Hi Robin,
SharpCap is very flexible and offers many ways to capture. I know the different methods are for different reasons, but I am trying to understand some differences.
I mainly ask because live stacking shows the histogram window, but other methods do not. I remember you told me that a reset histogram still has a mild stretch.
If I set my Exposure to 600s, and take the below different ways to Save 1 frame each method, which of below will give exactly the same result. I have all the settings same such as Gain, Brightness, White balance, Temp, Display Histogram reset (no effect anyway), and all preprocessing disabled. Only Fits files saved.
On SharpCap main window:
--Start Capture (single frame)
--Quick Capture
--SnapShot
--The saved raw frames in LiveStack. Histogram was reset.
In Sequencer Edit:
I can set the above settings again within the edited sequence.
-- Capture 1 still frames (guiding required: False)
-- Capture 1 live view frame.
-- The saved raw frames in Live Stack with exposure 600s. (histogram reset).
I also ask because I am doing this comparison using Sequencer Edit to generate the captures:
Test 1: Live stack 20x30s (600s), then repeat 30 times (histogram reset),
compared to,
Test 2: 1 x 600s Capture 1 still frame then repeat 30 times. (no reset histogram available to reset)
I have the Test 1 and Test 2 data already. I can easily see that the live stack stars are not as saturated. Next I will calibrate, register, debayer, and integrate each Test and compare the results after permanent stretch.
Thanks,
Roger
Frame differences: Quick Capture, Snapshot, Live Stack, etc.
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Re: Frame differences: Quick Capture, Snapshot, Live Stack, etc.
Hi Roger,
the key important difference is if the camera is in Live Mode or Still Mode (see https://docs.sharpcap.co.uk/4.0/#Live%2 ... ill%20Mode).
In Live Mode, the camera grabs frames continuously, and if you press 'snapshot' or 'start capture' for a single frame then the next frame to arrive from the camera will be saved. That frame may have started before you pressed 'snapshot' or 'start capture' - particularly for long exposures.
In Still Mode, the camera will only capture frames when asked to, so if you press 'Snapshot', then it will start capturing a frame immediately and finish when the exposure time is up. No chance of any part of the frame being captured before you pressed 'Snapshot'.
In terms of the menu options, Snapshot is just a quick way of doing 'Start Capture, single frame' and 'Quick Capture' is a quick way of doing 'Start Capture, limit by frame count or time'. The results will be the same whether you use the shortcut or the full 'Start Capture' approach. Note that in both cases the camera mode (live or still) will be what has already been selected.
The sequencer is a bit different here - the 'Capture <N> Still frames' step will put the camera into still mode and capture the required number of frames in still mode, whereas the 'Capture <N> live view frames' will put the camera into live mode before capturing.
You may have different options available as to save formats - for instance when the camera is in still mode, you cannot save to video formats (AVI, SER, etc).
Hope this helps,
Robin
the key important difference is if the camera is in Live Mode or Still Mode (see https://docs.sharpcap.co.uk/4.0/#Live%2 ... ill%20Mode).
In Live Mode, the camera grabs frames continuously, and if you press 'snapshot' or 'start capture' for a single frame then the next frame to arrive from the camera will be saved. That frame may have started before you pressed 'snapshot' or 'start capture' - particularly for long exposures.
In Still Mode, the camera will only capture frames when asked to, so if you press 'Snapshot', then it will start capturing a frame immediately and finish when the exposure time is up. No chance of any part of the frame being captured before you pressed 'Snapshot'.
In terms of the menu options, Snapshot is just a quick way of doing 'Start Capture, single frame' and 'Quick Capture' is a quick way of doing 'Start Capture, limit by frame count or time'. The results will be the same whether you use the shortcut or the full 'Start Capture' approach. Note that in both cases the camera mode (live or still) will be what has already been selected.
The sequencer is a bit different here - the 'Capture <N> Still frames' step will put the camera into still mode and capture the required number of frames in still mode, whereas the 'Capture <N> live view frames' will put the camera into live mode before capturing.
You may have different options available as to save formats - for instance when the camera is in still mode, you cannot save to video formats (AVI, SER, etc).
Hope this helps,
Robin
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rockenrock
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Re: Frame differences: Quick Capture, Snapshot, Live Stack, etc.
Hi Robin,
Your reply was spot on, and helped me differentiate the available capture choices. Yes, I needed to re-read the linked User Manual. We all should do that as a refresher.
For a single frame captured by the different modes below, and with same settings, will the images be identical, or some modes permanently stretched differently? I am particularly interested in the sequencer Mode.
A: 'Capture <N> Still frames'
--For my example (Set to 10x30 sec still frame)
B: 'Capture <N> live view frames'
--For my example (Set to 10x30 sec live view frame)
C: 'Live Stack for <Frame Count> frames then save as <Save Type>'.
--For my example (Set to 10x30 sec Live Stack frames, and capture the individual 10 x 30 sec raw frames).
Many thanks,
Roger
Your reply was spot on, and helped me differentiate the available capture choices. Yes, I needed to re-read the linked User Manual. We all should do that as a refresher.
For a single frame captured by the different modes below, and with same settings, will the images be identical, or some modes permanently stretched differently? I am particularly interested in the sequencer Mode.
A: 'Capture <N> Still frames'
--For my example (Set to 10x30 sec still frame)
B: 'Capture <N> live view frames'
--For my example (Set to 10x30 sec live view frame)
C: 'Live Stack for <Frame Count> frames then save as <Save Type>'.
--For my example (Set to 10x30 sec Live Stack frames, and capture the individual 10 x 30 sec raw frames).
Many thanks,
Roger
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Re: Frame differences: Quick Capture, Snapshot, Live Stack, etc.
Hi Roger,
A and B will be the same. The output of C from the final save will be the live stacked image, and may include a stretch (depending on which type of save you choose). However the *raw* frames saved by live stacking during C will not be stretched.
One more thing to be aware of... Any adjustments made in the 'Preprocessing' section of the controls (dark, flat, subtract background, satellite removal, etc) will be in the saved files for A and B, but will *not* be in the raw files saved during live stacking.
cheers,
Robin
A and B will be the same. The output of C from the final save will be the live stacked image, and may include a stretch (depending on which type of save you choose). However the *raw* frames saved by live stacking during C will not be stretched.
One more thing to be aware of... Any adjustments made in the 'Preprocessing' section of the controls (dark, flat, subtract background, satellite removal, etc) will be in the saved files for A and B, but will *not* be in the raw files saved during live stacking.
cheers,
Robin