Omegon off-axis-guider with Microfocus: Successful astrophotography without a guide scope
Why it is sometimes better to take photos with an off-axis-guider
With an off-axis-guider, you’ve almost got the perfect astrophotograph in the bag. Photos with long exposure times require precise tracking. That is exactly what this guider specialises in, making it an essential tool for astrophotographers. With it, you too will soon have the most beautiful astrophotographs in the bag.
The advantages at a glance:
- Take sharp, point-like and beautiful astrophotos
- For refractors, SC, MAK, CC and RC telescopes
- Off-axis-guider with a length of just 24 mm – adds very little bulk.
- Stable yet lightweight: just 180 grams
- 45 mm optical aperture: full illumination even for large sensors
- Microfocus: exceptionally smooth helical focusing with 0.05mm accuracy
An off-axis-guider is an ingenious invention. This component sits in the 2-inch focuser in front of the camera. A small prism directs a little light from the telescope into a separate tunnel: the slot for your guiding camera or reticle eyepieces. Whilst your camera photographs the object for several minutes, you have the opportunity to correct deviations immediately. For perfectly round stars!
The connections
Easy adaptation: The Omegon off-axis-guider features an M48 thread on the telescope side and an additional sleeve for 2-inch focusers. The accessory side has three screws. These clamp a flat M48 adaptor for connecting your camera. The advantage: you can rotate your camera at any time to find the optimal framing for your subject.
Precise microfocus with 10 mm travel: For autoguiders and crosshairs
A small prism directs light sideways into the control unit of your Guide via a 1.25-inch rotating focus. Now insert your autoguider (an automatic tracking camera) or the crosshair eyepiece. With the generous 10mm travel, you can find the optimal focus for your guide star. Impressive: this special helical focuser can be adjusted with a scale to a super-fine 0.05mm. This means you can quickly refocus at any time.
Guiding scope or off-axis-guider?
For many, this is a matter of preference. But there is more to it than that. During longer exposures, the positions of the guide scope and the telescope’s optics can shift slightly. This is particularly true for reflector telescopes. An off-axis-guider solves this problem elegantly. This is because there is only one optical path and therefore no misalignment.
Our expert comment:
To bring the guiding camera into focus, a number of extensions must be fitted between the off-axis-guider and the main camera. Which extensions and how many are required depends on the flange-to-flange distance of the guiding camera and that of the main camera.
The only way to find out is to try it out.
Using one 28mm sleeve and two 14mm sleeves usually provides a solution:
http://www.astroshop.de/teleskop-zubehoer/adapter/15_37?q=finetuning
For many DSLRs, adaptors are available from M48 to the relevant bayonet mount:
Alternatively, an M48-to-T2 adapter is required. A suitable option is, for example: Omegon M48/T2 adapter – short version
