OK the quote to have 8 variable sized masks cut out of 304 grade Stainless steel will cost $192.50 making them on average $24.06 each for this batch. Obviously the larger ones would be dearer normally. I think this is excellent value for money - and an economical way of getting a decent focus mask. Many thanks to Dennis for his help and the input of everyone who posted advice. and see post 197 for the CAD dxf file
I have ordered them and will have them next week - enough time to spray one side matt black and add felt to it before IISAC.
In your order, can you include one for my 12"? And maybe one for my ED80 too?
Do you need the OD of my tube?
My scopes and Dennis's focus masks are already ordered - so that job is currently being done. I see no reason why a seperate quote cannot be done - just need to draw up the plate mask - need the tube diameter so that it can sit in/on the tube and the centre obstruction diameter. Can submit the order to C and J Sheetmetal, I have included the quote that I got for reference.
Ok I picked up my masks today, and Dennis's. they look rough but very promising they are not flimsy, are tough - i dropped my ed80 a few times to see how it would go - no worries the bigger ones might deflect wit ha lot of force behind it - but will not break, are not flimsy, and hold their shape rather well. I need to get some felt now – and flat black paint. Looking good!!!!
For those who made inquiries they charge minimum $35 dollars each for the ED80 and 127ED size for those as they are one off’s and require to be set up. I bought mine in a job lot – hence the cheaper price. I have provided the CAD file of what I have and the contact details for the company, and how much they are minimum for single one off’s. it is up to you what you do – I will not be acting as a go between.
They look great – thanks heaps for including my masks with your order, I really appreciate your efforts in drawing them up and placing the order. Just let me know how much and I’ll transfer the funds.
Did a small experiment last night after spending some time cutting out a Bahtinov mask from a template. I just printed out Davids template onto a piece of very clear and uniform acetate sheet used for making overhead slides/presentations and stuck it onto the front of my scope theorising that you are just looking for a diffraction pattern and not resolution.
Worked perfectly, thus no need for tedious cutting out. Might be worthwhile for those of use not allowed to play with sharp instruments even with supervision
Woohoo, my x3 Bahtinov Masks arrived today, care of Mr H0ughy and Australia Post. Now all I need to do is prime them, spray them with flat black and make the closed cell foam fittings for the various OTA’s.
Needless to say, the weather forecast is cloud and rain for the next few days….
Thanks heaps Dave – the masks look really well made and if I had two of the smaller ones, I would even consider getting my ears pierced so I could wear them as a set of uniquely designed, ornate, ethnic looking earrings!
Did a small experiment last night after spending some time cutting out a Bahtinov mask from a template. I just printed out Davids template onto a piece of very clear and uniform acetate sheet used for making overhead slides/presentations and stuck it onto the front of my scope theorising that you are just looking for a diffraction pattern and not resolution.
Worked perfectly, thus no need for tedious cutting out. Might be worthwhile for those of use not allowed to play with sharp instruments even with supervision
Hi Allan
Arguably, if the plastic film is thin, taught and uniform, it should not affect focus when placed at the objective end of the ‘scope as the light rays are parallel there?
It’s only at the eyepiece end where the rays are converging that you will affect focus by placing e.g. glass filters in the optical train.
I did use an uncut, inkjet printed overhead transparency for my 1st prototype and it did produce quite a messy and horrible looking diffraction pattern, even with the A4 film glued to a foam collar placed over the end of the OTA.
When I’ve finished assembling my stainless steel masks, I’ll run some tests to compare the results with a non cut-out transparency, a cut-out transparency and the S/S masks just to see the differences, if any.
Woohoo, my x3 Bahtinov Masks arrived today, care of Mr H0ughy and Australia Post. Now all I need to do is prime them, spray them with flat black and make the closed cell foam fittings for the various OTA’s.
Needless to say, the weather forecast is cloud and rain for the next few days….
Thanks heaps Dave – the masks look really well made and if I had two of the smaller ones, I would even consider getting my ears pierced so I could wear them as a set of uniquely designed, ornate, ethnic looking earrings!
Cheers
Dennis
Hip suave and sophisticated – Big D you are perhaps focussed in the wrong direction…. is the fact you got some new gear today the reason you have storms and rain at the moment?
Hi Dennis,
Only recently did I discover this amazing thread.
After working my way through the whole thread and upon completion and testing of my first prototype of the Bahtinov Mask I felt compelled to add my comments to your thread.
