Bhatinov Focus Mask

[G4YVM]

Ah yes, I forgot to divide my 3rd order by 2! Thanks

I'll give it a whirl.

D

[carastro]

If I understand the pdf correctly, I could basically make a usable mask by twisting a couple of pieces of wire together and hooking them over the dewshield? (Where by "twisting together" I mean to create a "Y" shape.)

The idea is that the Y is a "CUT OUT".

Carole

[glowjet]

Carole there has been confusion with this in the past, the Y is a solid letter, not a cut out, although a cut out from a solid disk will work as Mark7331 has proved, I am not really a technical person, but from my reading of Chris Lord`s PDF, Babinet`s principle states that the diffraction pattern produced by a single slit is the same as that produced by a solid bar of the same width, you will have to remember though that a solid disk with a cut out will not allow as much light to enter the scope as with a solid Y, the whole concept of the Bhatinov mask is based round the space and bar principle, but it does reduce the amount of light entering the scope by as much as 1f stop I have read, hope this helps to explain it a little better

John.

[davew]

Here is my version. It's a " No order " mask with 2mm bars and still works.

Bit of plastic, a pair of scissors, two match sticks and five minutes work. Used on all lenses between 50mm and 630mm.

This is the super delux version. The delux is on the scope at the back.

Dave.

[glowjet]

Fantastic Dave, well done that should give some encouragement to the DIY folks among us

John.

[mikeknowle]

Brill discussion guys. I was thinking about a bartinov mask earlier today, but it looks as if a Lord 'Y' is the thing to try. Has it got a proper name yet?

[JamesF]

I think the "Lord Y" is an eminently suitable name.

James

[mikeknowle]

As its only for use on a Primary, it'll be 'Y-Fronts' then...

[MG1]

As its only for use on a Primary, it'll be 'Y-Fronts' then...

LOL....so obvious yet so good!