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!

3: Implement of a duo narrow filter

Today the duo narrow band I ordered has arrived. Now I can measure the exact dimension of it and judge if it's possible to fit into my adapter.

The little jewel box that arrived today.

The filter is well protected in a plastic box and protection films over the filter's surfaces. It's the model SV220, a duo 7nm H-Alpha and OIII filter.

Included was this graph over the filter's curve. Two pass band centered over 500 nm (OIII) and another over 656 nm (H-Alpha).

M48 (2") filter are on the limit to be too small (44 mm clear opening) for a full frame sensor. It's important to mount as close as possible to the sensor. In a DSLR camera this distance is relatively long, in this case 50 mm if I place it in the bottom of the adapter. That's the only place where it's behind the off-axis guider.

Drop the filter into the adapter and of course it didn't fit directly. The filter's outer diameter is 50.9 mm. The threads outside diameter is 47.8 mm. The thickness of it is 7 mm and of that the thread is 2 mm. It's the thickness of it that cause the problem, 5.5 mm had been okay, but 7 mm is problematic.