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Isaiah Adams
Isaiah Adams

Vivitar 3500 Flash Pdf Manual

On the front of the flash is the Auto Thyristor Sensor. This small device detects the amount of light present when the flash is triggered, metering the level of illumination on the subject. The outer collar of the sensor is the mode selector. This rotates to set for different aperture ranges while in the automatic mode, or to set for manual operation. Holding the unit upright and pointed to the right, the small window on the side of the sensor shows the ranges in different colors, flash power or M for manual.

Vivitar 3500 Flash Pdf Manual

The SLI will slow for 2-3 seconds after a flash if the sensor reads the correct light level during the illumination. You can check your exposure before taking a shot by manually triggering the flash unit and watching the SLI. If it doesn't light, you can do a number of things to correct the illumination. Set the Mode Selector to a value which will allow a wider f-stop and reduce the subject and flash distance; bounce the light from a more reflective surface.

Flash guide numbers will help you calculate f-stops for exposures using the manual position or when you bounce your illumination.Measure the flash-reflector-subject distance, and divide the total into the Flash Guide number listed for the ASA film you are using. Round off the result to the nearest f-stop and open one stop wider.Example: using ASA 25 film with a camera-reflector subject-distance of 20 feet -- Guide #20 divided by 20 equals 3 (f2.8 approximate) open an additional stop to f2.You can estimate flash bounce settings in other ways. In average rooms, a general rule is to open two stops from where you would set a direct shot.OR, using the Calculator Dial, estimate the camera-reflector-subject distance and open one more stop from what is indicated on the dial.

James, I don't know the 3500 specifically, and I don't know where to find manuals. But most of those little thyristor Vivitars are pretty simple to use. There will be a selector switch somewhere, with two colors and a position in between. There will be a scale on the back with a sliding gadget and some color indicators. To use the flash, make sure your camera's shutter speed is at or slower than the sync speed. Pick one of the colors on the selector (the position with no color is "manual"--full flash output every time.) Say you've put the selector in the RED spot; look on the back, set the film speed on the sliding gadget, and you'll see what aperture to set your camera to. (If it's NOT suitable, try the OTHER color setting on the front and see what aperture is recommended at THAT setting.) If all is correct, you can now shoot regular on-camera flash at any distance inside the flash's ability to cover, at the pre-set aperture, and the thyristor will shut off the flash output when it's put out enough light for your photo. I'm not good at explaining things, but it's really very simple when you've done it a few times.

