New DSI III Outback III Series Cooler is available.
In response to enquireis about the possibility of an Outback III series for the new DSI III cameras:
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.
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.
Proto type Platypus image.
Proto type Dingo image.
See web site Cart
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
Cooler from my on line store. (Platypus and Dingo in a day or two)
See web site for Outback pricing in other currencies.
Shipping is $18 on this item.
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."
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.
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.