Teleskop Service Off-Axis Guider - M48/T2

Off-Axis Guiders are probably one of the most ingenious inventions for astro-imaging. For exposure times of more than just a few seconds you need to correct the automatic motion of your mount for tracking errors. If possible this is done with a second telescope side by side to the main telescope (e.g. using a TS Duomount XL).

Advantages of the Off Axis Guider

A guide scope usually means a lot of extra weight for your mount to cope with. This is problematic unless you own a mount with sufficient power reserves. Of course a second telescope and side-by-side mounting gear tend to be quite expensive, too! An Off Axis Guider is often the cheaper solution. The main advantage however is that the main camera and the guider use the same optical train. No matter how much a telescope might flex, or the mirror shift, both the main camera and guider will experience the same deviation. This means that you can correct not only imprecisions in your mount, but also in your telescope!

How the Off Axis Guider works

The Off Axis Guider is put between the camera and the telescope. It will let most of the light pass unobstructed, but a small cone of light will be reflected 90 to the side. You can move the prism in order to center a guide star.

Applications for the Off Axis Guider

The Off Axis Guider is made for long exposure astro imaging. We consider anything that is more than a few seconds to be long exposure. All astronomical mounts require a certain amount of correction of their sidereal tracking.

Teleskop Service Celestron Off-Axis Guider Features

• The original Celestron Radial Guider is one of the most cleverly designed off axis guiders that we know. It is excellent if used with a Schmidt-Cassegrain as long as you do not plan to use a focal reducer.
• Based on this already excellent product we have developed the TS OAG 2 as a low profile variant. This variant keeps the great features of the original, but adds its own unique features:
• You can rotate the guiding turret by about 100 without unlocking the telescope connection. Thus you can effectively scan the sky for a guide star without the risk to lose focus with the main camera! Only if no guide star can be found in this 100 arc you have to release the telescope connection. With conventional off axis guiders you have to release it every time!
• The prism can be tilted easily and precisely in order to scan for a guide star in a much broader area! The tilt motion is done with a thumbscrew, offering a much smoother adjustment than the conventional method of sliding the prism further into or out of the guider.
• Even very heavy cameras, filter wheels etc can be used with very good stability. The central body of the guider is one part, from the telescope to the camera. The guiding turret sits outside on its rotatable collar. The movement of the turret does not affect the central body of the guider.
• All these great features have one key result: It is now very easy to find a guide star, much unlike many simpler off axis guiders.

Telescopes that the TS OAG 2 is compatible with

The TS Radial Off Axis Guider cannot normally be used with telescopes that have a 1.25" focuser. But due to its very short length and the versatile 2" short-barrel connection this Off Axis Guider can be used on almost any other telescope.

Newtonian Telescopes - The Off Axis Guider requires only 27mm optical path. This will allow you to use it in many Newtonian telescopes despite their notoriously short back focus distance. The TS Radial Off Axis Guider can even be used together with coma correctors. We offer the necessary adapters.

Refractors - The main advantage here is that you can frequently use the TS Radial Off Axis Guider together with field flattening lenses! Usually this is not possible with off axis guiders with a longer build.

Schmidt-Cassegrains and similar - Commonly these telescopes are used with focal reducers or other correcting lenses for photography. With conventional off axis guiders this can be problematic due to the longer distance between the camera and the reducer. With the TS Radial Off Axis Guider this is usually no problem. Please request your specific adaptation for this setup!

CCD Cameras (ATiK, Artemis, ...) - Normal CCD cameras require a much shorter back focus than SLR cameras. This opens some interesting possibilities such as using both a filter wheel and the off axis guider at the same time!

Teleskop Service Product Number: TSOAG27