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ZEISS DTI thermal imaging cameras. For more discoveries at night, and during the day.

Interview with Harpia Team Leader (1 Viewer)

What kind of distortion do you see in the Kowa at 60x? My recollection is of some barrel distortion at the low magnifications gradually decreasing to approximately zero rectilinear distortion at 60X, but with the expected large amount of angular magnification distortion.

Henry,

I have just checked the TE-11WZ for distortion using your method of viewing a grid pattern through the objective. My impression was of uniform slight pincussion (appearing as barrel) throughout the 25-60x zoom range. I could not quantify it but it was of similar magnitude to the excellent Swarovski 30x W eyepiece.

John
 
If high AMD distortion doesn't explain the Kowa's smaller than expected AFOV that would seem to leave a real field smaller than the 1.32º spec as the only other possibility.

Henry
 
Henry,

The 1,32° ties up exactly with the 23 m FOV @ 1000 m, so I think it's just the tangent error of what you call the "naive method" at large AFOVs.

Regards,
John

PS:- The ISO figure of 69° is also derived from the 23 m.
 
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