Configuring SharpCap

SharpCap configuration is carried out in the Settings dialog, which can be accessed from the File menu.

General Tab

The General tab contains a variety of settings that are divided into four groups – Startup, Display, Saving and Misc.


Startup Settings

Show tips when SharpCap starts

This option is checked by default.  The Tip of the Day appears when SharpCap is started but can be disabled for future start-ups here or when SharpCap starts.



Automatically connect to camera when SharpCap starts

When set, SharpCap will automatically reconnect to the last used camera at start-up.  If set, this setting can be overridden by holding down the Control key when starting SharpCap, which will skip opening a camera at start-up.  This setting is enabled by default.

Automatically restore camera settings

When set, SharpCap will save the current settings of each camera when you close the camera (or close SharpCap) and restore those settings the next time the camera is opened. The saved settings are stored in a hidden capture profile called ‘_autosave’ (this profile may be visible in older versions of SharpCap used on the same PC). If you do not wish to reload the previous settings then hold down the <CTRL> key while the camera is opening. This setting is checked by default.

Confirm Shutdown

By adjusting this setting, you can configure whether you are asked for confirmation when you try to close SharpCap. The options are

·         Never – SharpCap will always close immediately and not ask for confirmation

·         When Capturing or Live Stacking – SharpCap will ask for confirmation when actively capturing images or live stacking.

·         When a camera is open – SharpCap will ask for confirmation if a camera is selected

·         Always – SharpCap will always ask for confirmation of shutdown.

Note that you cannot close SharpCap while a sequence from the Sequence Planner or Sequence Editor is running – you must stop the sequence first and then close SharpCap.

Display Settings

Always show SharpCap in English, even if a translation is available

SharpCap now has partial translations to other languages (currently French, German, Japanese, Chinese). These translations will be activated automatically if one of the supported languages is set as the Windows Display Language. If you wish SharpCap to display in English even if your language has a translation, select this option.

Display in night vision colours

Selecting this option causes SharpCap to display in a dark colour scheme which is better for night-time use. You can also switch between the two colour-schemes by pressing the <F12> key. This option is unchecked by default.



Normal vision (day) colours

Night vision colours


Use night vision to preserve dark adaptation of the eyes during a capture session if intending to observe visually.

Prevent Screen and Computer from powering down when using SharpCap

If you enable this option, SharpCap will attempt to prevent the computer and the monitor from going to sleep while SharpCap is running.

Auto Stretch Intensity

This setting controls how aggressive the Auto Stretch functionality in the Mini Histogram and Live Stackingis. Setting this option to a larger value with result in the Auto Stretch buttons brightening the darker regions of the image more strongly. You can adjust this option until the Auto Stretch buttons give results that suit your tastes.

Saving Options

Save capture settings file alongside each capture

When this option is checked, SharpCap will save a text file containing all the camera settings alongside the capture file each time a new capture is started. This file is useful to check the settings used for particular images at a later date. This option is enabled by default.


22_06_22.avi & 22_06_22.CameraSettings.txt


The text file to the right contains capture settings from the Camera Control Panel – useful for reference in future observing sessions or analysis during a post-processing session. 


The name of the text file reflects the time of creation. 


The captured data (video or still) and the CameraSettings.txt file will have the same timestamp in their filenames.



Save image histogram data in CSV alongside each capture

When this option is checked, SharpCap will save the data from the image histogram in CSV format alongside the capture file and the capture settings file. The histogram data will be taken from a frame early in the capture (usually the first captured frame).

Start cameras with ‘Auto’ output format

This option is checked by default.  This option will set the Output Format control into Auto mode when a camera is opened. When the Output Format is in Auto mode a compatible video format will be chosen automatically for exposure times of less than 5s and a compatible still file format for exposure times of more than 5s. If possible, the preferred formats will be used (providing they are compatible with the camera settings in use).

Save 10/12/14 bit images in FITS files without stretching to 16-bit

This option is off by default and should only be enabled for special use cases where post-processing software has issues with pre-stretched images. If in doubt, do not turn this option on, and always test that you get the correct results with sample images before using this option for an imaging session.

By default, SharpCap will stretch 10,12 and 14-bit images up to use the full 16-bit range (0 to 65535) when saving those images to file (FITS, TIFF, PNG or SER formats). This is desirable because without applying this stretch the saved images would appear very dark and would all require brightening before the image could be seen properly. However, some image processing software (particularly photometry software) cannot process such pre-stretched images correctly. If you encounter this situation then you can turn this option on to make SharpCap save unstretched FITS files.

