Artemis CCD Camera
Some comments on the new Artemis Camera
The Artemis CCD camera has been developed principally by Steve Chambers, Jon Grove and Arthur Edwards. Steve Chambers is the "SC" of the webcam modifications. As far as I can tell, Jon is responsible for much of the software side of things and Arthur looks after the mechanical aspects of the casework and so forth.
Please note that due to commercial reasons Artemis kits are no longer available. Constructed cameras are available from Atik Instruments in the form of their ATK-16 range and can be considered as having comparable performance.
I am a long time member of the QCUAIG imaging forum, and, like most members have been anticipating this camera - which has been "home-grown" from amongst our ranks.
An introduction on how the Artemis came about is found on the Artemis website.
The Artemis camera is a USB1 astronomical CCD Camera featuring thermoelectric cooling and a choice of colour and black and white CCDs ranging from the small and inexpensive to the large and scary. The chips can be swapped in camera - although this is not quick job especially if changing to a chip with a different form factor - but this possibility makes for an attractive upgrade path.
My review copy of the Art 429 was hand delivered to me by Arthur in a lay-by near Thetford in the wilds of East Anglia. Arthur gave me a quick run through of the contents of his cardboard box, and handed over a hefty ream of instructional printed matter. A few days later, on returning home, I was able to examine things a little more closely.
The Artemis is not currently supplied as a complete camera. It is designed as a kit for those of a DIY bent to assemble.
Arthur did not hand me a completed full working camera - oh no. There was a certain amount of "user required assembly" - which is no bad thing. I am reasonably adept with a soldering iron and mallet, so this gave me a good opportunity to examine the inner workings of the camera whilst waiting for the skies to co-operate. I was not starting from the normal retail kit, some assembly has been completed, and I was able to get it up and running in the space of an evening.
The complete package consisted of:
The moment you take the exquisitely machined Artemis body out of the box, you know this is not something bodged up by your average DIYer on a sunday afternoon. The case is CNC machined from 1/4inch aluminum plate, and feels solid and hefty in the hand - no chance of any image destroying flexure creeping in here. The case itself is left unfinished so that the astronomer can personalise with whatever brightly colour paint they choose. I found the machined finish of the aluminum case so attractive I've left it like that - despite Arthur telling me I was welcome to add a finish of I wanted to. I must confess to a slight urge to graffiti "Tom was here 2005" on the inside of the case.
I have recently heard that future cases will come anodised in blue.
The case itself features :
In my opinion the tripod mounting thread is a weakness - this thread is just cut into the aluminum and communicates with the electronic areas - a few turns in here with a hard steel tripod bolt, and aluminum shavings are going to get where they shouldn't. I would recommend bolting a small steel block to this hole and putting the threaded tripod hole in that.
The Artemis casework is designed with a variety of CCD chips in mind. When I inserted the CCD into the camera and tried to assemble the optical window, I found the CCD was too close to the optical window. When the peltier cooling was engaged, the front of the optical window had a tendency to mist up. I experimented with shimming the optical window away from the CCD, which seemed to work for me. This issue later cropped up on the Artemis Yahoo group - and a final solution, in the form of another bit of machined aluminum, dropped through my letter box shortly afterwards. Arthur has produced a number of extension tubes to allow the user to increase the distance of the optical window away from the CCD to avoid any misting problems.
Artemis is designed to minimise the amount of backfocus required. These extension tubes will eat up a few more millimetres of backfocus. I have been using the artemis on my average F5 8inch Newtonian telescope in a "dew free" configuration - and I still have a good two inchs of back focus left. No problems there. I'd still have room for a filter wheel. This stage of the construction calls for experimenting with different combinations of the supplied parts to get a good solution for your particular CCD chip and telescope.
So far I have only had one slight problem with dew or ice inside the cold chamber. The design does a good job of keeping the chip dry. The desiccant is kept in a small syringe inside the case and communicates with the cold chamber via a short pipe. Unfortunately this does mean taking the back off the camera to refresh the desiccant. When changing the desiccant it is wise to leave the camera for several hours to dry. Not doing this caused me a slight misting late one night. I'm not sure how often changing desiccant is required. I suspect the paranoid user would want to do this each session. Being inherently lazy, I've not changed it once, and still not had any moisture issues.
