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Russian Optics and Spotting in general


nuzrak
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Interesting idea, but I suspect the image would have to be larger than 1 pixel to be useful.

 

 

I think i figured out a formula for the TIM1500 that translates target size and distance to the target to the size in pixels on the 640x480 display. I will now just post the fomula and instructions on how to use it. The mathematical proof is rather long, if anybody is interested i will scan the manuscript tomorrow when i am at work and upload it.

 

Here is the formula for the horizontal size in pixels:

 

pxh=(G*tan(0,5*alpha1)*2*f)/(res_h*(g-f))

 

with

 

pxh...horizontal length in pixels

G...size of target in meteres

alpha1 = horizontal FOV of the lens = 0,102 meters for wide FOV, 0,307 meteres for narrow FOV

f...horizontal focal length of the camera = 10,1 degrees for wide FOV or 3,3 degrees for narrow FOV

g...distance to target

res_h...horizontal resolution of display in pixels = 640

 

You can look up the horizontal FOV alpha1 and the horizontal focal lenght f here:

 

www.baesystems.com/download/BAES_020343/thermal-imaging-module---tim-1500

 

Appearently there are two distinct settings for FOV...narrow and wide.

 

The forumla for the vertical size in pixels is similar, just replace horizontal focal length and horizontal FOV with their vertical equivalents.

 

For testing purposes i calculated the horizontal size in pixels of a 3m long target 1000m away and the result was ~9 pixels. This seems reasonable to me. This is what it would look like on a 640x480 screen:

 

 

HsB9sL.jpg

Edited by agusto
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A foggy night? I would say ten feet is extreme, but yeah, regular (non-IR) night vision gear is pretty well degraded in those conditions.

Checked out the spotting distance again. It was actually 15m in dense fog + night. My US opponent says he can see up to 50m with thermals. So do you think the distances are alright?

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Checked out the spotting distance again. It was actually 15m in dense fog + night. My US opponent says he can see up to 50m with thermals. So do you think the distances are alright?

 

Fifteen meters is just about right for regular (image intensification) night vision in foggy conditions at night. I don't have enough experience to say that the thermal figure is just as accurate, but it fits the general trend and within the ballpark I'd expect.

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Fifteen meters is just about right for regular (image intensification) night vision in foggy conditions at night. I don't have enough experience to say that the thermal figure is just as accurate, but it fits the general trend and within the ballpark I'd expect.

Cool.

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