Compress TIFF files

This option is unchecked by default in new installs of SharpCap, meaning that SharpCap will not try to compress TIFF files. While using compression gives smaller file sizes, some image processing applications cannot read compressed TIFF files. Test with your image processing software if you decide to enable this option.

Preferred Video Format

AVI is the default video format. This determines the auto selected format for video images in the camera section of the Camera Control Panel.




Preferred Still Format

PNG is the default still format.  This determines the auto selected format for still images in the camera section of the Camera Control Panel.

Note that this format is also used in places where SharpCap does not prompt you for a file type when saving (for instance saving RAW frames from Live Stacking, or saving a newly created dark or flat frame).

Saved target names

This option is a pre-configured list of object names.  Objects can be added to the list or removed from the list and the list re-ordered.


To add a new object, for example M42 or Whirlpool Galaxy, type the name anywhere into the Saved target names list.  Click Apply to save the amended list.  The amended list will be available the next time SharpCap is started.


The list also appears in the Tool Bar near the top of the screen under Object Name.  Objects added in Saved target names will also appear in the Tool Bar dropdown list.



·         Object Name undefined (the default) : captures saved in folder:  YYYY-MM-DD\Capture

·         Object Name defined : captures saved in folder:  YYYY-MM-DD\Object

·         Moon selected as Object Name : captures saved in folder:  YYYY-MM-DD\Moon

Hardware Tab

This is the hardware screen for a default SharpCap installation.  The fields Focuser, Filter Wheel and Mounts all show as None. image

If you have a computer controlled mount, focuser or filter wheel then you can use this tab to configure SharpCap to communicate with it. In most cases, you will configure SharpCap to talk to ASCOM compliant, however there are some hardware devices that can be controlled directly via SharpCap:

·         ZWO EFW Filter Wheels

·         QHY Filter Wheels connected via a round plug (not USB) on the camera

·         Mount movement via ST4 cable on selected cameras when accessed directly from SharpCap (Altair, Player One, QHY, SVBony, ZWO). Not available when the camera is accessed via an ASCOM or DirectShow driver.

·         A Manual Filter Wheel. This does not actually need an electronic filter wheel, but shows in the SharpCap UI with a configurable selection of filter options. Select a filter in SharpCap when you manually chose that filter to allow SharpCap to include filter names in saved file names without an electronic filter wheel.

For SharpCap to detect ASCOM hardware you must have both the Ascom Platform and the Ascom Driver for your particular hardware installed. If you find that the drop downs are empty (or almost empty), check that the ASCOM Platform is installed and up-to-date (SharpCap may not work with older versions of the ASCOM Platform).

For each category of hardware, you can choose the device that you want to be able to use from the drop down. You can also configure that device by pressing the Properties button to the right of the drop down list. The window that shows when you press Properties is generally provided by the device’s ASCOM driver (written by the device manufacturer). In some cases this window may appear hidden behind SharpCap – check for new icons appearing in the taskbar if you do not see the device properties window appear.

Automatic Connection when opening a camera

By checking or unchecking the Connect Hardware automatically when opening a camera option you can control whether SharpCap will automatically try to establish a connection to your hardware or not. This is a matter of personal preference – if your focuser/mount/filter wheel are always available then enabling automatic connection can save the requirement to manually connect each time. If your hardware is sometimes not connected or powered off then you may get error messages when opening a camera if the automatic option is enabled – these may become annoying.

If you do not have the automatic connection option enabled then you will need to connect each device manually after opening a camera by checking the individual Connected check box for the device.


Configuring a Focuser

Select your focuser driver from the list in the drop down. If you have not used the focuser yet (or if you have changed how it is connected to the computer), you may need to press the Properties button to configure the focuser. In many cases you will need to specify a COM Port that the focuser is connected to. Sometimes the COM Port number can change unexpectedly after reboots, Windows Updates or hardware changes to the PC, so this is worth checking if your focuser stops working.


Once you have configured a focuser, you will be able to use it from within the SharpCap Scope Controls area when you have a camera open.


Focuser Backlash Handling

SharpCap can also handle backlash compensation for your focuser (your ASCOM driver may also offer this option). Setting up backlash compensation either in SharpCap or in your ASCOM driver will improve focusing reliability.

