Project:
Nikon D800 for astrophotography ?

Contents:

1. Nikon D800 overview
2. Adapter Nikon to Pentax 645
3. Lid, Dove tail, Tube ring
4. Focuser mechanism, driver
5. Off-axis guide camera
6. Main bracket
7. Wiring & USB-HUB
8. Test with Windows and APT
9. First Light
10. Balance system
11. Nikon vs Canon, Pentax FA vs Pentax
12. Tilt adjuster
13. KStars/INDI setup for Nikon
14. Correction of tilt
15. To be continued

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

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3: Lid, Dove tail, Tube ring

It's not only the adapter I need to use this lens and camera combination. I need something to attach the lens to the mount, a Vixen style dove tail. A lid to the adapter to not get dirt into the camera. Also a bracket to attach the lens to the dove tail is needed. Into the CAD design tool again.

Camera Lid:

Because the adapter is permanent screwed to the camera it's more practical to have the protection lid attached to the adapter. It's a easy task to design, the inner diameter is 76 mm.

The lid mounted on the adapter, red plastic make it look nice.

Dove tail:

I have this short dove tail with Vixen standard dimension. But it feels a bit sad to cut it in pieces to make it fit the demands for this system. I have not tried to 3D print a dove tail earlier but think the strength of the plastic is good enough. Lets give it a try if it's strong enough for this low weight system.

This is what I came up with in the 3D design. The dove tail is 170 mm long and has a lot of holes to attach the lens and other devices to it.

Tube ring:

At the front of the lens I must add some support to make it stable enough. A 83 mm lens bracket will do the job, a tube ring. I have to divide it in two parts to be able to mount it around the lens. It also has to be thin, 10 mm only, the space between the bracket and the dew shield is where I attach the dew heater and it's narrow.

The 3D-printed dove tail installed together with the front tube ring.

View from below and the countersunk holes for the screws. Some extra 6 mm holes and even more M4 threaded holes for all the extra devices that will come later. DC/DC converters, stepper motor driver for the focuser, Raspberry computer etc.

Balance stop:

One of the holes in the dove tail I use to have a stop screw where the equipment is in balance.

When mounted on the mount this screw set the balance point. Make it easier to setup in the dark cold nights.