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Messages - aleks

Modules Development / Re: Full-resolution silent pictures
September 09, 2014, 06:22:14 PM
QuoteWhat is the ratio between 'how the mount can track fine' and 'how long exposures are expected'? (should be interesting to know the sampling on the imaging camera and an tracking error log on the mount) Because if it is only a question of polar alignment drift compensation _every nn seconds_ there are other solutions (if you see what I point :) ).

The setup is very basic, it is a Meade ETX Alt-Az mount which has poor tracking when the camera is attached. It can manage only 3 seconds of good tracking before it needs a correction. My goal is to increase the S/N of the images, hence I wanted longer exposures on the cheap, and wanted to try guiding while exposing, hopefully using silent pics with ML.
Modules Development / Re: Full-resolution silent pictures
September 09, 2014, 03:26:39 PM
SpcCb: I have a specific astro-photo setup, and was not planning too long exposures. I needed the LV video as a reference (with a cross-hair overlay perhaps) to do periodic corrections manually (my mount is cheap and it tends to lag after a few seconds at the focal length I use), so not a proper autoguidng setup, but an exploration of the possibilities using what I have. And the silent image accumulating during that time would have been the exposure I need. At full frame there would have been probably an issue with detecting movement of the guide star, but there is an ability within ML to show the 5x zoom in a separate window during the LV, so maybe that would have been enough.

dmilligan: Indeed, there is a Raspberry PI project out there which takes an image input and does the rest (calculations and sends control signals to the mount). To do all that in ML may turn out to be too much for the camera.

To come back from OT, since I don't have a guidescope, my plan was as stated above. If per line readout of the CMOS can be achieved, then some possibilities exist, but I understand that it would take too much effort. ML is already impressive enough.
Modules Development / Re: Full-resolution silent pictures
September 09, 2014, 02:07:29 AM
No, that is impossible. From what data would the display be updated while capturing an image? The sensor can't make two different exposures at the same time.

I did not use FPS override because I was hoping that the readout of the sensor was done in such a way that a long exposure image could be captured while in uninterrupted LV (non-destructive read), but I guess I was hoping for too much :D

Maybe something like this would be possible if we could control the readout such that odd pairs of lines are read with 25 fps for the LV display, and the rest are kept on hold for a user defined exposure time. Before coming across this thread on the forum, I was reading around to find out whether this was possible; probably not, and even if it were, it is highly unusual and would be very time consuming to research and implement. In conclusion, it was a nice idea, but too ambitious. Thanks for the support.
Modules Development / Re: Full-resolution silent pictures
September 09, 2014, 12:52:12 AM
I have tried the approach suggested by a1ex, built the raw video branch, and the silent functionality works (the image is distorted and with black borders, probably because of the pix offsets being wrong for the 1100D). I could not build the branch referred to by dmilligan (probably checked out the wrong commit).

Anyway, with what I have right now I can't really do what I intended to. Namely, the exposure duration of the silent image is always the same, I can't seem to take a silent picture with a longer exposure (say 5 seconds). a1ex mentioned that longer exposures should be possible (at the first post of this thread), but that may apply only to full res silent pics. I activated LV, changed the exposure setting back and forth, but the silent pic was always recorded immediately, there was no perceptible "accumulation" time before the save message even at exposure settings of 5-10 seconds. I have tried both .raw and. jpg formats.

For the "autoguide mode" to be useful, I would need to have a silent pic with exposure time of say 10 seconds (the longer the better) while the LV shows uninterrupted video on the screen. Not sure if this is possible (was not mentioned whether the display is refreshed during a long exposure silent image).
Modules Development / Re: Full-resolution silent pictures
September 08, 2014, 01:39:09 PM
Thanks dmiligan! I think I have enough things to keep me busy for a while. When I have results, I will report back.
Modules Development / Re: Full-resolution silent pictures
September 08, 2014, 11:20:30 AM
Got it. Thanks Walter, and thanks a1ex for the explanation and the suggestion. I know now where I went wrong. I looked at the code for a short while before starting to hack, and I have probably commented out the references to the LiveView RAW. Of course, then the consequence was that the silent pic was not working as intended. I believe what sent me in this direction was that I saw somewhere on the forum that someone was able to use silent pic on 1100D (simple, before the full res ability was added), so I tried to "revert" back to that state (unsuccessfully).
I will try the raw video branch and see how that goes.
Modules Development / Re: Full-resolution silent pictures
September 08, 2014, 10:21:01 AM
Yes, only the silent pic part of the build. I was referring to the comment made by a1ex earlier in the thread that he broke the silent pic part of the build to motivate people. Otherwise, the build compiles just fine. Sorry for the misunderstanding.
Modules Development / Re: Full-resolution silent pictures
September 07, 2014, 11:05:46 PM
I have been thinking about the possibility of using the silent picture mode for an auto-guider setup (exp. time of only 15 seconds, but fine for my purposes) using an 1100D, but since the build for it is broken, I was out of luck. I only considered the simple mode (no high res), and I thought that that would be available, so I downloaded and built the code.
Alas, it seems that the build is broken for all things silent for 1100D (simple, etc.) hence I was not able to see if what I had in mind would work (I need the LV active while the image is being exposed).
Then, I have reverted to an old version of silent.c and commented out the offending lines. The build was a success, and while in LV I could activate the silent picture. However it just says that it is taking a frame, but hangs. A .dng file is written on the card, but it is black and the file size is too small. I don't exclude the possibility that I have commented out more than was permissible though  ;D
I guess I will have to wait until the build is enabled; in the meantime I can contribute by sending a test .raw image for the 1100D (if still needed). It would be good if the build was only broken in such a way that only the new silent functionality was missing, and the older silent features were still there for the 1100D...  8)