Availability

In response to enquireis about the possibility of an Outback III series for the new DSI III cameras:

Word travels fast. I am getting a DSI Pro III sent to me in a week (October 2007). My plan is to design an Outback III that will fit the new case and CCD using the same controller system. I expect the price to be similar. Sounds like it is a bit larger which will push it up a bit but not much as material costs are not a large factor. Also depends a bit on how much I can re-use from the Outback assemble. I am planning to have it available by the end of November.

The SLR adapters work with the DSI III series cameras. Sounds like the DSI III with the smaller pixels will make a better wide field camera so the use of SLR lenses in the 28 to 135mm FL range could deliver some interesting results.

The Outback III is available Now! See web site for ordering

Why are we doing it?

Take a look at Stephen P. Hamilton's Review of the DSI III Beta Test Team.

Reading this I initially wondered if a Cooler would be worth the effort given the improved thermal noise performance of the new CCD. I asked Stephen about this and got the following reply:

The article was written a few weeks ago before I started doing some much longer exposures and one thing I have found since then is that there is a great need for cooling though not super cooling which is where your outback cooler really comes into play. The noise appears to not be linear when approaching 20C or above and seems to increase quite a bit above that making 10, 20, or 30 minute exposure a lot tougher when above 20C. I have found that when it is at 18C or below, there is a dramatic difference in the signal to noise ratio and at 15C or so it is amazing how smooth it is. It appears also that the dark frame matching when below 20C can be off by a couple of degrees with no problem but above 20C you start to get to a point where you need to be closer and closer to the actual temp. In other words, if I take darks at 18C and it drops to 17C, no problem. But if I take darks as something like 23C and it drops to 22C, I need new darks without a doubt.

So that seemed to indicate that it would be worth effort and I was soon fielding enquires as to when/if an Outback would be available for the DSI III. So it looks like there is some interest out there. It will be interesting to see what a stable cooled DSI III CCD can yield in the hands of the dedicated armature astronomy community.

Outback I Series availability

The Outback I Series Cooler is in the Production phase. With the advent of the DSI III camera I plan to continue the Outback Series one production until at least the end of 2008. I am currently keeping all versions of the Outback Cooler with on the shelf stock as indicated in the shopping cart. If I happen to run out I will have another batch completed within a couple of weeks.

Price and Delivery

Return your original Razorback for retrofit to Dingo configuration US$115. Includes shipping the Cooler back to you.

Additional accessories such as pump and hose will be required to operate the liquid cooled versions of the Outback

You can order under Outback Cooler from my on line store. (Platypus and Dingo in a day or two)
See web site for Outback pricing in other currencies.

Development and Testing

Platypus

The Platypus is able to cool the CCD to 30Deg C (54F) below the coolant water temperature. So you don't need to use chilled water to cool below 0C (32F). The Platypus version cools independently of ambient air temperature and can go a lot colder. Currently the Outback Razorback regulates the temperature between 20C (68F) and -10C (14F) but only 15C below the ambient air temperature.

The question is how cold should the lowest setting regulated temperature be. Is the range from 20C (68F) to - 10C (14F) still appropriate or would colder be useful. Noting that the Platypus would be able to achieve operation across this range on any night as long as you have a bucket of water cooler than 20C (68F) handy. The operating range of the Platypus is much broader.

There are two limiting factors. Firstly, be aware that the the CCD window will condense water when the set temperature is below the dew point and
that water freezes when the set temperature is below 0C (32F). So while the colder regulated temperatures will reduce dark noise they also reduce the signal since the CCD window is covered in ice. Secondly the CCD chip is specified to operate only down to -10C. So going lower may cause long term problems with the camera. Feedback from the DSI Yahoo groups indicated that the current range from 20C (68F) to - 10C (14F) is still an appropriate range of regulated temperatures. Chuck Reese summed up the group feeling pretty well:

"I think the main benefit is the temp regulation...below a certain point, it really doesn't matter much. I do think it would be nice for those in warmer climes to be able to get down to 5 or 10C or so during the hot season. Below that, I think the down side of fighting frost/condensation would outweigh the benefits of reaching the cooler temps."

Dingo

The Dingo combines the best of both versions into one. The simple no fuss setup and operation of the air cooled Razorback and if required the broad operating range of the Platypus. For this you trade a little more weight and cost. Air cooled performance is very similar to the Razorback version and water cooled performance the same as the Platypus. If the coolant temperature is more than 20C below ambient air temperature the Dingo will tend to heat the water a little more as heat will be entering the water from the heat sink as well. I don't think this will be a significant issue.

Razorback

Production setup is complete. We where able to cool the CCD by 15 deg C below ambient with the heat sink and fan. This is approximately equivalent to cooling the CCD by 25 deg C below what it would normally operate at. The Outback is also able to maintain the CCD temperature constant as the ambient temperature varies. See specification page for performance graph. We are calling this version the Razor Back. In future we are looking to have a water cooled version but that won't be available for a couple of months.

Fan speed is controlled by the controller to optimise performance. The user can set the aggressiveness of the fans speed to modify vibration and power requirements.

NOTE: The Outback Cooler replaces the factor convection heat sink built into the DSI/DSI Pro rear case. You will need to open the DSI case and fit the Outback Cooler to the front section of the DSI camera via the same four mounting bolts. This obviously has warrantee implications for your DSI camera. You are taking full responsibility for the modification and continued function of your DSI camera.

Availability & Pricing

Outback III Series availability

What we did for the DSI III?