Big C11 options....
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Big C11 options....
Right, I know a guy with an 11” SCT who is bored of imaging the planets…. Didn't think he could observe the sun with it. I mentioned Baader foil and then we got thinking. So for white light some ND3 imaging baader foil over the front and a narrow filter… continuum of maybe a NIR filter to help improve the seeing… Should do quite well on the granulation.
The scope is native f10… Which is the same as the PST, so would it be possible to put a PST mod into the back of the scope (again with baader nd3 foil on the front) and do hydrogen alpha? Wonder if there Is enough focus in travel and not sure where you would put the ERF to reject the out of band wavelengths, maybe with the baader film you could just use a few stacked 2” filters.
Calcium ought to be possible the same way with baader foil taking the light levels down a safe level for a lunt cak filter on its own that then would give the narrow line width necessary.
Comments, experience please. Wondering if you could find some lower ND foil to keep the exposure times down for high magnification viewing.
Cheers
PEterW
The scope is native f10… Which is the same as the PST, so would it be possible to put a PST mod into the back of the scope (again with baader nd3 foil on the front) and do hydrogen alpha? Wonder if there Is enough focus in travel and not sure where you would put the ERF to reject the out of band wavelengths, maybe with the baader film you could just use a few stacked 2” filters.
Calcium ought to be possible the same way with baader foil taking the light levels down a safe level for a lunt cak filter on its own that then would give the narrow line width necessary.
Comments, experience please. Wondering if you could find some lower ND foil to keep the exposure times down for high magnification viewing.
Cheers
PEterW
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Re: Big C11 options....
No free lunch. He wants too much for a few cents. It need full aperture ERF or D-ERF = thousands $$$$PEterW wrote:Right, I know a guy with an 11” SCT who is bored of imaging the planets…. Didn't think he could observe the sun with it. I mentioned Baader foil and then we got thinking. So for white light some ND3 imaging baader foil over the front and a narrow filter… continuum of maybe a NIR filter to help improve the seeing… Should do quite well on the granulation.
The scope is native f10… Which is the same as the PST, so would it be possible to put a PST mod into the back of the scope (again with baader nd3 foil on the front) and do hydrogen alpha? Wonder if there Is enough focus in travel and not sure where you would put the ERF to reject the out of band wavelengths, maybe with the baader film you could just use a few stacked 2” filters.
Calcium ought to be possible the same way with baader foil taking the light levels down a safe level for a lunt cak filter on its own that then would give the narrow line width necessary.
Comments, experience please. Wondering if you could find some lower ND foil to keep the exposure times down for high magnification viewing.
Cheers
PEterW
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Re: Big C11 options....
You wont get enough light through like Valery says. Also, the SCT is a compound optical system, and while the overall EFR is f10, the focal ratio of the secondary is somewhere between f3 and f4 - not the same light cone for the optics in the PST etalon...
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Re: Big C11 options....
Mark,marktownley wrote:You wont get enough light through like Valery says. Also, the SCT is a compound optical system, and while the overall EFR is f10, the focal ratio of the secondary is somewhere between f3 and f4 - not the same light cone for the optics in the PST etalon...
The PST etalon will work with the final F/D of the SCT F/10. Perfect match. The only two problems:
1. Full aperture, good optical quality ERF filter.
2. very small field of view with PST etalon - about 1/10 solar diameter, not more.
BTW. If that guy with C11 is so much interested in H-a imaging through C11 (will be a leader in the size of the instrument in the amateur H-a imaging community) he can contact me and we can make such a full aperture filter for him. Four samples are in the progress now.
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Re: Big C11 options....
Your PSF will be quite weird with those aperture.
Note also that SCT are very poor in UV.
Note also that SCT are very poor in UV.
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Re: Big C11 options....
Not so catastrophically, as one may think. Can be corrected easily with SAFIX.fjabet wrote: Note also that SCT are very poor in UV.
Last edited by Valery on Mon Mar 30, 2015 11:54 am, edited 1 time in total.
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Re: Big C11 options....
