Search found 790 matches

by christian viladrich
Sat Mar 06, 2021 11:16 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: H spectrum tube first light
Replies: 1
Views: 57

Re: H spectrum tube first light

Great ! Keep up posted.
by christian viladrich
Fri Mar 05, 2021 7:54 pm
Forum: This is SolarChat !!
Topic: blocking filter chit chat chop chop - lets cut it out.
Replies: 41
Views: 790

Re: blocking filter chit chat chop chop - lets cut it out.

Excellent results Marty ! Thanks for sharing.This is in agreement with what I've found (with mica-spaced etalons). Just wondering whether who could replace the whole BF by two stacked 1.7 A. You might just need to add an ITF (like Beloptik's one). Well done Apollo. I don't think there is much to gai...
by christian viladrich
Wed Mar 03, 2021 7:01 pm
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Hello Marty, Ok, I see. Then the calculation is completely different since there is no telecentric or collimated beam falling onto the etalon. In the first case, you just have a f/16.67 beam. It means you will have both: - an enlargement of the FWHM (compared to its nominal value) because of the f/1...
by christian viladrich
Wed Mar 03, 2021 5:10 pm
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Hrm, Any help with this? Mica spaced etalon, 21mm aperture (Quark Combo) 60mm aperture F16.67 telescope (1000mm focal length) Sweet spot size and general thoughts? I just rough calced it with n=1.6 and the result was 1.59 degrees approximately? This seems to agree with the graph above? I'm curious ...
by christian viladrich
Wed Mar 03, 2021 5:04 pm
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Hi all... This is quite the read, and need to go over it a few more times. I have a question about the sweet spot ration from the d/D ratio. Does the result, say .2, have any units associated with it or is it 0.2 of the actual field of view, or some other relative detail? Just trying to make sense ...
by christian viladrich
Wed Mar 03, 2021 9:38 am
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Hi all... This is quite the read, and need to go over it a few more times. I have a question about the sweet spot ration from the d/D ratio. Does the result, say .2, have any units associated with it or is it 0.2 of the actual field of view, or some other relative detail? Just trying to make sense ...
by christian viladrich
Tue Mar 02, 2021 5:53 pm
Forum: This is SolarChat !!
Topic: New Sunspots! CaK Sun 2nd March
Replies: 12
Views: 125

Re: New Sunspots! CaK Sun 2nd March

Beautiful FD image Mark !
by christian viladrich
Mon Mar 01, 2021 1:15 pm
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

BTW, there is also a possible combinaison with a double stack Lunt 80 mm internal etalon. I don't remember what is the actual diameter of this etalon.
by christian viladrich
Mon Mar 01, 2021 8:52 am
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Does that sound about right? Yes indeed ! As an example, you might remember Antonello Satta's refractor (not sure of his pseudo here). He made a 150 mm f/10 refractor with an internal Lunt 60 mm etalon. It was a kind of truss tube OTA. This is also the principle at work in the 140/90 mm famous Ha r...
by christian viladrich
Sun Feb 28, 2021 8:58 pm
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Hello Marty, There is a simple rule for internal etalon in collimated beam : - in an "optimal" system, the sweet spot diameter is proportional to the ratio d/D, where d is aperture of the etalon (and collimating lens) and D the aperture of the refractor. Accordingly, the maximum diameter is acheived...
by christian viladrich
Sat Feb 27, 2021 9:56 pm
Forum: This is SolarChat !!
Topic: Solar observation with two old (XIX/early XX century) refractors
Replies: 18
Views: 184

Re: Solar observation with two old (XIX/early XX century) refractors

Beautifull refractors !!

BTW, Pedro I was wondering whether you could put a SSM on top of the water tower we see in the background ? It would be interesting to know the difference of seeing between ground level and up there (8 m high ?).
by christian viladrich
Sat Feb 27, 2021 9:29 am
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Re: Sweet spot, banding and tilted etalons ...where are the limits ?

