#21  
Old 01-12-2018, 02:59 PM
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RickS (Rick)
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Much easier to read than the standard bahtinov, less interference in the middle. So what does the final mask look like? Got a pic? Is that the red one? I'm thinking there is a use for this as well for a larger aperture at longish FL and only medium to low brightness stars in the fov. Saves a trip back and forth to a bright star nearby off field.
Here's a couple of pics of the negative Y mask, Marc. Ash (deadsimple) made me a new one with some small tweaks but it has been too cloudy the last couple of nights to try it.
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  #22  
Old 01-12-2018, 03:35 PM
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multiweb (Marc)
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Here's a couple of pics of the negative Y mask, Marc. Ash (deadsimple) made me a new one with some small tweaks but it has been too cloudy the last couple of nights to try it.
oh wow, yeah that won't work, it doesn't let enough light in for me.

Last edited by multiweb; 01-12-2018 at 06:51 PM.
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  #23  
Old 01-12-2018, 06:46 PM
RyanJones
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I like the negative "y" with its clearer core. I wonder what difference it would make if the slots were opened up say double that thickness. As Raymo mentioned earlier, on a larger scale, having the cut outs meet centrally would make it a little unstable. Maybe a common point in the centre is the way to go so the cutouts stop just short of centre ?
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Old 02-12-2018, 04:48 PM
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deadsimple (Ash)
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Maybe a common point in the centre is the way to go so the cutouts stop just short of centre ?
I've been thinking about that. I wonder if it'll remove some of the the core glow, so that the intersection of the lines is easier to distinguish?

The next version in the pipeline ... (see attached).
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Old 02-12-2018, 11:46 PM
RyanJones
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Keep refining the idea Ash and you'll have at least one customer

I don't have the equipment you have to create the ideas but I'm loving the bouncing around of ideas
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  #26  
Old 01-01-2019, 07:57 PM
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Here's a shootout between a Bahtinov mask and two different versions that Ash 3D printed. 2 second subs with a 3nm Ha filter, Borg 55FL f/3.6 scope and ASI1600mm Pro camera.
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  #27  
Old 01-01-2019, 09:15 PM
raymo
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I have never seen the horizontal lines displayed by the Bahtinov with any
of the three Bahtinovs I have owned. Maybe it is to do with the scope being very fast[f/3.6], or maybe the Ha filter. I'm speculating that a positive Y
would be better; I imagine that you'd have to use a pretty bright star with the negative one.
raymo
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  #28  
Old 01-01-2019, 09:49 PM
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Hi raymo,

We tried a positive Y earlier and I didn't like it much. Too much energy in the central blob and not much in the lines.

It doesn't matter too much what sort of mask you use. The 55FL needs a bright star and/or a long sub to show much of a pattern with the Ha filter.

Cheers,
Rick.
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