Connect 2 inch EFW to William Optics Flat73 Flattener

chris_g

I want to connect a 2 inch EFW to a William Optics Flat73 and a William Optics Z73 Zenithstar. The flattener has a M63 male thread on the telescope side and M48 on the camera side. The telescope has a M63 female thread on the focuser. The camera is a Canon 6D with a M48 T-ring.

How can I attach the EFW?

WalterT

The Flat73 lists a working back focus distance of 67.7mm. So with the EFW being 20mm and camera body 44mm you’ll need to find a T-ring that is thinner than (3.7mm +1/3 the filter thickness) instead of the standard 11mm. Then use your flatteners "adjustable" mechanism to dial in the back focus precisely. Would the camera even mount to the EFW if it’s that close?

Ps. I don't own any of this equipment, this is just my understanding of it.

chris_g

The flattener has a M63 male thread. I need a M63 female to M54 male adapter, so I connect the flattener to the filter wheel. Then I mount the camera to the flattener and don't need to worry about the 55mm working distance. I've done something similar with an EvoStar ED80 and was able to achieve focus.

Anyone know where I can get an adapter?

WalterT

Are you wanting to place the filter wheel between the scope and the flattener instead of scope>flattener>efw>camera?

I did a search at my usual places where I get adapters and didn't see one for those sizes. You may want to check out having a custom one made if you can't get any other leads: https://www.preciseparts.com/ppmain//index.html

chris_g

Yes, I managed to get that configuration to work with an EvoStar ED80's flattener and the EFW and achieve focus, though just barely because of the multitude of adapters I had to use. Thank you so much for the link!