Photo-Sensor for testing shutter-speeds with the iPhone

Discussion in 'Classic Manual Cameras' started by lukas_fritz, Jul 19, 2013.

  1. Hello,
    a few weeks ago I posted something about the iPhone App for measuring shutter speeds, which I wrote.
    To enable a higher accuracy, I invented a small phototransistor-plug, which can be attached to the headphone-jack of the iPhone:
    As an extension to my App, it enables measurements of the actual light passing through the shutter of a camera, instead of sound.
    I am now selling these plugs on eBay for a few bucks:
    Maybe there are some people here who want to try it out :)
  2. Hi Lukas,

    I'd be surprised if you are not violating some of the forum rules by advertising your eBay items,
    but as I bought this plug a few months back directly from you, I can only say to whomever else
    that may be interested and owns an iPhone/iPod touch or iPad, that it is a very useful tool and
    allows you to carry a shutter speed tester everywhere - which is great if you like me always are
    looking for working old cameras.

  3. Maybe there is another forum where this might be more appropriate, however, this item could also conceivably be used inline with the microphone jack on a home pc. It seems like it could come quite handy. The I-Phone app making it portable is very practical though.
  4. When will it be available for a droid app?
  5. I am immediately intrgued and it is against the rules to hawk items here. As Rob mentioned, can the app be used eslsewhere? I don't own an iPhone and it's not really on my wish list, but a portable shutter tester... well that might be on my wish list.
  6. Hi,
    thanks for the positive feedback Niels !
    I know, this post may not well consort with the forum rules here, and of course it can be deleted if necessary. However, I'm not a professional seller, and I'm not going to make a lot of money out of the few plugs I am selling ;)
    In the last few weeks I sold a few of the plugs and I only got positive feedback, so I think it's a good product and it would be sad not to show it to people who could use it.
    I haven't tried to use the plug on a home PC yet. You would certainly need some kind of adaptor cable, as the plug has 4 pins, but most regular sound cards have the common 3-Pin jack. However, such an adaptor cable shouldn't be too expensive so I definitely will give it a try and post my results :) If it works, you could use the plug with any sound-recording program available for PC/Mac.
  7. It might be viable to try to connect this type of shutter tester to a USB plug.
  8. This is a very nice application. I used a phototransistor connected to a battery and a hand-held digital oscilloscope (which, of course, was not my own) to check shutter speeds.
    However, you should not rely on this method for shutter speeds above, say, 1/125 sec. Leaf shutters need some time for opening and closing completely, this takes about 1-2 msec each. Shutter speeds are defined as the interval where light transmission, i.e. opening of the shutter, is at least 50 per cent of total transmission or opening. If you use a spot light source and a small sensor, measurements for high shutter speeds may not show the actual speed. Also, since the iphone obviously cannot measure DC voltages (the diagrams shown are typical for AC coupling) you will not see the opening and closing procedure of the shutter precisely. At 1/500 sec even my method (using DC coupling) shows just a short peak of 2 or 3 msec duration depending on how you detect the edges.
    But usually shutters do not have much problems with highe shutter speeds, it's rather the slow speeds which cause problems. Especially speed settings of 1/8 to 1/15 sec sometimes need precise adjustments. And in these cases you do not need to detect opening and closing times and the method described will be very helpful.
  9. 1/500 is 2msec.
    You speaking of mechanical shutter for the good high speed but inaccurate low speed. With electronic shutter the low speed from 1/125 and slower are much more accurate. 1/1000 and higher are generally never accurate. Shutter speed of 1/8 and 1/15 are usually dead on.
  10. Bought one, sounds useful as I have a truckload of leaf shutters and the slow speeds are the ones I really need to check.
  11. It always depends on the camera you are using. One camera might have a faster shutter than another. But what I experienced is, that this method works very well even up to 1/500sec on most cameras (both leaf shutters and focal plane shutters). Of course it will never be 100% exact, so you won't be able to tell weather the shutter speed is 1/500 or 1/495. But you will be able to detect larger deviations, which really affect your final image on the film. And that's what the app and the photoplug is intended to do: Saving you from under- and overexposed images due to a defect shutter in your camera :)
  12. I don't have iphone, can this device be used on an ipad or ipad mini ? If it does, I will buy one
  13. Yes, you can use the plug with an iPad, iPad mini, iPod Touch etc. as well.
  14. Lukas, I have several focal plane shutter cameras, does this plug useful for focal plane shutter too ?
  15. Yes, you can use the photoplug with focal-plane-shutters, too. It works very good up to 1/500s on most cameras.
  16. James G. Dainis

    James G. Dainis Moderator

    Note from Moderator. Lukas, I think that is enough. From the Community Guidelines for
    7. Don't post advertisements or classified ads in the forums, and don't post links to eBay auctions. has a Classifieds section where you can post personal "for-sale" and "wanted" ads (but not eBay links).
    I have been generous in allowing these posts to stand. It is a very useful device for collectors of classic cameras. But, I can't allow you to continue in violation of the rules. It would be unfair to others who would like to sell on the forums but are prohibited by the Guidelines from doing so.
  17. I'm sorry, probably shouldn't have posted this here. I understand this, of course, so I won't post links or other types of advertising in future.
    Thanks anyway for allowing this post to stand until now :)

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