The View Up Here

Random scribblings about kites, photography, machining, and anything else

Archive for March, 2015

Frankentransmitter Part 1 – Planning

Posted by Tom Benedict on 28/03/2015

If you haven’t seen a lot of kite aerial photos or posts from me recently it’s because I’ve been categorically spanked the last several times I’ve gone out. If it’s not weather, it’s my gear. If it’s not my gear, it’s my batteries. If it’s not the batteries, it’s just life being a pain in the rear. It’s depressing, so I haven’t been writing about it.

Some time back I decided I wanted to rebuild all of my KAP gear from scratch, but I never got around to it. A couple of things have brought this to the fore on my list of projects. The main one is this recent history of blown KAP sessions. But a second and much more motivating reason is some phenomenal work by Dave Wheeler, a fellow KAPer. Dave built a really beautiful controller he described in the KAP Forum and documented on his project’s Github site. The core of Dave’s transmitter is an Arduino and the RF board out of a HobbyKing 6-channel transmitter – the same transmitter I’ve done KAP with for years. Dave’s transmitter is honestly more than I need for my style of KAP, but now I have no excuses left. Time to design and build the thing.

Before launching into my plans for the new KAP gear, here are all the issues I plan to fix:

Ease of Use – My gear isn’t easy to use. My ground unit consists of an RC transmitter and a wireless video screen. To use them I have to attach them together, then stick a cloverleaf antenna on the video receiver. To pack up at the end of the day I have to reverse the process. I go through a similar process on my KAP rig: attach legs, attach a feedline to the video transmitter, then attach the antenna to the feedline, etc. There are so many steps, it’s easy for something to go wrong. I want to be able to pull an already assembled KAP rig out of my bag, stick a camera on it, pull out my ground unit, and fly. No screws, no plugs, no antennas to install, no nothing. Just pull it out and play.

Flexibility – I have several KAP cameras: Canon T2i, Canon A650IS, Canon A2200 (x2), and a Gopro. Depending on the wind, the subject, my mood, or what have you, I want to be able to fly any one of these. In the case of the A2200 cameras I want to be able to fly both at the same time and do four-color photography. Right now I have to swap tilt brackets when I change from one set of cameras to another. I want to have one tilt bracket that’ll take the camera of my choice without swapping or modification, even if it looks like Swiss cheese.

No Dangly Wires – One of the features the brushless gimbal designers incorporated a while back is either hollow cored motors so wires can pass through each axis, or slip rings so the signals are passed through without wires to twist. With the exception of the shutter cable and video cable, there’s no reason to have any exposed wires on a KAP rig. I’d like to have jacks on the bottom rear edge of the tilt frame so that all camera cabling terminates right there on the tilt frame and doesn’t have to pass from one moving part of the rig to another one. I want to make custom cables for each camera so they’re as short and stout as possible.

Suspension Independent – My current rig has this already, but it’s a feature I want to bring over to the new rig. I want to be able to use a Picavet, a pendulum, or whatever suspension I want without having to rebuild the top end of the rig. I like the system I already developed, so I’ll adapt that to the new rig with few, if any, modifications.

High Badass Quotient – This is a personal thing. I want my gear to look like it was made that way on purpose. My CNC mill is back up and running, including the rotary stage. I’d like to use it for most or all of the parts for the new KAP gear. We’ve been testing some new surface treatments at work, and one stands out for home shop work: Cerakote. It’s a ceramic coating that can be applied in the home shop. The coatings are amazingly durable, really good looking, and stand up to wear and tear better than any paint I’ve ever used. They’re about as durable as good anodizing. Every bit on my rig will be covered in Cerakote. I want Hasselblad to be envious by the time I’m done.

What I want, in the end, is a much smaller, completely self-contained ground unit I can just pull out of my bag, turn on, and use. I want a KAP rig I can pull out of my bag ready to run with no chance of a popped wire, broken connector, missing antenna, etc. I don’t care if I take on another 100g in the process so long as it’s flight ready right out of the bag. I want my KAP bag to come down to a winder, a rig, a ground unit, and the kites of my choice. And everything should just work.

After all, isn’t that what we expect out of every other piece of camera gear we own? That’s what I want for KAP.

The design phase is next.

– Tom

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Posted in Engineering, Kite Aerial Photography | Leave a Comment »

Friggin’ Cable Releases

Posted by Tom Benedict on 24/03/2015

A year or so ago I bought a remote cable release for my camera. I wanted something that would do time lapse, long exposures, delayed exposures, you name it. Turns out there are scads of these things out there. They all seem to use the same basic electronics. The difference mostly lay in the packaging and form factor. So I picked one, used it, and got a lot of good use out of it.

In my post about batteries I mentioned that I managed to kill my cable release by letting the alkaline batteries I’d put in it go stale. And leaky. And corrosive. And… >deep breath< Whew! Let the past be the past.

