Where do ASA field flatteners go in the image train

[nakbrooks]

Quick question for anyone using an ASA field flattener: Where does it fit in the image train, next to the backplate or further back towards the camera?

 

This is for a 4" flattener on a Cassegrain OTA but I assume the principle is the same for Newtonians and smaller correctors - do they go first, last or somewhere in the middle, or doesn't it actually matter?

 

I've installed mine next to the backplate but am having focus issues so just wanted to check.

Thanks

Nigel

Edited October 19, 2014 by nakbrooks

[nakbrooks]

Ignore that question. Just checked the data sheet and it needs to be 124.5mm from the CCD plane, which it is.