Bahtinov mask help

[bigal1]

Hi all i was wondering can i use a Megrez 72 bahtinov mask with my IKI 70mm ed refractor ? i know they are made to focal length and aperture but cannot find one for sale exactly right for my scope which is 420mmfl and 70mm aperture , i was thinking maybe the megrez 72 one from FLOas its the closest i can find but would this still work or do i need to build my own ?

Thanks .

[malc-c]

I believe it's more focal ratio than focal length. So if they are both the same you should be OK. If in doubt drop Keith at starsharp a mail, he may even be able to make you a custom made mask to your specification

[bigal1]

Thanks Malcolm I spoke with Keith and i'm in luck , can use the one made for the William Optics ZenithStar 70 .

[malc-c]

Result !