Bahtinov Mask help

[jnc71106]

Hi all

I've got a 102mm F/7 frac and I want to get a mask for it but I just want to ask a quick question

I can get a mask for it easily enough but I also have a flattener/reducer for it that takes it down to F/5.6

Would the mask I get for it at F/7 be ok or should I get 2 masks depending on whether I'm using the reduce or not

Jake

[glowjet]

There has been a lot of water passing under the Bhatinov bridge over time, before you spend your hard earned pennies, try a very simple Y mask made out of black plastic strips, for your scope between 3mm to 5mm wide, make the two short arms of the Y 20 degs above and below horizontal making a 40 deg angle, if you have a visual back on your camera all to the good, as you will be able to experiment with your reducer

[Scosmico]

This link is for a bahtinov mark DIY.

http://stargazerslounge.com/diy-astronomer/163426-marmites-contribution-astronomy-focusing-solutions-chap-ii.html