cheap diy shutter speed tester

[alexhill]

Saw this on one of the blogs I follow (hackaday.com) and thought it was pretty awesome. http://www.rusted.free.fr/speed tester.html

 

[ghostcount]

Made one a while back - works like a charm. I used Audacity. Found better results if you stop down the lens to about F16.

 

[jfdupuis]

Made one also. However, data acquisition with the sound card is not great at higher speed as there is no DC component. Accuracy especially goes down for high speed leaf shutter.

 

[Grif]

How about using an IR remote for a tv,,, hold the button down while you trip the camera. Seems the IR in them is chopped at a fairly fast rate.

 

[bvy]

I want to build one of these.

Is there something around the house or something cheap I can buy that has a mono plug?

 

[Ralph Javins]

Good morning, BVY;

Radio Shack is an obvious source for new pieces.

Goodwill, Saint Vincent de Paul, Deseret Industries, The Salvation Army Thrift Stores, and other second-hand stores often will have used computer mice, and various headphones and earbuds that will have some kind of a phone plug. If there are ones there that are broken (No, don't do that!), they might just hand it to you. Just make sure that the plug is the right diameter for your microphone input jack or socket on the sound card in the computer.

 

[bvy]

Thanks! I avoid Radio Shack except as an absolute last resort. Way overpriced. But searching the thrift stores for some misfit appliance that has a mono plug is a great idea. I’ll make a trip this week…

 

[Fotoguy20d]

I ordered all the parts I needed for mine from datakey. The case came from Home Depot - a nice 4x4x2 gray plastic outdoor junction box. At $6, the box cost as much as the rest of the parts put together.

I find accuracy is quite good until speed gets faster than 1/200s (.005s) or so. Audactiy's resolution is only to .001 second, and the time to open and close the shutter becomes a significant percentage of the total time.


Dan

 

[bvy]

I pulled one of the three-legged phototransistors off of an old mouse. The instructions reference "the back" of the phototransistor. How does one find the back? Does it matter? (He also mentions inverting the battery if it doesn't work.)

 

[BetterSense]

It doesnt' have to be a mono plug. It can be a stereo plug; just hook up one channel. Or even bridge L and R together; doesn't matter.

 

[bvy]

So I built this device to spec -- AA battery, phototransistor recovered from an old mouse, and a mono jack. I'm trying it on my PC now using Audacity software, and it just barely responds to light. To make sure I assembled it properly, I connected my voltmeter up to each contact on the mono plug, and shined a light at it. The meter pegged. Is there some way to boost the signal? Another design I saw was the same except that it added a 4.7k resistor. Will that help?

 

[BetterSense]

You should be able to get the voltage to swing from 0 up to the maximum battery voltage between light and dark. If it doesn't do that, you need to adjust your resistor values. You could try using a higher voltage battery. I used a 9v for mine.

 

[bvy]

Thanks. I'll try with a nine volt battery. As I mentioned, I don't have a resistor on the the circuit. So it sounds like I should add one?

 

[BetterSense]

Yes, typically you go from positive terminal, to the short leg of the photodiode, and from the long leg of the photodiode, into a resistor, and from that, back to the battery. You tap your output off between the photodiode and the resistor, and run that to your soundcard or whatever. The value of the resistor determines the sensitivity of the thing, so using a pot is a good idea. If the resistor is small, very small voltage will be developed when the photodiode is illuminated even with a bright light. If the resistor is very large, the full battery voltage may be developed even in room lighting, and the voltage will never go back down to zero.

 

[Ron G]

Make sure that your aperature is open enough to transmit a signal and adjust your input signal (mike input) in Audicity to at least 50% ot higher if you need it.That slider seems to default to a very low value but you should be able to increase it enough to see your waveform at any amplitude that you like.Ron G

 

[Perry Way]

I just found the need for a shutter speed tester. Found this thread and some others in other sites. There's a guy in Romania I think it is, who has designed a low cost shutter speed tester. He's got an entry level model that's only $14.99 on eBay. That one works like with the Audacity program. Then he has a model that doesn't need a computer at all, it has all the electronics inside. Those go for $99 without a light source and $119 with a light source. I think I'm going to buy one of these rather than build one myself.

On eBay, look for seller by the name "vfmoto" if you're interested.

 

[cscurrier]

This all sounds pretty easy, at least easy enough that I can probably do it! Thanks to every who shared above.

 

[pekelnik]

I just put the lens next to my laptop, turn on audacity and fire the shutter. You'll see large spikes where it opens and closes.

 

[Tom1956]

Saw this on one of the blogs I follow (hackaday.com) and thought it was pretty awesome. http://www.rusted.free.fr/speed tester.html

Seems like I've been asking a lot of questions lately, for which I thank you guys. OK, another one: I intend to fabricate the tester in the referenced link to test my old 5-speed Betax. Now my thinking or logic might be flawed here, but it seems to me on an iris shutter, the shutter is open for less time on the edges of the round opening than the center, right? The shutter takes time to open and close, nothwithstanding the time it stays open. The edges are the last to be un-covered, and the first to be re-covered, right?. So if I make my tester with the phototransistor just a couple inches away from the rear lens element, it seems like I'd get a false reading. Seems like the phototransistor would have to be at the film plane to get a true reading. Feel free to correct my logic. Thanks.