To calculate the backlash compensation value, turn off any existing backlash compensation and measure the position of best focus twice – once with the focuser moving outwards and once with it moving inwards (with no other changes to your setup). In each measurement be sure to start the focus check well away from the point of best focus to ensure that you are not in the backlash zone when you get to best focus.

Suppose that the two positions of best focus turn out to be 21150 (moving outward) and 21020 (moving inward) – take the difference between those two values (130) and that is the amount of backlash compensation you should set. Either set this value in your ASCOM driver (and check the Handled by ASCOM Driver option) or check the Handled by SharpCap option and enter the difference between your two measurements in the Amount box.

Note that if SharpCap is handling backlash compensation then the direction of last movement and backlash state of the focuser are remembered even if you close and re-open SharpCap (as long as the focuser position is not changed by another application while SharpCap is not connect to it).

Note also that if SharpCap is handling backlash compensation then the focuser position value shown in SharpCap takes account of the backlash adjustment when moving in a negative direction – that means that the value shown in SharpCap may differ from the value shown in any UI belonging to the focuser ASCOM driver.

Configuring a Filter Wheel

Select your filter wheel driver from the list in the drop down. If you have not used the filter wheel yet (or if you have changed how it is connected to the computer), you may need to press the Properties button to configure the filter wheel. In many cases you will need to specify a COM Port that the filter wheel  is connected to. Sometimes the COM Port number can change unexpectedly after reboots, Windows Updates or hardware changes to the PC, so this is worth checking if your filter wheel stops working.

ZWO EFW filter wheels can be detected directly by SharpCap and can be used without an ASCOM driver.

If you have a QHY filter wheel that connects to the camera via a round plug (not via USB), do not select the ASCOM driver here – SharpCap will automatically detect and activate your wheel when you open your QHY camera.


Once you have configured a filter wheel, you will be able to use it from within the SharpCap Scope Controls area when you have a camera open.


Focus Offset for Filter Changes

Some filter wheel ASCOM drivers allow you to store a focus offset value for each filter – this value indicates the amount that the focuser must be moved when selecting this filter to keep good focus (adjusting for the optical depth of the filter). If you check the Use Focus Offset information to adjust focus on filter change option then SharpCap will use this information to adjust focus when filter changes are made (provided you also have connected SharpCap to an ASCOM focuser). 

As an example, if you move from the red filter (perhaps that has a focus offset value of 12) to the green filter (which for example has a focus offset value of 17), SharpCap will change the focuser position by +5 (17 – 12 = 5) as a result of the filter change. If you then move back to the red filter, SharpCap will move the focuser by -5. For this functionality to work correctly, it is important to have backlash compensation properly configured.

Configuring a GOTO Mount

Select your mount driver from the list in the drop down. If you have not used the mount yet (or if you have changed how it is connected to the computer), you may need to press the Properties button to configure the mount. In many cases you will need to specify a COM Port that the mount  is connected to. Sometimes the COM Port number can change unexpectedly after reboots, Windows Updates or hardware changes to the PC, so this is worth checking if your mount stops working.

Along with ASCOM drivers you will also see On Camera ST4 listed as an option – if you select this option and are using a camera with a supported ST4 guiding port (Altair, Player One, QHY, SVBony, ZWO) then SharpCap will send guiding commands via the ST4 port when the mount movement buttons are used. In this case you will have limited functionality (no display of current position, etc), but will be able to nudge the mount’s location from within SharpCap as long as you have connected the ST4 port of the camera to that of the mount.


Once you have configured a mount, you will be able to use it from within the SharpCap Scope Controls area when you have a camera open.


You may also select either of the two Reverse direction options if you find that the direction that the mount moves when you use the arrow buttons does not match your expectations.

Notes on Mount Co-ordinate Systems

In order for plate solving, recentring and GOTO operations to complete correctly and accurately, it’s vital to ensure that your ASCOM mount co-ordinate system setting is setup correctly.

The direction of the Earth’s axis and the shape of its orbit vary over time. Although the changes are small and slow, over a period of years they become large enough to be noticeable. This means that the RA and Dec co-ordinates of a distant object (let’s pick the star Rigel as an example) slowly change. To deal with this problem, the co-ordinates for astronomical objects are usually listed as being for a particular date – J2000 is a common reference date, which means that the co-ordinates are those that would have been measured at the start of the year 2000. Astronomy software can convert these values for the year 2000 into the correct values for the current time (often called JNOW co-ordinates) as it knows how the Earth’s orbit changes over time.

