sound is not a reliable method to time shutters. the light method is the best.
a simple photo transistor such as a TIL81 or eqiv simply soldered to the wires (observing polarity) and jack plugged into your computer's mic input is all you need. btw the mic input has a pre amp so pluging into a "line in" wont work unless you add other components to the circuit.
Here is a schematic with a different TIL. Lomo is finally good for something!Originally Posted by Paul Ron
I haven't found the TIL81 yet, for less than $30 and as high as $50.
Tin Can
I believe this Phocron XA shutter tester is still available through the Internet page at the URL adelorenzo provided. I spoke to the maker on the phone and purchased one from him about a year ago, and it has worked perfectly. The Phocron also has a calibration mode feature. I created a little stand or jig to hold my lenses (which are all mounted in Linhof Technika-style lens boards) in a position aligned with the light probe of the Phocron, so I can test the shutter speeds really quickly and easily. If I recall correctly the only lenses I had to remove the front and rear glass elements from in order to test the shutter speeds were my 400mm and 600mm Fujinon-T telephoto lenses. All of my other non-tele lenses were tested in their lens boards with the lens elements intact. I was pleased to find that all but one of my lenses had shutters that were pretty accurate at all speed settings that mattered (I didn't bother testing test speeds shorter than 1/60sec.), and so only that one lens and shutter had to go out to Carol Flutot for CLA (which she returned much more accurate). Given the modest price of the Phocron unit, I wonder why you would want to make your own, unless you insist on DIY?
... JMOwens (Mt. Pleasant, Wisc. USA)
"If people only knew how hard I work to gain my mastery, it wouldn't seem so wonderful at all." ...Michelangelo
i havent bought them in years... they were 99 cents at one time. wow. but any photo transistor or diode will work. here is a quick search of alide electronics...
https://www.alliedelec.com/view/sear...%20transistors
.
how much? looks nice.
I use "Shutter Speed" on the iPhone WITHOUT the PhotoPlug. That is, I use the sound of the shutter for the test. I use in on my between-the-lens Copal shutters.
I find the output quite easy to inspect--to find the opening and closing of the shutter--at slow speeds. It provides a judgement/conclusion that the shutter is 0, 1/3, 2/3 f-stops slow or fast. It works very well at slow shutter speeds, but not, say 1/125sec or higher.
This is very useful because rarely do I use the higher speeds. I'm typically exposing and worried about wind moving the subject or the camera, i.e., at 1 sec, 1/2 sec, 1/4 sec, after application of filter factors and bellows extension corrections. I need, therefore, assurance about the slow speeds for each lens. I haven't felt the need to use the PhotoPlug or any light-path/duration detection method.
Just my $0.02 here.
Peter Collins
On the intent of the First Amendment: The press was to serve the governed, not the governors --Opinion, Hugo Black, Judge, Supreme Court, 1971 re the "Pentagon Papers."
The link provided by Randy Moe is instructive. Up to that point in the thread, I was just shaking my head in skepticism. The first part of the Lomo article shows the shortcomings of the sound method. How are you to measure a time from this kind of plot? Why were the red lines placed here rather than there?
The schematic with a light sensor (phototransistor) is better than similar ones seen elsewhere on the internet, because the current path is closed inside the schematic itself, not inside the (unknown) inside of the phone's or computer's soundcard. What is also good is the fairly low value of the resistor 4.7kΩ, ensuring the response is relatively fast.
In case you must use a microphone or line input that is not powered, you can include the power source as follows:
One drawback of soundcard inputs is they have a high-pass filtering, in practical terms, they have a series capacitor, which is why even the better Lomo schematic produces this kind of response, instead of the expected "brick" shape; nevertheless good enough for measuring times. I found that high-pass filtering sometimes more pronounced on the mic input than on the line input, presumably to prevent "proximity pop". And a Terratec external USB sound card to have more extended low-frequency response.
The ideal circuit uses a photodiode operated a zero-bias, an op-amp wired as current-voltage converter (transimpedance), and a hacked soundcard with a short-circuit across the input capacitance. Or a digital scope, if you have one.
This is $15 at ebay (search shutter tester):
It's a bare photodiode with case, cable and conector.
You have two models for the connector, one to be plugged to an smartphone an the other for PC, one has to be careful with that...
As will says, Audacity can be used to record the sound signal and from that measuring the aperture time.
I bought one of these but instead I removed the conector and I use my Pro USB oscilloscope to see the signal. This is more convenient because it freezes the screen when the impulse goes in, and it has a easy way to measure interval and HZ.
But you can buy an usb oscilloscope for as low as $25 (search ebay OmniScope 2xChannels 18MSPS oscilloscope)
In that case you may need the help of a teachy friend to get used to the way it works, not difficult at all for basic usage...
You have shutter testers under $100 (Tester-CAM-Lite Mini V2, also ebay)...
...but I found very interesting to see the signal from the photodiode in the screen because it shows how the shutter opens and closes, this interesting for diagnostics.
It doesn't matter much the way one measures it, but I found extremly interesting to test speeds of owned shutters, and the consistency of each speed !!! One can overcome a missmatch by adapting the exposure/aperture, but an inconsistent behaviour is a worse problem.
One has to remember that mechanical shutters were sold with +/- 30% accuracy specs, so 1/30 can be 1/20 or 1/40, 1 stop difference an still in specs!... and now we have decades old shutters, so a testing is a must, IMHO, specially for velvia
Bernard, I don't have a 'scope but have used them.
Would something like this very cheap oscilloscope work for our shutter speed application with the Lomo circuit and/or your improved powered circuit?
https://www.banggood.com/DSO188-Pock...r_warehouse=CN
I found even cheaper ones on eBay, but they had no box.
Former tube radio collector.
Tin Can
Not with the original "Lomo" circuit, because it relies on the microphone socket (on an iphone, I guess) being powered. Beyond that, I cannot vouch for the reliability Chinese USB-scope, only comment on the specs; here I'm guessing because I get an Access Denied, probably the URL you give is for US customers only, but from the URL itself I see 1MHz b/w, 5MHz sampling rate; modest values but amply adequate for shutter testing.
With that USB scope you have two marginal gains wrt using an audio input on a PC, plus Audacity software: (a) higher sampling rate, but the 44kHz (0.022millisecond) sampling of .wav file acquisition is OK for testing a 1/1000s shutter (and these are always slow anyway); (b)passing DC, showing you the true time profile of light admitted through the shutter, not just the duration.
You probably know that for a central shutter at maximum speed, the opening and closing time are a substantial fraction of the nominal exposure time; in that case, displaying the true light profile may be useful.
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