The Tool Bar
Start Capture
The Start Capture button
will start a video capture to a new file. The functionality
is identical to choosing Capture > Start
Capture from the menu. See Capturing
Videos and Images for a full description.
Quick
Capture
Clicking the Quick Capture button
will initiate a video capture to a new file but use a pre-selected
number of frames or seconds.
To
modify the pre-selected value, click the down arrow and select a
new value. This value will be ‘remembered’ for future quick
captures.
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<ALT> < Q> can be used as a hot
key combination to initiate a Quick Capture.
Stop
Capture
When a capture is in-progress, the
Stop
Capture button will be available and will stop the
current capture.
Pause
When a capture is in-progress, the
Pause button will be
available and will pause capture. This is useful if a cloud
is passing over the object of interest. Pause only works for
DirectShow cameras in SharpCap 2.9, but will be available for a
much wider range of cameras in 2.10.
Snapshot
The Snapshot button will
capture the current image as seen in the display area to a PNG or
FITS file. The location of the captured file appears in the
Notification
Bar below the Tool Bar, for
example:
<ALT> <A> can be used as a hot key
combination to initiate a Snapshot.
Live
Stack
This button initiates the Live Stack
process. The functionality is identical to choosing
Tools > Live
Stack.
See Live Stacking
for a full description of the tool.
<ALT> < L> can be used as a hot
key combination to initiate Live Stack.
Object
Name
Selecting Object Name in the
main toolbar allows a pre-defined object to be selected and used as
part of the capture folder hierarchy.
A new name can also be typed here to represent
the current object of interest – such as M42 or
Orion
Nebula.
Subsequent captures would be saved in a
sub-folder called M42 (or
Orion
Nebula) under the default capture folder. Objects
added here will not persist across SharpCap restarts. To
become permanent, the object must be added via File > SharpCap Settings >
General tab.
This tool is convenient for self-documentation
purposes (in the capture folder name hierarchy) during an imaging
session. For example, names such as ‘M42 CLS filter’ and ‘M42
f6.3 reducer’ can be created to identify equipment used for a
capture.
Preview FX (effects)
The Preview Effects,
FX,
dropdown contains the options shown below.
When an FX option is chosen, the
FX
Selection tool from the tool bar becomes active.
A red
rectangle, which can be dragged and re-sized, appears on the
image. In this way, the special effect can be applied only to
the selected area.
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Preview Effects (FX)
will apply only to the display and not affect the captured
data.
This tool can also be used with the
Image
Histogram and Calculate Focus
Score tools to limit an action to a section of the
image.
No effects are applied to the image.
Any part of the image which is deemed to be
over exposed is highlighted in red. In this graphic, notice
the red highlighted areas.
This is a more extreme example using the moon
– the camera exposure setting needs to be reduced to remove the red
highlighted area.
Image Boost is
useful when trying to find fainter objects. The image will
appear slightly grainy as noise is introduced.
Image Boost More
applies a greater boost to the image, allowing even fainter objects
to be revealed. An increase in graininess is to be
expected.
With Frame Stack (3), 3
images are stacked. This effect can assist when looking for
fainter objects. Stacking when this option is applied does not
attempt to align new images with previous images in the stack.
With Frame Stack (5), 5
images are stacked. This provides a further boost to
brightness when trying to locate faint objects.
With Frame Stack (10), 10
images are stacked.
RGB Align can be used for planetary imaging
when, due to atmospheric conditions, the object being imaged has
colour distortion at the edge. In this extreme example,
note the red on one side and the blue on the other, caused by the
varying refraction of colours of light as they enter the
atmosphere.
Use this option to adjust the red/blue values
to obtain a good image on screen to ensure best focus when
preparing to capture. The right-hand image shows the same
view of Jupiter with the colour channels aligned.
RGB Align applies
only to the previewed image, it does not affect the captured
data. Other programs, such as Registax, allow re-alignment of
RGB channels in the final captured images.
Since the RGB align only affects the image as
displayed on screen, its main use is to correct for RGB
misalignment to allow a better judge of focus quality to be
obtained, or for live broadcasting of planetary imaging.
This option will terminate an in-progress
video capture. A basic tool to allow stop motion frames to be
captured from any camera supported by SharpCap.
FX
Selection Area
The FX Selection Area
tool creates a red selection rectangle on the image which can be
dragged and re-sized. This selected area is used when
applying special effects (FX) or when using
the Calculate
Focus Score tool.
The FX Selection Area
tool can also be used to investigate the histogram of a reduced
area when using the Image Histogram
tool.
Reticule Overlays
The Reticule Overlay
tool has 3 options.
By repeatedly clicking the icon located in the
Tool Bar, the display area will cycle through the reticule
options. The reticule can be selected directly by using the
drop-down menu to the right of the button.
·
The reticule can be ‘grabbed’ by the mouse and moved around in the
display area.