I recently picked up an old 1980's Vivitar 3500 Zoom Thyristor flash with the DM/C module (for Canon). This is an "automatic" flash with no manual power setting other than full power. The head has three manual zoom positions, and it's powered by two AA batteries. I modified this flash so that it has manual selectable power settings down to 1/32 power, at a cost of less than $5 in parts. This flash is routinely available on Ebay for US$20 or less, so you can end up with a very nice off-camera manual flash at a very low price. The flash comes with other modules for Nikon (two versions), Pentax and Olympus, and it's likely this same mod will work for them too, but I've only modded the Canon version.I disconnected the light-sensing photo-transistor on the front of the flash, and tried various fixed resistors in its place.First, I found that the ASA setting switch on the module had no effect on anything. It's definitely a real switch, so it's possible it only comes into play when on-camera. Anyway, I just left it set at ASA 25.But the "Color" switch does change things, so I decided to incorporate that switch into the power level selection. That switch has four positions - Red, Blue, Orange, and Manual. The Manual setting is always full power no matter what resistor is used. With the right single resistor value, the four Colors are roughly two stops apart, except that Red, the lowest power selection, is only one stop below Blue. And I found that by switching between just two fixed resistors, in combination with the Color switch position, I could get a total of 6 power levels, one stop apart, which correspond to full, 1/2, 1/4, 1/8, 1/16 and 1/32 power.I determined the resistor values by first setting up my camera (in manual mode), flash and test subject in fixed positions, with the room being dark so the only light was from the flash. Then I took a properly-exposed picture at full power. Then, without moving anything, but with the camera's exposure increased by a full stop (either aperture or ISO), I took new pictures until I found a resistor value for the Orange switch setting which produced the same histogram as the original picture. Since the camera was at +1 stop, it could only produce the same histogram if the flash was at 1/2 power. The same method was then used to get the resistor and switch choices for 1/4 power, then 1/8th , and so forth.I found I only needed two different resistor values to get all the power levels I needed, and these were 1.5K ohms and 750 ohms. And these values are convenient because 750 ohms is just two 1.5K resistors in parallel.So the wires that went to the photo-transistor now go to a SPST switch. One 1.5K resistor is always in the circuit, but the switch, when ON, places another 1.5K resistor in parallel with the first, which gives a net 750 ohms. So the required power levels are produced by the combination of the Color switch and the SPST switch, as follows:Full ----------- Manual, ON or OFF1/2 ----------- Orange, OFF ----- (1.5K)1/4 ----------- Orange, ON ------- (750)1/8 ----------- Blue, OFF --------- (1.5K)1/16 ---------- Blue, ON ---------- (750)1/32 ---------- Red, ON ----------- (750)Notice that the Red/OFF combination isn't shown, but is also useable. It's about 2/3 stop below Blue/ON.I used Radio Shack #275-645 ($3.19) for the SPST switch and 271-1120 ($1.19) for the 1.5K resistors. I installed the switch on the back (see picture), but it's a tight fit because of where the switch sliders go . I think I would put it on the side next time where there's more room. But anywhere is fine. You would need a small Phillips-head screwdriver, a soldering iron, and a drill with a 3/16" bit.I fire the flash with the CowboyStudio NPT-04 trigger (about $22 on Amazon), and with the Seagull SYK-3 optical slave trigger (about $8 on Ebay), both of which work fine. My flash's trigger voltage is about 9 volts. I assume all 3500's are like that, but don't know that for sure.I've taken several hundred shots with the modified flash, and it has worked fine. It appears to be well-made. Eneloop AA's last quite a while. I've never had to change batteries mid-shoot. Recharge time after a full-power flash is about 8 seconds, but only about 2 seconds after a 1/4-power flash. And, you don't have no stinkin' auto-off to deal with. :-) So I think this is a nifty deal for geeks like me who solder.Note: There's a push-button release just above the audio switch on the side which lets you detach the module from the rest of the flash. Then it will be easy to work on the module with no charged capacitors to worry about.Originally posted at 7:35PM, 30 January 2012 PST(permalink)GBHPhotoArts edited this topic ages ago.

Ranger_9, thanks for the kind words. And I agree about the benefit of staying clear of that monster high-voltage capacitor.I think your explanation of how it works is correct. I've seen other hacks like this where the phototransistor was replaced by a pot, and this one is basically the same thing except that the resistors are fixed values. So I think this method should work for any of the older "automatic" flashes which have sensors on the front.But the advantage here is that the 3500 has the Color switch which already divides the power into four ranges that are two stops apart, and on top of that, the same two resistor values give you one-stop steps in all the ranges.So while using a pot with the flash set to M might give you infinitely-variable settings, duplicating a setting from shoot to shoot is very difficult because you can't get the pot back to exactly the same position. With the 3500 and this hack, you get precise, consistent power options, and they are almost exactly one stop apart. The parts for it are about $5, and you don't have to calibrate anything because I've done all that in advance.But for a flash that doesn't have the equivalent of a Color switch, you could still get the fixed one-stop increments by using something like a 6-position rotary switch with carefully selected fixed resistors at each switch position. So really, I think this general method would work with any older automatic flash if you're willing to do the calibration and find the right resistors..I've used my first modded 3500 behind a shoot-through umbrella setup for close to a thousand shots, and it works quite well. And it's really convenient to be able to change the power by one or more stops at the flip of a switch.I got my first 3500 as a gift - the owner thought it was obsolete and useless - and paid $12 on Ebay for my second one. So if I don't count the time I spent figuring out the mod, the two flashes cost me close to nothing.ages ago(permalink)

I've done a potentiometer variation of this hack on two flashes and documented the second one. The knob sits perfectly in the hole from the phototransistor. Also messing around with the guts of the unit I roughly figured out what the pins connecting the flashgun to camera modue do (trigger, power, ready-to-fire). Hence with a bit of effort can be hooked up to a ago(permalink) 350c69d7ab


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