For Rigel, the J2000 co-ordinates are : RA = 05h 14m 32s, Dec = −08° 12′ 06″

The JNOW co-ordinates (May 2021) are : RA = 05h 15m 31s Dec= −08° 10′ 44″

From this, you can see that failing to account for this can lead to a position offset of about 1 minute of RA and about 1.5 minutes of arc in Dec. If your mount co-ordinate system is set up incorrectly then this sort of error can occur in every GOTO, plate solving and re-centring operation.

SharpCap will take care of the differences between the JNOW and J2000 co-ordinates provided that your ASCOM mount driver correctly reports the co-ordinate system it uses. In theory, an ASCOM driver can report one of five co-ordinate systems: B1950, J2000, J2050, JNOW and Unknown/Other. In practice, B1950 and J2050 are unlikely to be used and are not handled. The other three options are handled as follows:

·         JNOW – SharpCap assumes that the ASCOM driver accepts and reports RA/Dec co-ordinates valid for the current date. The ASCOM driver must not make internal corrections to the co-ordinates based on the date if it reports this co-ordinate system.

·         Unknown/Other – SharpCap assumes that an ASCOM driver which reports Unknown/Other is really working in JNOW co-ordinates. This is the default setting for EQMOD for instance, which works in JNOW co-ordinates.

·         J2000 – SharpCap assumes that an ASCOM driver which reports J2000 is telling the truth – that is that the ASCOM driver will internally convert the J2000 co-ordinates to/from JNOW as necessary, and that a GOTO to a J2000 position will point the really telescope at the targets JNOW co-ordinates. If an ASCOM driver reports J2000 and does not perform this conversion then a position error will occur in GOTO, plate solving and recentring operations.

The plate solving tools supported by SharpCap always report their results in J2000 co-ordinates. SharpCap will convert these values to JNOW co-ordinates if the mount that you are using has been identified as needing JNOW co-ordinates.

If you are using other applications to interact with your ASCOM mount (for instance a planetarium application such as Cartes du Ciel or SkytechX), you should ensure that you configure it to send the correct co-ordinates to the mount when performing GOTO operations. Again, if your planetarium application sends J2000 co-ordinates to a mount working in JNOW or vice-versa, the GOTO position will be slightly wrong, as will subsequent results of the Plate Solve and Resync tool.






Simulated Hardware

The ASCOM platform comes with a range of simulated hardware drivers that can be used for testing and experimentation.

·         ASCOM Simulator Focuser Driver

·         Filter Wheel Simulator [.NET]

·         Telescope Simulator for .NET

These can be very useful for learning how to use your hardware with SharpCap in advance of an observing session. Additionally, you might find the following useful

·         EQMOD ASCOM Simulator – another telescope simulator that behaves just like the EQMOD ASCOM driver for Skywatcher Telescopes

·         ASCOM Sky Simulator ( – this provides a simulated camera that can be linked to the simulated focuser and mount provided by ASCOM – as you move the mount the image produced by the camera will update to reflect the part of the ‘sky’ that you are ‘observing’.

Filenames Tab

This tab allows fine control over how captured images and videos are named and organised.


Save captured files to

This allows the top-level capture folder to be selected.  All captured files will be saved into this folder or subfolders created within this folder. 

The capture folder in a default installation will be on the logged-in user’s desktop and is called SharpCap Captures. Note that SharpCap will check that the top-level capture folder exists and that it is not full each time SharpCap starts. If the top-level capture folder is found to be missing, full or read-only then the folder will be reset to the default of Desktop\SharpCap Captures.

The browse button allows other capture folders to be selected or created.

Speed Test

This button will carry out a hardware performance test of disk write speed.  Running this test will discover if the camera’s capture rates are being degraded by disk write speeds. See Disk Speed Test for more details.

Organise captured files into subfolders

If this is unchecked, all captures will be saved in the top-level capture folder.  When checked, captured files will be saved into subfolders according to the rules selected below.

Options and combinations for folder and file names are available.  Sensible defaults are offered in the initial, default installation.  Examples of using the options are given below.

Date and then Target Name

Below is an example of a saved file organised by date then target name.  File names are derived from the creation time of the capture and are in the format HH_MM_SS.  Note the higher-level directory is named after the date and the inner directory named after the target.


