Graflex.org

[45PSS]

Using this diagram as a guide
http://www.baytan.org/prak/shutter.html
go to Radio Shack and get a
1/8 mono phone plug catalog #274-286
Infrared Photo transistor catalog #276-145
and some hookup wire if you have none.

Go to ebay and get a red laser pointer such as
http://www.ebay.com/itm/New-Powerful-Red-Laser-Pointer-Pen-Beam-Light-5mW-/260568287781?pt=LH_DefaultDomain_0&hash=item3cab148a25

Download and install
http://audacity.sourceforge.net/download/

Using the hookup wire (22 gauge speaker wire works well) connect the photo transistor collector C to the center contact on the mono plug. Connect the emitter E to the outside connector of the mono plug. The length of the wire can be as long as needed to comfortably connect to your computers microphone jack and reach the camera/shutter you wish to test.

Using a piece of foam core, cardboard, matt board make a small hole that the photo transistor will just fit into.

Position the photo transistor over the rear of the shutter and centered.

Plug the photo transistor into the computers microphone jack.

Start Audacity then pause-record. In the resulting record window select Waveform db from the audio track drop down options.

Set the shutter to the speed to be tested, position the laser pointer on the front center of the shutter, release pause in audacity, trip the shutter, press stop in audacity.

Using the time expansion and shift tools in audacity measure the time between the point where the base line first goes down to where it starts to go above line. The peaks will flatten out more as the time line expands.

http://www.flutotscamerarepair.com/Shutterspeed.htm
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The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[Leigh]

An incandescent lamp will work much better than a laser, not being sensitive to direction.

Any photo-transistor will work. It doesn't need to be infrared.

Just some suggestions.

- Leigh

[45PSS]

Can you provide a source for those photo transistors that the average Joe can easily get?

They use to be readily available and when I tried to get one from my regular electronic parts supply they were not available.

The adaption post is a result of inquires on other photo forms from members looking for a source and comments from members here about shutter speeds and testing.

At $2 for the Radio Shack transistor and no need for the battery, bias resistor and coupling capacitor this is a very inexpensive option.
The transistor has a response of 650-900 nano meters. A #25 red filter over the transistor with a very bright incandescent light source works also but the narrow beam from the laser pointer makes for a precise on off.

So, please enlighten us.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[Leigh]

Mouser has over 300 different phototransistors. The cheapest one with leads being the Lite-On LTR-4206 at $0.14 in singles (1,550 pcs in stock). At 100mW dissipation, 100nA dark current and 10μS response it would seem well-suited to this application.

The Everlight EL-PT204-6B is the same price (7,721 pcs in stock), with 75mW dissipation and other specs similar to the LTR-4206. Sensitivity of both devices is 1mW/cm^2.

These are both infrared detectors, but remember that over 90% of the energy output from a tungsten bulb is in the infrared.

I expect Digi-Key would have a larger selection, but I didn't bother to check. Mouser has no order minimum; Digi-Key does.

I've never bought anything from RS, and never will.

Using a laser source adds an aiming constraint to equipment operation that would be eliminated by using tungsten. On/Off switching times are strictly a matter of the energy impinging on the detector, regardless of its source, and the response time of the detector.

However, rise/fall times are very dependent on load resistance (Rl), with the 10μS value being for a 1,000-ohm load. The Tr/Tf values change almost linearly with increases in Rl, so at Rl = 4,000 ohms the value is about 40μS.

You don't need a red filter in this application. They're used in environments that have lots of fluorescent light impinging on an unshielded detector, which can induce noise and possibly swamp the detector. You don't have that in this case.

If you're concerned, both the Everlight part mentioned above and the Lite-On LTR-4206E part have black epoxy cases that filter out all light above the sensitive wavelengths, at the $0.14 price.

