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Frgsn
Tinkerer
Username: Frgsn
Post Number: 1
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, March 24, 2008 - 07:52 pm: | 
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I wanted to share an easy way to test shutter speed. I use any microphone attached to a PC, hold it next to the lens, run Audacity a free program, hit record, trip the shutter, zoom in on the click made by the shutter and measure the interval in milliseconds and calculate the reciprocal. I find it fairly easy to determine the shutter opening and closing on the graphical display of the sound. Perhaps not perfect but cheap and easy. |
Alex
Tinkerer
Username: Alex
Post Number: 50
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 25, 2008 - 04:51 am: |
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I'm guessing this is for leaf shutters, is that right? What sort of results have you been able to get for slow and fast shutter speeds? |
Jersievers
Tinkerer
Username: Jersievers
Post Number: 3
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 25, 2008 - 08:00 am: |
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How does this work with Copal shutters? (good, bad, haven't tired) |
Jersievers
Tinkerer
Username: Jersievers
Post Number: 4
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 25, 2008 - 08:05 am: |
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Forgot to note, The Tomosy book #1 has all the math done already in the appendices. |
Frgsn
Tinkerer
Username: Frgsn
Post Number: 2
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 25, 2008 - 07:40 pm: |
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Yes, leaf shutters. The recording includes the depression and release of the button but the signature of the shutter opening and closing is pretty consistent and identifiable except at 1/500th and above. The slow speeds are most easily identified and reproducible. Depending on the camera and its condition, the shutter times vary between about 10% slow up to bang on right. Copal shutters are no exception, the recording is just picking up the noise of the opening and closing. There is some judgement as to where to identify the onset and offset of the interval but not alot. |
Frgsn
Tinkerer
Username: Frgsn
Post Number: 3
Registered: 03-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, March 25, 2008 - 07:45 pm: |
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Yes, leaf shutters. The recording includes the depression and release of the button but the signature of the shutter opening and closing is pretty consistent and identifiable except at 1/500th and above. The slow speeds are most easily identified and reproducible. Depending on the camera and its condition, the shutter times vary between about 10% slow up to bang on right. Copal shutters are no exception, the recording is just picking up the noise of the opening and closing. There is some judgement as to where to identify the onset and offset of the interval but not alot. |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 101
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 28, 2008 - 03:53 am: |
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I've never tried a microphone but instead cut off the mic and install a light sensative transistor or diode. Run the same software and you will have a very accurate shutter tester.
There is an article on this forum with instructions how to build one although it recomends using a reisitor n battery, it isn't really needed. The simple photodiode is all you need. just be sure the polarity is right otherwise it won't work at all. |
Adrian
Tinkerer
Username: Adrian
Post Number: 155
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 28, 2008 - 07:59 am: |
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I, for one, am interested in these - I've never really had a lot of clue what speed my shutters are, except when the film comes back under- or over-exposed, when set by the lightmeter...
The use of an audio program with a light sensitve diode makes me smile, but it's just another way of converting your input into electronic data, isn't it?
I'd be inclined towards the diode, simply because one of the shutters I'm interested in testing makes the loudest noise I've ever heard from a leaf shutter - up to SLR standards.
Any chance of some pics of your setups, and an idiot's guide to the maths? (and I do mean idiots - if you read the Wikipedia entry, I am lost before the first full stop...). |
Paul_ron
Tinkerer
Username: Paul_ron
Post Number: 102
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 28, 2008 - 12:53 pm: |
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Can I post pics here? I'd be glad to show ytou how simpole it is. Otherwise e-mail e I'll send you come pics that way.
[email protected] |
Jawson76
Tinkerer
Username: Jawson76
Post Number: 1
Registered: 07-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 30, 2008 - 05:06 am: |
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For any kind of PC up gradation or PC maintenance a best place i know is ( http://www.pcrepairexperts.net )PC Repair Experts you can have a look by yourself i hope you won't be disappointed because one of my friend referred me this site and by that time i am with this site and recommending others |
Sigkyrre
Tinkerer
Username: Sigkyrre
Post Number: 8
Registered: 01-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, July 30, 2008 - 06:11 am: |
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I've used the light diode method as well, hooked up to the sound card. It works well up to about 1/100. Above that, the opening/closing time of the shutter will have an effect, and you can't really analyze the graph output in terms of exposure.
A different approach is posted here http://decisivemomentum.blogspot.com/2008/07/using-dslr-as-shutter-tester.html
Here it is possible to judge exposure directly, taking into account shutter efficiency and aperture errors. A similar setup should work for focal plane shutters. |
August
Tinkerer
Username: August
Post Number: 19
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 07, 2008 - 09:33 pm: |
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I use the photodiode method with the simple battery circuit. Very simple and almost foolproof to build. Using the battery probably sends a stronger signal to the computer which may help with picking up and interpreting the trace.