Very well reported Christian, and this is unfortunately the humpty dumpty story of solar filters! companies will not throw underperforming glass filters in the trash unless there is a severe defect; companies will attempt salvage of the rejects by allowing an extended acceptable tolerance range. Th...
by christian viladrich
Sat Feb 27, 2021 9:21 am
Forum: This is SolarChat !!
Topic: New Setup, New Pier 26th February
Replies: 32
Views: 271

Re: New Setup, New Pier 26th February

This is a very promising start. Congratuations !
by christian viladrich
Fri Feb 26, 2021 7:30 pm
Forum: This is SolarChat !!
Topic: Sun in Ha, CaK and WL 26th Feb 2021
Replies: 8
Views: 69

Re: Sun in Ha, CaK and WL 26th Feb 2021

Nice set of images Stuart, with beautiful processing !
by christian viladrich
Fri Feb 26, 2021 7:26 pm
Forum: This is SolarChat !!
Topic: White Light Herschel/Solar Wedges
Replies: 32
Views: 222

Re: White Light Herschel/Solar Wedges

Hello Pedro,
Clavé helioscopes are collector items. I should have bought them years ago when I was a student. But ... I didn't have enough money ...
by christian viladrich
Fri Feb 26, 2021 7:20 pm
Forum: Solar Scope Modifications
Topic: Sweet spot, banding and tilted etalons ...where are the limits ?
Replies: 49
Views: 626

Sweet spot, banding and tilted etalons ...where are the limits ?

Hi, ************************************************************************************************************************************** To the moderators, I am not quite sure to what section this post belongs to, so feel free to move it in the correct one. ****************************************...
by christian viladrich
Fri Feb 26, 2021 12:30 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Solar Continuum Filter
Replies: 6
Views: 166

Re: Solar Continuum Filter

As explained by Bob, you can take any filter to observe/image the photosphere. As a general rule : - the contrast of granulation increases when going to the blue end of the spectrum, - turbulence increases when going to the blue end of the spectrum, - some refractors have a lower optical quality in ...
by christian viladrich
Fri Feb 26, 2021 10:30 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: Advice requested on Quantum filter purchase
Replies: 56
Views: 2500

Re: Advice requested on Quantum filter purchase

Just wondering whether you could post a larger version of the test report ?
by christian viladrich
Fri Feb 26, 2021 10:22 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Testing a Lunt LS50FHa etalon with a H spectrum tube.
Replies: 14
Views: 428

Re: Testing a Lunt LS50FHa etalon with a H spectrum tube.

Hi Peter, The only measure I know of a Lunt etalon is this one : https://luntsolarsystems.com/were-proud-of-our-etalons/ They say : Specifications: Lunt Solar 50mm Etalon Center Wavelength: 656.28nm Peak Transmission: 79.89% Bandwidth: 0.7 Angstroms (FWHM) R: 12.5 Angstroms https://luntsolarsystems....
by christian viladrich
Thu Feb 25, 2021 8:10 pm
Forum: This is SolarChat !!
Topic: Seeing impact of imaging in a Dome
Replies: 9
Views: 141

Re: Seeing impact of imaging in a Dome

As said by Bob, domes can have good or bad impact of day-time seeing. During the day, the heating of the dome surface will degrade the seeing. A difference of 2°C between the surface of the dome and the ambient air is sufficient to seriously degrade the image quality. You can check this with an IR t...
by christian viladrich
Thu Feb 25, 2021 7:54 pm
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Testing a Lunt LS50FHa etalon with a H spectrum tube.
Replies: 14
Views: 428

Re: Testing a Lunt LS50FHa etalon with a H spectrum tube.

Hi Peter,
I am puzzled by the factor 2x between the "expected" and measured values. As you said, it could be because of the f/16 ratio used. I tested different values from f/1.8 to f/11. It was a good way to learn about the true optical quality of my lenses.
by christian viladrich
Wed Feb 24, 2021 10:12 am
Forum: Solar Radio, Magnetometry and Spectroscopy
Topic: Testing a Lunt LS50FHa etalon with a H spectrum tube.
Replies: 14
Views: 428

Re: Testing a Lunt LS50FHa etalon with a H spectrum tube.

In my experience with tilt-tuned etalons, a large inner ring might indicate the etalon cannot be brought on-band, and even if it can, it might therefore be plagued by "banding" due needing excessive tilt from having a too high of a CWL. It might be just as important to define the outside limit for ...