This webpage contains information on the foci characteristics of the INT.
Foci at the INT
There are two types of foci at the INT telescope, the Prime and the Cassegrain foci.
Optical characteristics of INT foci
|
Focal Station |
Prime (without corrector) |
Prime (with corrector) |
Cassegrain |
TV finder
|
|
Focal length (mm) |
7475 |
8357 |
38130 |
2104 |
|
Focal ratio |
F/2.94 |
F/3.29 |
F/15 |
F/16 |
|
Field diameter (arcmin) (no vignetting) (50%vignetting) |
40 52 |
20 22 |
15 |
|
|
Scale (arcsec/mm) |
27.6 |
24.7 |
5.41 |
98 |
| Scale (micron/arcsec) | 36.2 | 40.5 | 184.8 | 10.2 |
|
Diameter of central obstruction (1) (mm) |
914 |
914 |
914 |
139 |
|
Focus/mirror shift (2) |
27 |