Modification of a Skywatcher 200 Quattro 

We have built a prototype for our new model series, which will be available for you in the future.

The Skywatcher 200 Quattro is a very good telescope, which is excellently suited for astrophotography. But even such a good product can be optimized. 

The aims of the modification:

• The secondary mirror should remain stable in its collimation. Sometimes it happens that the original secondary mirror spider loses some of its adjustment during frequent transportation.
• The spikes produced by the secondary mirror spider should be nicer
• Der Okularasuzug soll feinfühliger werden und höhere Lasten bis 6 kg im Imagetrain stabil halten und bewegen können
• The primary mirror should have a diaphragm to eliminate the influence of the three mirror mounts

We have decided to show these modifications transparently.

Why the Skywatcher 200 Quattro as a base?

• it has a stable steel tube, which retains collimation even with different asure directions in the sky and bends only minimally
• the mirror is of very high quality for a mass-produced product

What additional components have we chosen?

• Focuser: 2" BDS-NT Baader Diamond Steeltrack® focuser: this can hold a load of 6 kg, runs very precisely and can be adjusted in all planes. It has the shortest mechanical design, with an optimal balance between shortest length (= gain in backfocus) and greatest possible rigidity: Produkt
• secondary mirror spider: Backyard Universe secondary mirror spider SW200, CNC-milled: this is excellently manufactured, very stable and has a significantly lower reflection than the one from Artesky (see article)
• our own aperture ring: Produkt
• Baader 2" coma corrector MPCC Mark III: Produkt 
• 3d-Gummi als Lichtschutzfaktor unter dem Okularauszug

The modification

On the left the Baader 2" BDS-NT Baader Diamond Steeltrack® focuser, on the right the BaxkYard Universe CNC secondary mirror spider.

Due to the joy of installing the Baader OAZ, I forgot to document the steps. This will be made up for in the next setup.

Unfortunately, the auxiliary holes provided by Baader cannot be used with the 200 Quattro, so we had to develop our own drilling template.

Under the focuser you can see a white component that fills the gap between the focuser and the tube. This works very well, but will be printed in black for the series.

For the first step, the end cap is removed, whereby 6 Phillips screws have to be loosened.

Hier wurde die Endkappe entfernt. So ist auch deutlich die Befestigung der Original-Fangspiegelspinne zu sehen.

The secondary mirror spider is released by removing the four knurled screws.

Removal of the secondary mirror unit.

The new CNC secondary mirror spider. Another advantage of the Baykvard Universe secondary mirror spider: a suitable washer for the secondary mirror holder is included. The grub screws tend to leave impressions in the soft aluminum body, so that the secondary mirror tends to spring back into its old position during collimation. This effect is now prevented.

Inserting the CNC secondary mirror spider.

View from the front. The orientation of the collimation screws is important and must be exactly the same.

The end cap is mounted again. On the side of the primary mirror you can still see the three fixings that impair the star image.

Dismantling the main mirror.

Mounting the aperture ring, which was coated with special anti-reflection paint. In the foreground you can see the three plates that were on the rubbers of the main mirror mount. These are no longer needed.

Conclusion:

The focuser is a dream. Very precise and yet smooth-running. If required, it can be equipped with a focusing motor. A report on this will follow.

The Steeltrack has a toothed belt profile 3M, so that a focusing motor can easily be attached either with a toothed belt or directly to the axis. This is carried out in a second step. At the customer's request, either a ZWO-EAF (as soon as a cold-suitable version is released, this will be used) or the Pegagus FocusCube 3 Universal can then be used.



The CNC secondary mirror spider keeps the collimation very stable and is really fun to adjust. A defocused image produces double spikes, which become a single spike when in focus. Just like a Bahtinov mask.



The baffle ring on the primary mirror eliminates fan-shaped emissions through the secondary mirror mounts in the case of bright stars. After the conversion, only homogeneous stars can be seen (of course with the sharp secondary mirror spikes).





Further information follows...