Outside Diameter?

[Stargazer Jack]

Hi,

I am hoping to get a Bahtinov mask soon from Morris engraving however I need to know one thing. I know my focal length is 900mm, my mirror diameter is 130mm but I don't know what my outside diameter is. I measured the front of my tube and got 167mm however I don't know if this is correct

[nightfisher]

just order one from flo for your model of scope, they are sooo worth getting

[Stargazer Jack]

Thanks for that, I am sure FLO never used to sell the one I wanted but IMHO it seems cheap

[LukeSkywatcher]

I would be very surprised if the OD (outside diameter) is a full 37mm wider then the mirror. I'd hate to mislead you but i think it should only be about 135mm.

Dont take my advice. I'm sure someone else will know better.

[Stargazer Jack]

I didn't believe I was correct but just wanted to see how to work it ok however it doesn't matter too much now. Thank you for the help

[kharga]

Measure round the outside and divide by pi. Simple!

[Stargazer Jack]

Thanks

[LukeSkywatcher]

If FLO sell them for a 130mm scope (and they do) then thats the one for you.

[Stargazer Jack]

Yep, found the one that says 130/130M and I have the 130M so I presume that is the one I want