Equipment
|
This
is the new 12" F/4 home made astrograph on the Fornax 51 mount.
|
|
TMB 130 refractor on EQ6 mount This is the most recent portable setup. It is a custom made tube with the gorgeous TMB130/780 triplet apo objective inside. I use the original TMB field flattener, which gives pinpoint stars to the very edge of the APS-C sensor. It is not surprise, because this FF developed to cover medium format film, have been used succesfully a few years ago. The mount EQ6 has been modified, a belt drive system has been built into the mount. It is controlled by the compact and reliable Dynostar X3 GOTO controller from Boxdörfer, Germany. The system gives very smooth tracking despite the relatively big overall periodic error, which is around +/-15". Autoguiding is easy with the Sbig ST-4, tracking performance can be sub arc sec on steady nights. |
 |
|
12" F/4 Newtonian on Fornax 51 mount This 300/1200mm Newtonian telescope is home made too. Tube made of carbon fibre material (in sandwich composit structure), which is not beautiful this time, but temperature stable and very-very rigid. Tuberings are made of wood (!), and there are also home made holders for the mirrors. Primary is from Orion Optics England (Professional grade, 97% Hilux coating), secondary (4") is from Antares, Canada. Both are very good quality products. To correct coma now I use TeleVue Paracorr, which is very sharp on axis, and corrects coma perfectly of the F/4 mirror within the 28mm image circle. At the same time it multiplies the focal length of the telescope by 1.15, so the effective FL is around 1370mm and it gives F/4.6 focal ratio. This telescope has recently been equipped with a new 3" Crayford focuser, specially made for accepting a 3" Wynne coma corrector. This corrector perfectly corrects coma within a large 50mm image circle, making possible to image with large full frame (24x36mm) sensors. It has a reduction factor of 0.95, so the effective FL is shorten to 1130mm, giving a focal ratio of F/3.8. The Fornax 51 mount is not very beautiful, but definitely a very good mount, and it has a gerat value for the money. It has no backlash, and react immediately to guiding corrections on both axes. Tracking is very smooth of course, periodic error is also in a smooth +/- 5" range. Head weights 25kgs (55lbs), load capacity is around 50kgs (110lbs). There are also bigger models available of this mount up to 150kgs (330lbs) loading capacity. |
 |