Indeed aperture would be strange, but could it works?fjabet wrote:Your PSF will be quite weird with those aperture.
Note also that SCT are very poor in UV.
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Re: Big C11 options....
It's easy to test that solution on the polar or Jupiter with holes on paperboard If it's OK then we can test on the sun with 4 or 5 (100-150mm) erf on a 400mmDSobserver wrote:Indeed aperture would be strange, but could it works?fjabet wrote:Your PSF will be quite weird with those aperture.
Note also that SCT are very poor in UV.
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Re: Big C11 options....
If you don't mind I'll try first on my C11zorgdotnl wrote:It's easy to test that solution on the polar or Jupiter with holes on paperboard If it's OK then we can test on the sun with 4 or 5 (100-150mm) erf on a 400mmDSobserver wrote:Indeed aperture would be strange, but could it works?fjabet wrote:Your PSF will be quite weird with those aperture.
Note also that SCT are very poor in UV.
Re: Big C11 options....
You will gain resolution only on the ERF axis, and it'd better be symmetrical.
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Re: Big C11 options....
Not sure to understand it correctly....fjabet wrote:You will gain resolution only on the ERF axis
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Re: Big C11 options....
Well I think that C.viladrich already more or less answered to my question....
http://www.cloudynights.com/topic/49178 ... ?p=6460933
http://www.cloudynights.com/topic/49178 ... ?p=6460933
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Re: Big C11 options....
Re the UV with SCT's....
I regularly use the C11 with the Spectra-L200 (with ATiK 314L) for spectroscopy and can image spectra well below 4000A
The attached is a spectrum of Sirius down to 3700A
I regularly use the C11 with the Spectra-L200 (with ATiK 314L) for spectroscopy and can image spectra well below 4000A
The attached is a spectrum of Sirius down to 3700A
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Re: Big C11 options....
Hi Ken
a very fine plot
a very fine plot
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Re: Big C11 options....
Very interesting post.. no way to put the ERF between the primary and the secondary? Too much heat trapped in the tube?
The ERF reflects the heat, this couldn't be directed outside by tilting the ERF ?
just my imagination..
The ERF reflects the heat, this couldn't be directed outside by tilting the ERF ?
just my imagination..
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Re: Big C11 options....
Yes, but bear in mind all that heat makes the air warm in the tube and that is what causes the problem...Marcello wrote:Very interesting post.. no way to put the ERF between the primary and the secondary? Too much heat trapped in the tube?
The ERF reflects the heat, this couldn't be directed outside by tilting the ERF ?
just my imagination..
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Re: Big C11 options....
As it's cloudy, I made some simulations, with a closer spacing than C. viladrich. It's promising resolution wise, even the first ring is interesting.DSobserver wrote:Well I think that C.viladrich already more or less answered to my question....
http://www.cloudynights.com/topic/49178 ... ?p=6460933
Ready to try with 4 erf or 4 FP?
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Re: Big C11 options....
But excuse me, probably i' have not understand.
How you would make it closer if you have a central obstruction coming from the secondary ?
How you would make it closer if you have a central obstruction coming from the secondary ?
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Re: Big C11 options....
+1dellecavet wrote:But excuse my, probably i' have not understand.
How you would make it closer if you have a central obstruction coming from the secondary ?
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Re: Big C11 options....
With the pattern simulated, central obstruction is (2-sqrt(2))/(2+sqrt(2))=17% (if my maths are correct), it would fit tight a newton Sorry for Cats
5 or 6 holes version for cats?
5 or 6 holes version for cats?
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Re: Big C11 options....
5 please!zorgdotnl wrote:With the pattern simulated, central obstruction is (2-sqrt(2))/(2+sqrt(2))=17% (if my maths are correct), it would fit tight a newton Sorry for Cats
5 or 6 holes version for cats?
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Re: Big C11 options....
It looks quite good with 5 holes (obstruction is 26%, small diameter is 37% full one), here it is:
The 6 holes version (obstruction is 33%, small diameter hole is 33% the full one):
It seems that with odd number of holes, less energy is poiled on the rings, so contrast should be better.
