Yoshizen's Blog

F-Aperture / Iris Control (2)

Sigma Macro Auto-Iris(1)A09A4574

This is the up-date of the post with the same title before.

Sigma Zoom(2)A09A4525

The temporally test circuit of the Iris control then has been made to

a proper board.  Still, where to put the battery hasn’t yet fixed.

(At moment the power was connected through the cables.)

Sigma Macro Auto-Iris(2)A09A4578

To make the drive circuit of Iris control was rather simple (= Just put the

necessary components on a piece of strip board.) though, where to put the

Open-Close Switches gave me a headache.  —– Ideally, it should be inside of the

Camera or make the Camera’s shutter button function for the trigger of this Iris

control too.  (Asking too much !)    Or, alternatively, put the Iris Close Button

right next of the shutter button and press both of them in the same time.

—– On the end, I decided to use the Camera’s remote trigger switch.  

Sigma Macro Auto-Iris(3)p-001

Remote trigger switch is double switch.    First half press activates the

auto-focus then deeper press trigger the shutter.  Though, to the hand made

macro lens, auto-focus switch is no use.   I decided to use this switch to close

the Iris, and put a change-over switch to select  either Focus or Iris close.

(The button to Open the Iris was put the back of Remote trigger.)

Sigma Macro Auto-Iris(5)2-001

In this setting, Focus and Framing can be done while Iris was fully open,

then the press of button, first close the Iris then expose the picture.  

With a use of  TTL Flash-light, almost automatically a photo was made !

—–  a short coming was, as the trigger was made by Remote Switch in the

left hand, camera was held almost right hand only. = a bit heavy.  😦  

Still, the Camera in the free-hand, then just click the shutter and enable

to take picture is a great convenience.  🙂  🙂



6 Responses

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  1. edgar18 said, on September 23, 2014 at 05:46


    I have a lens from a Fisher camcorder.
    I want to adjust the iris but can not find a suitable circuit.
    The iris has two drive coils (200 ohm) and Damp (1.2K ohm) – http://www.dipol.com.pl/images/info/00012.gif.
    If you have a simple control scheme to adjust the iris with a potentiometer would be very good.
    Thanks in advance for your answer.

    • yoshizen said, on September 23, 2014 at 06:59

      When you see 4 cables coming out from the driving device, 99 % certain,
      it is the [Bipolar two phase Stepping Motor] = it’s mean you have to give
      symmetric square wave to each coil but in antiphase.
      You can find a Driving circuit by googling (in fact it would be a so-called H-drive circuit)
      though, the complication is, as it is a pulse driven digital motor = control is
      “How many pulses were given” from pulse generator = and you need to have either a counter
      (always reset when fully opened) or a precise timer which can give exact number of pule in given time.
      And to have an indicator which shows “what F at the moment” need to have a memory.
      = The controlling circuit would be ten times larger then H-drive circuit not mention LCD panel
      to show current F aperture. —– This was the reason why my circuit in the photo didn’t have
      controlling part and just the direction of open or close (press a switch only short moment
      and close a bit, or fully press to fully open kind of rough setting 😀
      = Even with such rough setting, while using TTL flash, the exposure would be OK ! )
      In certain extent electronics is not very difficult to deal but if you need a sophistication,
      it would be a bit daunting task.
      I hope you have a Good luck.
      PS : I checked the circuit of “your Ref” = dipole —– I’m not sure what this circuit meant =
      what is “damp” = I wonder was this author did know what he (she ?) was talking about ? ? ?
      —– A,ha there could be an analog survo motor kind, 200 ohom could be simple DC motor and
      the damp 1k ohom might be potentiometer to feed back a position — in this case, just connect
      DC 5~7 V to the cables of 200 ohom and change polarity = if the motor (iris) moves, it was
      the DC Motor. Then measure the resistance of “Damp” was it change with iris position ?
      If it was not in this case either, it is necessary to check and analyze the original circuit
      board and find how it was designed.

  2. edgar18 said, on September 26, 2014 at 06:11

    Thanks for the response !
    Meanwhile I wrote an email to Fisher electronics and wait an answer from them.

    • yoshizen said, on September 26, 2014 at 08:06

      Generally the manufacturer doesn’t give a technical information of the design by their rule.
      Still, good luck.

  3. Johnd293 said, on April 18, 2015 at 01:40

    Hi there, just became aware of your blog through Google, and found that it’s truly informative. Im gonna watch out for brussels. I will appreciate if you continue this in future. Many people will be benefited from your writing. Cheers!

    • yoshizen said, on April 18, 2015 at 05:46

      If you are talking about a kind of electronics, I’m preparing to show another one soon.
      Thank you John to visit here.

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