Target Name and then Date

Below is an example of a saved file organised by target name then date as seen in the Notification Bar (green = success).  Note the higher-level directory is named after the target and the inner directory named after the date.image

Create WinJUPOS Compatible File Names

Below is an example of a saved file using a WinJUPOS compatible name – a combination of date and time.  This uses mid-point time in the capture for the WinJUPOS name.  Using this option will make loading video files into WinJUPOS for de-rotation easier.


Use UTC times in files and folder names

When this option is checked, all dates and times used for filename generation will be UTC times. When it is unchecked, local times will be used.

Below is an example of a saved file using the UTC time format.


The letter designates time zone, Z = United Kingdom.

Use sortable date format (YYYY-MM-DD)

When checked, the date format YYYY-MM-DD will be used for all dates, making it easy to sort file and folder names in Windows Explorer.  When unchecked, the date formatting rules appropriate to the PC’s regional settings will be used.  This option is checked by default.

Sequences (Multiple Still Images)

This section provides extra options for filenames generated as part of a sequence of files (for instance when capturing frames to PNG or FITS format a file will be created for each captured frame). Do not confuse this setting with the SharpCap Sequencer or Sequence Planner. These options apply when multiple still image files are created by any means within SharpCap – for instance when pressing the Snapshot button multiple times.

Include time in filenames will put the current time (the time at which the frame was captured) in the filename for each captured frame.

Create subfolder for each sequence is enabled by default. When enabled, each new sequence of files will be stored in a separate subfolder. When disabled, many sequences may be saved in the same folder, depending on higher level folder naming choices.


Append Filter Name will add the name of the current filter to the file name. For this option to be effective, you must have selected a filter wheel in the Hardware Tab and ensured that it is connected correctly.

Sample Filenames

This section shows sample filenames that would be generated based on your choices for file and folder naming above. The first sample shows how a filename will be generated for a single file capture (where multiple frames are saved into a single video file in AVI or SER format). The second sample shows how filenames will be generated for a sequence of files capture (where each saved frame is stored in a separate image file in a format such as PNG, FITS or TIFF).

If Filename Templates are in use then these samples show the filenames that would be generated by the Single File and Sequence templates.

Filename Templates

All capture file names in SharpCap are generated through a system of filename templates. When you adjust the various check boxes and options for file naming, SharpCap automatically generates filename templates that represent your choices. These templates are then used later to generate the actual file names. In fact, as you change the various options in for file and folder naming you can see the Filename Templates shown in the lower portion of the tab updating to represent your choices.

Sometimes you may find that you cannot obtain the file naming that you wish to achieve using the various file and folder naming options available. In this case you can choose to Edit Filename Templates Manually rather than have the templates created automatically based on your file/folder naming selections.


Editing the filename templates manually requires some care, but provides ultimate control over how your saved files are named. Each filename template consists of text containing one or more tags. A tag consists of a tag name surrounded by curly braces ( ‘{‘ and ‘}’ ). Tags are replaced by values when a filename is needed, so the tag ‘{Date}’ is replaced by the current date and ‘{Time}’ is replaced by the current time. The available tags are:



The date and time that the capture was started


The date that the capture was started


The time that the capture was started


The name of the target object entered (or ‘Capture’ if no name entered)


The name of the camera being used


The name of the currently selected filter


The extension of the file (i.e. AVI or PNG). There is no need to put ‘.{Extension}’ at the end of a template.


Sequence captures only. The index of the current frame in the sequence.


Sequence captures only. The date on which the current frame was captured


Sequence captures only. The time at which the current frame was captured




Live Stacking only. The total number of stacked frames so far


Live Stacking only. The total exposure of stacked frames so far


Live Stacking only. Is the current save an autosave?


Sequence captures only. The exposure of the current frame.


Sequence captures only. The gain of the current frame.


Sequence captures only. The black level (offset/brightness) of the current frame.


The type of frame (i.e. light/dark/flat) as selected from the toolbar dropdown.


Live stacking only. This is the exposure time of the individual frames that are being stacked.


The camera offset/brightness/black level of the current frame.


Some Tags can have an optional format string to change the way they are used in the filename:


Applies To




Date, DateTime, FrameDate

Use a sortable format for dates



Any time or date tag

Use UTC times and dates



DateTime, FrameTime

Use WinJupos compatible format



On any time/datetime tag

Use UTC times, but no trailing Z is added to the time



On any date/datetime tag

Use yesterday’s date if between local midnight and local noon (i.e. dates will not change at midnight)



On Index tag

The number of digits to use for the index



When you make changes to the filename templates you will see typical filenames updated in the Sample Filenames area described above, helping you understand how your filename templates would work.

