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Author Topic: Bahtinov mask generator  (Read 28351 times)

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Offline Psychobilly

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Re: Bahtinov mask generator
« Reply #75 on: 18:03:03, 20 January, 2009 »
I had a load of different designs laser cut before christmas and posted them out to quite a few of the active imagers on another forum  for them to try  Biggest I had made was 14"... Even though some of them were a little sceptical they all found them to work really well with the results being confirmed by FWHM measurement is various analysis packages..

One of manufacturing costs will likely to be quoted quite high... because of the hassle factor... plus fixed cost of programing etc are the same if your making one or hundreds...


I can do all the cad work for the company that makes them for me so it takes no time at all for them to transfer designs to the machines for manufacture... the laser took 12 hours to produce a lot of masks...

Altair Astro are going to be selling Kendrik "Pavel" approved mask fairly soon...









And the biggest I have been asked to price to date... for a 36" Refractor....





Billy...






Nr Swansea UK

Scopes CPC800XLT , WO Megrez 72, ETX 105EC

DSLR's  Modded Canon 350d, Nikon D200 & D50 , KM 5D

CCD's   LPI, Philips 840k and SPC900 , DSI I C and DSI II C

Celestron  f6.3Meade F3.3 Reducer William Optic FF III

Hutech, Lumicon and Meade Filters

Offline Dangerous_Dave

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Re: Bahtinov mask generator
« Reply #76 on: 14:44:23, 21 January, 2009 »
Dave in answer to your question,I came across this on the ice in space forum


Thanks Roy. I think I would be reducing the number of bars on mine though, I can't imagine trying to cut that many strips out of laser-printer acetate!
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline Psychobilly

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Re: Bahtinov mask generator
« Reply #77 on: 18:06:56, 21 January, 2009 »
If you print a black mask on acetate you dont have to cut anything out....

Billy...
Nr Swansea UK

Scopes CPC800XLT , WO Megrez 72, ETX 105EC

DSLR's  Modded Canon 350d, Nikon D200 & D50 , KM 5D

CCD's   LPI, Philips 840k and SPC900 , DSI I C and DSI II C

Celestron  f6.3Meade F3.3 Reducer William Optic FF III

Hutech, Lumicon and Meade Filters

Offline Dangerous_Dave

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Re: Bahtinov mask generator
« Reply #78 on: 16:14:00, 22 January, 2009 »
If you print a black mask on acetate you dont have to cut anything out....

Billy...


I tried it, the dark parts were too transparent (single sheet) or the clear parts were too opaque (several sheets stuck together).
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline Psychobilly

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Re: Bahtinov mask generator
« Reply #79 on: 08:31:59, 23 January, 2009 »
Burger....

As I was thinking of using that method for making masks for shorter length SLR lenses :(

Oh well time to push the laser cutter button again then...



Nr Swansea UK

Scopes CPC800XLT , WO Megrez 72, ETX 105EC

DSLR's  Modded Canon 350d, Nikon D200 & D50 , KM 5D

CCD's   LPI, Philips 840k and SPC900 , DSI I C and DSI II C

Celestron  f6.3Meade F3.3 Reducer William Optic FF III

Hutech, Lumicon and Meade Filters

Offline petevasey

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Re: Bahtinov mask generator
« Reply #80 on: 10:45:14, 23 January, 2009 »
If you print a black mask on acetate you dont have to cut anything out....

Billy...


I tried it, the dark parts were too transparent (single sheet) or the clear parts were too opaque (several sheets stuck together).


Maybe you could overprint it a couple of times to increase the ink density - the printer should be accurate enough if the feed tray is properly set up.

But doesn't the presence of the acetate film in the light path affect the focus, albeit only slightly?

