I posted more or less the same stuff on the GTA forum, but may as well share my take on the T20 here, as there aren't a lot of places where potential buyers can see how one of these can be used. My purpose with this thermal unit is practical short-range rat hunting, using it on my Pardini K12, a target pistol, with a Home Depot aluminum square tube mounted around the barrel so as to have a place for a Picatinny rail to live.
For those too impatient to read my long-winded diatribe: it looks like by adding a small magnifying lens in a scope mount behind the T20 and using it like a compact scope I'm able to group tightly enough for rats to maybe 10 metres, perhaps further with some experience. Not good enough with reading glasses in my opinion.
I made a delrin collar and put a lens pair recovered from a broken projector into an old scope ring. Also put together a phone mount,, killing time while waiting for Canada Post. First thing of note when mounting the T20 is that the 5mm clearance with one of the low-rise steel 30mm rings I ordered is just barely sufficient; the T20 is a paper thickness away from the rail. Not two sheets, just one could slip in. Got lucky there.
Got is zeroed from 7 metres using a 2" (5cm) aluminum disc as a target, heating it with a torch every few minutes. Shot my first group with reading glasses and made a messy 3cm group. Not good enough for ratting if one's being conscientious about it... but I knew that, my eyes not being so great any more. Here's a composite of three sets of shots, with reading glasses being so-so, phone somewhat better, and with the magnifying lens obviously ideal. POA was disc centre so the smallest groups averages 1.3cm (about half an inch) low, where Chairgun predicts impacts for an optimized trajectory with this setup. Zero holdover is 12 metres.
The reading glasses and close up lens groups are 7 shots each, the phone group is 9 shots, as one of the low hits and the one off to the right were me pulling the gun as I shot - seems the phone camera apps all try to stabilize video, no way to shut that 'feature' off apparently, so I was sort of chasing a moving target. Seems like using the phone for ratting might work - that's a 2cm group of 9 at 7 metres - but not for anything distant. The close up lens is really neat to look through. Screen on the T20 looks much nicer, details of everything downrange much easier to understand when the screen fills my eye. Here's an approximation of how that appears, though it's actually a fair bit nicer than this:
This is the phone mount thing, then the lens mounted in a stepped delrin ring (took a couple of minutes on my little lathe) and a 1" scope ring.
And here's a rather poor quality video straight from the phone. Doesn't seem to be much point using a higher resolution when the native camera app and Open Camera both insist on making the captured image wander all over the place, with the bonus diagonal banding just for fun. Tried killing anti-banding, tried 50Hz and 60Hz anti-banding, tried Auto, but these just change the rate of the bands' travel across the screen. So for what it's worth, here's a brief clip showing a single hit on the 2" aluminum disc from 7 metres (23 feet). Ah, I see this forum isn't allowing embedding either, but rather goes to a simple page with a link to the video. That link works for me.
[video]http://www.luthier.ca/other/forum/T20_on_5cm_warm_target_at_7metres.mpg[/video]
Overall my first day reaction in point form:
- The 5.5x zoom maximum doesn't feel all that much more magnified than the 3x zoom, and this thing is going to stay set to maximum zoom because I'll need at least that to take clear shots on rats. A 2" hot circle looks like a circle at 7 metres - I'm guessing it'd look like a little spot at 20 metres, not really safe to take a shot on that.
- I REALLY wish they'd followed through on the T25. 8X zoom and double the pixel count in both dimensions would have been a HUGE leap in quality. Oh well, their call. I'm glad at least to have this one, which is a dramatic improvement over the T12N.
- The sense of quality is very solid. This thing is built tough, operates well. I ground down the spring tip and polished it smooth so it won't eat my batteries, but that's the only thing I can see to complain about.
- Startup time might be a second or so slower than that of the T12N, but not a big deal, just a 5 second wait from initially pressing and holding the button until there's a viable image on screen.
- Screen quality is probably good enough with the magnifying lens, which unfortunately isn't something a lot of end users are likely to put together with this, so most are going to find precision shooting on rats difficult. Unless of course you've got good, young eyes. I left those behind a decade ago, so am stuck with a grandpa lens - I'm just 57 but man, I miss my old eyesight. Looking at distant objects is a lot easier. Cars or cyclists going by at 50 metres are easily seen in considerable detail. I can tell a taxi from a family car, a pickup truck from a van, no problem. Even easy to tell a male from a female cyclist at that range, and it's 20 degrees C here, a very comfortable spring day, so thermal contrast isn't very high. Sensitivity with the T20 is apparently excellent.
- Oh, and there's a subtle but considerate modification to the two monochrome views. On the earlier units these where black & white. On the T20 there is a distinct reddish tinge, no pure white, making either white-hot or black-hot screen options a lot easier on the eyes for night use. This sort of thing is standard for astronomy apps on phones and other night-use-specialized displays. Good to see the T20 incorporating it.
- One small negative; occasionally the screen will buffer for a moment, not refreshing for up to a full second. In perhaps an hour of screen use today with various tests I've seen this happen about half a dozen times, usually very brief like 1/4-second, but as long as a second in one case.