·
When the reticule is displayed, the centre point
can be moved by clicking anywhere on the preview
display.
·
Dragging or clicking with the right mouse button
instead will adjust the orientation or size of the
reticule.
For
some cameras, 'Auto' output format selection will be chosen by
default. You can turn off auto selection and select an output
format manually or disable 'Auto' being the default in the
settings.
'Auto'
output format will typically pick the best output format for the
exposure and colour space selected. For short exposures (<5s) a
video format will be chosen, for longer exposures a still format
will be chosen.
'Auto'
will select basic output formats (avi, png) where they support the
colour space being used, otherwise it will pick advanced output
formats (ser, fits) - for raw capture or 16 bits per
pixel.
For
most cameras except Webcams and Basler Cameras, SharpCap now
supports a live stacking mode where many short frames can be added
together and faint images will appear in real time.
When
you select Live Stacking from the toolbar you will be able to see
details of your stack so far (number of frames, total exposure,
histogram) and you have the ability to clear and save the stack.
You can also adjust the white and black levels used when generating
the display image from the stack (these adjustments will not affect
the saved files).
Saved
stacks are always saved in .fits format and will be named using the
same rules as any other captured image.
SharpCap
will warn you if the frame rate is too fast for the live stacking
code to keep up.
For
all supported cameras (except DirectShow cameras), SharpCap
includes a 'Display Controls' group in the control panel. These
controls allow you to adjust the brightness, contrast and gamma
used to display images, allowing you to bring out faint detail
easily. They provide similar effect to the 'Image Boost' options in
the FX dropdown but with finer control.
Making
adjustments to the controls in the Display Controls section only
affects how the images are displayed on screen - it will not make
any changes to the images saved to any capture files.
Any
camera controls that show a numeric value (gain, exposure,
brightness and many others) can be changed by typing a new value
into the display box and pressing <Enter> or <Tab>. If
you type a value that is out of range, the value will be
ignored.
For
the exposure control, you can type a new exposure value with
appropriate units, i.e. 15ms or 10s (Sadly last bit this doesn't
work for most DirectShow cameras, which only accept exposures as
numbers like -3 or -5).
Cameras
that you access using DirectShow (webcam) drivers have a rather odd
way of controlling exposure. Unfortunately there's not a lot
SharpCap can do to improve this as the way to control exposure was
designed by Microsoft when they created DirectShow many years
ago...
A
DirectShow exposure value is a whole number. Zero indicates a 1
second exposure, negative values (most common) are exposures of
less than one second, positive values (rare) are more than one
second. Every change of the value by 1 is a doublying or halving of
the exposure. That means that -4 is 1/16s and +4 is 16s; -6 is
1/64s and -8 is 1/256s.
Unfortunately,
some webcam driver writers got this wrong (Logitech even got it the
wrong way round in their drivers for several years), so some
cameras don't actually obey these rules.
SharpCap
can add a timestamp showing the date and time to captured frames
from many cameras. Supported cameras include ZWO, QHY, Altair and
iNova cameras, and DirectShow cameras when capturing in MONO8 or
RGB24 format.
DirectShow
cameras capturing in compressed formats (I420, MJPG, YUY2, etc) are
not supported as SharpCap would need to decompress, alter and then
recompress each frame.
If
you are running out of space on your screen, you can make the
SharpCap control panel auto-hide itself by clicking on the pin icon
to the left of its title. Once you have clicked the pin, the
control panel will hide itself when you move your mouse away from
it and reappear when you move the mouse back. Click the pin again
to go back to the default behaviour.
You
can also drag the control panel to the left hand side of the
SharpCap window or detach it from the window completely.
Capture
Profiles allow you to save all the settings for a camera once you
have adjusted them to your satisfaction. You can save multiple
profiles and give them useful names (Moon, Jupiter, Saturn, etc).
SharpCap automatically adds the camera name to the name you enter
for each profile - after all, you may well need different settings
for the same target depending on which camera you are
using.
You'll
find capture profiles at the top of the control panel. To create
your first profile, get the camera settings adjusted as you want
them and then click the 'New...' button.
You
can also set a profile as default. Each camera can have its own
default profile. The default profile is loaded automatically when
the camera is started. This is a great way to set a default
exposure, gain, resolution etc. each time you open a particular
camera.
When
you select a camera in SharpCap (or SharpCap automatically selects
a camera when it is started), SharpCap starts grabbing and
displaying frames from that camera straight away. Don't worry -
SharpCap isn't saving these frames, just showing them on the
screen. SharpCap will only save images after you've used the 'Start
Capture' or 'Snapshot' buttons.
You
might think of the automatic preview as being a bit like looking
through the viewfinder of a camera.
If
you are using an ASCOM focuser from withing SharpCap and you use
one of the focus aids that displays a graph (FWHM or Contrast
detection), SharpCap will display a trace of the focuser position
overlaid on the focus score graph.
