What’s New in SharpCap 3.0

Well SharpCap 3.0 is finally here – it’s the biggest SharpCap release ever in terms of the amount of code written and the number of new features since the last version! This post gives a high level view of what’s new and changed since SharpCap 2.9 – more detailed description of these features will be coming soon in the updated SharpCap 3.0 User Manual.

SharpCap Pro

Perhaps the biggest change in SharpCap 3.0 is the introduction of the option to upgrade from the free version of SharpCap to SharpCap Pro. While the majority of the functionality of the program is still entirely free to use, some of the most advanced features now form part of SharpCap Pro.

SharpCap Pro licenses are available for the low price of £10 per year and give access to the following features

  • Real-time Flat Frame Correction
  • Dark Subtraction
  • Polar Alignment guided adjustment
  • Focus scanning and auto-focus assistance
  • Scripting

You can try all of these features (except the polar alignment adjustment) without buying a license – the only restriction is that once you have used these features without a license, saving is disabled until you close and restart SharpCap. Learn more about SharpCap Pro features here.

More exciting new feature will be added to both SharpCap Pro and the free version of SharpCap in future releases.


On the hardware front, the big changes in 3.0 are the addition of support for Point Grey cameras and a revamp of how SharpCap handles Webcam and Frame Grabber input to bring those sources closer to the level of the dedicated astro cameras in terms of the functionality SharpCap can offer.

Point Grey Cameras

A big thank you to Astrograph for providing a sample Point Grey camera to work and develop with. Having a sample camera to develop against is pretty much the starting point for getting any new brand of cameras supported in SharpCap – without one it’s almost impossible to get things working in a reasonable amount of time. Currently SharpCap supports FlyCapture based cameras (not Spinnaker Cameras) and it should be fine with GigE, USB and Firewire models. As always, bug reports are welcome with as much detail as possible as it’s likely that different camera models might need a few more tweaks to the code throughout the beta process.

Point Grey camera support requires you to install some extra Microsoft components on your PC. To avoid making the SharpCap installer a lot bigger for everyone, these have been packaged separately in the ‘SharpCap PreRequisites Installer’. You can find this on the SharpCap Beta Downloads Page and you only need to install it once (not every time you upgrade SharpCap 3.0).

Webcam Improvements

The change to the processing of Webcam/Frame Grabber video is the other major change in SharpCap 3.0. Right from the first versions of SharpCap up until version 2.9, SharpCap has let DirectShow (the Microsoft Video components) take charge of showing webcam images on the screen and saving them to AVI file. As SharpCap has added more and more features for Astro cameras, Webcam users have been a bit left behind, since adding those features for them was either impossible or would have meant writing the code twice – once for Astro cams and once for Webcams. Now in SharpCap 3.0, SharpCap takes full control of displaying and saving the images from Webcams – DirectShow is only used for grabbing the image data in the first place. This means that features that couldn’t previously be supported for webcams are now available – these include

  • Dark frame subtraction and flat frame correction
  • Saving in SER or FITS format
  • Display adjustments of Gamma, Contrast and Brightness that affect the screen only

There is one drawback – if you have a camera that captures in a compressed format (primarily MJPG, possibly I420, YUV, YUY2 etc), then the new approach will lead to bigger capture files as the output files are always saved as RGB (three bytes per pixel). In this age of cheap SSD storage and even cheaper hard disk storage, it’s unlikely that the increase in file size is going to cause a problem, but if it does you can switch back to the old way of doing things in the settings dialog.

Camera SDK Updates

SharpCap 3.0 contains new versions of the camera SDKs from the major Astro camera vendors (Altair, QHY, ZWO) which fix bugs, add support for new models and add new features. If you have a new model camera from any of these vendors you may well find that it will work better with SharpCap 3.0 than it does with SharpCap 2.9

Other Hardware

SharpCap3.0  adds direct support for ZWO EFW filter wheels without needing to have ASCOM installed. There is also now an option on each type of supplementary hardware (Focuser, Filter Wheel, Mount) to allow the hardware to be temporarily disconnected then reconnected while the camera is running.

Image Processing

Flat Frame Correction

Flat frame correction is a brand new feature in SharpCap 3.0 – it allows flat fields to be captured in the same way that previous versions of SharpCap assisted in capturing dark frames and then the flat field can be applied to correct each image captured, correcting both the image viewed on screen and the data saved to file.

SharpCap uses the special high speed CPU instructions that are usually for games and multimedia to allow flat frame correction to be carried out at very high speed. With a modern high power processor you should be able to apply flat frame correction to the video stream from a USB3 camera (like a ZWO ASI174MC) at full speed.

Thanks to Gary Palmer for his suggestions and discussion that led to the creation of this feature.

