My astronomy project:
TS130 refractor to Nikon D800 adapter

Content:

1. TS130 to Nikon adapter
2. Adapter prototype
3. Implement of a duo narrow filter
4. Preparing for first light
5. Aberration analyze
6. Shorten the adapter length
7. Adjust tilt and back focus
8. New bracket for guide camera
9. Baffles
10. Prism bracket
11. RayTrace advanced
12. To be continued

Note:
I take no responsibility or liability for what are written here, you use the information on your own risk!

4: Preparing for first light

Now it closing in for a First Light with this setup with the TS130 APO refractor and the Nikon D800 camera. But first I must prepare some things to make it possible to do this. I must have brackets for the peripheral devices and cables for the electronics and its power.

Most refractors tend to be very long, this one (TS130) is 108 cm long from front of the dew shield to the back side of the camera.

But with dew shield retracted and camera with it's adapter removed it's only 80 cm long. And now when using an Off-Axis guider there is no need for a guide telescope, more compact and not so heavy. In background, many small boxes with my astro spare parts.

I made four of these brackets to mount the peripheral devices to the telescope. They clamps around the telescope tube.

Tube rings mounted on the telescope's tube. Lot of extra places to add extra equipment with M4 threaded holes.

The devices are: Focus controller, 3 independent Power supply box and the Raspberry Pi5. I have offset the power module to let the power cable to the Raspberry be on the inside where it's more protected. The normal is to power the Raspberry Pi5 from the USB C connector. But I find it to not be so safe, it fall out sometimes. I change it and power it now through the 40 pin connector. Note that by this it override some of the safety system.

A stop installed on the Vixen tail stop the telescope to slide out from the mount and from fall to the ground. The stop is adjusted to where the balance point is which make it easy to setup at night.

In front off the camera the push pull focuser of my own 3D-printed design. It can lift 5 kg and have only a small backlash.

When in focus the focuser extend out another 55 mm to the right, the telescope must be balanced with the focuser in its correct focus position. The camera and the field flatter is heavy and move the balance point when it focus. The spiral cable is to the battery dummy for the camera, adjusted to 9 volt. If I later find USB cables of correct length and 90 degree connectors I will replace some of them.

When tested out that everything works I can cut the power cables to shorter length. The cable to the left is to the dew heater, constant 6 Watt at 13 Volt, no power regulation. It sits direct over the triple lens cell so not very much power needed.

EQ6 mount with OnStepX controller software, no more need of a EQDirect cable. On top of the EQ6's lid a Power splitter with ampere and volt meter, inside there are automatic fuses. The counter balance weight consist of two 5 kg weights. The mount is relatively naked today, I have sold the hand controller and the polar scope.

I took a new look on my two guide cameras that I have. The red one is the ZWO ASI120mm (USB2) and the black is QHY 5. They are both monochrome. ASI120 has very small pixels, 3.75 my and the QHY 5 has 5.2 my pixels. Both cameras are old, the ASI120 must be flashed when using it with Linux, still don't work perfect. The QHY 5 can't be used in Windows anymore what I know, but in Linux it works well.

The refractor has three times as long focal length, 910 mm, compared to the 300 mm lens I use. That make the field more narrow and more difficult to find proper guide stars. The QHY 5 with its bigger pixels is more suited for the refractor. Its sensor has almost twice the area compared to the ASI120, bigger area means more guide stars to chose from. Bigger pixels collect more photons also. The prism has an inlet opening of 10x10 mm and will not cut off the incoming light, less vignetting problem.

The flange of the QHY 5 camera is only 48 mm in diameter compare to the ASI 120's 51 mm. I have to design a new bracket for it. I have now learned how to 3D-print threads and can make a T42 thread. Both cameras have this T42 (M42x0.75) flange, a standard from the 1950s.

Here are some test threads. I increased the diameter in steps of 0.1 mm until I got it to fit. The diameter 40.8 mm fit best and on top of that the threads. It depends a lot of how well the 3D-printer is calibrated. The profile of the threads is triangular with a pitch of 0.75 mm.