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| focal length/f# | horizontal FOV | vertical FOV | arcsec/pixel | 900-1000 span (pixels) | filter threads | reasonable combo |
|---|---|---|---|---|---|---|
| 50/1.2 | 39.6 | 27 | 33 | 443*(lpmm/500) | 72 mm | 500 lpmm gives 443 pixels, gets zeroth and first order |
| 85/1.8 | 23.9 | 16 | 19.4 | 754*(lpmm/500) | 58 mm | 300 lpmm gives 452 pixels, gets zeroth and first order |
| 135//2.0 | 15.2 | 10 | 12.2 | 1198*(lpmm/500) | 72 | 300 lpmm gives 720 pixels, misses zeroth and first order 100 lpmm gives 240 pixels, gets zeroth and first order. Works well! |
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