With a number of IIS members talking about commencing work on a cold finger mod it is timely to point out the wealth of information buried in this thread on IIS, you just need to go back in time to find it here. For example, the work done on a low cost set point temperature controller and TEC power management system is covered in this thread. The box that I built out of an ebay 12V temperature controller and a PWM (total cost about $30) has served me well for some time now and will be used on my new Mono DSLR as well. It doesn't require a knowledge of electronics to build as it uses readily available parts, if you can wire up 12v supply for your various astro equipment, you can build the set point temperature controller/TEC power management system.
Re the TEC itself, a standard (#12706) TEC which is 40x40mm is sufficient and cheap. It draws only 6 amps but is good for a delta T of -25C at full power. As we know, it is possible to get good low noise performance out of a 450D sensor at 0C, so don't worry about trying to get down to below -5C as your chasing improvements at the cost of other potential problems (frosting, etc). In summer night time temps (say 20 - 25C) this TEC will do the job on full power, and in winter you can throttle it right back to your setpoint. If your facing night temps of greater than 25C then the next TEC up (which draws 8 amps) might be worth considering if you can power it.
I am still happy with Argon bagging as a way of eliminating condensation/frost issues but it can add a dimension of complexity and there are other ways emerging now that I want to investigate as well. The dessicant silica paper strips used in GoPro camera enclosures are promising, and low cost, readily available locally, and they are also rechargable and can fit inside your camera in various places.
I have done a lot of reading on this subject on all the forums, and without a doubt (IMHO) this thread on IIS is the definitive and best source of information on the topic, and backed by examples from people that have actually done the work and use a cold finger camera in the field. I thank Rowland for all the work he's done on development and promotion of the solutions, and the continuing inspriational work on the electronics side of things (far beyond me most of the time).
So for you guys thinking about it, don't be scared to give it a go, plenty of support here to help you out. Just go back and review key points in this long thread to work out what you can use or learn from.
