Bahtinov Mask for 5 Euro

I have just completed my first Bahtinov Mask. I eventually found a suitable material in Easons. I used the plastic covers from a "poly" pocket folder and a craft knife to make it. The material is thick enough to withstand constant use and just about easy enough to cut through with a craft knife. This one is for my 8" newt, I have printed templates for my 4" refractor and one for my 300mm APO lens, though this will be a tough one to cut out as the aperature is only 58mm and as a result the pattern is very small and fiddly. However, all three masks will only have cost 5 Euro to produce, plus some blood and much cursing as I cut my fingers a number of times. Just got to wait now for the next clear night to test this out, and hopefully some of the guess work will be gone from focusing the camera.


Regards,
John Murphy
www.flickr.com/photos/jcmurphy

Hey John, If I throw ye a fiver will you make me one??

Will ye make me one for a 16in Dob John??

All joking aside, I've been reading about these for months now, It'll be nice to get a chance to actually see one in action so to speak.

Can I ask you a question about the material though. Do you think its stiff enough to make a dew/lightshield out of? I'd be flocking the inside surface and putting vinyl wrap on the outside surface. How big is the largest single piece from the 'poly' pocket folder - ?inches x ?inches

I was going to approach a plastics company for a kydex like material but unless I could salvage some from a skip outside their premises, I imagine I'd be asked to fork out 50 or 60 euro for a sheet measured in feet!!

This poly pocket material looks perfect if its stiff enough and a damn sight cheaper even if I have to buy 2 or 3 and glue them together. Might even have enough left over for my own 16" bahtinov mask

Easons on O'Connell street was it?

Any Easons should do them I got mine in the Square. Size of the material is a real drawback. As the folder is designed to contain A4 sheets in poly pockets the covers only measure just over 9" * 12" - so the largest Mask is likely to just fit an 8" aperature. However you do get a front and back cover on each folder. The material is rigid enough for use as a mask, but is flexible if you wanted to use it for a dewshield - the size though is the issue, and it doesn't seem to be the type of plastic that'll take glue easily.

James - Once I've got the rest of mine done I'm never going to look at a craft knife again. 39 holes to cut for each mask, and each cut has to be done over and over till you get through the plastic. I did it in 2 nights just to stay sane, and have some fingers left. The mask for my 300mm camera lens is going to take a long time because it will be so fiddly, but this is the unit that I need it most for so it'll be worthwhile.

Next step is to find a neat way of fitting it to the telescope. I'm thinking of using a foam rubber ring which would hold it tightly in place and my next step is to find a suitable piece, I'm sure I can find something in Woodies in the plumbing section - you know the foam rubber pipe insulation?

Can you post a link to the pattern please?

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