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!

2: Adapter prototype

To do a test if my design ideas are correct and working I have to make a prototype. I print it with 0.2 mm layer to shorten the time it takes to print it, it shortens from 8 to 4 hours.

Field flattener adapter:

This is the part of the adapter that connect to the field flattener. I can use it after some grinding where the dimension isn't correct. Later I will try to make a M80x1 mm thread here, but the resolution of the 3D-printer is a bit low for that to work well (at least I thought so). Until that is solved I use the four stop screws to lock it to the field flattener.

This side connect to the other part of the adapter, the one that connect to the camera. What you see here is the slit that block light from coming into the optical area.

Backside of the field flattener, it's a heavy 3" flattener. The threads are M92x1 mm and M80x1mm, the outlet lens' diameter is 65 mm.

Squeeze the adapter on the field flattener's thread and lock it in place with the four M3 screws. The screws are made of nylon to not scratch the threads on the field flattener. They are a bit weak for this purpose, better with steel screws that has a rubber tip. The white bracket in the background is my DIY push pull focuser , it can lift 5 kg and almost no backlash.

Adapter against the Nikon body:

Adapter against the Nikon body with an off-axis function. I hope it's light tight now with the new slit. This is the side towards the telescope. Two of the holes at the rim in the bottom is for locking the filter in place. This part of the adapter I can reuse to all optical system that has a back focus of 70 mm or more.

This side screw to the Nikon body where the former bayonet where. The holes around the ring are for stuff that protrude out from the camera body, mechanical focus etc.

Prism bracket:

This tiny bracket will hold the prism in correct position. Printed with 0.1 mm layer thickness and here it's right out of the printer.

The bracket will slide into the rectangular hole to the guide camera. These black parts are shiny, later I 3D-print them in matte black. Maybe also add some structure to the flat surfaces to reduce the reflections.

The prism bracket can be pushed in and out. The edge of the prism will stick out about 1 mm from the bracket. Distance to the optical axis can be adjusted between 12 to 15 mm, optimized for full frame sensors (36x24 mm).

Prism installation:

The prism is squeezed into the prism bracket, the design of it can have to be fine adjusted in the CAD drawing.

Prism and bracket installed and the off-axis adapter with guide camera. The two M3 screws at top and bottom of the hole is for the M48 filter to hold it in place.

Top adapter:

Top part of the adapter installed. It's here on the top ring I need a M80x1 mm thread, I will do some experiment if it's possible to 3D-print that fine threads in my 3D-printer.

A 3D-printed test ring with inside M80x1 mm threads.

The threads looks very good, maybe I could do this. This one didn't fit, I can screw it on 2 turns then it get stuck. I think I have to increase the outer diameter by 0.1 or 0.2 mm.

After some trail and error I found that if I set the radius to 40.3 mm I get a functional thread, it was on the limit that I could use the 40.2 mm radius too. Very happy for this, now I can 3D-print threads down to a pitch of 1 mm.

From the other side with the guide camera, a ZWO ASI120mm with very small pixels. I have flashed its software, but still there are some problems. I have another guide camera, a QHY 5 which has bigger pixels, maybe better for this slow f/7 system.

Adjusting the tilt, set the split to 1.5 mm to start with. I will analyze the images later to let me know if I need to tilt, shorten or extend the slit. Now the camera system is ready for a first test. I now have to built a new computer and I have a Raspberry Pi5 to use for that purpose.

A test if the camera and adapter fit on the telescope. Looks really nice and I want to take it outdoors already tonight. But must setup a new Raspberry computer to control the devices first.

I don't dare to let the camera hang like this, I have to add a safety strap that save the camera if it falls down. With the later version of the adapter with M80x1 mm threads it should be safe as it is.