It is important to take care when customizing filename templates as you may accidentally set up templates that have undesirable results (for instance writing over previous capture files!). You should always test manual changes to filename templates before embarking on an observing session.

Memory Tab

On 64-bit versions of Microsoft Windows, SharpCap can access additional memory to improve performance and help handle the large amounts of memory needed to perform certain functions like running Live Stacking on very high resolution cameras.

If you have only have 4Gb or less of memory, or you are using a 32-bit version of Windows then your only option here is to remain on the Classic option for memory management.

If you have more than 4Gb of memory and are using a 64-bit version of Windows then Paged will be the default option for memory management (although you can switch back to Classic if you prefer).


Choosing Paged memory allows SharpCap to access more memory in total. Paged memory is divided into two categories:

·         High Speed Frame Cache – this memory is used to store frames captured from the camera before they are written to disk. If you are using a high speed USB3 camera and have a trouble with dropped frames when capturing because your disk drive or SSD cannot keep up then a large high speed frame cache will help.

·         Live Stacking and Display – this memory is used to support live stacking operations and also to support the transformation and processing of images prior to display on screen. If you are Live Stacking with a high resolution camera then having a large amount of memory allocated to this category will help avoid out-of-memory errors.

By default, 1Gb of paged memory is allocated to each category, for a total of 2Gb. If you have a SharpCap Pro license then you can increase the amount of memory allocated to each category, up to a total of 50% of your physical memory. If you wish to increase the amount of memory assigned to one category, you may need to reduce the amount assigned to the other category first to keep the total at or below this limit.

If you change the settings on the Memory tab then you should restart SharpCap to ensure that they take effect correctly.

Note: The 64-bit version of SharpCap does not offer the option of Classic/Paged memory – you will only see the memory adjustment sliders in the 64-bit version.

Plate Solving Tab

Plate Solving is a technique to work out the location in the sky of a particular image by recognizing the pattern of stars it contains against an index of known stars. If this technique is applied to an image just captured from your telescope then the calculated location will be the point in the sky that your telescope is pointing at.

Supported Plate Solving Engines and Detection

SharpCap can integrate with a number of plate-solving tools, including Astap and a variety of tools based on the plate solving engine. This engine is found inside plate solving tools such as AstroTortilla, Ansvr and All Sky Plate Solver.  In order to plate solve images you must first install and configure one of these tools. Remember that you must also install plate solving index files – please see documentation for the plate solving tool which will guide you on how to install index files and which index files to install.

SharpCap will automatically detect the installation of the plate solving tools mentioned above if they have been installed into their default locations and show a summary of the detection status.


SharpCap will also check for common problems with the installation of each application (for instance missing index files) and flag any problems detected.

Note that if you have installed to a custom location or installed a different based tool, you will need to configure the location of the ‘solve-field’ command which performs the actual plate solving process by selecting the Enter Manually option and then browsing to the location of the solve-field script.


Selecting a Plate Solving Engine

You can select which plate solving engine SharpCap should use – either Astap or an installed engine (Astrotortilla/ASPS/Ansvr)


If you wish to select which of Astrotortilla/ASPS/Ansvr is used (and you have more than one installed), use the Manual configuration of the location of the solve-field script as described above.

Configuring Plate Solving

You can choose the actions that SharpCap will take after plate solving and also configure the focal length of your telescope (which may speed up plate solving operations)


The options for actions after solving from Telescope Controls / Solve and Resync are

·         Sync Mount and Re-centre target – this option will send an ASCOM Sync command to the mount based on the plate solving results and then perform a re-GOTO to the original mount co-ordinates. The net result should be that the original target is placed in view.

·         Sync Mount only – this option will simply send an ASCOM Sync command to the mount based on the plate solving results.

·         Offset the mounts position to centre the target – this option will perform an GOTO to a calculated position (based on the plate solving results and the original mount co-ordinates) to try to place the target in view. This option is recommended if you use a complex synchronization/pointing model in your ASCOM mount as it avoids sending Sync commands. Note that results may be inaccurate very close to the celestial poles.

·         Do Nothing – this option will take no action after plate solving.

If you specify the focal length of your telescope then SharpCap will use the focal length to try to speed up plate solving operations.

