Ti 35 f/3.5 Astrograph – OPTICAL PERFORMANCES

Telescopi Italiani has decided to show a full review about the awesome optical performances of our TI 35  f/3.5 Astrograph

No other manufacturer shows detailed diagrams like these.

SPOT DIAGRAM

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

• On Axis (1)
• 11.6 mm from axis – corner of the KAF8300 (2)
• 17.29 mm from axis – corner of the KAF16200 (3)
• 26.10 mm from axis – corner of the KAF16803 (4)
• 30.65 mm from axis – corner of the KAF39000/KAF50100 (5)

TI 35 f/3.5 (350 mm aperture- 1230 mm focal length): IT IS REPRESENTED THE SPOT DIAGRAM CONSIDERING THE WAVELENGHT FROM 400 TO 700 nm.

TI 35 f/3.5 – Spot Diagram

THE GRAPH BELOW SHOWS A  SPOT DIAGRAM vs FIELD UP OVER 31 MM OFF-AXIS (MORE THAN 62 MM REAL DIFFRACTION LIMITED CORRECTED FIELD)

TI35 f/3.5 Spot radius vs Field

TI35 f/3.5 Spot matrix

SPOT DIAGRAM vs WAVELENGTH

A very important diagram that nobody shows. Only after analyzing these curves we can see that the optic is really excellent for every wavelengths. The black line is the Airy Disc radius, the numbers are the five fields. Despite the awesome aperture of f/3.5, this TI35 shows great performances for every wavelengths

TI35 f/3.5 Spot vs Wavelength

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. Thanks to special optical design and to the use of conical baffling, we are able to limit the total obstruction to 56% (ever consider the fast f/3.5 ratio !) and have limited loss of light to the angle of bigger CCD.

TI35 f/3.5 Relative Illumination