The 6 holes version (obstruction is 33%, small diameter hole is 33% the full one):
It seems that with odd number of holes, less energy is poiled on the rings, so contrast should be better.
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Re: Big C11 options....
Would it make sense to use 2" Baader CCD Filter red as a front erf
followed by a 2" KG3 UV/IR from beloptik before a Ha system like PST or quark?
Like this, changing the red front filter to blue one, we can move change from Ha with a PST to Cak with Lunt Cak filter.
Would this cheap idea intelligent and safe for a C11 SCT????
followed by a 2" KG3 UV/IR from beloptik before a Ha system like PST or quark?
Like this, changing the red front filter to blue one, we can move change from Ha with a PST to Cak with Lunt Cak filter.
Would this cheap idea intelligent and safe for a C11 SCT????
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Re: Big C11 options....
It will work such as simulated in the case you place all small filters perfectly parallel. Otherwise there will be no single imagezorgdotnl wrote:It looks quite good with 5 holes (obstruction is 26%, small diameter is 37% full one), here it is:
and no correct interference to create such a single image. Or there must be no glass in the holes.
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Re: Big C11 options....
+1 with Valery.
Stuff from the same batch.
I did some biblio. Here are some interesting simulations optimizing the sub apertures diameters, and relative positions (the 4 subs is interesting) I will run the psf on them when clouds come back
I think DSobserver will have some stuff to test on his C11
http://laurent.mugnier.free.fr/publis/M ... SAA-96.pdf
Stuff from the same batch.
I did some biblio. Here are some interesting simulations optimizing the sub apertures diameters, and relative positions (the 4 subs is interesting) I will run the psf on them when clouds come back
I think DSobserver will have some stuff to test on his C11
http://laurent.mugnier.free.fr/publis/M ... SAA-96.pdf
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Re: Big C11 options....
Zorg
can you make a last simulation for a 200mm SCT using 5 and 7 2" IR cut filters like baader or astronomik one's?
Anyone against this idea if before eyepiece I place an last KG3 filter from beloptic for security reason?
can you make a last simulation for a 200mm SCT using 5 and 7 2" IR cut filters like baader or astronomik one's?
Anyone against this idea if before eyepiece I place an last KG3 filter from beloptic for security reason?
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Re: Big C11 options....
Some very interesting references if you want some clues about optimizing positions/sub apertures:
http://www.rop.cnrs.fr/IMG/pdf/F_Cassaing.pdf
https://tel.archives-ouvertes.fr/tel-00140049/document
I did the simulations: The five is still better
http://www.rop.cnrs.fr/IMG/pdf/F_Cassaing.pdf
https://tel.archives-ouvertes.fr/tel-00140049/document
I did the simulations: The five is still better
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Re: Big C11 options....
Hi loic
that looks good
that looks good
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Re: Big C11 options....
hello during our last french solar meeting we had the opportunity to try this new mod on a C8 SCT using x3 2" UV/IR cut baader filter on a home made mask :
We placed a pst body on its back protected by an other UV/IR cut filter (just in case):
Previous night, star test show exactly the results mentioned by zorgdotnl (that you can see on previous picture )
Before placing our eyes we check that the 3 UV/IR cut filter were good enough to block IR filters : placing our hands on focus point we couldn't suffer any burning feeling.
The results on the sun were really interesting and we could get the focus.
I'll post some pictures as soon as possible....
We placed a pst body on its back protected by an other UV/IR cut filter (just in case):
Previous night, star test show exactly the results mentioned by zorgdotnl (that you can see on previous picture )
Before placing our eyes we check that the 3 UV/IR cut filter were good enough to block IR filters : placing our hands on focus point we couldn't suffer any burning feeling.
The results on the sun were really interesting and we could get the focus.
I'll post some pictures as soon as possible....
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Re: Big C11 options....
Hi Vincent
that looks great
that looks great
Only stardust in the wind, some fine and some less fine scopes, filters and adapters as well. Switzerland 47 N, 9 E, in the heart of EUROPE
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