Digital Imaging Advice
Colin
have just ordered a Skymax-180 Pro Maksutov-Cassegrain catadioptric
telescope plus HEQ5 Pro mount and SynScan set-up plus a few eyepiece
and filter accessories. While awaiting delivery I would very much
appreciate advice from members of this forum with practical experience
on:-
i) Suitable electronic imaging devices (Charge Coupled Devices /
webcams) to connect between the telescope optics (Sky-Watcher 1.25"
compatible attachments) and my laptop via a USB port so as to bring up
suitable pictures of what is being viewed.
ii) Please also advise on your recommended suitable image device to
picture software (my laptop has a Windows 7 operating system) and
possible image enhancement software.
My initial requirements will be to take simple photographs of planets
and some Messier objects.
Regards,
Colin
Robin Scagell
This is a big subject, as I'm sure you're aware. The setup you've
ordered is ideally suited to planetary imaging, and you should also be
able to capture views of a range of deep-sky objects, particularly
galaxies, globular clusters and planetary nebulae that benefit from a
longer focal length.
You'll need different cameras for planetary imaging and deep-sky
imaging. Webcams are perfect for planetary imaging because of their
ability to capture a video stream from which software can select the
best images. But webcams are not in general very sensitive, so rather
than try to adapt them as some people do, it's better to have a
separate camera for deep-sky imaging.
At one time, people dipped their toes into the waters of webcam
imaging using off-the-shelf webcams, notably the Philips ToUcam and
its successors, but these are no longer available new and there are no
simple replacements. You can get results of a sort using even the
simplest webcam with its lens removed and taped to the eyepiece
barrel, and for the outlay of about a fiver it's fun to do this and to
get some useful experience in focusing and grabbing images. But the
controllability of the cheap instruments is poor, while the more
expensive ones don't have readily removable lenses and may be equally
hard to control for astronomical use.
The only replacement for the Philips range is the Celestron NexImage
(£134), which is the same camera and comes with 1¼-inch adapter. There
are also the Meade Lunar and Planetary Imager (£86), and the Sky-
Watcher Acuter (£60), which do not enjoy such good reputations.
You will, however, get better planetary results with DMK cameras,
starting at about £300, or Lumerera Skynyx cameras, which cost at
least double that though I don't know who distributes them in the UK.
For deep-sky imaging, you can start with any DSLR camera but for
better results you really need a cooled CCD camera, which can cost
rather more than most DSLRs. Atik, Artemis, Starlight Xpress and SBIG
all have their adherents and I'm no expert so you'd have to take more
advice. Ian King, of Ian King Imaging, would be a good person to ask,
and he can also advise on software. There is also the Meade Deep Sky
Imager (£356), which is uncooled and of limited value, though it can
give tolerable results with its clunky software. But I'd recommend
starting with a DSLR if you have one, to get experience.
You'll find, for example, that the drive of the HEQ5 isn't good enough
as it stands for unguided long-exposure imaging, and by long-exposure
I mean more than about 25 seconds. You need to correct for the
periodic error, which then requires an eyepiece with crosswires and
subsequent problems with retaining the corrections from one night to
the next. Or you can use a separate guidescope and imaging device,
which introduces problems of finding a guide star near the object you
want to photograph.
With all cameras, either planetary or deep-sky, there are single-shot
colour options, but the best results come from mono cameras plus a
filter set. To get top results with all cameras, you have to get
deeply involved, and pay a fair bit of money. It's best to stick to
the objects that are easy to photograph wit the equipment you have,
get good results with those then push the boundaries a little.
All the best
Robin Scagell
Colin Bayliss
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Dear Robin,
Thanks for the very sound advice. I do have a Pentax Kx DSLR and have already ordered a tele-camera adaptor so I should be able to see on the camera's screen what the telescope is up to. As you say, you have to start somewhere and recognise the boundaries between a hobby and what is professionally possible with a large budget! I'll keep the forum posted of results in the months ahead.
Regards,
Dr Colin Bayliss -------Original Message------- |
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