Reset capture start time

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pgn
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Joined: Wed Mar 08, 2017 9:46 am

Reset capture start time

Post by pgn »

Can you include a scripting command to start a capture from the time it is run. At present a capture can get information from a buffer - potentially going back seconds. This means timing can be out on the purported time if a sequence is taken.

Enabling this will enable the better determination of velocity and position and sychronisation with external equipment.

Following you scripting help I have found changing gain/exposure to be unreliable and the time taken variable; though better with latest versions :!:
[Have also disabled virus checking and it's not that causing the variability. I have also even tried changing color space and de-selecting/reselecting the camera which take even longer; + some other interesting byways :D ]

I may be the only one who wants this at the moment - but is it difficult?

My plea is in.
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admin
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Re: Reset capture start time

Post by admin »

So, when taking a snapshot while scripting you want to be able to turn off the behaviour of saving the previously grabbed frame (ie the one being viewed right now). Sounds reasonable, especially if it is for scripting only.

But... I'm still not sure if this is going to be exactly what you want - consider with 5s exposures running, if you try to snapshot half way through an exposure, what will happen now is that you will get the frame that started 7.5s ago and ended 2.5s ago. Turning off the previous frame behaviour will give you the next frame to arrive - that is the one that started 2.5s ago and ends in 2.5s time. There is no frame that is starting *now* at that moment in time and without doing something to force the camera to change it's exposure sequence there can't be.

Somewhere along the line I'm going to write a companion app to SharpCap that works like a still camera - in which case you will be able to capture a frame starting at any point in time, but that's a while off yet.

Please let me know whether the suggested change above will help or not.

cheers,

Robin
pgn
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Joined: Wed Mar 08, 2017 9:46 am

Re: Reset capture start time

Post by pgn »

Yes that sounds useful; as it will be more accurate. And I assume it would have a shorter "dead time" than exists with the current method; of gain reset?

Your sentence ending "and without doing something to force the camera to change it's exposure sequence there can't be" tells me there are things here I don't understand. Can you enlighten me or point me in the right direction as why there can't be? Further confused as you imply with the camera app there would be this control. [Am I confused by the link between the bar in SharpCap showing a frame being started and what the camera is doing. Is it also the same as the behavior below one second exposures? I know you explained something before in scripting and I thought I had a handle on it - now not so sure.]

Like the idea of a camera app if it also has a python wrap I will sign up now!
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admin
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Re: Reset capture start time

Post by admin »

I think the point I was trying to make is that SharpCap is like a video camera - it takes frames all the time, starting one as soon as the previous one has finished. That means that you can't tell it to start an exposure at a particular point in time easily - the sort of tweaks I suggested with changing exposure are about the only way to do that, and even they aren't 100% ideal.

A future program that works like a still camera would fix that (and would inherit the python scripting in SharpCap).

One suggestion - maybe you could set the exposure to a short value - say 0.1s, then change it to your target longer value when you want to start an exposure.

cheers,

Robin
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Re: Reset capture start time

Post by admin »

Implemented for next build - extra optional parameter on SharpCap.SelectedCamera.CaptureSingleFrameTo()

cheers,

Robin
JBX
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Re: Reset capture start time

Post by JBX »

I run SharpCap Pro v3.2.6173. I do not create videos. Instead I take still images and guide manually. Your statement below is relevant to what I am doing:

"I think the point I was trying to make is that SharpCap is like a video camera - it takes frames all the time, starting one as soon as the previous one has finished. That means that you can't tell it to start an exposure at a particular point in time easily - the sort of tweaks I suggested with changing exposure are about the only way to do that, and even they aren't 100% ideal. A future program that works like a still camera would fix that (and would inherit the python scripting in SharpCap). One suggestion - maybe you could set the exposure to a short value - say 0.1s, then change it to your target longer value when you want to start an exposure."

I have tried your suggestion: fill the exposure-time field with a very short value and then change again to a longer value when I want to start an image. I use an alternative. Set the desired long exposure time, then reconnect to the camera. Reconnect starts the new still image when I want. This is heavy-handed, but it works.

This thread is more than two years old. Perhaps I am behind the time, and work-arounds are no longer needed. Have you changed SharpCap to better accommodate the start time for a single still image? If yes, I have not found it.
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Re: Reset capture start time

Post by admin »

Hi,

your reconnect trick is probably the easiest workaround for now. I have a prototype of still camera mode in progress for the next major version, but that has been slow to progress due to the RSI issues I have been suffering from for the last year or so.

cheers,

Robin
JBX
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Re: Reset capture start time

Post by JBX »

Thank you for your reply. Since single long-exposure images are how I observe, it would be helpful to find such a new function under Capture/Configure Capture/Select Capture Limit. If you want a tester for a beta version of your forthcoming still-camera mode, please contact me. I am happy to help.

James
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