Mike, while I admire your attempt to make a "moderate cooling system" for DSLR, I am starting to wonder where this project is going. It has definitely lost it's simplicity and it has developed from a simple cooling to the camera mounting to something that requires camera opening and modification. It seems to be slowly approaching a full cold-finger mod. You are even mentioning a dew control now (more about that below).
Also, you keep quoting Rowland (rcheshire) but there is a very important sentence that gets quoted and gets skipped over:
Quote:
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Temperature consistency is more beneficial to a data set.
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Firstly, your cooling is applied to the "wrong place". Your sensor temperature will also depend on the temperature of the camera body and hence on the ambient. Also temperature consistency can only be achieved if a cooling system has a temperature sensor at the imaging sensor (exif data is useless as we know). While your design is simpler than a full cold-finger mod, it lacks all these aspects. Also, the cooling system needs to have the extra cooling capacity to deal with temperature variations that happen during nights and between different nights (30C hot Australian nights come to mind...).
Regarding dew control, your system seems to be more complex than the fully-cold-finger modded DLSR. Instead of cooling the sensor, you will be also cooling the camera electronics and actually the whole camera. Condensation on the electronics can do serious damage unlike the simple fogging up of the sensor. Rowland used a simple resistive heating of the front glass of the sensor to solve the dew issues but you will have to address dew control of the whole camera body. You should have a look at Glen's great idea of packing the whole camera body inside a plastic bag containing silica gel and which is filled with argon gas. But as I already said, this is getting closer to a full cold-finger mod.
Also, I can see that in one of your tests you used ISO2000. You should probably stick to full-step ISO numbers (200, 400, 800, 1600, 3200 etc) as lots of DSLRs still take exposures at full-step ISOs and then use multiplication to get the ISO values in between.