Revolutionary new way of focusing! No less!
Posted 10 September 2008 - 08:25 PM
Would the spider veins play havoc with this method?
Posted 10 September 2008 - 08:31 PM
Posted 10 September 2008 - 08:40 PM
As someone else posted you will still see some diffraction spiking from the spider but the Bahtinov Mask diffraction spikes should still be very easy to see for focusing. You will just have some extras in there.
Thanks Adam. I should have looked closer to the other posts to find my answer. I must have put isramirez to sleep. Not sure that was most polite way of comming across, but anyway...
I'll look up the program to download the scaled template.
Posted 10 September 2008 - 08:52 PM
I think isramirez is asleep waiting for his skies to clear up. The poor guy has an awesome Bahtinov Mask to use but no clear skies to use it on.
Posted 10 September 2008 - 09:28 PM
Posted 10 September 2008 - 09:47 PM
Do you suppose it would be possible to establish a PayPal Donation account for Pavel Bahtinov?
I'd certainly contribute as I'm sure many others here would...
Just a thought.
Posted 10 September 2008 - 10:56 PM
Posted 10 September 2008 - 10:59 PM
I think you can contact him, here's his account page with e-mail from the Russian forum
We didn't have any luck with his email directly. Not sure if it was a firewall or what - Jerry finally signed up on his forum and translated everything into Russian! Very creative!
Posted 10 September 2008 - 11:09 PM
but you probably have to register for that. Or post a message in the thread about the mask itself http://www.astronomy...index.php/topic,10421.300.html I don't think there will be a problem understanding English. Understanding what those automatic translators write might be harder.
Posted 10 September 2008 - 11:11 PM
Posted 10 September 2008 - 11:23 PM
Put in the numbers, press "submit" and voila, an SVG file appears scaled to the rules I found perusing the thread.
The *big* caveat (other caveats appear on the page) is that I haven't actually tested the results. The second biggest caveat is that while Inkscape *displays* the resulting SVG perfectly, it doesn't *print* it worth a darn. Apparently there are some Inkscape print bugs.
I did actually print a couple from Firefox, and they seemed to be scaled perfectly, but what do I know (see big caveat, above).
You might have to tweak what I call the "Bahtinov Factor" in order to get the lines on the left to show up where they should (i.e., with a gap in the middle), but I don't know if that's super critical.
If you see any issues, or have any suggestions, either PM me here or drop me a line at the e-mail address on that page.
Note, however, that I'm going away Friday morning for a romantic weekend with the wife - no computer (and, sadly, no scopes - tho I might try to sneak the binoculars into the car), so I won't be able to respond for a couple of days.
Posted 11 September 2008 - 12:35 AM
That is such a seriously cool little generator you made! Can you have a variable to adjust the right side's line angle? Also, can you group the sections together so the 90 degree slits can be unblocked (as the right sides are) so they can be centered more easily?
Posted 11 September 2008 - 12:52 AM
Posted 11 September 2008 - 01:49 AM
I sent Pavel a message asking him for a permission to use his design for commercial purposes. He has no objections on using the mask for any purposes, including commercial production. As for royalties, he leaves that to producers If you think you can and want - feel free to do so. His only condition is that you have to mention that the mask was invented by him. "Bahtinov Mask" sounds good, and it is also widely used in Russian speaking forums.
John, I also asked him about your e-mail. He said that it was lost in his Spam folder. Seems like he found it now.
Posted 11 September 2008 - 03:24 AM
Posted 11 September 2008 - 07:12 AM
Mert- Your horizontal cuts should start in the center axis and mirror out. I think the odd spacing of the cutouts will make the diffraction spikes wide. they still will be in the center if the axis is centered, but may be too wide to see a clear difference between the angled and straight spikes.
Thanks Jerry for pointing this out, I was out last
night trying the mask I posted.
Never had such a good focus, soo easy and clear in soo
little time, though the spikes were not so clear as
you pointed out!
Still I got FWHM of 2" which is unknown for me
in the area where I live, with the eyes I have to focus.
I will make more masks to try out different setups before
making the final one.
Thanks and regards,
Posted 11 September 2008 - 08:09 AM
I have seen several nice images from Spain. FWHM of 2 is not too bad. That is about all I get here. Once on a very good night I was able to get 1.6.
Posted 11 September 2008 - 09:02 AM
Does this look right? I used 315mm for my clear apeture, 85mm for the central obstuction, 1500mm for the focal length, 100 for the Bahtinov factor, 10 for the angled stripe count, and -1 for the angled stripe offset.
Well after I did the first design I thought about what you guys meant by "clear apeture" so I decided to measure the inner opening of my newt, and it came out to 339mm so I redesigned the Mask with those numbers, and came up with this...
Does it look right?
Posted 11 September 2008 - 11:38 AM
Now, the news: The new and improved Bahtinov Mask Generator version 0.2!
Here's a list of changes - I think this will address everyone's issues.
- Greatly simplified the generated SVG - seems to fix the Inkscape printing issues, as well as letting Adam adjust the left cutouts. See next item.
- Horizontal stripes now start with a cutout on the center line - since apparently this *is* important.
- Added parameter for controlling number of horizontal cutouts.
- Decoupled the structural bar thickness from edge thickness; added a parameter for specifying the thickness of the structural bars (the up/down and left/right bars).
- Added optional "center line" crosshairs for alignment/testing purposes.
- Elimated "bumps" on outside of circle at the intersection with the structural bars.
- Fixed the background/fill colors so they work completely.
- I changed "Submit" to "Generate!" because I thought it was more exciting that way.
- Decoupled the margin from the edge thickness; added a parameters for left and top margins. Width and height are now calculated as aperture + (2 * edge thickness) + (2 * appropriate margin).
- Added a parameter for the angle of the angled cutouts.
Let me know...
Posted 11 September 2008 - 12:38 PM
Posted 11 September 2008 - 01:55 PM