Note: If the focal length is specified incorrectly then plate solving may fail.

Note: Some ASCOM mounts do not allow you to set the focal length – if the ASCOM option is selected by the mount does not provide a focal length measurement then SharpCap will proceed as if the ‘Do Not Use’ option was selected.

Note: If SharpCap cannot determine the pixel size of your telescope then the focal length setting will be ignored.

Configuring Astrotortilla/Ansvr/ASPS

Further options to configure and fine tune the based plate solving engines are available as follows:


The Star Noise Detection Threshold can be configured by adjusting the numeric value of the ‘—sigma’ parameter. Higher values will tend to detect fewer stars, lower values will mean that more stars are detected. If too few stars are detected (less than 20-3) then plate solving is more likely to fail. If too many stars are detected (more than 200) then plate solving may take a very long time to complete. You may need to adjust this parameter depending on the camera/telescope combination in use.

When Automatically down sample large images when solving is enabled, images that are wider than 2000 pixels will automatically be down sampled (binned) to make them smaller before attempting to plate solve them. This option tends to dramatically improve the speed and reliability of plate solving large images with large numbers of stars visible in them.

Polar Alignment Tab

SharpCap’s Polar Alignment routine can become more accurate and easier to use if SharpCap knows your latitude and longitude. By default, SharpCap estimates your longitude from your computer’s time zone settings and estimates your latitude to be 45 degrees North or South. This is sufficient for Polar Alignment to work, but setting your correct latitude will allow SharpCap to correct for atmospheric refraction giving a more accurate result. Setting your correct longitude will ensure that up/down/left/right movement instructions are accurate.


You can choose to leave the observing location as the default setting (Estimate automatically from time zone) or choose either of the two accurate location options – using the location from your ASCOM mount or specifying a location manually. If you choose an accurate location option then you can enable the option to correct for atmospheric refraction.

The location provided does not need to be perfectly accurate – latitude and longitude correct to the nearest degree are accurate enough.

Finally, you can use the ‘Geolocate’ button to find your current location automatically if you are connected to the internet. This will send your IP address to an internet server which will respond with your approximate location. This approach may not work for all internet providers and will probably not work well if you are connected to the internet via a mobile device.

Guiding Tab

SharpCap can work with the popular freeware guiding application PHD2 and also the MGEN3 Autoguider to monitor and control guiding and dithering while live stacking or running a capture sequence using the Sequencer Tool or Sequence Planner. SharpCap can also send dithering commands to your ASCOM GOTO mount without needing a guiding application.


Using PHD2

In order to enable integration between SharpCap and PHD2, ensure the following:

·         PHD2 is a recent version and running on the same computer as SharpCap

·         the Enable Server menu item must be selected in PHD2

Using the MGEN3 Autoguider

In order to use your Lacerta MGEN3 autoguider, you must install the MGEN3 Windows drivers (scroll down and choose the Windows drivers from the top row of the driver table). You must also connect your MGEN3 device to your PC using a USB cable.

Using Dither Only Guiding

Dither only guiding provides a way to include dithering in your live stacking and imaging sequences without needing to actually have a guiding application/device active. Dither only guiding is considered by SharpCap to always be active (guiding), but will never send guiding corrections to your mount. Dither only guiding will however send a small, random, movement command to the mount whenever dithering is needed.  

When using an ASCOM mount, Dither Only Guiding will use the Pulse Guiding functionality of ASCOM to send movement requests to the mount. This is available on most (but not all) ASCOM mounts. You may also be able to adjust the rate at which the mount moves in response to the pulse guiding requests in your ASCOM mount setup.

If you do not have a GOTO mount, or your mount does not support pulse guiding, you may still be able to use this option if

·         Your camera and mount both have ST4 (guiding) ports

·         SharpCap supports ST4 control for your camera (Altair, PlayerOne, QHY, SVBony and ZWO cameras)

·         You connect the camera and mount ST4 ports using an ST4 cable

·         You select ‘On Camera ST4’ for the mount in the SharpCap Hardware Settings.


SharpCap Pro users can also enable dithering using one of the supported guiding options while live stacking or using the Sequencer/Sequence Planner. In order to enable dithering, tick the Automatically Dither checkbox in Live Stacking or select dithering in the Sequencer/Sequence Planner. You can set options here to control details of each dither operation.