 

[SMBooth]

If you shut down to f16 your opening is quite small so not really an issue, anyway your measuring the time light is hitting the film so as soon as the shutter opens light is coming through the hole so you measure time open to time close. With the photo transistor distance I only think it would be out by the percentage of the speed of light to cover the extra distance is photo transistor is away.

 

[shutterfinger]

http://photo.net/large-format-photography-forum/0044cW or http://www.graflex.org/helpboard/viewtopic.php?t=6105
The infrared photo transistor/led used in the final refinement has a 10 ° angle of view. The one from the old mouse most likely has a similar angle of view.

I do all testing with the lens removed. It makes little difference if the sensor is at the center of the shutter opening or if its center is at the smallest marked aperture opening of the lens.
The photo transistor/led has a rise and fall time of .1ms. The rise time is the time delay from when the sensor is first sees light and starts to conduct to when it reaches the maximum peak for the amount of light reaching it. The fall time is the time the sensor continues to conduct once the light source has been removed.

Now my thinking or logic might be flawed here, but it seems to me on an iris shutter, the shutter is open for less time on the edges of the round opening than the center, right? The shutter takes time to open and close, nothwithstanding the time it stays open. The edges are the last to be un-covered, and the first to be re-covered, right?. So if I make my tester with the phototransistor just a couple inches away from the rear lens element, it seems like I'd get a false reading. Seems like the phototransistor would have to be at the film plane to get a true reading.

A leaf shutter is a dual aperture device with one aperture manually set via a lever according to a calibrated scale and the other a continuously variable from full closed to full open and back to full closed via a controlled timing system.
When a leaf shutter is set (cocked) high spring tension is locked onto a lever that when released will try to force the shutter blades ( continuously variable aperture) fully closed but is locked in the set position by another lever. When the shutter is tripped the shutter blade controller is released and thrown open by a weaker spring with no opposition to the blade controller moving except for its and the blades pivot pins resistance. The shutter blades go from full closed to full open in .15 to .3 milliseconds. When the shutter blades reach full open the blade controller releases the locking lever allowing the main setting lever to try to close the shutter blades via the blade controller. The main setting lever encounters resistance to closing from the delay timing gear train.

Setting a speed testing sensor close to the outer edge of the shutter will give false shutter times. Setting the speed testing sensor at the smallest marked aperture edge will give more accurate fast speed times.

Testing is normally done with the aperture wide open and the sensor at the center of the shutter opening or lens center. By the time the shutter blades have closed down to be effectively 2 stops smaller than the smallest aperture the lens is marked for the resulting extra exposure the film receives is insignificant on a properly working shutter. A installed lens may cause false shutter test speeds unless a very bright light source is used for testing. I use a minimag flashlight with fresh batteries set to spot at 2 inches held just above the shutter opening. I have the top edge of the photo sensor near center of a piece of 1/4 inch foam core and the foam core is rested against the rear edge of the shutter. Increasing the distance to or from the shutter blades only affects the intensity of the test light source needed for testing.

http://www.flutotscamerarepair.com/Shutterspeed.htm

http://www.photographyuncapped.com/...ps-shutter-speeds-by-third-and-half/articles/ (click on the chart to download for printing)

 

[Tom1956]

Well, I've constructed the tester as described with a 1.5V battery and the photodiode from an old Mac mouse. It DOES move the signal strength indicator in Adobe Audition, but not nearly sensitive enough to produce a blip in the record mode. Looks like I'm going to have to step up to a 9V battery and put in a pot, till the signal strength is enough to be useful. I wonder why the designer gets away with 1.5V and I have to go through this ordeal of rewiring mine for a 9V. Seems nothing works out as described.

 

[Bill Burk]

Scratch one mouse... Sorry that didn't work out yet...

Do you have a turntable you can view through the shutter as you fire it? Maybe lay a strip of white tape on the turntable and run at the highest speed... Work your way back from the apparent angle of the blur that you see. And the RPM's... to a shutter speed estimate.

 

[Tom1956]

No I'm going to go on with the shutter tester fabrication. It's been done enough times out there to where mine should work out also. The mouse has 4 photodiodes in it, and the one I used I de-soldered from the circuit board. Could be fried. Will continue on with the 9V and potentiometer design before calling it a fried photodiode. When I'm at that point I'll cut another off the circuit board and use my super-fine wire and wrap it around the legs, and keep the soldering iron out of the picture. Not time to give up just yet. This is going to work.

 

[shutterfinger]

It DOES move the signal strength indicator in Adobe Audition, but not nearly sensitive enough to produce a blip in the record mode.

Try a different audio recording program such as http://audacity.sourceforge.net/
Try reversing the polarity on the sensor, at 1.5V you won't damage it.
Try different lead configuration as your mouse sensor may have a different lead configuration from the diagram you are using.