Cheers,  Peter.
Telescopes: GSO RC10 Truss, Meade S5000 127, TMB 105, TS65 Quad, Solarscope SV50
Binoculars: Canon 15x50 IS
Camera lenses: Canon 400L f5.6, Canon 70-200L f4 zoom, various old M42 thread
Cameras: QSI 683wsg, SX AO, LodestarX2, Artemis285, Canon 350D (modded), Canon 700D, GPCAM2 (colour), GPCAM2 (mono), LE Vesta Pro, Toucam.
Mounts:  Gemini G41 with Pulsar controller. EQ6 Pro, EQ3-2 with Autostar. Star Adventurer
Observatory: 8' Astronomydome

Offline RobH

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Re: Bahtinov mask generator
« Reply #81 on: 16:33:56, 23 January, 2009 »
Billy made masks for my 14 inch, and my 80mm.
I tested them thoroughly and now use them exclusively for focussing. They are every bit as accurate as the FWHM method in Maxim, and many times faster to use.
Cheers
Rob
Lots of kit in a big green shed.

Offline Psychobilly

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Re: Bahtinov mask generator
« Reply #82 on: 10:53:07, 24 January, 2009 »
Apologies to the forum - I'm not advertising....

Billy...
Nr Swansea UK

Scopes CPC800XLT , WO Megrez 72, ETX 105EC

DSLR's  Modded Canon 350d, Nikon D200 & D50 , KM 5D

CCD's   LPI, Philips 840k and SPC900 , DSI I C and DSI II C

Celestron  f6.3Meade F3.3 Reducer William Optic FF III

Hutech, Lumicon and Meade Filters

Offline Dangerous_Dave

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Re: Bahtinov mask generator
« Reply #83 on: 21:51:18, 24 January, 2009 »
If you print a black mask on acetate you dont have to cut anything out....

Billy...


I tried it, the dark parts were too transparent (single sheet) or the clear parts were too opaque (several sheets stuck together).


Maybe you could overprint it a couple of times to increase the ink density - the printer should be accurate enough if the feed tray is properly set up.

But doesn't the presence of the acetate film in the light path affect the focus, albeit only slightly?

Cheers,  Peter.


Thanks Peter. Unfortunately I tried overprinting too but it seemed to be a fraction of a mililmetre out every time I printed it. I suppose a better printer might have allowed more accuracy but I was at work looking over my shoulder at the time.  :embarrass:

I think the laser printer acetates were slightly matte too, which affected their opacity - even before I started with the spray mount.  :laugh:
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline swashy

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Re: Bahtinov mask generator
« Reply #84 on: 22:00:16, 24 January, 2009 »
Dave, if you adjust the settings in the generator and have fewer bars it will probably be OK, then just scalpel out the clear bits of the printed transparency and black the rest up with a permenant marker

It would be interesting to see just how few bars you actually need for this to still work well
Ade

Imagine...  above us only sky!

Offline Dangerous_Dave

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Re: Bahtinov mask generator
« Reply #85 on: 22:03:51, 24 January, 2009 »
Dave, if you adjust the settings in the generator and have fewer bars it will probably be OK, then just scalpel out the clear bits of the printed transparency and black the rest up with a permenant marker

It would be interesting to see just how few bars you actually need for this to still work well

Ade, thanks - that is more or less what I did. I reduced the bars, printed off half a dozen, aligned them and stuck them together with spray mount then cut out the clear slots with a craft knife. I've been using it for a couple of months now to good effect.

D
EQ6 Skyscan, Vixen GP, WO Megrez 90FD, WO Megrez 72FD, Vixen R200SS, SXV-H16, Modified EOS 20D, DMK 21AU04.

Dave's pics

Offline afm038

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Re: Bahtinov mask generator
« Reply #86 on: 21:55:01, 18 March, 2009 »
Just to let you folks know that I've tried out the masks that Peter (pyschobilly) produced for me and they do exactly what it says on the tin.  :urock:

I found that focusing was easy and accurate on stars down to mag. 4+ and the focussing sequence looked just like the photos I've seen on how they work.

Well pleased.

Many thanks to Peter for these,

Andy

 

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