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SharpCap - free Astro Webcam Capture Software

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If you have the same exposure time, then check out the gain - roughly equivalent to varying the ISO on a DSLR. If you have been capturing at ISO100 then set a minimum gain, ISO800 set a mid range gain and ISO3200 set a high gain. I still wonder if you are only seeing the brightest inner part of the pattern for some reason?

cheers,

Robin

 

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I did have the gain set high, I remember that, as the exposure was so long otherwise. Thanks Robin.

Peter

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I've got one question and one possible problem..... Since upgrading to the new version, the images that I take very 4 mins are now saved as numbered instead of timed. This means that I can't easily see what time cloud comes across when I leave it running all night when imaging. Is there a way to get it to save with time order again?

Also, when the clock clicks over to midnight, Sharpcap opens a new folder, but continues to put the images in the old folder....... It used to save them in the new folder after midnight.

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Hi Sara,

right now the answer on the time in the filename is no, but I have to look into a couple more issues with file naming, so I will see what I can do. The best you can do right now is look at the file properties to see what it's timestamp is (right click, choose properties in Windows Explorer).

I must admit that I rarely stay up until midnight (odd for an astronomer maybe, but not so much when you have to get up at 6am), so I'd never noticed the midnight issue... Not sure how easy that would be, but will have a think...

cheers,

Robin

 

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Thanks Robin..... It's only something that happened on the last update ..... it was all fine before :)

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I've noticed that despite saying it does, I have never been able to get PIPP to extract file dates and times from the Sharpcap filenames. This hasn't caused me a problem, as it gets the time from the 'modified' field - (the created field is no good as I copy the files across from laptop to desktop, so the modified date is before the created date!)

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Hello Robin.  I have recently learned about SharpCap and would be very interested to try it.  I have downloaded version 2.9 from your website but cannot get it to install.  I suspect because I am running XP (SP3 - 32 bit).  I already use Microsoft.NET framework (I have version 4) which I use for Astrotortilla without problem.  When I try to install SharpCap I get a message to see the log file but this does not open, and in fact does not seem to exist.  However, I do get the message:

0x80072ee7 - Unspecified error

Any ideas?

Chris

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I'm using the latest version of SharpCap I can find (2.9.2936.0) and the dark frame subtraction seems to be broken.  I created libraries of 20 darks for 2,4,8,10,15,20 and 30secs and they simply don't remove the noise. There is some reduction but only maybe half the warm pixel noise is removed. An earlier version was OK but I cannot remember which I updated from, so I'll now have to go back and see if I can find one that still works.

ChrisH

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@ChrisLX200

Looks like an issue with RGB colour space I think (probably RGB24 *and* RGB32). Seems ok in RAW and Mono. Looking into the reason now.

@cfpendock

I haven't deliberately made version 2.9 not support Win XP, but I don't test it either. I wonder if it is something to do with the installer which also installs a pre-requisite for supporting Celestron cameras. One thing you can try if you want is to clear out your temp folder, then run the installer until the error appears. If you then go have a fish around in your temp folder you will probably find the actual SharpCap install .msi file somewhere in the temp folder or a sub folder - if you can find that, try running it and maybe you will get a good install.

cheers,

Robin

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20 minutes ago, rwg said:

@ChrisLX200

Looks like an issue with RGB colour space I think (probably RGB24 *and* RGB32). Seems ok in RAW and Mono. Looking into the reason now.

cheers,

Robin

Thanks Robin - I should mention I'm using a QHY5L-II mono for this, colourspace is mono8.

ChrisH

 

SharpCap2.jpg

Edited by ChrisLX200

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It looks to me like the Dark files themselves are broken...  I had an earlier 4sec dark (average of 10 subs) which seems to subtract OK, the latest master dark I made tonight (20 subs) shows much more noise when used and is clearly not removing the hot pixels.

ChrisH

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@ChrisLX200

The RGB thing turned out to be a bug with the test camera code that I use when I haven't a real camera to hand - it was getting RGB24 and RGB32 all mixed up - wouldn't happen with real cameras, so a red herring.

Just tested 2.9.2965 (latest version for download from http://www.sharpcap.co.uk/sharpcap/downloads) - seems fine with the closest I can come to your camera (an Altair mono GPCAM in MONO8 mode). Made a new master dark over 10 frames and subtracting it definitely clears the hot pixels and drags the histogram right down removing the 'warm' pixels too.

Dark frame with no dark subtracted

nodark.PNG

Dark frame with dark subtracted

withdark.PNG

Might be worth having a look at the master darks that are being saved and comparing them with a single dark frame to see if anything jumps out as wrong - you could send me one of each (single dark frame, master dark) if you wanted.

cheers,

Robin

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Hi Robin, I'll try tomorrow to see if I can get a better idea what is going on, right now I'm running the camera remotely via Remote Desktop so I'm unable to take any more darks (one of the reasons why having the Darks library is so valuable!).

ChrisH

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Thanks Robin.  No joy.  I emptied temp file as you said, but no sign of any msi file. Tried installing SharpCap 2.8 also - same problem - a message to see the log file and 0x80072ee7 - Unspecified error.

Is there a version which will work with XP?  I know, one day I really will have to upgrade!!

Chris

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Hello Robin (or anyone else who might be able to answer my question),

I am playing around with the ZWO ASI224MC camera and was noticing that the software binning option is giving me some very detailed and interesting results; they could even be considered superior to the output from the hardware binning option. This is counter intuitive to me because I was under the impression that software binning would be accumulating readout noise.