Wireless Timer Release

Anyway, while shopping for a new one I saw that Yongnuo had a wireless version for not too much money. I picked one up off of Ebay, tested it, verified that it worked, and… promptly had it fail when I took it out in the field. It would focus on a half-press, but wouldn’t trip the shutter on a full-press. The weird thing is the display said “Release”, so I knew the switch was good. But it wouldn’t actually do anything.

The wireless release comes as two components: a handheld transmitter with a display, button pad, shutter button, etc., and a receiver that you stick on the camera. The receiver doubles as a cable release, complete with a shutter button of its own. When I tested it it worked perfectly! So I wasn’t entirely dead in the water. Just mostly.

The Yongnuo MC-36R also allows for a cable to be used instead of the wireless connection. Today I made a cable using some spare 1/8″ stereo headphone plugs and some spare wire I’d salvaged from a dead sensor at work. I built the cable, plugged it in, and… had the same exact behavior! Half-press would focus the camera, but the full-press did nothing!

Digital devices are usually pretty self-contained. Except for witnessing the battery-driven demise of electronics, there’s typically very little you can do to salvage something that has stopped working. But this was sounding a lot less like a logic fault in some chip and a lot more like a failed connection. So I opened the unit up.

The MC-36R has two circuit boards inside. One houses the LCD, buttons, and processor. The other houses the 2.4GHz transmitter, the channel-selecting DIP switch bank, and the 1/8″ stereo jack for the optional cable. I expected the connection between the two to be some sort of three-wire UART. Instead I found Vcc, Gnd, 1, and 2, and the #2 wire had popped out of the connector. ??! Each state of the switch had its own discrete wire! I shoved the wire back in and everything worked perfectly!

When I put the thing back together I saw what the underlying problem was. There’s almost no room inside the thing. The connector for the 2.4GHz board bumps up against the big honking half/full press switch for the shutter. So if one of the wires is even slightly out of place when the unit is assembled it’ll get pulled out of the connector. In my case the #2 wire was the one who lost. A little care during re-assembly and I avoided the problem.

I have to wonder how many of these things fail during QC testing. I wonder how many more are eventually returned when they quit working. In the event mine dies again I can replace the connector with a new one. It’s a 4-conductor micro-JST. I have a bag of them. Meanwhile I’m back up and running. And now I have a cable I can use, too.

– Tom

Posted in Electronics, Engineering, Photography | Tagged: , , , , , , , , | Leave a Comment »

Bend a Little and Have Fun

Posted by Tom Benedict on 14/03/2015

Years ago I joined a group called Utata – a group of photographers, writers, and like-minded folks who enjoy lively discussion and creating and promoting art. Utata has several ongoing projects as well as two big annual projects. At the time I joined I was almost exclusively doing aerial photography from a kite, so I found myself unable – or to be truthful, unwilling – to participate in many of the projects. One in particular, the Iron Photographer, routinely kicked my butt.

The Iron Photographer project is modeled along the same lines as Iron Chef: All of the participants are given the same three elements to work with – two compositional and one artistic or calling for a specific technique – and are asked to create new, original works. On the face of it it’s a welcome challenge for any photographer. But if you’re limiting yourself to creating only aerial landscapes it’s less of a challenge and more of an impossibility. Take, for example Iron Photographer 211. The elements were: 1 – a bowl; 2 – something broken; 3 – photographed simply. You can make an aerial photograph that would qualify, but it would be a mighty tall order. I quickly became frustrated and stopped participating.

The lesson I didn’t learn back then was this: bend a little. The whole idea of Iron Photographer is to knock people out of their comfort zone and get them to put their thinking caps on. I staunchly refused and missed out on a lot of opportunities to have fun with a camera.

After a three year dry-ish spell I’m finally starting to get back into photography. This time not all of it is aerial. I figured I’d give Iron Photographer another try. I started with IP 212. The elements are: 1 – the photographer’s hand resting on a flat surface; 2 – an object resting in the palm of the hand; 3 – holga-fied. The only element I needed clarification on was that third one. The idea is to make it look as if the photograph came out of a Holga camera. I don’t own one, so I downloaded Holgarizer – a Photoshop action that would produce a similar result.

The Iron Photographer projects make you think. Yeah, I could’ve done a set of photos of my hand on a table with various objects in it. But where’s the fun in that? Better to ask why my hand is lying on a flat surface. Which flat surface is it lying on? What is sitting in my palm? And who chose to make the photograph? Of course for the requirements of the project it must be the owner of the hand. But from the standpoint of the narrative all of these are open-ended questions.

The first idea that sprang to mind felt cliché even before I made the photograph, but I made it anyway.

