A spectrograph without slit is essentially a spectro-imagor, i.e. an instrument able to acquire the spectrum of several objects simultaneously. When an object has a structure, it is the case with a planetary nebula, it makes it possible to analyze its morphology according to the wavelength.
The image shows the field of planetary nebula NGC 2392 (the Clown nebula) captured with a Jeulin grating (100 lines/mm) placed 21 mm in front ot the surface of KAF-0400 CCD equipping the Audine camera. The telescope is a flat-field camera of 190 mm at F/D=4. The final image represents a combining of ten 2 minutes exposures. The zero order of this one is just on the right center of the image (one may guess the nebular glow). Notice that each star has a spectrum associated. The nebula spectrum is complex: one sees at the same time the spectrum of the central star which is of magnitude 9 approximately and several monochromatic images of the nebula which are superimposed on it. The Jeulin grating concentrates approximately 50% of the signal in the order #0, 40% in the order #1 and 10% in the other orders.

The following figure presents the spectral profile of NGC 2392 extracted from the preceding image. The lines [ OIII ] at 5007 A and Ha at 6563 A are particularly intense. The spectrum shows in fact monochromatic images of the nebula (the "continuum" spectra of its central star is also visible). The hole in the lines is explained well if one remembers that nebula is a ring and that spectral profile pass roughly by its center.

Spectral profile of nebula NGC 2392.
The spectrum of planetary nebula M57 taken with a prism spectrograph. Chromatism of the photographic objectives used in the spectrograph is very severe. It results in a strong widening (defocus) in the infra-red part of the spectrum. The image of comparison, on the left, captured in polychromatic light (extracted from the BT-Atlas).
The spectrum of the nebula NGC6826 captured under the same conditions as for the preceding image. The spectrum of central star is quite visible here.
The nebula NGC 6210 observed with the 190-mm telescope and a grating Rainbow Optics of 200 lines/mm (April, 24, 1999). We favorise here luminosity rather than the spectral resolution. Thus, the grating is placed very close to the CCD: 13.4 mm in front of it. This was possible with Audine camera by placing the grating even inside the box of the camera. Dispersion is 32 A/mm approximately.
Spectral profile of NGC 6210 captured with the grating Rainbow Optics.
Detail on the weak emission lines of NGC 6210. The use of CCC KAF-0401E, by its great sensitivity in blue, made possible the detection of  the line [OII] at 3738 A.
The spectrum of nebula M57 in the vicinity of line Hacaptured Aug'99 with a spectrograph at the resolution of 3000 approximately. Sampling is of  0.93 A/pixel. Co-adding of 17 images, 120 seconds exposures each. This document shows that line Ha is not the only source of light in this area of the planetary nebula spectra. This one is surrounded by the lines [ NII ], which still are more intense. The line at 6364 A is [OI]. For a peculiar processing of this image, click here.
Spectrum of M57 in the green region. Note the small size of the nebula in the 4686 A He II line (only the central part emit at this wavelength).