2009 AstroPhoto Set Up

This is a short description of my wide field astrophoto set up. The main components are:

1) Equatorial Mount: Vixen SP with Skysensor 2000PC

2) Imaging: Pentax A* 400 /2.8, dedicated 1.4x with Pentax *ist D (IR modified or standard)

3) Guiding: Vixen 80/400 short tube with QHY5 camera.

4) Focusing: Robofocus on both optical tubes.

5) DSLR shutter is controlled by an opto isolated USB-RS232 cable.

Everything is connected and remotely controlled from a laptop. A DC-DC converters provide power to all components from the laptop power supply.

Software:

1) Guiding: PHD Guiding http://www.stark-labs.com/phdguiding.html

2) Pentax *ist D controlled by ASCOM driver (written by me). More details on ASCOM: http://ascom-standards.org/

3) Exposure scheduler (Written by me)

4) Focus: FocusMax http://users.bsdwebsolutions.com/~larryweber/

5) Poalr Alignment: PoleAlignMax  http://users.bsdwebsolutions.com/~larryweber/

Fig. 1 - Astrophoto Set -up seen from NNE

Fig. 2 - Astrophoto Set -up seen from SW

Fig. 3 - Particular of the system for auto focusing. A step motor is controlled from software and drives with a timing belt the focusing of the lens. Regular in camera autofocus is not good enough for astrophoto. I machined a removable pulley to go around the focus ring.

Fig. 4 - Camera attached to 1.4x rear converter + 400/2.8

Fig. 5 - Step motor driving guidescope focus

Fig. 6 - The DSLR is powered by the box on its flash shoe. It is a 6V DC output DC-DC converter. The guide camera is powered from the USB cable.

Fig. 7 - Bundle of cables going into the PCMCIA 4-USB powered hub. See also the Robofocus controller and the Skysensor 2000 PC on the tripod. On the right are the DC-DC converters sending power to Robofocus, Skysensor and DSLR.

USB hub connections are:

1) DSLR file transfer

2) DSLR remote shutter (USB-RS232)

3) Robofocus (USB-RS232)

4) Skysensor (USB-RS232)

5) Power supply for the USB hub

Another USB cable goes into the PC. That's the QHY5 guide camera.

Fig. 8 - Temperature sensor for the Robofocus. This compensate thermal drifit in focus.

Fig. 9 - Close up of both motors for the Vixen SP mount. I modified the drive train to go from 1:1 ratio to 1:3 so to get 3 times more torque. The load specification for this mount is smaller than what I'm putting on it. This way everything works like a charm and guiding accuracy is always within +/- 1 pixel of the guide camera.  Stainless steel gears are: S10T05M090S0505 and S10T05M030S0505 from SDP/SI.

Fig. 10 - This is M42 combined from exposures of 10s, 30s, 120s and 180s. It was taken from the middle of a city with a NON-modified Pentax *ist D and A* 400/2.8 + 1.4x. I haven't spent much time in post processing this image so it still needs a better handling of the nebula core highlights and enhancing some of the fainter regions. It takes much more time and skills to do post processing than the actual shooting :-).

Vincenzo Miceli

3-March-2009

contact me at:

vincenzomiceli at hotmail.com

vincenzo.miceli at gmail.com

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