As Found

It’s not a happy picture. I wanted it to look like a crime scene: a dingy floor, the weak greenish glow of fluorescent lights, a pallid cast to the skin, and stark shadows outlining someone’s final act. In fact I’d just scrubbed the floor clean so I wouldn’t contaminate my prescription medication. The lighting was all provided by daylight-balanced strobes. And I’m actually pretty tan at the moment. But who’s keeping tabs? The only really stressful moment came when I started to clean up and realized I’d misplaced one of my pills. As tiny as these things are, they’d be lethal to my cats. I spent the time to track down every single one.

Then, of course, I saw that another participant in IP212 had come up with the same idea. Darn!

That’s when I started to wonder: Did the owner of the hand have to be the one who put the object in it? When I figured out the answer was “no” the idea for the next photograph came to mind. I opened the door to my daughter’s room and said, “Wanna be a totalitarian? Grab your boots!”

Of all of the events that mark the passing from childhood to adulthood, one my daughter celebrated with no small amount of gusto was the successful completion of her last high school PE class. She proudly announced that her only reason for wearing tennis shoes to school was null and void, and that she wanted combat boots. She and Rydra picked out a pair that would make any real princess proud.

“Ok,” I told her. “I’m gonna lie down on the ground outside, and you’re going to stand on me.”

Stunned silence. “What?!”

Even I had to admit she had a point. But once I described the photo to her she got into the swing of things.

The Regime

It took a while to work out the balance of the lights. Then it took a while to work out the best angle for my arm. Then it took a while for us to work out how she had to stand so it looked like she was bringing all her weight to bear on me without actually crushing my hand under her heel. In the end she wound up with one boot on and one boot off, standing en pointe on one sock-covered foot while squishing my hand with her booted heel. Early on she was tripping the shutter, but the contortions she was having to go through were more painful than what she was doing to my hand. We switched to a self-timer for the final few frames.

Though the Iron Photographer project lets you tag up to six photos for submission, you’re only really supposed to post one to the discussion forum. I chose this one. This becomes important later.

I had a couple of other ideas I wanted to try, but by this time I realized my first two photos were real downers. Despite the smiles and the laughter and the fun my daughter and I had making The Regime, I knew that no one looking at it would feel anywhere near as upbeat as we did. So I set morbid aside and went after something different.

The challenge called for something to be in the palm of the hand. It didn’t say that it had to be a physical object, just that something had to be there. I thought it would be neat to put something less tangible than a physical object in my hand. “I know!” I thought, “Light!”

I went through a couple of iterations on this one: I could have a beam of light coming out of my hand. (I might still try that one at some point, but not as part of this IP.) I could make the palm of my hand glow. The idea I finally settled on was to have an object in my hand influence light rather than generate it: a prism.

Years ago I worked in a lab that etched diffraction gratings into silicon using MEMS techniques. It was kind of a one man show, so I was responsible for the photolithography, the anisotropic etching setup, maintaining the safety and materials in the lab, characterizing the gratings we were making, etc. I also photographed the bejeebers out of everything we did on color transparency film. To see how much power went into each order of the gratings we were making we aimed lasers at them and measured the power in each of the return beams. It was an important step in characterizing the gratings. But it made for an even better photograph.

Each photograph was done as a single long-exposure frame. I’d turn off all the lights in the room, open the shutter, “paint” out the beams using a business card or some other flat white object (my hand stood in a couple of times), then turn on the lights for the prescribed amount of time and close the shutter. As painstaking as it sounds, once you got into a routine it went pretty quickly.

I used the same technique with the prism.

Can We Get There By Laser Light?

Even having used the technique, it took awhile to work out the details for this photo. Initially I illuminated the prism from the side. But the human palm isn’t all that flat. The prism kept rolling toward my fingers, directing the outgoing beam into the table or some other part of my hand. And painting a beam that’s going toward the camera is tough if you’re using a business card. The camera’s looking at the back side of the card! Eventually I figured out I should place the laser under the camera, and aim it back toward my hand. This gave me a way to see how well aligned the prism was to the beam: put the reflected light back into the laser’s aperture. It also made painting the foreground beam a lot easier since the camera could see the illuminated side of the card.

The difficulty was the outgoing beam. No matter what I did, the prism moved around in time with my heartbeat. You can see it as tiny wiggles in the painted beam. I could’ve Photoshopped that out, but where’s the fun in that?

Since that’s my own hand there on the table, I really didn’t have the option of turning on the room lights at the requisite time. Instead I set up a single strobe and a shoot-through umbrella up and to camera right. I kept the wireless transmitter handy on the table. Once I’d painted the beam I triggered the strobe and closed the shutter. It worked like a charm.

For my last IP212 photo I wanted to make something of a visual pun. The two compositional elements were a hand resting on a flat surface and an object resting in the hand. What if the object in the hand was a flat surface? In keeping with the whole optics theme I considered using a mirror, but honestly that’s kind of a boring photo. Besides, I’d already touched on the optics side of what I do for a living. I wanted to touch on the mechanical side, too. What if the flat object in the hand was being made into a flat object? Milling machine!

