Auto Shutter Release

Build an Automatic Shutter Release for the Dimage cameras. (D7ug/D7i/D7Hi)

 

Overview:

This article shows how I built an automatic shutter release for the D7ug and D7i. This shutter release will allow you to...

1) Take periodic shots that can't be taken with the interval mode, such intervals less than a minute, and more than 99 shots per session.

2) For astrophotography, automate the taking of 30 second exposures. This release will alternate shutter depressed, and an (approximately) equal period without the shutter depressed. When set to about 35 seconds, the camera when set to bulb will take a 30 second exposure, then a 30 second dark frame, then will save the shot, and this cycle will repeat.

The finished Auto Release attached to a Dimage 7

Close up of the release. Note temporary label for calibration, I plan to replace this with a better label later.

Construction details showing shoddy construction ;) I had planned to make a board for this, but didn't since there are so few parts.

The circuit diagram. See the notes below for details.

Construction details and notes:

You should be able to build this either from parts that you have, or with about $20 in parts if you have to buy everything. The box is something that I had laying around, as were most of the parts.

 

* The camera connector is a modified CDROM audio cable. I cut off one of the 4 connections, and melted the rest of it until it fit the camera. I even melted a notch into the connector to match the pin on the camera.

* On the camera, I'm calling the pins for the remote (counting from left to right as seen from the back) "common", "Focus" and "release"). To focus the camera, common and focus are connected. To release, common, focus, and release are connected. Note that you have to have Firmware 2.00 in a D7 for this release to work. Prior to firmware 2.00 the camera required a full release of the shutter before you could take another shot.

* The auto release keeps the common and focus connected all the time. These are connected through the switch (SW1) which is a double throw switch. One side of the switch controls the power, the other connects the focus contact. When the release is "On" the camera will act as if you have half pressed the shutter and you will not be able to make adjustments. To adjust the camera, you have to turn the release off which will disconnect the focus connection. This is the reason that a double throw switch is used.

* The circuit will run off the 4AA batteries shown, or you can use a 9V battery to save space... I just happened to have a nice AA battery holder. The circuit will run on anything from 4.5 to 14 volts. The current draw is minimal, so you could even use button cells if you want to.

* Some comments on the parts...

C3 is a 47 uF electrolytic. It decouples the circuit, and may not be needed for battery power.

R1 can't be any smaller than 1K. It should not be bigger either or the on and off intervals of the timer will not be the same.

R2 and R3 and C1 control the timing. C1 has to be pretty big to get times in the 30 second range, and you want to avoid any really big values for R2 and R3 since when they get over 1M ohm there could be leakage that ruins your accuracy. Anything from about 100 to 400 uF can be used. R2 and R3 control the timing, and R3 is variable. The purpose of R2 is to prevent you from setting the release to a very short time cycle (less than a couple seconds) that could (I worry) damage the camera if you didn't notice it. The values shown provide a cycle time of from about 3 seconds to 4 minutes in my unit. You can play with these values to get different results. I may replace R3 with a 250K pot instead, which would giver better accuracy in the 30 second range that I am interested in at the expense of times over maybe 2 minutes.

The LED comes on when the release is "pressed", then stays off for an equal period.

RY1 is a small reed type relay. The smaller the better.

The value of C2 isn't critical. Something small is fine.

* Note that you can use this as a "manual" release since the unit turns on in the "shutter pressed" configuration. Just set the knob for a long time and turn it on and off for manual release.

* I plan to put some velcro on this to hang it on my telescope.

Parts List:

Dan Kalikow has built this project, and provided this list of parts available at Radio Shack (tm) to complete it!

Dan's Parts list:

This a list of the required parts as you can obtain them at your local Radio Shack.  The parenthesized dashed-numbers are the Radio Shack SKU numbers.

SW1 -- SPDT -- (275-0663)

555 IC, standard-power version (276-1723)

DIP socket -- (276-1999)

C1 -- 200 uF electrolytic (There weren't any in stock so I got two 100 mfd (272-1026) and put them in parallel, adding to 200)

C2 -- 10 uF -- ten NANOfarads -- (272-1436)

C3 -- 47 uF electrolytic -- (272-1027)

9V battery clip (270-0325)

9V battery (23-875)
 

LED -- 9V regime -- assembly, (276-0011)

LED Socket -- (not needed -- above LED is a neat assembly that fits into a hole drilled into the project box)

Resistor between it and ground -- Bryan's original circuit calls for 160 ohms, but I used two of the five 100-ohm resistors in a (271-1311) pack, yielding 200 ohms, and it works fine.


R1 -- 1 K ohm fixed (271-1321)

R2 -- 10 K ohm fixed (271-1335)

R3 -- 1 M ohm variable (1/4" shaft diameter for a knob) (271-0211)

Matching diameter knob with good pointer-line (274-0407)

Reed Relay -- (275-0232)

Project box large enuf for battery, cct, switch, LED, PCB, socket, surface enough for knob pointer -- 6"x2"x1" box (270-1804)

PCB suitable for DIP socket etc. (276-0148) -- I had to file down the edges  so it would fit within the project box, and trim off one pair of corners so it could leave enough space for the potentiometer and battery within the length of the box)

Multi-colored hookup wire, solder, soldering iron, plug suitable for DiMAGE 7i's remote shutter release -- obtained by other means...