Handbook for the TRIUS PRO-25C Issue 1 April 2019
After the exposure and download have completed (about 4 seconds) an image of some kind will
appear on the computer monitor. It will probably be poorly focused and incorrectly exposed, but any
sort of image is good! In the case of the pinhole, all that you can experiment with is the exposure
time, but a camera lens can be adjusted for good focus and so you might want to try this to judge the
high image quality that it is possible to achieve.
Various other exposure options are available, as can be seen in the picture above. For example, you
can ‘Bin’ the download 2x2, or more, to achieve greater sensitivity and faster download, or enable
‘Continuous mode’ to see a steady stream of images. ‘Focus mode’ downloads a 128 x 128 segment of
the image at high speed. The initial position of the segment is central to the frame, but can be moved
by selecting ‘Focus frame centre’ in the ‘File’ menu and clicking the desired point in a full size image
with the mouse. The focus window has an adjustable ‘contrast stretch’, controlled by the 12-16 bit
slider. The image will be ‘normal’ if 16 bits is selected, while setting lower values will increase the
image brightness in inverse proportion.
If you cannot record any kind of image, please check the following points:
1) Ensure that the power indicator lamp is on and that the cables are properly home in their sockets.
2) If the screen is completely white, the camera may be greatly overexposed. Try a shorter exposure
time, or stop down your lens. See if covering the lens causes the image to darken.
3) If the USB did not initialise properly, the camera start-up screen will tell you that the connection is
defective. Try switching off the power supply and unplugging the USB cable. Now turn the power
supply on and plug in the USB cable. This will re-load the USB software and may fix the problem
after restarting the SXV_hmf_usb program. Otherwise, check the device driver status, as
previously described, and re-install any drivers which appear to be defective.
4) If you cannot find any way of making the camera work, please try using it with another computer.
This will confirm that the camera is OK, or faulty, and you can then decide how to proceed. Our
guarantee ensures that any electrical faults are corrected quickly and at no cost to the customer.
As the SX25C is a ‘Single-shot’ colour camera, the full resolution raw image will show a fine grid
pattern, due to the RGB colour filters on the CCD chip surface. This is normal and will disappear once
the image has been converted to colour by the software. Unlike commercial digital cameras,
astronomical colour cameras do not normally output a colour image directly. This is so that various
image corrections can be performed on the raw data (e.g. dark frame subtraction), as these are
impractical after conversion to colour. Also note that binning the raw image at anything other than
1x1, will destroy any colour information and so output only monochrome images.
Converting your images to colour:
The images from your camera are monochrome at the moment and they need to be converted into
true colour before enhancing them. Any processing of the image, other than calibration with dark
frames etc., will distort the colour rendering of the result and so the conversion needs to be done
before proceeding. Important! You cannot convert a binned image to colour, as binning sums the
different colour pixels together and averages out the colour information. All images that you intend to
colour convert must be taken in binned 1x1 mode. Also please note that you cannot sum frames
together before colour conversion. This must be done after the images have been colour converted.
Here is a small enlarged section of a daylight image which may be similar to your test image taken
with a 50mm camera lens
