The following table might be of interest for those that have observed or are planning programs on other instruments. The table compares the expected performance of FIES with other instruments (so far only FEROS)
| Instrument | FIES | FEROS |
| Telescope | 2.5m | 1.5m |
| Resolving Power R | 60 000 | 48 000 |
| Wavelength range | 350 - 820nm | 350 - 900nm |
| Entrance aperture | 1.3 arcs | 2.7 arcs (image slicer) |
| Quantum efficiency (max) | 15% | 27% |
| Atmospheric Dispersion Corrector | not yet | yes |
| Reduction Pipeline | not yet | yes |
| CCD | ??? | Marconi 2kx4k, 15micron |
| Simultaneous Calibrationlight | yes | ??? |
| Fiber diameter | 100 micron, 5m | 100 micron, 12m |
| Sky fiber | no | yes |