I was wondering if anyone knew what process is used for software binning or if there is any additional image processing happening.

cheers,

Jess

 

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Hi,

on CMOS sensor there is no real equivalent to the hardware binning on a CCD sensor where the charge is added up over several pixels and then that total charge is fed to the A->D converter. For CMOS cameras all binning is done in digital space after A->D conversion. However the read noise on these cameras is so low that it really doesn't matter that you have 4 lots of read noise rather than one (since the noise is uncorrelated adding 4 lots for 2x2 binning only doubles the read noise in the binned pixel).

Anyway, hardware binning on these cameras means that the calculation of the sum (or average) of the pixels is performed on the camera's processor. Software binning means it is done in the PC driver. Aside from a possible effect on frame rate because less data needs to go over the USB bus, the results in terms of image quality will be the same.

Some people get hung up on whether binning sums the pixel values (makes the image brighter) or averages the values (reduces noise). It really doesn't matter - in both case the S/N ratio for the image increases by the same factor and it's the S/N ratio that matters. If you want binning the increase the brightness and your camera is averaging then just turn up the gain - you will be able the achieve *exactly* the same result that way that you could if your camera was doing summation binning.

cheers,

Robin

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On 31/10/2016 at 22:11, ChrisLX200 said:

Hi Robin, I'll try tomorrow to see if I can get a better idea what is going on, right now I'm running the camera remotely via Remote Desktop so I'm unable to take any more darks (one of the reasons why having the Darks library is so valuable!).

ChrisH

Still playing with this. I took another set of darks - this time using mono16 colourspace, same result when subtracting with the warm pixels not fully corrected.

I looked at the two 4sec dark frames I had from earlier (27th and 30th Oct), the earlier one does correct and the later one does not - the later dark definitely shows less warm pixels which would explain why it fails to correct.

The mono16 saves darks as FITs files so not so easily compared, but I did notice the timestamp is in the dark frame! (it isn't in the png dark files using mono8). As a result the timestamp is corrupt when the dark is used. I know, the obvious solution to that would be to turn off the timestamp when taking darks..

ChrisH

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Ah yes, having the timestamp running when taking darks is probably not a good plan! I think I should be able to disable that during the capture of darks/flats without too much trouble in a future version.

I have been looking at improving darks a lot for the next version and found some bugs, so hopefully I will be able to take those fixes back into 2.9 to fix up the issues - I think I have it pretty much fixed now apart from not being able to read back 16 bit depth PNG files correctly.

cheers,

Robin

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Hello Robin,

I had a follow up question about the binning methods. For software binning, are you combining the pixels on each separate color channel? My output for hardware and software binning still do not seem similar. I'm trying to recreate the method and apply it so some of my captures in order to attempt to diagnose what is happening. Any more information you could share would be wonderful, I feel like I am missing something fundamental.

thank you so much,

Jess

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Robin

Just to report back on problems I had been having with the Bahtinov mask - I solved it last night by setting the colour space to RAW16 and it was fine.

Unfortunately, I had other problems in as much as when I tried to take snapshots in LX mode it just fell over every time. I had been taking AVIs of Uranus quite happily (although the frame rate was very low even using a USB3) but every time I tried to use LX it just would not do it and kept unticking the LX box.

Peter

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Hi Peter,

the LX box actually is a bit of a fake - all it does is change the scale of the exposure slider, since having a single slider with a range of from 0.001ms up to 1000s is incredibly unwieldy. With LX unticked then you get the exposure range from the shortest possible up to 5s. With it ticked you get from 1s up to the maximum possible.

If something else changes the exposure (for instance loading a capture profile) then the LX box may get ticked or unticked to match the new exposure. I can't quite remember which gets selected if you are in the 1s to 5s range that is covered by both...

Anyway, when you say 'fell over' do you mean crashed? If so did you get a chance to submit a crash report?

Also it's worth remembering that 16 bit mode is only worth doing at low gain where you can't see any significant noise from frame to frame. If you are doing planetary imaging, have a high gain and can see pixel noise that changes from frame to frame then 16 bit mode is doing you no good at all - all it is doing is doubling the size of the capture file, slowing down the frame rate and recording the noise in incredible detail - it won't add any extra info to the final stacked image!

cheers,

Robin

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@JaeMarie

I think that by default the ZWO will keep colour in the image when binning - I'm not sure of the exact algorithm used to do this, I expect it bins four red pixels to make one binned red pixel, etc. I remember someone asking on the ZWO forums for a mode where the binning of a colour image would give a mono binned image, but not sure if it got implemented.

All of this calculation for binning is done in the ZWO driver or SDK - before the frame gets as far as SharpCap - so for the most accurate answers you might be best going to the zwoug forums and asking there - Sam is very helpful.

cheers,

Robin

 

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@ChrisLX200

Just to let you know that I have just put up a new version of SharpCap 2.9 for download that will hopefully fix the dark subtraction issues that you have found. Certainly the creation and subtraction of darks seems correct now in my testing. You still have to turn off the timestamp manually before creating dark files though!

Please let me know if this helps or not.

cheers,

Robin

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Thanks Robin, will download now..

ChrisH

 

Edit: looks promising - it successfully dark-subtracted using an older dark frame (the previous version did not fully correct), but I will need to take a new full set of darks to check. It's operating as my cloud detector just now during an imaging run so don't want to interrupt :)

Edited by ChrisLX200

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