make a major difference in how you approach the whole project. At least your first time, try both (and verticals will absolutely require you to lean out of the plane) and try the obliques from all around the stadium (although sun position will be a factor here). Then sort out what the owner wants, assuming he doesn't have any firm ideas up-front.

Your FT-QL and 55 1.2 would probably be able to take in the whole park from 1000 ft. AGL as an oblique. Use as slow a film as you can, to minimize grain. Or consider for that one shot, renting a 6x6 or 6x7 with normal lens. Given that you'll be flying around dusk on opening day, you may not have much choice about film ISO.

I'd suggest that rather than trying to do a panorama by re-flying the line (flying for aerial photography is a specialty your pilot likely won't have), you consider (beg, borrow, or steal) a second camera and rig a bracket and remote release so you can fire both of them at once. A pair of DRs would be easier to work with than 10Ds because the remote release connector will be easier to make up. Use matching (tape them in place, too) lenses and splay them slightly for good coverage and overlap. You can bore-sight them on the ground. And the wider the lens you're using, the more overlap you'll want (because of increased distortion/stretching toward the edges).

[fslshooter]

Thanks Jon -The boss told me that the airplane is high wing and that the pilot has aerial photo shoot experience. We'll see. As for vertical vs oblique -- he has no choice on that one if I do the shooting 'cause ole ish won't be leaning out of any airplane unless it's on the ground and chocked. As of now I plan to use the equipment that I have the first time up and get as many shots as I can with both the 10D and FT-QL. Then if neither the pano nor film photo appear to be what we'll want for the wall mural, I'll explore other equipment options. Although it will be near sunset when I shoot, whatever sunlight we have should be good because the sun goes down behind third base line. Fans in the east grandstand along first base line look into the sunset across the diamond. This is good because the boss wants the picture on his conference room wall to be fans in the ballpark watching his team playing baseball.

[mdmedicgod]

legally you won't be able to get down to 600 feet. The absolute lowest you can go will be 1000ft. If that stadium holds holds more than 30,000 you won't be allowed no less the 3500 ft. (I doubt thats the case. since you said it was minor league ball)

Here are some aerial pics. I have shot. (not on assignment, but just test shots.)

http://img.photobucket.com/albums/v471/Skydogs/aerialpics002.jpg

This one was shot with 800iso film at about 1100 ft with75-300mm lens. The focal lenght of the shoot not sure. If it was dig. I could tell ya.

http://img.photobucket.com/albums/v471/Skydogs/IMG_0788.jpg
this one was shot at focal 130mm,ISO400 one hour before sundown.

Here are the 2 obvious observations. The first one is pretty grainy. Thats not important to my next comment.

You notice how the first one is clear and the 2nd has a little haze or distortion to it?

The first one was shot outside the aircraft (not thru the windows). The 2nd was shot thru the lexan window of the aircraft.

The side windows are on a cessna are usaually hinged to open out. If the catch is removed the window will open out and up flush against the wing. If its not removed the window will only open "out" about 12inches. Just something to think about.

Oh yeah one more than watch out for that wing strut.(thats the whitish object rightside of the frame.
http://img.photobucket.com/albums/v471/Skydogs/IMG_0776.jpg

These are just some things to think about. I know the dig photos look out of focus, but I was pilot and photographer on a bumpy day.

[Jon]

Hey, mdmedicgod - we ought to get together some time, since I'm just down the pike. Most of my good aerial work (film) has been out of Cessnas. Not a pilot - too many other expensive hobbies, but an aviation bug since way back.

[Jorgo]

Couple of basic pointers....

Aircraft windows are generally scratched and faded. Avoid shooting through them.

If the Cessna door is removed, wear a tethered Harness to prevent becoming a freefaller.

Attach all of your photography equipment to yourself or to the aircraft. If it drops out, you might damage the aircraft "MAYDAY" or be sued by a Baseballer's lawyer.

Wear warm clothes, use the headset for effective communication with the pilot, and learn how to switch off the microphone. It will be noisy in the slipstream.

For more hints, please see my article at:
http://www.fencecheck.com/articles/tips_tricks/article_01_02_2004_mike_jorgensen.php

Be aware of the aircraft engine's exhaust. If you shoot through that super hot air, your photos will be warped (and look like they are simply unfocussed).

[Jorgo]

One more thing....

If you have a choice, have the pilot to fly INTO the prevailing wind.

This will give you a slower groundspeed, and will give you a few more seconds to get all of your shots.

[fslshooter]

Thanks mdmedicgod and Jorgo -- excellent info and great photos!
To all - This was my first post on the forum and I'm overwhelmed by the responses -- I really, really do appreciate everyone taking the time to help me. I will have a comprehensive check list with me on the day WHEN that day comes -- unfortunately it looks like we're in a holding pattern now for the renovation shoots. Take care, Jerry

[mdmedicgod]

Just out of curiousity. I notice your in central, FL whats the stadium your gonna shoot (or town)

[fslshooter]

Jackie Robinson Ballpark, Daytona Beach. And you're correct our capacity if far below 30,000 -- more like 3,000.

[mdmedicgod]

Thats cool. I used to live in Sarasota. I did a lot of flying when I was there. Didn't know if had flown over the stadium before. Yes I have. Good luck

[PhotosGuy]

If you shoot Kodachrome 64 in sunlight, you should be able to shoot at 1/500 at f-5.6 which should give you good DOF as you'll be focusing at infinity.
You'll need the high shutter speed to eliminate the airframe vibration. Be sure not to let the cam contact the airframe, + it's best to not put your case on the floor, either. Carry some foam or bubble wrap to put the case on. (Vibration is even worse on helicopters, & those little screws in the cam & lenses...)
:wink:
You may need a good UV filter to cut haze, too.