This
can be very helpful as you can see which position on the focuser
gave the best focus score. Remember that most focusers have some
degree of mechanical backlash, so always aim to approach the target
score from the same direction.
If
you want to enable the alignment feature in Live Stacking, you need
to make sure that SharpCap can detect at least 3 stars on each
frame. SharpCap looks at the shapes of triangles it can create from
the stars it finds to work out how to align each frame onto the
stack.
To
adjust the star detection parameters, go to the 'Alignment' tab in
the Live Stacking window. You can make SharpCap highlight the stars
it is using (yellow box) and other stars it has found (red
box).
SharpCap
polar alignment works by plate solving two fields of stars near the
celestial pole and comparing the point that they rotate around with
the position of the pole. SharpCap will then guide you through
making the Alt/Az adjustments needed to correct any alignment
error.
Select
'Polar Align' from the Tools menu and follow the instructions. You
will need a field of view of bewteen 0.5 and 2.5 degrees (a guide
camera in a 200mm finder-guider works well) and a camera with
square pixels (the aspect ratio of the image on screen must not be
distorted).
Just
tick the 'Save Individual Frames' checkbox. Each frame that is
added to the stack will be saved as a PNG file (for 8 bit frames)
or a FITS file (16 bit frames). Frames that are not added to the
stack due to filtering, frame rate or alignment issues will not be
saved.
Enable
any focus score method and then select the 'Graph' tab (shown to
the right of the main history chart). This shows how the focus
score changes with different focuser positions.
Green
upward pointing triangles show points where the focuser was last
moved in the +ve direction, red downward pointing triangles show
points where it was last moved in the -ve direction. Older points
are shown with paler colours. To get best focus, move the focuser
through a range of values in one direction to find the best score
achievable and the position for it, then go back to that point
making sure you arrive moving in the same direction to avoid
backlash problems.
As
well as collapsing any control groups that you don't often use, you
can also change the order of the control groups by dragging them
into a new order using the drag grip (three horizontal bars) to the
right of the group title.
Use
'Capture Dark...' from the Capture menu to start capturing a dark
frame. You can choose the number of source frames to average and
SharpCap will do all the work for you. SharpCap will also file the
newly created dark frame in a folder structure split up according
to camera, resolution, exposure, gain and temperature, to help you
find the correct dark frame later on.
You
can apply a dark frame by selecting it using the 'Browse' button on
the 'Subtract Dark' control in the preprocessing group. When you
browse for a dark, SharpCap will automatically start you in the
most appropriate folder in your SharpCap dark library.
Using
dark frame subtraction will apply not only to the frames as
displayed on screen but also to the captured frames saved to file.
Note that for webcams and frame grabber devices you can apply a
dark frame in the Live Stacking options only (not in the main
camera controls).
The graphic is cleared from the image.
This is the default.
A crosshair graphic is imposed over the image
in the display area. This can be used to facilitate accurate
mount alignment using a camera rather than an eyepiece.
A circular graphic is imposed over the image
in the display area. This can be used to facilitate accurate
mount alignment using a camera rather than an eyepiece. The
rings can also be used to assist with collimation.
Zoom
The Zoom tool gives the
ability to zoom in or out of the image in the Capture Display
Area.
This
feature can be used to:
·
Zoom in when searching for fainter objects.
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Zoom in when trying to place the FX Selection Area
over a single-star when using the Calculate Focus
Score tool.
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Zoom in when trying to accurately set the Black Level % when
using the Calculate Focus
Score tool.
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Zoom out to reduce the image when Live Stack or
Image
Histogram are in use.
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Zoom out to reduce the image size displayed when capturing at
higher camera resolutions.
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Zoom has a range of 16% - 800%.
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Auto
zoom is a sensible working setting for most purposes – it will fit
the image to the screen space available.
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Image Histogram
A correctly shaped Histogram is a key
requirement to producing quality images.
Clicking the Image Histogram icon in
the Tool Bar:
will display the Image Histogram in the
Work Area of the Main Screen.
See The Histogram for a full
description and examples including information on logarithmic
versus linear scales and the impact of solar/lunar/planetary/deep
sky/ROI on the shape of a histogram.
Calculate
Focus Score
SharpCap has a several
options to help acquire focus on targets (possibly one of the most
challenging aspects of astrophotography). The tools are
particularly powerful if an ASCOM focuser is configured in
SharpCap.
Focus assistance is
started by selecting the Calculate Focus
Score icon from the Tool Bar.
Focus tools for planetary
or surface targets:
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Contrast (Edge) Detection
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Contrast (Brightness Range) Detection
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Fourier Detail Detection
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Focus
tools for stars or other point sources:
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FWHM Measurement
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Multi-Star FWHM Measurement
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Bahtinov Mask
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See Focusing for a full description
including introductory materials and examples.