- Leigh

Mouser: www.mouser.com
DigiKey: www.digikey.com
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“Wise men talk because they have something to say; fools, because they have to say something.” - Plato

[45PSS]

When testing the RS infrared transistor it did not respond well to an incandescent light bulb, a 250 Watt Photoflood, or a CFL. It would respond to a 2 AA cell Mini Mag shone through a #25 red filter. The RS IR transmitter output is too weak to use.

I did put a 1.2K (1200 ohm) resistor between the transistor's collector and the center contact of the mic plug but it is not absolutely necessary.

Use rosin core solder only for electrical applications.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[45PSS]

After testing several shutters this simple tester is not accurate above 1/100 second. It does not read the focal plane shutter found in Graflex SLR's correctly.

The response time of the RS transistor is not listed. The response time of most similar transistors at one of the retailers linked above is .010ms rise, .015ms fall.

The view angle is 30° to 40° which is playing a part also.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[Leigh]

[45PSS]

After picking up another RS photo transistor and a stereo plug, mounting both transistors on a board 1 inch apart, covering with some dark red light gel sheet, lighting with a 60W clear ceiling fan lamp in a work socket, positioned so that the reflex mirror just clears the bulb, I got the same results with both and the same time delay between the start times at all apertures and tensions.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[45PSS]

I have switched to using the diagram at http://www.kyphoto.com/classics/combinationtester.html .
It was set up for 35mm shutter testing but can be used on any shutter.
I have also purchased photodiodes from Mouser.
The transistor collector(s) or diodes cathode(s) are connected through a resistor to the common lead of a mono or stereo plug. The transistor(s) emitter(s) are connected to the signal lead(s) of the plug. The battery is not needed. The output of the transistor(s) or diode(s) are much higher in this configuration and no special adjustments in the recording program are needed but you may have to lower your microphone input level.

For a leaf shutter you use 1 photo transistor or diode and a mono plug.

I posted a reply to http://photo.net/large-format-photography-forum/0044cW?start=10 detailing this with Radio Shack catalog numbers for the parts and tools needed.
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.

[Drew Bedo]

Hello everyone,

I am new to this issue and not an electronic DIY guy. I have a passing understanding of current, resistance and so on, but don't really understand circuts or how the various components interact.

With all that said: I am interested in the concept of using a light sensor to generate an audio signal and analysing it with a computer. Having read this thread and some of the links: Does it work as a practical matter?m Is there a definative set of directions for the hardware?

[45PSS]

This is a composite of screen shots of the waveform produced and expanded in Audacity. The shutter being tested is a freshly serviced Graphex #2.
The tester was the kyphoto linked diagram with a Radio Shack transistor with Bogen red lighting gel over it and a mini mag set to spot focus and held 1/2 inch above the shutter opening with the lens cells removed.
The aperture was wide open (f4.7) and the waveform/time did not change when the shutter was stopped down to f16 at the same speed setting.
After testing at the 1/400 speed I switched to a narrow view photo diode (from mouser) tester and got the same waveform and time for that speed.

Radio Shack used for reference as they are hobbyist oriented and in many smaller towns.
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Parts to build:
15W soldering iron
http://www.radioshack.com/product/index.jsp?productId=2062728
Rosin core solder (only type usable in electronics)
http://www.radioshack.com/product/index.jsp?productId=2062711
24 Gage speaker wire
http://www.radioshack.com/product/index.jsp?productId=2036278
10k ohm resistor
http://www.radioshack.com/product/index.jsp?productId=2062347
1/8 inch mono plug
http://www.radioshack.com/product/index.jsp?productId=2062452
Photo transistor
http://www.radioshack.com/product/index.jsp?productId=2049724

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If you have no electronics knowledge I suggest getting a beginners electronic hobby book that explains the basics and read/study it. One such book may be
http://www.dummies.com/store/product/Electronics-For-Dummies-2nd-Edition.productCd-0470286970.html
_________________
The best camera ever made is the one that YOU enjoy using and produces the image quality that satifies YOU.