DSLR Timer
DSLR Timer is a Freeware DSLR Interval Timer using the parallel port or serial port of your notepad or PC.
It can control series of long exposures of digital cameras as it is needed for astrophotography. For astrophotos it is usual to have series of exposures with 2 to 5 minutes exposure time. DSLR Timer is the convenient tool to control this for you. I use it with Pentax *ist DS and Canon EOS 20D. It should work also with other cameras.

The programs delivered by the manufacturer of digital cameras usually support only exposure times up to 30 seconds (exposure control M). However, this is too shor for usage in astronomy. There are also some other freeware programs, but they usually support only standard parallel port addresses. Using a PCMCIA-Interface as parallel port, you have other addresses, e.g. FED8. So I made my own program.

DSLR-Timer can be used for single shots as well as intervall timer. It connects to the camera via the serial or parallel port of your computer. On the camera side it connects to the jack of the cable remote control. USB connection can be used in addition to download the images, but DSLR-Timer does not use USB.

DSLR-Timer offers you the following functions:

  • Single shot (Start - Stop). Mainly for testing the correct setup before starting an intervall series. 
  • Intervall timer. This is the main feature of this program 
  • Exposure time from 1 second to 1 hour per image
  • DSLR Timer can consider the time for mirror lock-up, noise reduction and the time which is needed to save the images.
  • Pause-Function to interrupt and continue a series of shots. Using pause, the current image will be finished and saved. It stops before the next exposure starts. In this status you can change the settings or exchange the batteries of your camera. Then you can continue the series. 
  • Display of the total remaining time for the complete series, including the time for exposure, mirror lock-up, noise reduction and save.
  • Display of the time of day, when the series will be finished. So you can easily go for a coffee and come back in time.
  • Camera control via parallel port. You can use LPT1 to LPT3 or any port address. This is very important for the usage of PCMCIA cardbus cards..
  • You can specify, which PIN of the parallel port is used to control the camera. Only the one bit which corresponds to this PIN will be changed. The other PINs can be used by other programs. So you can control a webcam with long exposure via the same parallel port.
  • Camera control via serial port: Rts or lx200. When you use the LX200 protocol, you can control the camera through your mount. This saves a cable, but you need  special cable electronics. You can find it on Rajiva's website.    

For the connection of camera and computer you need a special cable with a simple electronic circuit. You can either buy it or you can do it by yourself. The idea of the cable is, to simulate a cable remote control by connecting two cables using a trasistor or optocoupler. There are plenty of instructions how to build such a cable available in the internet. I tried both, transistor and optocoupler and both worked fine. I stayed with the optocoupler, as this seems to be more save for the camera. I added some links at the bottom of this page for your reference.
DSLR Timer is freeware. You can use it for free without restrictions. However you use it at your own risk. Please be carefull when you connect the camera. Not using the appropriate cable may damage your camera.
System Requirements: Windows XP or Vista, .NET 2.0

Download DSLR-Timer


Installation: Extract the downloaded Zip file and execute Setup.exe.


Freeware-base Winload- Softwaredownloadportal 




1.09 - 30.12.2011: small improvements, automatic version check

1.07 - 10.01.2011: translation added

1.06 - 02.09.2010: dark blue layout

1.04 - 12.04.2009: added inpout32.dll, which was missing in the installation package

1.03 - 28.04.2008: with French translation, language selection according to Windows language

Single Shot


The exposure begins when you press the Start button. The timer counts up the seconds. Pressing again this button with stop the exposure and the timer counts down the seconds, assuming that noise reduction is active. To stop completely, just press the button again.


Intervall Timer


Enter the number of pictures and the exposure time. Then specify a time that is needed to save an image. Otherwise problems may come up when the next image starts while the previous images is saved. Setting mirror lock-up means, that 2 seconds for mirror lock-up are taken into account. You should mark it, when this is active in the camera. For a Pentax camera use the self-timer for 2 seconds. For a Canon EOS 20D, set mirror lock-up active and self-timer on. Camera settings and DSLR Timer settings must fit together. The program does not actively control the mirror or noise reduction of your camera. So mark the noise reduction indicator, when it is switched on in the camera.


Note about Saving of the Images


DSLR Timer simulates a remote cable control. So the images will be stored on the memory card of the camera. If you want to transfer them to you computer, connet with a USB cable and start the connection software of the manufacturer. It works fine for my Canon, when I start EOSViewerUtility and EOS Capture. I was not so successfull with my Pentax. Pentax Remote Assistant starts downloading, but it does not end.   


If the shutter does not release ...


Typically the shutter does not release at all, or it releases always when you connect to the PC, independent of DSLR Timer.

Please check the settings:

  1. Did you specity the correct type of port? Parallel port has 25 PINs, serial port has 9 PINs
  2. If you use the parallel port: is the port address correct? My PCMCIA Parallelport Adapter shows LPT3, but it does not use the standard address. You can find the I/O-address in the Windows devicemanager.
  3. Is the correct PIN used? Have a look the the settings (Screwdriver-Icon next to the port). If you have doubts, open the parallel plug and have a look, or just try out.
  4. First start DSLR Timer, then connect and switch on the camera. Otherwise it may release unintensional.


If the shutter releases for a time and stops then, the resistor in the cable may have a too high value.


Links with information needed to build a cable:

Rajiva's Forum

Michael A. Covington
Paul Beskeen