DSLR Shutter control

[mick pinner]

l assume that DSLR shutter control takes into account ICNR before the next capture is performed. is this correct?

[bojan]

It is done after the current exposure (if ICNR is enabled).

[g__day]

From memory - control is not returned to DSLR Shutter until ICNR takes and equivalent dark frame and subtracts this from the light frame.

[bojan]

Yep.
You can not open shutter while camera is taking dark frame (as part of ICNR procedure).

[rogerg]

I have found when using DSLR Shutter with ICNR I need to specify a delay of the exposure time + 15 seconds such that DLSR Shutter does not attempt to take the next exposure while the ICNR is still occuring.

If I do not specify a delay to allow for ICNR I find the DSLR Shutter thinks it starts the next exposure as soon as the previous one has finished, but of course doesn't because the camera is still busy, but DSLR Shutter doesn't take note of that, it simply starts ticking down the next exposure. Obviously things get confused from there on, so you end up with an incorrect number of exposures and all sorts.

To me this seems to match functionality in Nebulosity 2 and Craig's belief that ICNR should not be used, and so is not supported in either Nebulosity 2 or DSLR Focus.

(Personally, I find it annoying, but anyhow..)

Roger.

[erick]

I was a bit confused. Yes, if you are talking about "DSLR Shutter", the software, it just does what the computer tells it, regardless of what the camera is doing! (This is for the simple control connections that I have on my Pentax K100D - a simple wired remote connection via a "stereo plus".)

Craig (DSLR Shutter) says:-

DSLR Shutter is really moronically simple. It sends "go" and "don't go" signals to simple parallel port data lines, the RTS/DTR lines of a serial port, or to the ShoeString DSUSB. The former two are very simple, binary signals. The ShoeString is “semi-intelligent" in that I need a software library from Shoestring and need to code up support for it. Doug's libraries are trivial to use and it's still sending very simple commands. It is still just sending "go" and "don't go" signals to this bulb port on the camera.

So you need to work out appropriate intervals to set in the software, to match what the camera is doing, as Roger says.

My K100D has a light which flickers as the image is written to the memory card, so I know when it has finished all its INCR stuff and processing and is yearning to open the shutter again.

So you can set an "after frame" delay or a "before frame" delay to allow the required time. As far as I can tell, it doesn't matter which you choose.

As far as I can tell, my camera takes a dark exposure for the same time interval as the "light" exposure, then spends another second or two processing and writing the resulting image to the card.

I'm going to try to capture the Leonids on Wed morning with DSLR Shutter driving the camera, but with INCR off. So have to work out the timings tonight in the comfort of my lounge room!