Recently, I came across a nifty light modifier for small battery flashes called the Saberstrip. It’s a tube with a mount for the flash at one end, and a mirror at the other end, and a long window covered with diffusion fabric. The long linear light source makes a diffuse shadow in one direction. They can be doubled up and oriented as an “L” to give a look closer to an umbrella or soft. One big advantage of the Saberstrip is that it’s not a big sail that’ll catch the wind out on location. At US$135 plus another 15 for shipping, though, it’s rather expensive for the hobbyist.
Continue Reading…
**** UPDATE *****
UPDATE: NEW DESIGN COMING SOON THAT REDUCES CURRENT IN THE CAMERA/TRIGGER SWITCH AS ~20mA MAY BE TOO HIGH FOR CAMERA INTERNALS.
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This post needs to be prefaced with a major disclaimer: Open your Norman 200B at your own risk. The 500V inside is potentially lethal. The author was careless once and accidentally discharged the cap with a meter probe which caused a big char streak in the connector and took a hunk out of the meter probe and one of the head plug pins. Proceed/attempt at your own risk. If you die, break your 200B, or both, I am not responsible.
Now that that’s out of the way, on the to the good stuff.
The Norman 200B trigger voltage is on the order of 100V. It was fine for old film cameras with mechanical sync switches. Modern digital cameras don’t care for such high voltages, so some sort of conversion or adaptation needs to be made. Optical slave triggers are one way to go, but the author smoked one accidentally by just letting the 200B sit waiting to flash. Apparently, some modern optical slave triggers do not care for such a high trigger voltage either. They are also going to end up dangling and exposed where they can become disconnected or in the extreme, get broken off.
Slave triggers and the like are not inexpensive, either. Sure, they come encased in a nice little plastic package and all, but at $8-10 or more apiece, they add up quickly, especially after having acquired four complete pack and head sets. Sometimes, it’d be useful and nice to use all that fire power at the same time and not have to carry all those little slave triggers and wires and stuff…
So, what to do? Reverse engineer the trigger circuit and make and a low voltage adapter for it using piece parts… Here’s the photo of the board alongside a mirrored and colorized photo of the traces on the bottom side that was used:
Here is the partial trigger circuit (please ignore all the extraneous numbers and notations) of the stock 200B blue circuit board:
Observant readers of Harold Edgerton’s book, Electronic Flash, Strobe, will notice that this circuit is pretty much the opposite of one within his book. The difference is that the Norman 200B is uses a positive ground, so everything is upside-down in comparison to Edgerton’s circuit. Another thing that should be noted is that when the SYNC connection is grounded, the charged 0.02uF capacitor discharges, turning on the gate of the SCR. Only a small amount of current will flow if the SYNC connection is held grounded, probably as an added safety benefit.
One would think that adding an optoisolator across the SYNC connection and the chassis would be sufficient to adapt the 200B for low voltage operation. That was tried but it did not work because the current that flows is too small to latch the triac within the optoisolator ON, so the capacitor does not discharge quickly enough, and the 200B never triggers. An early attempt to correct this consisted of shorting the diode. When the two resistors dividers are shorted together at their center points, the 200B could be fired with an optoisolator between SYNC and the case. But then additional current flows unnecessarily from the high voltage supply.
The first incarnation of the low voltage adapter was built into a plastic Tic-Tac and hung off a house hold plug that was plugged into the head. A sync cord then plugged into the Tic-Tac trigger. It was too many connections, something extra to carry and/or break. So when the opportunity to use two of the Normans for a photo shoot presented itself, it was time to move the adapter inside the pack and make the outside connections simpler…
In order to hook this into the 200B, three parts on the blue controller board need to be removed: a diode and two resistors. The colored circles indicate where the tap points are for the adapter board. The three parts need to be removed to completely isolate the SYNC connection to the head so that only optoisolated low voltage goes to the head socket. Note that two of the removed devices have a colored circle on one of their leads. The third one is unmarked in this photo but it is to the right of the orange filter capacitor and +12V connection (it can be seen in a later photo).
