Bahitinov

[shropshire lad]

Is this acceptable for focus or do I still need to tweek it?

[Richard_]

It depends on your setup*, but it could do with a very slight adjustment. If you look at the bright rainbow bits, they're ever so slightly on the right side of the X so a small adjustment in focus could bring them more central.

*This is more easily done when using an auto focuser but may be time consuming for a manual focuser like on a DSLR camera lens. 

[malc-c]

Slightly out... the central line isn't quite in the middle between the two that form the cross, needs to come "up" slightly

[shropshire lad]

Thanks for the replies ... it's a dslr and a Sigma 150-600mm lens. so finely adjusting the focus is not that easy.