I only thing I was surprised not to find in the kit was a threaded cover for the optical window when its not in use.
Also note that Artemis requires an external 5v and 12v power supply. I used an old PC AT power supply, which was worked flawlessly in this role.
Other than fiddling with the cold chamber, I found the remaining construction straightforward. All the instructions are plain the follow. There is only a small amount of soldering to do - if you have modified a webcam then this will be easy for you. An deep knowledge of electronics is not required either. There are no complex circuit diagrams to understand or surface mount components to struggle with, unless you buy the bare boards, which I would not recommend unless you like that sort of thing. There is a certain amount of soldering to do, so if you do not like soldering, find a friend who does. Artemis is not for people who expect a working fuss free camera out of the box - but it has a price tag to match. I would estimate that from the standard kit I would certainly be able to get it working over the course of a weekend or two.
Moving on... Artemis requires a computer. Getting it to talk to your PC is simple. plugging in the powered up camera to a USB port and Windows (I was using windows 2000 professional) will detect the camera - then it is a simple matter of pointing it at the driver software and its up and running.
The camera is supplied with both its own stand-alone capture software (originally named "ArtemisCapture") and a MaximDL plugin. I do not have MaximDL, so stayed with ArtemisCapture.
I'm neither rich or lucky enough to own a copy of Maxim DL - so I have to settle for Jon Grove's "ArtemisCapture". The Capture software is very simple and obvious to use. I only had to consult the instructions when I could not locate the controls for the zoom function.
Some notes on the software features:
So far I have been able to use the camera with my scope on three clear nights. Now follows some sample frames taken on my 8 inch F5 Newtonian. It should be noted that most of my time at the telescope was during May 2005, when true darkness is not reached.
A single 10 minute frame of the Crescent Nebula in Cygnus. Astronomical twilight. No processing. Download the original FIT file.
A single 3 minute frame of the M94. No Processing. Download the original FIT file.
A single 3 minute frame of the M82. Astronomical twilight. No Processing. Download the original FIT file.
I have taken a series of darkframes, with an without cooling. It is normal to operate Artemis with the cooling on - but interesting to show the effect of no cooling. All these images have been histogram stretched by the same amount. The original FITS are also made available. Cooling is provided with a small thermoelectric cooler (peltier). This sits between the CCD and the bottom case of the cold chamber. This way the whole case acts as a heatsink. A small fan is used to keep the case cool.
A 30 second exposure with no cooling. The camera was left for 20 minutes to warm up prior to this image. The fan was on. Download the original FIT file.
Following this, a 10 minute exposure without the cooling. Download the original FIT file.
Cooling was plugged in, and the camera left to cool. A 30s second exposure. Remember, the histogram stretch is identical to the "warm" images above. Download the original FIT file.
A 300s second exposure. Remember, the histogram stretch is identical to the "warm" images above. Download the original FIT file.
A 600s second exposure. Remember, the histogram stretch is identical to the "warm" images above. Download the original FIT file.
Needless to say, the cooling works pretty well, and its vital for good imaging.
Further images taken by this camera can be found below. All were captured in ArtemisCapture and stacked in Registax 3. Finally processing was done in Photoshop. Iris was used to co-register and scale the colour images.
My complaints about this camera are few and far between.
These few items aside, the Artemis has certainly impressed me. Its not quite as easy to use as a webcam. You do not get a 5 frames per second "live" image on the screen - which makes focusing harder. Its a very different way of working from a webcam, but I found I soon got used to it. The exposures can be far longer than with webcam - putting extra strain on tracking. Although I do not doubt that good results can be obtained with the more "normal" short exposures+stack methods. I hope Peter Katreniak is reading this - I would very much like to see integration between the Artemis camera and the familiar territory of k3ccdtools.
For the money (about 450ukp to 750ukp depending on CCD) It is hard to beat. Experienced long exposure webcam users could certainly do no wrong with this camera - an obvious upgrade path which still keeps things "in the family". The extended exposure times allowed by the Artemis will mean existing Sc1/3 cameras will be well employed as autoguiders.
Tom How - May 2005. The Curdridge Observatory, Southampton, UK.
Further update.. Artemis is now supplied with an M42 dustcap, and comes anodised in a funky blue case.
There is now a gallery of images taken by the various users of the different Artemis (www.artemisccd.co.uk) CCD cameras.