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08-09-2014, 01:44 PM   #1
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Syncing shutter on a K20D and K100D

I've been dabbling in 3D stereophotography lately, making image pairs and presenting them in crossview format (so you just need to cross your eyes a little to get the effect, no need for special glasses). Mostly I've been using a Fuji W3 stereo camera for this, which is rather point-and-shoot-ish and does a great job within its limited parameters, but I'd really like to use my Pentax DSLRs for better image quality. I have a K20D and an older K100D.

The problem I am running into is synchronizing shutters. Sometimes it's good enough to just use one camera: get the left-eye image, move the camera to the side a bit and shoot again -- unless your subject is not stationary, or maybe the wind is blowing foliage around or something. Then you want two shots from different points in space at the same time. I don't necessarily need control it right down to the millisecond, but want something that would reliably get a signal to both cameras together, resulting in near-simultaneous firing if both cameras are set to manual-everything mode.

Trying to get them both to fire from either one or two wireless transmitters has proved unreliable; splitting the connection from a wired remote doesn't work on this pair of cameras (once they're connected, both cameras start firing nonstop even if no button was pushed). I tried connecting the two cameras together with a simple 2.5mm stereo cable, as suggested by someone I know who does this with a pair of Canons; he says you just connect them together and then firing one also trips the other, but I found it doesn't work for this camera pair.

I saw a suggestion in another thread here about possibly using a resistor in the wired remote circuit, and have experimented with that some, with no success. Unless I'm doing it wrong, depending on the value of the resistor, I either get no response from the second camera or they go back to the non-stop firing behavior.

Has anyone else been actually able to make this work with a pair of Pentax DSLRs? Do they have to be the same model maybe (or "similar enough," e.g. K10D and K20D)?

08-09-2014, 02:02 PM - 1 Like   #2
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You may have your wires crossed. A diagram or a closeup photo of your switch wiring would help. A diode is what you would need to prevent back pathing.
08-09-2014, 02:18 PM   #3
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Try the Pentax IR remote F. One push of the button will fire both cameras at the same time (except for shutter lag differences).
08-09-2014, 03:00 PM   #4
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Ole, thanks but I haven't been able to get that to work. Maybe it's because I'm using an inexpensive Chinese ebay remote instead of a real F, but I can't reliably aim the thing so the beam takes in both IR sensors. And anyway I'd like to be able to shoot wide stereo sometimes - with the cameras a meter or more apart, on landscapes and such.

NaN - intriguing thought about the diode. Maybe I want two, one in each branch of the Y?

08-09-2014, 04:23 PM   #5
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This seems to work! Time to go out and try being "bicameral."

08-09-2014, 04:43 PM   #6
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Why not use a double pole switch (two sets of contacts)? The circuits would be isolated.

BTW: If you are using a PC StereoPhoto Maker can make the job a whole lot easier.

http://stereo.jpn.org/eng/stphmkr/index.html

Last edited by Not a Number; 08-09-2014 at 04:52 PM.
08-09-2014, 04:53 PM   #7
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That would work for sure, but I already have the single pole switch built into the wired remote I was playing with, and can now keep it intact in its plastic hand case.

Edit: I'm on Linux. There's a GIMP script that takes most of the tedium out of making the crossviews, so it's okay.


Last edited by Sluggo; 08-09-2014 at 05:22 PM. Reason: replying to an edit
09-19-2014, 05:12 AM   #8
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Hi, i just registred to this forum after searching for that precise question .
I was having fun with w3 but need to go a bit more pro so I just aquired a second K-5,and a rig from berezin.com , and will try some wiring (but i m no pro at that,So i guess i ll go for double pole switch,)
so thx for all those advices
09-19-2014, 06:27 AM - 2 Likes   #9
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Because the different sensor types made it a little too difficult to get matching images, I sold my K100D and bought another K20D to make an identical pair. The addition of the pair of diodes makes the rig work just the way you'd expect - in my opinion it's easier to wire it that way than with a double pole switch. Below is one result from a few days ago (in crossview format: cross your eyes to perceive the pair in 3D). Good luck - this is fun stuff!

09-19-2014, 09:43 AM   #10
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Beautiful stereo effect! What is the separation distance between the cameras or optical axes?
09-19-2014, 11:35 AM   #11
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QuoteOriginally posted by Not a Number Quote
Beautiful stereo effect! What is the separation distance between the cameras or optical axes?
Thanks! These were 28mm lenses, probably about two feet apart. I really should take notes, as EXIF is no help. Anyway I'm finding the shared remote seems to really help with crispness on trees and other foliage when there is breeze, although the timing likely isn't precise enough to share a flash or anchor a quickly moving object.
09-19-2014, 12:00 PM   #12
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So you're not using a dual mount rig and just positioning on two tripods? Experiments with flash would be interesting. I wonder if a master and slave flash would do better. Or slow sync vs trailing curtain settings.

Just for fun a while back I tried a view cross-eyed shot using a macro lens. I only used one camera mounted on a focus rail set 90 degrees from the lens axis. Separation was about 4 inches or near to what the average pupil distance is for adult humans. I did "converge" the angle somewhat by picking a central aiming point. I was using a flash but again it was with one camera.



I used Stereo Photo Maker - a share/freeware program (Windows) to create the frame. You can use it to make anaglyph stereo photos too.
09-19-2014, 12:48 PM   #13
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Great pics indeed . I more used to parallel viewing ,but in any case,it just works for small versions for me , for bigger i usualy just look at those on passive stereo screen .
And you convinced me on that diode set up, but my electicity classes are so far away, might I ask you some precisions on what type and which orientation to set them ?
Can t wait to try
09-19-2014, 02:26 PM   #14
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If you remember how to cut and splice and solder things in general, then the only bit of information you seem to be missing is how to read the diode symbol in the diagram. The triangle-arrow in any circuit diagram points toward the striped end of the diode, as illustrated:



(Picture borrowed from here.)
07-08-2017, 08:23 AM   #15
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A postscript on this thread for whoever might land on it later in a search. It turns out to be helpful to wire the third contact, even in manual focus mode; without it, sync suffers because one camera might be ready to shoot and the other not. A half-press connects the "B" line and wakes the meters in both cameras.

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