C8 with GSO Batinov Mask...

[RichieJarvis]

Hi All,

A curious thing.... The Bahtinov mask for the 8" GSO perfectly fits the Celestron C8 I just got....

As the focal length/ratio are completely different, and I thought these masks were very dependent on this, how does this work??

This is through the C8 with a .63 focal reducer, and an Ha filter in the way.

Not that I am complaining

Cheers,

Richie

[Psychobilly]

Looks like your getting lines of bright dots rather than a "continous" bright line so I guess thats the difference between a "Non-optimal" design and a "tuned" one... although the Ha filter would also cause that as its only allowing through a small part of the diffracted spectrum...

Whats the ratio focal length of the GSO and C8.... if its close to an odd number then the "numbers" will work

Never did get round to experimenting with this sort of thing but its all "academic" now

Peter...

[adamsp123]

I have made 2 so far, the one for my 120ED I fiddled about with the input data till I got an easy one to make, ie not too many thin slots to cut out. The one I use on my 10" SNT is a C6 SCT one just printed larger to fit.

Both work fine, I get a dashed line effect but it is still easy to use.

Looks like they just work and as Peter says it is down to optimisation of the pattern but it doesn't bother me that mine are not optimised.

[RichieJarvis]

The clear filter shows nice sharp lines - like this:

[Psychobilly]

Cool

The only difference based on a casual glance is the banding in the lines... but its still perfectly useable

Glad you got clear skies RJ sitting under 90-95% cloud here ... is there an NLC display going on in the N-NW? - theres a distinct glow coming through the small holes...

Peter...

[steppenwolf]

The banding/dots in the lines are the indicators that you are using a non-optimal mask although have noticed that smoother lines are achieved with refractors than with Newtonians.

[Tim]

I have tried this with a C9.25 mask over my GSO. The focus point as found by centralizing the middle line was dead on, just the pattern looked wierd with the Ha filter in place.