37 replies to this topic

[Borodog]

Light pollution is irrelevant. The problem is the 1 ms exposure.

[TicoWiko]

Light pollution is irrelevant. The problem is the 1 ms exposure.

Ok. So even if the text file said 150 average fps, that's not necessarily reliable ? Like I said I was just discovering the tool, and so left too many things at their default value. Now I just need the clouds to go away to try again 😅

Thanks for the tip !

[KpS]

The value fps=150 generally implies only that the exposures were not longer than 6.6 ms. However, each .ser file has its own log file and the exposure time is also recorded in that log file.

[Borodog]

Ok. So even if the text file said 150 average fps, that's not necessarily reliable ? Like I said I was just discovering the tool, and so left too many things at their default value. Now I just need the clouds to go away to try again

Thanks for the tip !

 

The camera can only transfer data at some maximum rate. Turning the exposure down shorter than the camera can transfer data will not increase the frame rate. It will only reduce the photons captured by each frame. If you want to increase frame rate, you generally have to reduce the ROI, which is obviously limited. 

[TicoWiko]

That's actually encouraging, should be an easy enough fix for hopefully better results next time

For Jupiter should I aim for something around 5 to 10ms ?

[Borodog]

That's actually encouraging, should be an easy enough fix for hopefully better results next time

For Jupiter should I aim for something around 5 to 10ms ?

These days I shoot for the highest FPS I can get that captures virtually all of the light, i.e. fps x exposure in ms ~ 1000. That requires a tight ROI (true ROI, not a FireCapture “cutout box”) and excellent guiding on the planet. For Jupiter at f/10 in my 11” SCT that was 3.85 ms, ~260 fps the last time out.

But yes, 10ms, give or take, as long as you are capturing almost all the light.

[TicoWiko]

Ok so now I'm understanding : you can actually set both exposure time and framerate, since exposure time won't imply an actual framerate. It'll set an upper bound on fps, but if the camera can't readout fast enough for fps to match exposure, then I have a bunch of dead time between the exposure time and single frame time. And that's why there's an option to even impose an FPS or not in the first place, in addition to exposure time, because there's no hard guarantee the 2 match. Meaning last time I really was capturing 1ms exposures but at a much lower framerate/longer frame time (the txt file does indeed claim a 1ms shutter time). Do I have all of that right ?

 

As for ROI, I think I'm doing it right, because the screen clearly says ROI. But just to confirm, when I select an area on the screen using the red rectangle, that's a real ROI right ? At least that's what FireCapture says... And when it says "center planet in ROI", is that also fine ? Or is FireCapture misleading in one or both cases ?

[Borodog]

There is a frame rate control that limits the frame rate, even if the camera could go higher with the current exposure and bandwidth. That is never useful for planetary imaging. Always leave that set to maximum. 

 

Generally my procedure is pretty simple:

 

1. Set the ROI to be as tight as possible, given that there is always some movement of the target, even if you are guiding on it. Guiding corrections are only issued in response to movement, after all.

2. Set the exposure to 1 ms and observe the frame rate that results for the ROI. Say for example it is 250 fps.

3. Set the exposure to 1000ms / fps. In this case that would be 4 ms.

4. Set the gain to optimize the use of the histogram without clipping. For me that's usually 75-80%.

5. Capture 3 minute videos for Jupiter, 5 minutes for Mars & Saturn.

 

Remember that the frame rate is generally limited by the vertical ROI and not the horizontal ROI; this is because the camera has to read data in entire rows. So if your camera is oriented properly (the moons and Jupiter all arranged horizontally) you can get "family portraits" of Jupiter and the moons without increasing the vertical ROI or decreasing the frame rate.

[TicoWiko]

There is a frame rate control that limits the frame rate, even if the camera could go higher with the current exposure and bandwidth. That is never useful for planetary imaging. Always leave that set to maximum. 

 

Generally my procedure is pretty simple:

 

1. Set the ROI to be as tight as possible, given that there is always some movement of the target, even if you are guiding on it. Guiding corrections are only issued in response to movement, after all.

2. Set the exposure to 1 ms and observe the frame rate that results for the ROI. Say for example it is 250 fps.

3. Set the exposure to 1000ms / fps. In this case that would be 4 ms.

4. Set the gain to optimize the use of the histogram without clipping. For me that's usually 75-80%.

5. Capture 3 minute videos for Jupiter, 5 minutes for Mars & Saturn.

 

Remember that the frame rate is generally limited by the vertical ROI and not the horizontal ROI; this is because the camera has to read data in entire rows. So if your camera is oriented properly (the moons and Jupiter all arranged horizontally) you can get "family portraits" of Jupiter and the moons without increasing the vertical ROI or decreasing the frame rate.

Perfectly clear, thank you so much ! Hopefully now I'll end up with something I'd be happy to share next time the clouds go away.

 

Clear skies

[TicoWiko]

Had a chance to do a quick capture in between the clouds tonight. Nothing to write home about but passable enough that I'm willing to share :

 

 

Lots of room for improvement obviously but I have everything I need to keep at it now

[Spacedude4040]

Very good! Now you're on your way.

A quick rework

 

[TicoWiko]

Very good! Now you're on your way.
A quick rework

Dc-second-jup7 rework.png

Very nice ! Can I ask how you reworked it ? Gamma change ?

Edit : managed something similar by playing with the blue balance and a more intricate gamma curve.

Edited by TicoWiko, 26 March 2025 - 11:33 AM.

[Spacedude4040]

Well I'm probably not the best person to ask how to edit photos but I used Astra Image- curves,levels and deconvolution. Registax wavelets and then Photo Shop.

My point was that you're on the right path. Always remember (garbage in = garbage out) so spend time acquiring the best data you can and it will minimize photo editing.

Mike