Firstly thanks so much for introducing the topic to IIS.
What a pioneer this Pavel Bahtinov is and just how significant is his contribution to amateur astronomy.
In my humble opinion this is one of the greatest innovations that I have seen in amateur astronomy and rates right up there with the Telrad, Dob and Surrier truss. Surely there must be some sort of design award that this must qualify for.
My prototype is for my 16" F4.5 Eq mounted Newt. I used light cardboard, with the outer rim reinforced with a heavier cardboard ring. I applied the formula to my specific scope, spent hours very accurately marking it out then cut it out using a machined steel rule and a very sharp blade.
I designed and built my own secondary mount and it utilizes a central piece of studding that protrudes out past the end of the telescope tube. I was able to punch a matching central hole in the mask and will reinforce that area of the mask. The mask slips nicely over that studding which locates the mask quite well.
Obviously I have read the thread and taken note of the results that you all have been getting but there is nothing like experiencing it for your self. I have a JMI motofucus on my scope and spent about an hour running it in and out of focus, watching the central line moving up and down is a special thing, even dragged my better half and rug rat down to my observatory to check it out.
Could not believe just how crisp the lines of the diffraction pattern appeared.
All in all a most memorable experience and will be a boon for astrophotography.
Pavel Bahtiov take a bow and thanks again Dennis for making all on IIS aware of this stunning advance for amateur astronomy.
I find it quite inspirational that even in this era dominated by sophisticated, expensive, high-tech equipment, such a relatively simple and passive focusing aid like the Bahtinov Mask, has had such an impact on our hobby.
Pavel Bahtinov’s remarkable contribution to achieving perfect focus, with such accuracy and ease, through the use of such a simple tool, will surely go down in history as one of the most significant advances in amateur astronomy - a brilliant aid to focusing.
I have skimmed this thread -- looked at all the images attached.
I was wondering, if I was to be attempting focus with an ED80 with a William Optics 0.8x field flattener/focal reducer, will I have to buy/make two versions -- one for the native focal length, and one for the reduced focal length -- or will just one suffice for both focal lengths?
Apologies if this has already been definitively answered.
My experience so far has been that my prototype printed mask on A4 transparency (with the gaps cut out with a sharp knife) for my C9.5 has worked at the native focal length of F10, with the Celestron Reducer/Corrector at F6.3 and also using various PowerMates from x2.5 to x4. A similar story for the Mewlon 180 at F12 (native), F9.6 (Reducer/Flattener) and all the way up to F48 with a x4 PowerMate.
For DMK webcams and my Canon 40D, I simply eyeball the focus as the camera control applications I use don’t have a means of measuring focus by e.g. FWHM. However, when using my SBIG ST7E and CCDSoft, I may end up making very small tweaks using a motorised focuser, as CCDSoft (camera control software) has software assisted focusing.
My experience so far has been that my prototype printed mask on A4 transparency (with the gaps cut out with a sharp knife) for my C9.5 has worked at the native focal length of F10, with the Celestron Reducer/Corrector at F6.3 and also using various PowerMates from x2.5 to x4. A similar story for the Mewlon 180 at F12 (native), F9.6 (Reducer/Flattener) and all the way up to F48 with a x4 PowerMate.
For DMK webcams and my Canon 40D, I simply eyeball the focus as the camera control applications I use don’t have a means of measuring focus by e.g. FWHM. However, when using my SBIG ST7E and CCDSoft, I may end up making very small tweaks using a motorised focuser, as CCDSoft (camera control software) has software assisted focusing.
well i painted up my masks today and places clear sticky rubberised feet on them and a stick on handle. will post pictures later as every camera I have has a flat battery at the moment
You didn't order any extra 80ED sized masks, did you?
If we mention your name to the laser cutting mob, do we get a 90% discount?
If I send them the 80ED file that you've created, they'll know what to do with it, aye?
Regards,
Humayun
Quote:
Originally Posted by h0ughy
well i painted up my masks today and places clear sticky rubberised feet on them and a stick on handle. will post pictures later as every camera I have has a flat battery at the moment
they are not flimsy, are tough - i dropped my ed80 a few times to see how it would go - no worries 
the bigger ones might deflect wit ha lot of force behind it - but will not break, are not flimsy, and hold their shape rather well. I need to get some felt now – and flat black paint. Looking good!!!!
is the fact you got some new gear today the reason you have storms and rain at the moment?
