Spirit532,
There is a lot of interesting history behind ISG and it's camera designs. The man behind ISG was Ex EEV ARGUS. Basically It appears he took his EEV ARGUS TIC knowledge and started a new company.
The Talisman is basically a 'cottage industry' thermal camera that is built around the Raytheon BST Core kit that the ARGUS 2 used. It should be stated at this point that the EEV ARGUS products are a far more professional piece of hardware that incorporates sound engineering and excellent electronic design.
When I first saw inside a Talisman I thought it was a dodgy DIY build. There was a very basic bent aluminium plate chassis and masses of RTV spread around the unit. The whole unit looked home made and very amateur when compared to the ARGUS 2 that I know so well. The RTV was intended to stop parts and connectors moving if handled roughly.
The Talisman case is also a very crude affair and could never be described as good looking or of impressive design. I personally dislike the Talisman cameras but have a few for projects that may, or may not happen
In the world of bespoke, limited production run equipment, it is not that unusual to see the build style and questionable build quality found in the Talisman. Some such units are iterally built in a shed with basic tooling and limited budget. Such equipment often looks very home made, but it performs the desired task. A 'It ain't pretty but it works' kind of situation. The Talisman prototype might be excused such build style and quality, but this was a professional fire fighting tool. It should have been better.
The good news is that the chopper wheel is relatively resilient and the Raytheon Core kit is easily extracted in order to use it in a different format case. Take a look at the EEV ARGUS 3 for an alternative camera format that uses the same style of Raytheon BST core kit. It is EEV's attempt at moving from the 'gun' or camcorder style ergonomics to the upright camera format that is now common in mobile phones. The E2V Mi-Tic (microbolometer sensor) that I own continues with this format and I must say I love the Mi-Tic
Fraser