Here is the schematic for the low voltage adapter:
And here is the parts list with Digikey part numbers:
Digikey part number
|
Description
|
Note
|
497-2960-5-ND
|
IC REG LDO -5V .1A TO-92
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negative 5V regulator
|
160-1378-5-ND
|
OPTOISO 400VDRM TRIAC OUT 6-DIP
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optoisolator, MOC3023
|
CF18JT180RCT-ND
|
RES 180 OHM 1/8W 5% CF AXIAL
|
I limit resistor
|
399-1249-1-ND
|
CAP CER 0.1UF 50V 10% X7R 1206
|
output cap
|
399-1285-1-ND
|
CAP CER 0.33UF 25V 10% X7R 1206
|
input cap
|
The negative 5V regulator is probably not absolutely necessary, but the most often quoted number for DSLR maximum sync voltage I’ve seen is on the order of 7-9V; 12V would then be too high. A negative regulator is required because of the positive ground design of the 200B. The two capacitors are required by the regulator; surface mount chip caps were used because they take up a whole lot less room. The 180 Ohm resistor limits the current for LED inside the MOC3023 to about 20mA.
The circuit was wired onto a small perforated prototype board as can be seen below on the left. The board is positioned in this photo so the devices can be seen. The bottom of the board is normally up when assembled into the pack.
The pack assembled with the “protective” plexiglass cover can be seen in the photo below. The protective plexiglass is often broken on these old units… The cover also does not afford a whole lot of protection anyway since fingers can still get at the high voltage. I typically keep my fingers well clear when the power is applied and for a long while after the power is turned off as a precaution.
A couple of months back, I saw a Craig’s List listing for a Norman 200B pack, head and charger. The battery was dead and would not charge but the owner reported that it worked the last time he’d used it, it worked. I figured that for 200 Watt-seconds, $65 was not too unreasonable to gamble, so I bought it.
After purchasing, it was very interesting to note the date codes of the parts on the circuit board. They were all circa 1979. What’s more, it has the battery positive connected to the case: it was one of those positive ground devices I’d heard about but had never seen. Very interesting, indeed.
When attempting to power it up with a power supply, I had difficulty finding a power supply that would source enough current to get it to anything other than trip the over current and shut off the power supply. I ended up having to charge a large battery in the lab and using it. The pack draws pretty near 20 Amps while it’s charging up the capacitors, no small amount of current…
Intrigued by the 200B, three more packs, heads, flash tubes and chargers were cheaply acquired from the net and eBay. All the units, including the original had something wrong with them, though… I also picked up a 20 foot extension cord, and an 18 foot cable with no connectors that was turned into an extension cord by re-purposing the connectors from a charger and dual Y charging cable. The total investment in hardware for 4 complete units (pack, head, tube, reflector) and two extension cords, and an extra tube was about $300. That’s about $75 per 200 Watt-second unit…
While there are service centers that will repair old Norman hardware, the $65 starting fee for each unit plus the shipping forced digging into the hardware and reverse engineering the design. All four packs were restored to working order pretty quickly, easily and inexpensively. Two of the units failed because the foam packing inside allowed the torriodal transformer to shaker around too much and break a wire – supremely easy fix. All that remains currently on three of the units is repacking to completely restore them. Along with the repairs was the modification for low voltage triggering by modern DSLRs – the original sync voltage is about 120V…
Replacement batteries run near $100, a very unappealing price point. Gel cells that fit into the battery compartment run about $25 but only have a 2.9 Amp-hour capacity. I found 12V 7 Amp-hour UPS batteries on Amazon, two for $30, so I ordered them. The big disadvantage with the UPS batteries is that they are way too big to fit into the Norman pack.
Thus we arrive at the purpose of this post: Packaging up the Norman 200B pack with the UPS battery so that it can be taken on location.
A carried was built using 1×4 and 1/4″ thick particle board as can be seen below with one of the extension cables connected. The battery is held in place with a tight friction fit. The battery cable passes through a hole filed into the case halves.
The battery connections are brought out to banana connectors as seen below. They are spaced at 3/4 of an inch, the standard spacing for a dual banana plug/socket. The jacks allow for charging or powering something else. I’ve considered adding a cigarette lighter socket above the battery in the left 1×4 but not having one, I’ve shelved that for the time being. What’s missing for safety is a fuse. The pack itself has one internally, but there really should be one up and close to the battery, particularly if a cigarette lighter socket is added.