Max Dither Step – this specifies the maximum distance that any dither movement can be, measured in guide camera pixels (i.e. pixels in PHD2, not in SharpCap). Note that MGEN does not take any notice of this setting, and that if Dither Only Guiding is selected then this setting is interpreted as the size of the dither movement step in arc-seconds.

Settle Threshold – when the movement between two guide camera frames drops below this number of pixels then the dither is considered to have ‘settled’ – i.e. the mount movement is complete and images taken should no longer be blurred by movement. Only applies to PHD2 guiding.

Minimum Settle Time – a dither will not be considered to be settled until this amount of time has elapsed after the end of the movement, even if the Settle Threshold is met before this time has elapsed. Only applies to PHD2 guiding.

Maximum Settle Time – a dither will always be considered to be settled after this amount of time has elapsed, even if the settle threshold has not been met. Only applies to PHD2 guiding.

Dither in RA only – restrict dithering to the Right Ascension axis only. Only applies to PHD2 guiding.

Logging Tab



SharpCap writes a significant amount of information to its log by default, particularly if any problems occur, but sometimes extra information is required to track down an issue.

By selecting one or more of the options here, you can configure SharpCap to log additional information to help diagnose an issue. When one or more of these options are turned on, SharpCap will write significantly more information to its log. Turning these options on may result in SharpCap running more slowly or becoming less responsive due to the extra information being logged, so it is not recommended that you turn this option on unless you are trying to track down a problem or are asked to by SharpCap support.

If you turn on one or more of these options, you will be prompted to confirm whether to keep them turned on each time you start SharpCap.

The categories of additional logging that you can enable are :

·         General – any information that does not fall into the categories below.

·         Camera Hardware Communications – details of any communications between SharpCap and the hardware/manufacturer provided software of a camera in use.

·         Wheel Hardware Communications – details of any communications between SharpCap and the ASCOM driver of a filter wheel in use.

·         Mount Hardware Communications – details of any communications between SharpCap and the ASCOM driver of a mount in use.

·         Focuser Hardware Communications – details of any communications between SharpCap and the ASCOM driver of a focuser in use.

·         Camera Control Values and Capture Profiles – log information about changes to camera controls (but not other camera related information)

·         Live Stacking – log additional information related to live stacking progress and errors to the main SharpCap log

·         Guiding – log additional information relating to communication between SharpCap and a guiding application/device.

GPS Logging

Log all QHY GPS data to file

SharpCap supports QHY cameras with built in GPS. When the GPS is activated on such cameras, the default behaviour is to store the GPS data (time, date, location) in FITS headers or in the capture settings file. However sometimes it is desirable to keep a more detailed record of the GPS information – enabling this option will create such a log file in CSV format in the root capture directory each time a GPS enabled camera is used.

This option is disabled by default and you should restart SharpCap after changing this option to be sure that it takes effect.

The format of each line of the log file is

<PC Clock Time>, <GPS Status>, <Frame Number>, <Frame Start Time from GPS>, <Frame End Time from GPS>, <Latitude>, <Longitude>, <RawLatitude>, <RawLongitude>

The RawLatitude and RawLongitude are the un-decoded values received from the camera. Contact QHY for the steps necessary to decode these values if you wish to decode them separately.

Start-up Scripts Tab

This tab allows a list of Python scripts, to be run at SharpCap start-up, to be configured.  Such scripts can be used to add additional features or customizations to SharpCap every time it is started.  Use the Add, Remove, Move Up and Move Down buttons to manage the list of start-up scripts.

For example, the following Script will create a button on the toolbar that selects the first camera when pressed.  The code can be created and saved by following the information in Scripting.

def selectFirstCamera():
SharpCap.AddCustomButton("Test", None, "Select the first camera", selectFirstCamera)


Save the script somewhere (call it for example), say on the desktop and configure File > SharpCap Settings > Startup Scripts accordingly.




Deselect the camera, restart SharpCap and the button Test should be added to the right-hand end of the Tool Bar, together with the camera having been selected.




This technique is good to use for the start-up script as it allows creation of custom toolbar buttons and have them load every time SharpCap is started.

The Test button can be removed via File > SharpCap Settings > Startup Scripts, highlighting the script, selecting Remove and restarting SharpCap.

Note that although it is not currently possible to run a sequence using the SharpCap sequencer at start-up, the sequence can be launched from Python scripting using

SharpCap.Sequencer.RunSequenceFile('<sequence file path and name>')