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What's New in SharpCap 3.1

posted Oct 11, 2017, 2:27 PM by Robin G   [ updated Nov 18, 2017, 11:52 AM ]
With SharpCap 3.1 now ready for public Beta testing, here's a quick rundown of the new features and improvements that have been added. More detailed descriptions of the features and how to use them will follow shortly - check back here for links to those updates.

Mini Histogram

Something I probably should have added long ago - an always on mini histogram in the control panel that's integrated with an easy-to-use way of stretching the image for display to bring out the fainter details...

This doesn't have all the power of the main histogram - for instance it only updates a couple of times per second to conserve resources and it doesn't support the selection area option, so it always shows the histogram of the entire frame, but it makes up for that by always being available.

As well as being able to inspect the image histogram, you can tweak the display stretch function by dragging the three dashed vertical lines that indicate the black point, mid point and white point. These adjustments make it very easy to pull out faint detail on the screen (they don't affect data being saved to file). You can also use the auto stretch button (the lightning bolt) to have SharpCap automatically stretch the image for you and also reset the stretch back to default using the reset button. To round things off, the intensity of the auto stretch is configurable in the SharpCap settings, so you can pick an auto-stretch intensity that works for you.

Smart Histogram

Ever wondered whether you are using the right gain or exposure when deep sky imaging? Whether 6x ten minute exposures really do give you more detail than 12x five minute exposures? No more guesswork required with the new SharpCap Pro Smart Histogram feature. In combination with the results of Sensor Analysis (see below), SharpCap can measure the sky background brightness for you and then perform a mathematical simulation of the impact on final stacked image quality of using different gain and exposure combinations. You can also see graphs showing the impact of using longer or shorter exposures (or lower or higher gain) than suggested.

If you try this using a modern, low noise, CMOS sensor you might be pleasantly surprised to find out that the optimal exposure length isn't nearly as long as you imagine and that maybe the complexities of guiding will become a thing of the past (The use of long - 5 to 10 minute or even longer - exposures in traditional deep sky imaging is not required to see faint targets, it's actually required to deal with the high typical read noise of CCD sensors. Since the optimal exposure length is proportional to the square of the read noise and CMOS read noises can be 1-3 electrons instead of 8-10, exposures can often be much shorter with no loss of quality)

Sensor Analysis

Ever seen those graphs provided by camera manufacturers of Sensor gain and read noise? Wondered how they were created? Well, they used to be a lot of manual adjustments and tedious measurements and calculations, but now SharpCap can perform those measurements automatically for you to generate a custom sensor analysis of your very own camera.

Why would you want to do that? Because the sensor data that is produced feeds into the SharpCap Smart Histogram functionality, which provides accurate guidance on the best gain/exposure to use for deep sky imaging based on the characteristics of your imaging sensor. With those numbers, SharpCap can perform a mathematical simulation of the amount of image noise that would occur in a whole range of different gain and exposure values and guide you to the ones that will give the best result.

Run a sensor analysis (Tools Menu) on your camera in RAW8 and RAW12/16 mode (or MONO8 and MONO12/16 for mono sensors) and SharpCap will save the results and use them to provide Smart Histogram guidance in future imaging sessions.

Note that SharpCap requires fine control over the camera exposure to perform Sensor Analysis - this means that it's not possible on Webcams or Frame Grabbers. Also, if you have a colour camera it must be in a RAW mode to perform sensor analysis as the debayer process used to convert RAW images into RGB or MONO images causes sensor analysis to give incorrect results.

Feature Tracking

This lets SharpCap use your connected ASCOM mount (or ST4 connected camera) to guide the telescope and track on screen image features. Currently it is designed to work with high speed (Solar/Lunar/Planetary) imaging. SharpCap analyzes several frames per second and tracks movement of features between those frames - when the movement exceeds a threshold it will begin to make adjustments to bring the image back to it's original position. An initial calibration step must be performed so that SharpCap can learn which way and how fast the image moves for the various mount movement directions.

Feature Tracking is a SharpCap Pro feature and can be started from the Tools menu.

