Focal Length Field of View Size of Sun 50 mm 27° x 40° 0.5 mm 105 mm 13° x 19° 1.0 mm 200 mm 7° x 10° 1.8 mm 400 mm 3.4° x 5.1° 3.7 mm 500 mm 2.7° x 4.1° 4.6 mm 1000 mm 1.4° x 2.1° 9.2 mm 1500 mm 0.9° x 1.4° 13.8 mm 2000 mm 0.7° x 1.0° 18.4 mm 2500 mm 0.6° x 0.8° 22.9 mmImage Size of Sun (mm) = Focal Length (mm) / 109