Dark Frame Subtraction Enhancements

SharpCap 3.0 adds the ability to create and apply high bit depth (16 bit) dark frames when using 8 bit cameras (or 8 bit modes). This is important when using live stacking with low gain (low noise) as otherwise the repeated use of an 8 bit dark frame negates the improvement in signal that would be expected as the number of stacked frames increases and the SNR of the stack increases.

Live Stacking Improvements

This version of SharpCap adds a filter option for for frame brightness which can be used to reject frames that are dimmer than the average – this should allow detection of incoming or patchy clouds. Additinally there is a new tab showing history graphs of the rotation and offset of each frame in the stack to allow a better understanding of how well the mount is tracking.

Lots of other improvements have been made to live stacking to improve both performance and user experience, including

  • Ability to soften the black point of the histogram stretch to give better image tones around the black point
  • More options to tweak the parameters used for star detection
  • Improvements to file naming so that the total stack duration is included in the file name
  • Warnings shown if a number of frames in a row are not stacked for some reason

Finally, SharpCap no longer re-detects stars in the stack every time a new frame is added, meaning that the time taken to stack each frame is approximately halved!

Focus Assistance

SharpCap 3.0 adds focus assistance if you are using an ASCOM focuser. This appears in the ‘Graph’ tab of any of the focus measurements if you have a focuser connected. Rather than having to adjust the focuser through several positions one at a time to find the best position you can use the ‘Scan Out’ and ‘Scan In’ buttons to perform a series of measurements of the focus score. Once a scan has been performed and has a maximum (or minimum) score in it, you can use the ‘Goto Best Positon’ or ‘Goto Best Score’ buttons to put the focuser back to either the position where the best score was measured or to seek the best score value.

The ‘Goto Best’ buttons both take the focuser back to the beginninng of the scan so that the best score is approached in the same direction to avoid backlash problems.

You can use the ‘Options’ button to adjust the size and number of steps used when scanning.

Plate Solving

SharpCap now supports plate solving using AstroTortilla, All Sky Plate Solver or AnSvr if you already have one of them installed on your computer. You’ll need to have AstroTortilla itself  (or ASPS or AnSvr) installed (including the Star Index files).

You can kick off plate solving using the locate button (GPS Symbol) in the mount control (you have to have selected an ASCOM mount to access the plate solving). When you press the locate button, the current frame will be plate solved, the mount will be synced to the solution and then will perform a re-GOTO to the position it was originally supposed to be pointing to.

Polar Alignment

Some significant improvements have been made to the star detection algorithm used when polar aligning, which means that 3.0 can find enough stars to plate solve in situations where SharpCap 2.9 struggled. In addition, SharpCap 3.0 uses the latitude and longitude of your ASCOM mount (if connected) when determining the direction to adjust the pointing of the polar axis – that should give more reliable directional indications.

UI Improvements

The UI has been refreshed in some areas with a new Splash screen and many simple message boxes being replaced by more informative task choice dialogs.

SharpCap had some issues up to and including version 2.9 if you had changed the Windows colour scheme to a high contrast scheme – In a number of areas of the program, text would appear as black on a black background! These issues are fixed in SharpCap 3.0, so the program can be used properly with a high contrast colour scheme.

Control groups now have colour coded headers, helping your eye (and mouse) go to the group you are looking for more easily.

Other Improvements

SharpCap scripting is improved by the inclusion of a full python standard library so that it’s no longer necessary to use the .NET API for basic tasks like file I/O in scripting. It’s now possible to run an RPC server like Pyro inside SharpCap to allow SharpCap to be controlled by other applications. Unfortunately due to limitations in Pyro it’s not possible to directly exposre the SharpCap object model, but it’s possible to write Python objects to wrap the SharpCap object model and expose those objects.

As astro-imaging has evolved, sensor sizes and pixel counts have increased vastly from the 640×480 webcam sensors that were typical when the first versions of SharpCap were released. Now sensors with 6, 10 or even 20 megapixels are not uncommon and these place a bigger load on your PC’s memory and CPU. SharpCap 3.0 brings improvements to memory usages (particularly for live stacking) that should improve performance when working with very large sensor sizes. It’s still a good idea to have plenty of memory (8Gb+) and a 64 bit version of Windows if you want to use SharpCap with high resolution cameras.

SharpCap performance in general has been improved, with the time taken for the application to start reduced by up to 50%.
An enormous number of issues and minor bugs have been fixed in SharpCap 3.0 (thanks to those who have beta tested the various builds and sent in crash reports).

Finally, SharpCap 3.0 adds the – long requested – ability to manage capture profiles, which includes the ability to delete unwanted profiles and to set/clear the default profile for each camera.