This is a collection of notes regarding my own experience with a Meade DSI. It
was purchased in in UK, October 2005.
- You must have USB 2 support on the
computer in order to connect the camera. I could not get the system to connect
to my DSI without USB2.
- You must download and install the latest software
update from Meade. The software in the box would install apparently OK but
the system would try and re-install the DSI driver every time I plugged it in.
The software on the Meade site is now (2009) MUCH better than the original.
The latest software for Win7 seems to be more stable.
- The camera is fussy about the type of USB cable used to connect it.
A modest length of additional USB cable works OK but a general purpose powered USB extension
does not. (I have seen some special powered extension cables for the DSI
advertised but not tried them).
- The camera may not work with exposure times less than 1 second.
Sometimes an exposure time of less than 1 second causes the camera window to
go fuzzy. I have to unplug the camera, reboot the computer, reconnect the
camera. This is less of a problem with the latest version of Envisage.
- It really is necessary to use dark frames.
Unlike cooled cameras the DSI is quite noisy at short exposures. There is a
big patch of brightness in the top left of
the image caused by internal heat. This is unacceptable for anything over a 1
or 2 second exposure, especially if you intend to enhance (stretch) the contrast. This
patch is removed if dark frames are taken and used. They must be of the
correct exposure (same as the images) and taken immediately before/after the
images (to get the right temperature).
- The software has a built-in "take dark frames" procedure that is very
useful but remember you only need the dark frames for the exposure length(s) you are
actually going to use. The software will tend to waste time gathering dark
frames for a wide range of exposure times unless you tell it otherwise.
Hot Pixels and Cosmic Rays
- I have several bright white pixels regardless of exposure. These are
removed by using dark frames.
- I seem to get cosmic ray hits quite often. They appear like 'temporary' hot
pixels and can be very bright. That is one good reason for saving all your uncombined or raw images so that you can (re)combine them later excluding the
Procedure for Deep Sky
Having used a Starlight Express MX5-C with very basic software the Autostar/Image
software makes me feel rather out-of-control. For deep sky objects the
auto-combine feature is OK for an initial look-see, but I prefer to capture the
un-combined or raw images and process them later. That way I can try several different
Also, the contrast control is rather
crude and I much prefer to take the image into some other software (like Maxim
DL or PaintShop Pro) for contrast or histogram adjustments.
The procedure I use is:
- Scope set up with reasonably good N/S alignment.
- Focus on a moderately bright star in 'live' mode and get best possible
- Align to the chosen object and use 'long exposure preview' to find the
best exposure that is a reasonable compromise between brightness and tracking
drift. Try different settings of sharp/soft colour and high gain. Decide on
- Take dark frames (minimum 5 but 10 is better) at the chosen exposure.
Switch on dark-frame subtract.
- Adjust contrast setting so that the image being displayed (and saved) is
not too stretched. (i.e. set the low end to an image that makes the background
a bit grey and the top end well above the brightest star). This will give
plenty of scope for contrast/histogram adjustments later.
- Set 'colour auto' and 'save proc - save all uncombined images (jpeg).
- Select a star to track in the deep sky field (for the auto-combine).
- Start taking pictures. Collect as many as possible, (minimum 10 but I like
to get 30-50 if time allows).
Autotracking and Drizzle
- If you have a telescope with appropriate connection protocol( e.g. LX200)
then its worth trying autotracking with Drizzle. Exposures need to be quite
short to get the autotracker to 'lock on' but you can leave the camera running
for long periods and collect lots of images for stacking later.
- Using the drizzle options allows you to take images of a larger area of
sky. The software will move the 'scope around the area and combine all the
overlapping images. It will want to take a large number of exposures so be
sure you have plenty of time.
Dont Fiddle with the 'live' image contrast.
The software will save each individual image while building up a combined
image on the screen. Its best NOT to fiddle with the contrast settings while
capturing images. Certainly do not fiddle with the 'live' image contrast as this
will effect your un-combined images and make them unsuitable for stacking later.
There are various pieces of software that can be used to combine the raw images.
- Registax or Maxim DL to align and stack the images. Registax is free and
gives you the option of automatic or manual alignment, 'drizzle', colour
control, 'wavelet' filters etc. However, Maxim sometimes produces better
- The images may be quite noisy, especially after contrast stretch. I use
Neat Image to reduce noise.
PSP's Edge Preserving Smooth is also quite good.
- Sometimes maximum entropy deconvolution (e.g. Astroart or Maxim DL) can
improve the stars, but more often than not it just makes a mess of an image.
- I use PaintShop Pro (PSP) for gamma/histogram/colour (etc.) adjustments.