DADOS Slit – Spectrograph

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DADOS Slit – Spectrograph

# 2458550

€ 1,845.00 Price excl. German VAT tax (19%): € 1,550.42
  • Two different reflection gratings for high light output
  • The spectral resolution (lambda / delta lambda ~ 500) allows precise spectral classification of stars
  • The whole visible and near infrared spectral range (350nm - 950nm) can be covered with a SBIG ST-7
  • Scope of Delivery: DADOS 1¼" eyepiece 20mm Kellner, DADOS 1¼" guiding eyepiece 10 mm Kellner, T-2 exchange system, adjusting ring 1 1/4", eyepiece holder 1¼", Allen wrench 1.3 mm and 1.5mm, gap viewer unit
Important note: DADOS will be produced on request and may have longer delivery times. Thus we do not accept prepayments. Please contact us by mail if you are interested.

Product Questions

My spectra show dark stripes (see mark in picture) - where do they come from?
Question by: Martin F. on Nov 15, 2017 8:25:00 AM | 1 Answer(s)


DADOS optical path

DADOS® - a slit spectrograph made by Baader

developed at the Max-Planck-Institute for Extraterrestrial Physics in Garching

The first draft of the DADOS®-slit spectrograph was based on our simple Blaze grating, which we had made for schools for more than 20 years. When we unveiled the prototype of the DADOS® some years ago, we listened closely to the following online-discussions, which lead to several large changes in the design of the product.

So, many ideas and critics from active spectroscopists were incorporated in the design of the DADOS®. We are very grateful for all feedback, because we are sure that the final product has become much better because of this.

DADOS® is designed for telescopes with about f/10 or slower. Faster apertures will cause some vignetting. The spectral resolution is not affected by this in any way.

Slit – Spectrograph scope of delivery

DADOS Slit Spectrograph – scope of delivery

  • DADOS Reflection Grating with 200 lines / mm, cemented onto tilting grating holder
  • DADOS 1¼" Eyepiece 20 mm Kellner # 1304120
  • DADOS 1¼" Guiding Eyepiece 10 mm Kellner # 1304110
  • T-2 Quickchanger # 2456313 + # 2453620
  • Focusing Ring Collar 1 1/4" # 1905131
  • Focusing Eyepiece Holder 1¼" # 2458125
  • Allen Key 1.3 mm and 1.5mm
  • Slit-viewer unit
  • Gloves
  • Manual
DADOS Reflection Grating

DADOS Reflection Grating

Nowadays, we use the following three reflection gratings (200 L/mm as standard, 900 L/mm and 1200 L/mm sold seperately) which are copies of special master gratings (they are no standard gratings from a catalogue!) - the Blaze angle of the gratings (as well as the optics, see below) is matched perfectly to the geometrical and optical properties of the DADOS®.

  • #2458557 Reflection Grating with 200 lines/mm, cemented onto tilting grating holder
  • #2458556 Reflection Grating with 900 lines/mm, cemented onto tilting grating holder
  • #2458559 Reflection Grating with 1200 lines/mm, cemented onto tilting grating holder

The desired wavelength range can be set with a micrometer gauge. A sturdy T-2 connector for large CCD-cameras (e.g. SBIG) or several adaptations of eyepiece holders (as well a much larger "Backfokus") is included.

Other gratings with the common size of 25x25x6mm with more or less resolution can also be used with the DADOS®.

The efficiency of the DADOS® slit-spectrograph is at least 60% at  550 nm.

Properties of the specially designed gratings of the DADOS®

GratingDispersion at 550 nmspectral resolution lambda/delta lambda
at 550 nm with the 3 slit diameters
spectral range covered
lines/mmnm/mmnm/ 9 µm Pixel25 µm35 µm50 µmST-7/ST-402ST-8/ST-1603
200 47,61 0,443 543 388 272 328 656
900 12,67 0,114 3818 2727 1909 87 174

The slits

the slits

The second core element besides the gratings is the reflecting slit element with a precisely manufactured triple slit (with gap widths of 25/35/50µm). You can see all three slits at the same time and easily choose the right one for each object at a glance.

Because of the forward-reflecting slit element with razor-sharp, perfectly smooth edges and an additional, sophisticated optical system of tilted mirror and projection lenses, you can focus – just as with larger spectrographs – directly onto the image of the star with affordable, common CCD-guiding cameras or webcams (not inluded) or even with a guiding eyepiece and easily guide the telescope!

the slits

Guiding eyepieces

Two reasonably-priced 1¼" DADOS Kellner eyepieces with 10mm (#1304110) and 20mm (#1304120) focal length are included. They can be used for finding objects and for manual guiding without a guiding camera. A slit illumination (included in the scope of delivery) made of a dimmable red LED helps you to focus the guiding star and the slit itself. It illuminates the slit from the back towards the guiding camera/eyepiece, so that the LED's light will not reach the lens of the collimator.

