Thanks for the comparison Dennis.
As I suspected, the same spacings would suffice at different FL on the same scope IMO.
I wouldn't be too fussed and would only make one mask per scope.
I think it would get you to very near perfect focus each time.
Anyway I'm looking forward to making up a mask for my scopes and trying it out with the 20Da.
Should be ok... How do you think it would go for planetary imaging, with say, a 2800mm focal lenght + 5x powermate (lets just assume that we ever get seeing nice enough for that... thats an increase of 12,000mm in focal length or there abouts... Do you think it would still be effective then?
I haven’t investigated the maths behind Pavel’s equation (I cannot read Russian!!). Also, the CN thread doesn’t seem to have gone into any mathematical analysis of the equation in terms of wavelength of light, focal length, diffraction patterns, etc., so I am limited to empirical testing and so far, a single mask seems to have worked within the range that I have experiment with.
I’m not crash hot on the mathematics of diffraction and how different instruments behave so perhaps it is a blessing that I can’t read Russian! LOL!
The x2.5 and x3 Barlow shots required exposures of around 2 seconds IIRC.
I just made up one of these in thin paper from a scaled image in MS Word, with a sharp blade and a steel rule, and it works beautifully, looks like the image of Altair in Dennis' post. Great information
It is (accidentally, I did not really try) optimised for the Skywatcher f1000, being 3 + 3 = 6mm, and the electric focuser I just fitted to it helps a lot as well.
Thanks for that Dennis, this design is doing the rounds on the UK boards at the moment its a brilliant bit of kit. I don't agree tho with whats happening with this company http://www.spike-a.com/
The guy is ripping Pavel off plus NOT even mentioning him as the inventor, this is shameful beyond belief and will only put off people in the future from sharing ideas.
Hi all, I'm new to your forum and would like to explain what is going on with www.spike-a.com
The focus mask was offered because of the interest people had at cloudy nights to have me make them masks. So John helped me by placing the spike-a web site up so people that could not make a mask had somewhere to purchase one. We have attempted to get Pavel to allow the use of his name on the mask. So far we have no response from e-mails. I went to an lawyer to find out what the correct royalty should be and how to send Pavel the credit he deserves. If anyone here speaks Russian, I sure could use the help communicating.
Welcome to Ice In Space and thanks for the details provided.
I do recollect reading one of your posts on CN along the lines of “what a surprise Pavel will get when the Royalties start flowing in” so I figured you were pursuing some kind of arrangement to recognise his contribution!
Are you considering setting up a distribution outlet in Australia?
OK I got the quote back from an Australian Laser Cutting manufacturer (Lightning laser cutting in Victoria), for a 1 off made to test it will cost me $82.50 a pop. Obviously a single one is dear but multiples are a lot cheaper. This is based on a dia 200mm and a central bar of 20mm with 20mm added to the outside, and 250mmm for the larger one. Looked at two different materials – black acrylic and stainless steel 304 grade. I haven’t looked at a way to fit these to the scopes, although a 90degree clip screwed to the template with a plastic screw to attach to the scope did come to mind, or even a Velcro attachment? As didn’t get a quote for the 10mm spacings, as I thought at this stage that was pointless, but I would say it falls between the two. Smaller diameter masks were not looked at yet, but where they are less in material the same setup costs would be involved, so I don’t envisage them to be much cheaper. Postage is not included in these prices, obviously there are economies of scale – so quantities of more than 5 will bring the prices down – but then it all comes back to how much do you value a gadget? For me I think this will be priceless, especially considering all the crap images I have taken off late that are out of focus.
1 Diffusion grating dia 200mm, 5mm slots from 2.0mm black acrylic $82.50
1 Diffusion grating dia 200mm, 5mm slots from 0.8mm SS304 $82.50
1 Diffusion grating dia 250mm, 13mm slots from 2.0mm black acrylic $82.50
1 Diffusion grating dia 250mm, 13mm slots from 0.8mm ss304 $82.50
5 Diffusion grating dia 200mm, 5mm slots from 2.0mm black acrylic $28.60 143.00
5 Diffusion grating dia 200mm, 5mm slots from 0.8mm SS304 $33.00 165.00
5 Diffusion grating dia 250mm, 13mm slots from 2.0mm black acrylic $27.50 137.50
5 Diffusion grating dia 250mm, 13mm slots from 0.8mm ss304 $31.90 159.50
Hi all, I'm new to your forum and would like to explain what is going on with www.spike-a.com
The focus mask was offered because of the interest people had at cloudy nights to have me make them masks. So John helped me by placing the spike-a web site up so people that could not make a mask had somewhere to purchase one. We have attempted to get Pavel to allow the use of his name on the mask. So far we have no response from e-mails. I went to an lawyer to find out what the correct royalty should be and how to send Pavel the credit he deserves. If anyone here speaks Russian, I sure could use the help communicating.
Jerry
Hi Jerry and welcome to IIS. I have read the happenings on CN. No one i know speaks russian, but would a translator like bablefish help?