Hand Work

Before getting into the hows and whys of this I need to point out that I take shop safety very seriously. At no point did I do anything that put my hand or my tooling at risk. The only way to pull that off was to do this as two separate frames – one with the spindle moving and one with it stopped – and combine them.

I milled five of the six sides of this block using the 1″ cutter shown chucked in the mill. I milled the last side halfway, then stopped. Lighting was pretty straightforward: an umbrella in front and to the right, and a stofen bounced off the white wall behind the mill to provide speculars on the block and vise. I brought the spindle down until it was pressing the block into my hand, and made the first exposure. I wanted some motion blur out of the cutter, so I made a second exposure using ambient light, rotating the spindle by hand from above. Once I’d balanced the light between the two in Lightroom, I brought both frames into Photoshop for layering.

While going through the lighting for this a number of other photographs came to mind that didn’t fit into the IP212 requirements, but that nonetheless would make for pleasing photographs of machine work in progress. And that, to me, is the real benefit of taking on Utata projects like the Iron Photographer: The final result isn’t the photographs made for the project. It’s the ideas that the process of thinking through those photographs leaves you with. That’s what I missed out when I joined Utata years ago. I don’t plan on missing out on it again.

To my utter delight, Greg, the moderator who sets up the Iron Photographer challenges, favorited The Regime and wrote a really thoughtful comment on it. This is the first time one of the Utata moderators commented on one of my photos. Even more delightful, Debra Broughton wrote a short piece about it for the front page of the Utata web site and wrote a comment of her own. I admit I banged my forehead on my desk a little at my obtuseness for taking this long to jump into Utata projects with both feet. But thanks to Greg and Debra I did it with a smile.

– Tom

Posted in Machining, Photography | Tagged: , , , , , , , , , , , , , | 2 Comments »

Batteries for Photography

Posted by Tom Benedict on 14/03/2015

I’ve been told by more than one photographer over the years that for gear that uses AA or AAA batteries, alkalines are best. “Put a fresh set in at the beginning of the day and you’re good to go.” I swear if I hear this from one more person, I’m going to throw up.

I… Hate… Alkalines…

Alkaline batteries have an inherent shelf life. When they reach the end of that shelf life they like to do violent, nasty things. If they’re still installed in a piece of equipment when that time comes, it’s usually the piece of equipment that pays the ultimate price. I’ll give you three examples:

About a year ago I needed to use a light meter. (Yeah, an honest to goodness light meter!) We have a really nice Minolta meter at work, so I borrowed it. I got to where I was planning to do the photography only to find out it didn’t work. So I opened up the battery tray. UGH! You guessed it: battery innards were everywhere. I took it home, pulled it apart, and found that the acid hadn’t attacked the electronics, but it had gotten inside the wires from the battery tray, and had eaten down inside the insulation. I cleaned it out, bead blasted the battery terminals, and soldered in new battery wires. The meter was back in business, but my frustration with alkalines only grew.

Back in December I used the Canon 5D at work to photograph the damage to some of the optics in one of our instruments. (Our current working suspicion is that battery acid played a role in the damage to the optics. Hmmmm!) I grabbed the ring flash that’s stored in the case with the 5D only to find it wouldn’t power up. No problem, I thought, I’ll replace the batteries! I opened the battery compartment to find battery goo had oozed all over the place. I cleaned it out as best I could, but didn’t even bother to take it apart. I gave up on the idea of using the ring flash and used my own Speedlites instead.

A couple of weeks ago I went down to the beach to do some long duration sunset photos. I pulled out my timer release, tried to set it up to do some five minute exposures, but couldn’t get half the buttons on the thing to work. I set the timer release aside until I could take a better look at it and did what I could with 30 second exposures, but none of the frames I exposed really looked right. Earlier today I opened it up only to find the batteries had blown their goo all over the inside, and had eaten the ground plane out of the circuit board, taking half the buttons along with it. I chucked it in the can and ordered another one.

So what’s a photographer to use if not alkalines? My favorite so far are nickel metal hydrides – NiMH. They’re rechargeable, they’re durable, they hold charge well, and when they finally die they die quietly. They don’t take stuff with them the way alkalines do. When I get home after a day out with my cameras, I pop out all the batteries, stick them in chargers, and load my pictures onto the computer. By the time I’m done editing, the batteries are done charging. Back in they go, ready for the next day. In all the years I’ve been using NiMH batteries, I’ve never seen one destroy a piece of equipment. Not once.

When my new timer release shows up I’m replacing whatever batteries that come with it with a nice pair of Eneloop NiMH batteries. No more alkalines in my camera bag! EVER!

– Tom

Posted in Photography | Tagged: , , , , | 1 Comment »