Two long focal length (590 mm, f/2.5) cameras, optimized for different wavelength regions are available for use on the echelle spectrograph. Both are folded Schmidts of essentially identical design, except for the correcting plates and optical coatings. The blue camera correcting plate is made of fused silica, while the red camera correcting plate is made of barium crown glass. The blue camera can be mounted only on the left camera port and the red camera only on the right port. The camera port baffle must be rotated into the proper position to block stray light from the camera which is not in use.
The orientation of the spectrum at the camera focus differs for the two camera ports. In both cases the echelle orders are nearly vertical with wavelength increasing upward. At the left camera port (blue camera), longer wavelength orders are to the left, while at the right camera port (red camera), longer wavelengths are to the right. At both ports, order separation increases with wavelength.
Only two cameras may be installed on the spectrograph at any one time; thus, either both of the long focus cameras or one of the long focus cameras and the UV camera (§3) may be mounted. Please consult your staff contact to determine the appropriate camera for your program. A further complication often arises due to more than one user scheduled succesively on the instrument during the time it is mounted on the telescope. Thus, compromises in the available cameras may be necessary. Final decisions in this regard will be made by Kitt Peak personnel after discussion
with the observers. Observers who must use a particular long focus camera or the UV camera should state their needs clearly in the observing time request to allow compatible instrument scheduling.