This method can be accurate at speeds well above 1/100. Some people do it by getting a higher-performance (faster responding) diode than the standard issue Radio Shack model. Another way is to learn, through trial and error, how much error the photodiode lag introduces and correct for it mathematically. I do the latter; when I test a shutter, I do 3 or 5 trials at each setting, enter them into an Excel worksheet, compute the average and then apply the correction I've developed to get the best estimate of the shutter speed. I have confidence in the results up to 1/500, which is all I need for the type of cameras I test. |
Nickon51
Tinkerer
Username: Nickon51
Post Number: 14
Registered: 05-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 08, 2008 - 09:37 pm: |
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IMHO the easiest way is to use a solar cell. Solar cells have a good frequency response and the output is proportional to the light input, provided the cell is not saturated. No need for any power supply as the cell generates its own. The light source can be a cheap LED torch, the cell was liberated from a solar garden light. I used this method with an DC coupled oscilloscope, but I see no reason why it would not work with a sound card.
I think the limiting factor here would be the frequency response of the sound card itself.
Solar cells are used in 35mm theatre projectors as the replacement for the old cold cathode tube detectors. The limiting frequency response factor there is the optical slit width, but 15Khz was about the norm. |
Jayd
Tinkerer
Username: Jayd
Post Number: 35
Registered: 06-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 09, 2008 - 04:38 am: |
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I want to build one of the photo diode testers but have to find a source for a good Photo transistor, like most things Radio Shack theirs is lower quality at higher price.
Jay |
August
Tinkerer
Username: August
Post Number: 22
Registered: 06-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 09, 2008 - 02:09 pm: |
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Every CD or DVD drive or player has one, so you could get it out of just about any junk computer that someone is throwing away.
The Radio Shack one works fine for me but I may upgrade one of these days. |
Arnoldharris
Tinkerer
Username: Arnoldharris
Post Number: 35
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 10, 2008 - 01:39 pm: |
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The only camera whose working mechanisms I know well is the Voigtlander Vitessa-T rangefinder (1956-1958), of which I have a large collection.
The Synchro-Compur 00-MXV "Wide" CN-1110-030 shutter in this camera is relatively easy to remove from its carrier, for purposes of thorough cleaning with naptha, followed by only the tiniest amount of the lightest shutter gear oil applied to the star wheel and pallet on the eacapement gear train.
That has enabled me to get numerous partially or fully stuck shutters working again, at all speeds from B through 500, without sending the cameras to a repair shop.
Any attempts to pull these shutters apart further than that, I would not advise, other than for people who have the skills of Rick Oleson, most of whose online advice I have carefully read in the past few years.
Is there likely to be dessicated and hardened lubricants both on the shutter blades and on other shutter parts? Why would anyone think otherwise, considering that these cameras came out of their German factory 50 years ago or more, and that many of them never have been cleaned and re-lubricated at all, or were lubricated in all the wrong places by people who didn't know better?
As for shutter timing, I've done this visually on all the cameras in my collection. With both the lens and caseback easily removable, and with the shutter installed, it is easy to test the Vitessa-T at all speeds, for which I use my bright computer screen as a light source which I can see through the shutter blades.
In my experience, the lower speeds have been the ones that I found frozen up on most of the Vitessa-T units I've bought on eBay or elsewhere in recent years.
(That, and problems with the film advance, shutter cocking and film release mechanisms and their interlocks, is probably what made them relatively affordable. These other problems are relatively easy to fix, once you have figured them out. But taking apart shutters is another story.)
So those low speeds are one the ones to which I pay closest attention. And I have found that if the lower speeds are relatively accurate, so too are the higher speeds.
I'm not sure that what I have described here is the "right" way. But it certainly has worked for me.
Arnold Harris
Mount Horeb WI |
Arnoldharris
Tinkerer
Username: Arnoldharris
Post Number: 36
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 10, 2008 - 06:08 pm: |
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PS.
I forgot to mention in the message above that in order to get access to the star wheel and pallet in order to lubricate them ever so gently, it is first necessary to unscrew and lift off the set of five rings on the front of the shutter that comprise the interchangeable lens mount.
Stop there, and DO NOT pull off large C-ring that holds in the guts of the shutter micro-mechanisms, levers, springs that go "shprong!!", etc. Not unless you know exactly where to find the tiny springs that came down on your floor. And unless you know exactly how to put them back in place. But you can lube the star wheel and pallet without pulling out that stuff, and without having a camera shutter encounter of the third kind.
Arnold Harris
Mount Horeb WI |
Jaroslav
Tinkerer
Username: Jaroslav
Post Number: 2
Registered: 08-2008
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 12, 2008 - 06:27 am: |
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That is quite simple and neat idea, I also have been doing this, see the post on photo.net from 2001:
http://photo.net/medium-format-photography-forum/000Acn
It is evident that the accuracy will fade for shorter speeds. The other factor to consider should be some shutter opening/closing effects when the shutter blades f-stop the lens for some short period. |
Adrian
Tinkerer
Username: Adrian
Post Number: 189
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 12, 2008 - 07:39 am: |
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Yes, I've "built" one of these with help from a forum member, and have found that it works best on the slower speeds - faster speeds have a distinctive shape to the curve which, I suspect, reflects something of the shutter's operation. Interestingly, it goes "snow blind" on very slow speeds, but there's a little blip in the trace when the shutter closes again.
If I ever get a mo I'll post a screen shot.
If you are doing it in the UK, you may need to poke round dead appliances for an appropriate photodiode. With the demise of Radio Shack and Tandy as high street stores, all that is left is Maplin and their photodiodes just don't generate enough current for the software to detect (yes, I have tried them both ways round!). I was eventually sent one from the USA...
Adrian |
