I have an ASI174MM Mini being used on my ZWO OAG-L. What I'm having an issue with is adding a UV/IR filter to it and being able to get to focus as it would not allow me to rack the focuser in as far as would be needed with the filter on. Without the filter it focuses with no issues. Does ZWO have a UV\IR cut filter window glass for the ASI174MM Mini that can be purchased?