Lens system

The collimator system in front of/behind the Blaze grating is made of an achromatic and a triplett system. These were specially designed for the best-possible resolution and are coated with the best available anti-reflection-coating. These are no standard lenses from a catalogue!

The collimator lens can be moved over a wide range with a 2" Helical focuser very precisely, so that (almost) all known CCD- and DSLR-cameras (as well as almost all standard eyepieces) can be focused.

Adaptation and Mounting

Dados Rohrschelle

On the telescope side, the DADOS® has got a black 2" nosepiece. You can attach an optionally available Neon-calibration lamp (#245 8590 - not included) with 2"-adaper and 220V cable to it.

If you remove the nosepiece, you can use the standard 2" SC female thread inside of the front part of the DADOS® for a variety of other adaptations. We have several adapters for a sturdy connection using this thread, e.g. a 2"/T-2 reducer (# 295 8242) to attach the DADOS® directly to optics with the standard T-2 photographic thread (M42x0.75).

You can also the female 2" thread of the front cube to screw the DADOS® without the nosepiese directly at a Schmidt-Cassegrain-telescope. Use our 2" Locking-Ring (#245 8270) to fix the DADOS® in any orientation - this way, you can even mount it between the fork arms of many Schmidt-Cassegrain with an alt-az mount. Both guiding and imaging camera are mounted in a 90°-angle towards the DADOS® to keep it as compact as possible.

Dados Rohrschelle

To mount the DADOS® on a telescope or attach other accessories, a clamp with 3/8" and 1/4" thread (#245 8593) and 38mm diameter is available.

The two-piece clamp has got a 3/8" thread at the bottom side (a 1/4"-thread is included) and a 1/4" thread on top.


You can use it to mount the DADOS® on a ball-head or a tangent assembly as secondary unit. You absolutely need it in a classroom to mount the DADOS® on an optical bench or for any setup without a telescope.

There are plenty adapters available for all kinds of guiding cameras a well as for almost all imaging CCD-cameras – just take a look at our Astro T-2® accessories.


DADOS features

This user-friendly slit spectrograph, which was designed especially for use in schools or universities and for amateur observers, offers all features of a professional spectrograph. Especially remarkable are the following features:

  • Two diffent reflection gratings and a specially designed optical system deliver a high light efficiency
  • micrometer gauge for precise adjusting of the grating
  • in contrast to spectrographs without a slit, even large objects (nebulae, planets, comets) can be analyzed – just like in a professional observatory
  • the spectral resolution (lambda/delta lambda ~ 500) makes a precise spectral classification of stars possible
  • the complete visible and near infrared spectral range (350nm – 950nm) can be covered with a SBIG ST-7
  • the slit is directly visible with an eyepiece or webcam, which makes it easy to center and guide a star
  • the slit spectrograph can even be used at fast optics up to f/6.3, although a slight vignetting is visible at optics faster than ca. f/10
  • fits at standard 2" focusers
  • compact, can even be used if there is not much space
  • the spectrum of brighter objects is directly visible in an eyepiece
  • there are three slits side by side (25/35/50µm)
  • the slits can be illuminated from the back with a red LED for easier focusing of a camera on the slit
  • the spectra can be taken with web-, digital or CCD-cameras
  • all cameras and eyepieces can be attached with our T-2® adapters
Projektionskuppel 2.5 Meter Durchmesser
Spectra of NGC 6543 and M57, taken by OStR Dipl.-Phys. Peter Stinner, Kopernikus-Gymnasium, Wissen
Projektionskuppel 2.5 Meter Durchmesser
Test images with SBIG ST-402 ME, white LED + green laser + neon-calibrationlamp

Additional Information

Manufacturer Baader Planetarium
SKU (#) 2458550
Weight (kg) 0.95
Usage Perfect for visual and photographic use with or without a telescope. Suitable for amateur astronomers for private use and for spectroscopy education on schools and universities.
Spectral Resolution with different reflection gratings: up to R = 5000
Optimized Spectral range 395-700nm tuneable (ca. 365 - 900nm with 200 L/mm reflection grating)
Break-even value 200 L/mm: m = 8 mag. vis | 900 L/mm: m = 6 mag. vis (30cm-telescope S/N=50, 20min. exposure – see instruction manual)
Mechanical Design Blaze Grating Spectrograph with moveable and exchangable reflection gratings
Field size optimized for sensor sizes: ca. 13x18mm, usable from 6.9 x 4.3 mm (ST-402, ST-1603, STF-8300M, DSLR, ...)
Collimator aperture ratio f/10
Optimized for focal ratio f/10 telescopes
Adaptable to DSLR-, CCD- and Video-cameras
Slit size Multi-slit plat with three slits 25, 35 and 50μm
Illumination manual red LED for Slit-Focusing
Special Features 110-page tutorial. Flip-Mirror with callibration unit under preparation
Guiding Port with 1¼"-connection for eyepieces, video- and guiding cameras
Included Accessories DADOS, reflection grating 200 L/mm, 10mm and 20mm eyepiece

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