Billo wrote:niteowl do you know who's lenses and sensors GSCI use ? I also noticed they don't share much of the sensors specs, whats that about ?
Some of the lens sizes are huge, would certainly help with ID'ing critters
BE AWARE THIS WILL BE LONG AND BORINGA huge lens is not completely necessary for good ID.
A couple of things here, lenses and sensors are European as GSCI has Govt regulations governing as to where their parts may come from. ( Not Chinese )
Now you mention not much info, have you looked at the "Australian" site? GSCI do not put a lot of detail on their site as they want their distributors to pass on the info and brochures. These have a lot of detail in them.
Re the big lenses, the focal length governs the
magnification, whereas the f Number governs the lens speed and
overall system sensitivity.
With the older TWS series the lenses were all f1.0 up to 100 mm focal length then f1.1. this means that a TWS 675 has a 75 mm long and 75 mm diameter lens. Yes they are bulky devices, the 6100 has obviously a 100 mm long lens and 90.9 mm diameter.
Very big.But now things need to be considered here, the 75 has 3 X magnification regardless of lens speed the ID is very good. Lens speed will make virtually no noticeable difference to the user (If any at all). Lens diameter (f No) does NOT alter the Field of View, only the focal length / magnification changes that.
Now the Ti series and the new TWS series use an f1.3 lens that is a good compromise of sensitivity and physical size. (Except the 50 mm model with an f1.0 lens). A problem with the faster lens is cost, as the lens is a MAJOR cost of the device and speed (f No) does not provide any noticeable benefit within reason, don't expect an f4.0 to be unnoticeable. Another point is that a faster lens becomes more susceptible to recoil !! GSCI will withstand up to 50 Cal.
and machine guns.
When you get to say 12 micron sensors, be wary as they are physically smaller even with the same number of pixels and therefore will provide a magnification increase of 1.4 X with any lens length, and the image viewed will be exactly the same as on at the same magnification with the next longer lens at a
higher price. When you have large 12 micron sensors that are the same physical size as an equivalent 17 micron one, the magnification will be the same, but at a substantially higher price. They do have the magnification benefit with the shorter and therefore cheaper length lens though.
Now this is where the "advertised" sensitivity of dodgy manufacturers mislead the user with ridiculous figures ! All tests should be carried out on a heated target of 30 degrees C with an f1.0 lens. This is because you are looking at the temp. difference between the target and the sensor. So, if you use a target of 40, 50 or even 60 degrees you get a lower and "better" figure with the
same sensor.
This is where cryogenically cooled sensors come up with such low figures.
Some just give figure as they know it will impress the punters and they also know the punter will not see the difference anyway and have no way of actually testing it.
There is so many variables in the atmosphere that alter the users results. Even on the same night when looking in various directions, especially in hilly country that has "dry" areas and "wet' areas with differing humidity where ever you turn.
Now there are things like gain control if fitted in the device. This will enhance the image to a degree until you get to an image that will give you a headache from the stark image and no actual improvement. At the same time you enhance the all atmospheric crap in the air.
Brightness is often used to try to make the image look like day time but does not help with detection or image quality. Lower brightness settings are more beneficial.
At the end of all this, if anyone is still reading (Oh get a life) I / we almost exclusively use 75 mm 640 x 480 17 micron devices and can ID cattle at 2000 metres from horses at 3 X magnification.
I have a 100 mm 640x 480 17 micron Ti that I used a couple of times to show people, but have never used it on a firearm.