What's the ATFLIR's Field of View in NAR mode? What about 1x and 2x NAR? This has been addressed elsewhere, but I wanted to make things easier to find, and to add a new observation about FLIR1
The above, from official Navy documents, makes it pretty clear. The ATFLIR has three FOV settings, all of which are square (so same FOV horizontally and vertically). They are:
- NAR = Narrow = 0.7°
- MFOV = Medium = 3°
- WFOV = Wide = 6°
In addition there 1X and 2X zoom form NAR and MFOV. But not for WFOV
1X is kind of meaningless, it's just that FOV. 2X is zooming in, so it's essentially halving the FOV. So we have five effective FOVs:
- 2X NAR = 0.35°
- 1X NAR = 0.7°
- 2X MFOV = 1.5°
- 1X MFOV = 3°
- 1X WFOV = 6°
The only times we see MFOV and WFOV are in the FLIR1 video: Here's 2x MFOV (1.5°)
Compare with 2x NAR (0.35°)
Going from 1.5° to 0.35° means the image should be 4.2 times as big, which we can verify by copying the MFOV image multiple times under the NAR image:
About 4.2, as close as we are going to get with this poor quality video.
Hang on! That looks like it says "WFOF"! That's actually just a quirk of the font. The M and the W are very distinctive, when not that blurry. Have a look at them in Gimbal or GoFast, which is twice the resolution, and better compression.
M hase a distinctive gap in the middle of the top half. The w ends up more like a rectangle. See that in FLIR1.
The M is actually distinguishable from the W.
In addition, something I only recently noticed (I thing, these things sometimes recycle), is the toggle order, and what happens in FLIR1.
The docs say it goes NAR->MFOV->WFOV (and them presumably ->NAR).
In FLIR1, the first 1m12s (most of it) is in NAR, with some 1x/2X changes. But then at 1:12 there's a switch to MFOV. Here again:
Notice it initially looks like WFOV 2X, but knowing the actually font we can now see it's MFOV 2X (1.5°).
But THEN, there's a change that I used to think was to MFOV 1X (3°), but now I see it's actually to WFOV 1X (6°)
It has to go to 1X, as there's no 2X in WFOV. This is also a 4X change in scale from what was already a small white dot. And now, for a seval frames, the object is too small to be visible, at least in this mode.
WFOV is only there for 10 frames (1/3 of a second) until Chad toggles through to NAR 1x, at which point we've lost lock, the tracking has stopped and the object is continuing left.
Lock is never regained. Half a second later it the system changes to NAR 2X, which just makes thing worse.
None of this really changes anything, but I think it's brings some clarity to what is going on with the various zoom modes.
For viewing the videos, I recommend using the Sitrec video viewer in Chrome or Edge:
It defaults to Gimbal, but you can change the "Preset Video" to FLIR1. Then use the arrow keys or right nouse to scrub and < and > to single step. Zoom in with the mouse wheel. By default it uses original pixels. You can toggle this with "Smooth", and there some adjustments under "Tweaks"
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