Before you and others commit to an order, or multiple orders, I would recommend that the team perform a design review to validate the design, dimensions, proofs/templates, materials, fixing methods, anodising, flat black paint finish, etc. to minimise any surprises or glitches.
As a minimum, an independent person(s) should:
Review the measurements to ensure that the calculations have been performed correctly.
Review the proofs/templates prior to submitting them to the cutters to verify that they are correct.
Discuss having tabs or ears included at the outer edge which can then be bent over (SS only) for fitting.
Discuss the finish as SS is a bit too shiny?
Discuss any other issues that may enhance the performance and use of this device.
We have already seen how easy it is to misinterpret the denominator in the range 150 to 200.
As they say, measure twice, cut once.
Cheers
Dennis
Last edited by Dennis; 10-09-2008 at 08:50 AM.
Reason: File attached showing fixing tabs
How do you think it would go for planetary imaging, with say, a 2800mm focal lenght + 5x powermate (lets just assume that we ever get seeing nice enough for that... thats an increase of 12,000mm in focal length or there abouts... Do you think it would still be effective then?
I suspect that the mask 'spacings/gaps' is more a function of the scopes aperture (diameter) and native F.L.
If you design it for a specific aperture it should work within the limits of adding a reasonable 'barlow' to that scope.
What you will notice IMO is different size spikes but using a barlow within reason on the same scope should still yield a usable 'focusing image'.
What I meant when I said multiple masks for multiple F.L's was having to make individual masks for individual scopes with v.different apertures/native FL.
So I believe I'll only need one mask for my 5" and 6" APO and one for my 12" SCT.
All credit goes to Pavel for sharing his design, demonstrating the noble and constructive use of the internet.
Like you I was enthralled by how effective the Bahtinov Mask is when used visually. I must confess, I spent several minutes working through my eyepiece collection, just pushing the motorised focuser buttons and watching through each eyepiece as I cycled through the extra-focal, at focus and intra-focal patterns!
My wife was quite impressed too, although somewhat bewildered at how I could just sit there engrossed in the whole focusing experience thing.
All credit goes to Pavel for sharing his design, demonstrating the noble and constructive use of the internet.
Like you I was enthralled by how effective the Bahtinov Mask is when used visually. I must confess, I spent several minutes working through my eyepiece collection, just pushing the motorised focuser buttons and watching through each eyepiece as I cycled through the extra-focal, at focus and intra-focal patterns!
My wife was quite impressed too, although somewhat bewildered at how I could just sit there engrossed in the whole focusing experience thing.
Cheers
Dennis
nothing like a few playthings to keep one amused for hours - my son can play in the sand pit up the back for hours - and in a cardboard box for longer
Before you and others commit to an order, or multiple orders, I would recommend that the team perform a design review to validate the design, dimensions, proofs/templates, materials, fixing methods, anodising, flat black paint finish, etc. to minimise any surprises or glitches.
As a minimum, an independent person(s) should:
Review the measurements to ensure that the calculations have been performed correctly.
Review the proofs/templates prior to submitting them to the cutters to verify that they are correct.
Discuss having tabs or ears included at the outer edge which can then be bent over (SS only) for fitting.
Discuss the finish as SS is a bit too shiny?
Discuss any other issues that may enhance the performance and use of this device.
We have already seen how easy it is to misinterpret the denominator in the range 150 to 200.
As they say, measure twice, cut once.
Cheers
Dennis
i fully agree Mr Simmons - I haven’t jumped in and ordered anything - just getting a ballpark guesstimate to see whether it could be feasible
I have just knocked up a three triangle hartmann mask from the instructions on the Paul Russell, IIS projects pages and it works like a treat!
I drew it up on a piece of A4 (my scope is only 130mm after all) and then scanned it, painted the white areas black in photoshop, printed, laminated it, cut out the triangles and attached it with velcro to the aperture (I have a ring around the opening for a light shroud using vinyl from Clark rubber)
Focusing is now a complete DODDLE! Woooohooo!
Thanks for the inspiration, I might endeavour to make one of these later on, however the basic three triangle one took me all of 10 minutes and a compass/ruler, no CAD required.
my son can play in the sand pit up the back for hours - and in a cardboard box for longer
Cardboard box….he is lucky…. Well we had it tough. We used to live in a small shoebox in the middle of the road.
We used to have to get up out of the shoebox at twelve o'clock at night, and LICK the road clean with our tongues. We had half a handful of freezing cold gravel, worked twenty-four hours a day at the mill for fourpence every six years.
But you try and tell the young people today that... and they won't believe ya'.
Cardboard box….he is lucky…. Well we had it tough. We used to live in a small shoebox in the middle of the road.
We used to have to get up out of the shoebox at twelve o'clock at night, and LICK the road clean with our tongues. We had half a handful of freezing cold gravel, worked twenty-four hours a day at the mill for fourpence every six years.
But you try and tell the young people today that... and they won't believe ya'.
will looka t the design in detail over the weekend and look at how to attach to scopes - to guage sizes and shape for design. the tab idea might work as for the central bars/circles not too sure on those
Hilarious.