On the other side, I added D rings for carrying and for strapping the carried to a light stand. The whole assembly doubles as a weight, given all the lead in the battery, so why not put that to use? No need for carrying sand bags as well…
These photos were taken about 3 feet in front of a 70″ octobox with the Norman LH2 head inside. The octodome had an Alien Bees insert in the speed ring, so an adapter needed to be made. Fortunately, 3″ threaded PVC just fit inside the Alien Bees hole in the insert. A bracket for the head was made with PVC cut from a short length of gutter (the mount details will be the subject of a subsequent post…). At the moment, the mount does not swivel up or down since a Manfrotto super clamp holds the PVC fitting atop a light stand. Tilting will hopefully come later…
From behind the octobox with the shroud removed, we see the flash tube:
From the front side, with the inner and outer diffusion moved to the side:
I’ve been giving some thought to adding IGBT triggers to these for variable power control. Given the cost of parts, the possibility of popping the IGBTs, and the time to get it to work reliably, it probably does not make sense to modify or update these further. Used modern Alien Bees strobes with variable power can be picked up for around $250 or less.
But boy do these Normans recycle fast, even at full power, compared to fully charged, AA-batteried modern flashes… Popping at full power in quick succession warms up the black and red cable from the battery to the pack.
This is was a draft post for the longest time. Finally getting around to finishing and publishing it…
Jacci made a baby shower invitation for our daughter, Tricia using some stuffed animals and other items. Jacci also tried her hand at stop motion animation while taking the still photo for the invite. Here’s one of the photos she took in the series:
The movie can be seen here: elephant and monkey stop motion-desktop
It was early on a Sunday morning when Jacci started trying to set up the shot. She was having some difficulty in getting some white foam core to stand up and stay where she wanted it. I went out into the garage and rounded up some 1/2″ PVC and fittings from an old project. I cut the PVC pipe into 8 equal lengths. Then using 8 90-degree elbows, the structure below was assembled. [I'd recently seen a PVC box design like this somewhere, but owing to the long time sitting as a draft, I no longer remember where so I can't give credit for it.]
A sheet of white foam core makes the white floor. A piece of white Tyvek hangs from the top back and slopes down to meet the foam core floor makes the continuous white background. Translucent white material hangs down on the left and right sides and over the top. Two SB-600s were placed on the left and right sides and an SB-900 was suspended over the top of the cage.
All told, creating the box and taking the series of photos took no more than about 2.5 hours total.
David Hobby of the Strobist web page posted recently about assembling a large softbox on location using two backdrop stand kits and two extra cross members, hanging rip-stop nylon in black and white to block and diffuse the light where he wanted.
In the comments of that post, there were mentions of using EZ-UP canopies in white to the same effect but a little more inexpensively. Further down in the comments, RocketRick states that buying canopy fittings is cheaper and more flexible than buying a canopy. As he mentioned, Yuma’s Bargain Warehouse does indeed seem to have the best prices on the fittings when shipping is also included.
That all got me to thinking, since we are planning on having a photo booth at a youth conference next January, getting the canopy hardware could serve more purpose than just an outdoor humongous soft box. With a good mixture of fittings and half length EMT (5 feet), a number of free standing walls of adjustable size as well as a complete cube can be easily constructed.
I made a posting mentioning the parts list I think I want to buy. I was not able to include a diagram but now do so here:
While using sliding fittings will certainly be a little less convenient at times than the regular closed fittings, the sliding fittings are more flexible in that it does not fully constrain one to using integral lengths of the EMT. Adjusting the dimensions of the panels and fixtures created is possible with the sliding fittings.
The sign holders allows the height of the top to be adjusted. Since I wanted to be able to use these pieces indoors, possibly even in my own living room, a full 10 feet is not always going to be possible. By putting the vertical EMT of the tops in one side of the four sign holders, and the bottoms into the other, the height can be changed without leaving EMT sticking out over the top and hitting the ceiling.
After drawing the picture and thinking on it, adding four more couplers and four more feet will allow two complete and independent structures to be built, provided there is enough EMT available. Then again, that’s more to store and more expense for maybe not so much usage. It is a starting point, though…
Thoughts?
