The best optical performances ever seen – Ti 45 Astrograph f/4 and f/8

Telescopi Italiani has decided to show a full review about the awesome optical performances of our TI 45 Astrograph DFL – reached thanks the design work carried out by the aerospace engineer Leonardo Priami.

No other manufacturer shows detailed diagrams like these.

SPOT DIAGRAM

The Spot Diagram and the other performance diagrams, was calculated:

• On Axis (1)
• 9 mm from axis – corner of the KAF3200 (2)
• 21.65 mm from axis – corner of the KAI11002 (3)
• 26.10 mm from axis – corner of the KAF16803 (4)
• 30.65 mm from axis – corner of the KAF39000/KAF50100 (5)

TI 45 f/4 (450 mm aperture- 1800 mm focal length): FOR THE F/4 CONFIGURATION IS REPRESENTED THE SPOT DIAGRAM CONSIDERING THE WAVELENGHT FROM 400 TO 700 nm.

FOR THE F/4 CONFIGURATION THE GRAPH BELOW SHOWS A POLYCHROMATIC SPOT DIAGRAM UP OVER 40 MM OFF-AXIS (MORE THAN 80 MM REAL DIFFRACTION LIMITED CORRECTED FIELD)

NEAR INFRARED PERFORMANCES The TI 45 f/4 shows an extraordinary good performances also in Near Infrared field. The graphs below shows spot diagrams from 400 nm to 1,2 micron and RMS Spot radius vs. wavelength that shows well below the diffraction limit line.

TI 45 f/4 Near Infrared Matrix Spot Diagram

TI 45  f/8 (450 mm aperture- 3600 mm focal length): FOR THE F/8 CONFIGURATION IS REPRESENTED THE SPOT DIAGRAM CONSIDERING THE WAVELENGHT FROM 400 TO 1000 nm

MATRIX SPOT DIAGRAM

TI 45  f/4 (450 mm aperture- 1800 mm focal length):

SPOT DIAGRAM vs FIELDS

TI 45  f/4 (450 mm aperture- 1800 mm focal length):

TI 45  f/8 (450 mm aperture- 3600 mm focal length):

SPOT DIAGRAM vs WAVELENGTH

A very important diagram that nobody shows. Only after analyzing these curves we can see that the optic is really diffraction limited for every wavelengths. The black line is the Airy Disc radius, the numbers are the five fields. TI 45  f/4 (450 mm aperture- 1800 mm focal length):

TI 45  f/8 (450 mm aperture- 3600 mm focal length):

DISTORTION and FIELD CURVATURE

A great result also about field curvature and distortion. Only 0.32% of distortion @ 30 mm off-axis for the f/4 configuration.

TI 45  f/4 (450 mm aperture- 1800 mm focal length):

TI 45  f/8 (450 mm aperture- 3600 mm focal length):

RELATIVE ILLUMINATION

The Relative Illumination curve is the ratio between  the light hitting the focal plane and the total light  incoming. After said this, it is clear that we could reach very high relative illumination only reducing the total incoming light (for example reducing the secondary mirror size (!)). With a under-dimensioned secondary mirror we could have higher relative illumination but with a great loss of light (as if the primary mirror was working with a smaller diameter). We decided to optimize the illumination up to 30 mm off-axis with a well dimensioned secondary mirror. To understand this can help to see also the “Unvignetted Ray graph” that shows the complete collected light from the primary mirror. The 30% of lost light is the exact amount intercepted by the secondary mirror cell.

TI 45  f/4 (450 mm aperture- 1800 mm focal length):

TI 45  f/8 (450 mm aperture- 3600 mm focal length):