Seeing Monitoring and Auto Capture

This is a new application of the image quality measurement techniques that SharpCap has provided to assist focusing for some time. Instead of helping you find the point of best focus, you can now use the image sharpness measurements to help you capture the moments of clearest seeing without having to sit with your eyes glued to the computer screen at all times.

Launched from the Tools Menu, the seeing monitor shows a chart of the recent range of image quality with the most recent values highlighted. This gives a much more objective measurement of when the seeing is good. SharpCap Pro users can additionally enable two automatic modes:

* Seeing triggered capture - this starts a capture when the seeing value exceeds a user picked threshold
* Seeing filtered capture - this will start a capture but only save the frames that exceed a user picked quality threshold

Starlight Xpress Camera Supprt

SharpCap 3.1 now supports StarlightXpress cameras natively - no need to use the ASCOM driver any more. This provides better control over the camera and greater reliability. During the Beta period I am very keen to get reports from as wide a range of models as possible to flush out any final issues.

Blind Plate Solving

SharpCap 3.0 contained integration to 'Astrometry.Net' based local plate solvers, but it required you to have a connected ASCOM mount as it used the mount pointing as an initial estimate of location to allow the plate solve to complete quickly. SharpCap 3.1 also contains blind plate solving (on the tools menu) which does not require a connected mount, it will just run your local copy of AstroTortilla/ASPS/AnSvr on the next frame and show the results in the notification bar.

Filename Templates

Lots of users have asked for little tweaks to be made to the way that capture files are named. Adding more checkboxes and dropdowns to the already complicated file naming tab of the settings wasn't really an option, so instead I've added the ability to completely customize the file naming using filename templates. You'll find these at the bottom of the filename settings tab and you'll notice that the templates update automatically if they are disabled and you adjust other settings on the page, which will give you a good idea of what is possible for now.

One thing you may notice is that there is the option to include the current filter name in the filename using the {Filter} tag. If you are not using an ASCOM filter wheel then you can still use this feature by selecting 'Manual Filter Wheel' in the hardware settings - this will give you a filter wheel control in the camera controls panel which will not do anything except give a filter name to the file name template.

SharpCap Max Memory

Improvements to allow SharpCap to access considerably more system memory if it is available. This reduces the chance of running out of memory when working with high resolutions and allows SharpCap to cache many frames in memory when performing high speed captures (if the Hard Disk can't keep up).

This feature is only available to users who have 64 bit versions of Windows and more than 4Gb of total system memory.

SharpCap Pro users can allocate up to 50% of their system memory to this feature, so if you have 16Gb of memory you could allocate 8Gb, which would allow SharpCap to cache nearly 6000 1280x1024xRAW8 frames in memory waiting to be written to disk! Non SharpCap Pro users can only allocate 2Gb to this feature, but that still gives a cache of 800+ frames available. Note that 1Gb is set aside for non-frame cache purposes.

Configure Max Memory settings in the 'Memory' tab of the SharpCap settings.

Live Stack Improvements

The Live Stack histogram has a had a significant facelift for this version

As you can see there are now separate traces for the different colour channels and colour balance adjustment sliders available if you are imaging with a colour camera. The adjustment of the display stretch is also improved and simplified by the removal of the various sliders in verion 3.0 and the addition of 3 simple draggable levels bars to set the black, mid and white points. An auto stretch button (the lightning bolt one) and a reset button complete the improvements to the histogram.

On the stacking side, addition of a Sigma-clipping stacking option which will help reduce final stack noise and also keep artifacts like satellite, meteor and aircraft trails out of the stacked image (Pro Feature). Improvements to memory usage during Live Stacking will help with performance particularly on high resolution cameras.

Polar Alignment Improvements

SharpCap 3.1 introduces some usability improvements to Polar Alignment to help you get great results - these include making sure that you don't see any adjustment instructions until the final adjustment stage has been activated, since adjusting at an earlier stage gives incorrect results. SharpCap now also tracks the apparent center of rotation position as the rotation angle is increased - this will help spot mechanical issues where the scope mount flexes significantly during rotation leading to poor results.

An increased polar alignment star database means that the initial position can be out to about 7 degrees from the pole (previously five degrees).

ASCOM device/camera Improvements

Updates to improve compatibility with various ASCOM cameras/focusers/filter wheels/