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I would like to know if there is some shutter delay after an external trigger is issued via wire on a Canon DSLR (I am interested in the mid-range models - 300D, 350D etc.) The wired trigger sends an electric pulse which I consider to be time = 0 ms. I guess there may be some ms to the start of exposure since the shutter is mechanical and it takes some time till it opens?

EDIT: I will use manual focus but I need auto-exposure (plus maybe auto-gain/ISO).

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    This sounds like an XY problem. That is, do you have an underlying question or problem that you're really trying to solve? Such as using a DSLR as part of a larger computer vision system, where timing delay of the entire acquisition is important to your process / etc.? – scottbb Jan 24 '17 at 23:31
  • If you are using autoexposure you'll probably never get consistent enough times for the precision which you seem to be after. That is because the time needed for AE systems, especially the ones found in DSLRs such as the examples given in your question, will vary based on the contents of the scene. – Michael C Jan 25 '17 at 4:31
  • @scottbb I want to precisely geotag photos with cm-precise RTK GPS. However I realized I can use flash sync signal from horseshoe to workaround the shutter lag. Also exploring the use of DSLRs for robotics - here the shutter lag ruins everything for real time, flash sync can again be used for non-realtime applications. – Kozuch Jan 25 '17 at 21:09
  • @Kozuch Then make the geotagging problem the question. – Michael C Jan 26 '17 at 5:11
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Kozuch, I don't have direct knowledge, but would expect that since shutter buttons and external triggers both trigger an electrical current, causing the shutter to activate, the shutter delay/lag should be very close or equivalent between them.

Below is a chart that someone put together online. He subtracted the time to focus, etc., which is good:

https://www.dpreview.com/forums/thread/3925402

  • I forgot to mention I need manual focus - the tests you link are valid, but for auto-focus... – Kozuch Jan 24 '17 at 23:08
  • @Kozuch What is the underlying problem you are trying to solve that requires such precise shutter lag times? – Michael C Jan 25 '17 at 4:32
  • @Kozuch is correct, there will be no more delay then when pushing the regular shutter button. This is precisely how high speed triggers such as lasers, light, and sound work - via the external trigger. From an electronics standpoint, it's called "electrically the same". – MikeD Jan 25 '17 at 13:42
  • @MichaelClark Please see my comment on my question above. – Kozuch Jan 25 '17 at 21:12
  • There will be neither more nor less delay when using a wired remote vs. using the shutter button. But with DSLRs such as the 300D, 350D, etc. either means of activation will have significantly variable shutter lag based on metering mode, exposure mode, scene contents, etc. – Michael C Jan 26 '17 at 5:14
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Many remote controls have a two-phase shutter button just like the camera's own shutter release button. The first detent activates the autofocus and exposure calculation. Pushing it fully home activates the shutter release.

The shutter lag for the second phase should be fairly constant. So if you use this pre-release, and trigger the second phase at the wanted moment, the lag should be constant.

Note that as these cameras have a focal plane shutter, at higher shutter speeds (faster than the flash sync speed) one side of the sensor gets exposed before the other side due to the travel time across the sensor. The time difference may be several milli-seconds, which, however, is not a problem in most normal photographic situations.

Many cameras, including my Canons, have configurable settings for this so-called AF/AE lock function, where you may select which functions are done at pre-release and which at the second final phase. Read the manual and be sure your camera is set up the way you want.

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