Search found 555 matches

by christian viladrich
Tue Sep 17, 2019 8:14 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: What do you think is the most versatile high resolution solar telescope design?
Replies: 43
Views: 1818

Re: What do you think is the most versatile high resolution solar telescope design?

Hello Valery, Going back to the initial question of this post, and after the tests recently done à St Véran, I agree that the combination of a large ERF and a reflecting telescope is the best HR solar telescope in large diameter. The Cassegrain configuration is indeed very attractive. Best regards C...
by christian viladrich
Mon Sep 16, 2019 4:43 pm
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: What do you think is the most versatile high resolution solar telescope design?
Replies: 43
Views: 1818

Re: What do you think is the most versatile high resolution solar telescope design?

Hi, I would like to go back to the question of spherochromatism which is inherent to the Schmidt- Cassegrain design. As I have already said, this is nothing new, optics beeing optics. Let's see what Celestron wrote in their White Paper : https://s3.amazonaws.com/celestron-site-support-files/support_...
by christian viladrich
Sun Sep 15, 2019 2:12 pm
Forum: This is SolarChat !!
Topic: H-alpha 31 august, 7 inch Intes, reflections and a BF30.
Replies: 15
Views: 315

Re: H-alpha 31 august, 7 inch Intes, reflections and a BF30.

Hello Bart,
This is a quite good image. Getting rid of these reflections is quite tricky. Keep us posted !
Christian
by christian viladrich
Sun Sep 15, 2019 11:54 am
Forum: Commercial Solar Filters/Cameras/Hardware
Topic: What do you think is the most versatile high resolution solar telescope design?
Replies: 43
Views: 1818

Re: What do you think is the most versatile high resolution solar telescope design?

Hello langleif2, Spherochromatism in Schmidt-Cassegrain is nothing new. You can open any good books on telescope optics to get some information on it. This is just basic optics. You can read for example the two books I co-authored with some friends (unfortunately in French language for now) ;-) Ther...
by christian viladrich
Sun Sep 15, 2019 11:24 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 27
Views: 570

Re: A big solar newton for ultra narrowband imaging, possible?

I also have the TS concenter. It is indeed quite good to align the secondary mirror of the 300 mm solar Newtonian.
by christian viladrich
Sun Sep 15, 2019 11:23 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 27
Views: 570

Re: A big solar newton for ultra narrowband imaging, possible?

Hello langleif2, This is a textbook example of loss of information in a communication process : A tells a story to B, which B repeats it to C, etc. After a short while the story becomes quite another story :-) So here the actual story : Every year, we have a solar gathering at Serbannes (France). Ne...
by christian viladrich
Sat Sep 14, 2019 8:04 pm
Forum: Solar Scope Modifications
Topic: Budget scope for visual
Replies: 17
Views: 280

Re: Budget scope for visual

430 nm filters are available at Edmund Optics with 10, 25 and 50 nm FWHM, and also at Andover Optics (2 nm FWHM).
by christian viladrich
Tue Sep 10, 2019 7:11 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 27
Views: 570

Re: A big solar newton for ultra narrowband imaging, possible?

Hello lanleif2, thanks for this clarification. I am afraid you were a bit mislead. I know rather well AiryLab and MCM. Alex do so since he is the one you got his 250 mm coated by MCM. So far, this is the larger Newtonian telescope with such a coating on the mirror. This telescope and MCM coating is ...
by christian viladrich
Sun Sep 08, 2019 7:30 pm
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 27
Views: 570

Re: A big solar newton for ultra narrowband imaging, possible?

The DOT is a Gregorian telescope, not a Netwonian. This is a huge difference and explains why a cooled diaphragm can be installed at the primary focus. Remember that in a Gregorian telescope the focus of the primary mirror is in front of the secondary mirror, not behind. This makes thing much easier...
by christian viladrich
Fri Sep 06, 2019 7:14 am
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 27
Views: 570

Re: A big solar newton for ultra narrowband imaging, possible?

We were on top of a mountain, 2930 m altitude. Ambient temperature was from 2°C to about 15°C.
So an increase of 10°C is huge. Basically, a delta of more than 2°C between ambient air and an optical part is detrimental to the seeing.
by christian viladrich
Thu Sep 05, 2019 6:48 pm
Forum: Solar Scope Modifications
Topic: A big solar newton for ultra narrowband imaging, possible?
Replies: 27
Views: 570

Re: A big solar newton for ultra narrowband imaging, possible?

Unfortunately, these tests proved that this idea was a dead end. For Ca K imaging with my TOA150, the 50 mm internal ERF is 33% of the diameter of the objective. I have no internal turbulence. With the 300 m Newtonian of Alex, the ratio is 16%. Now, we can say this is too low... Maybe, another facto...
by christian viladrich
Fri Aug 30, 2019 8:32 am
Forum: Solar Scope Modifications
Topic: Removing mirror’s coating
Replies: 6
Views: 172

Re: Removing mirror’s coating

Hello STu,
Thanks a lot for your input.
Could you tell us a little bit about the differences between iron perchloride et HCl ? I understood than the first one is less agressive ?
by christian viladrich
Sat Aug 24, 2019 3:34 pm
Forum: This is SolarChat !!
Topic: HR images taken with the N300 on August 21
Replies: 9
Views: 210

Re: HR images taken with the N300 on August 21

Thanks to all :-)
I like the fourth one too !
by christian viladrich
Sat Aug 24, 2019 3:33 pm
Forum: This is SolarChat !!
Topic: 24Aug19 - Some fibrils with C11
Replies: 14
Views: 233

Re: 24Aug19 - Some fibrils with C11

Well done Alfred !
by christian viladrich
Thu Aug 22, 2019 6:06 pm
Forum: This is SolarChat !!
Topic: HR images taken with the N300 on August 21
Replies: 9
Views: 210

HR images taken with the N300 on August 21

The Internet is back at St Véran .. Here is a set of pictures taken on August 21 with the 300 mm Newtonian and the 396-5 nm filter. Let's start with a region close to the Eastern limb, with many faculae and darker areas. http://www.astrosurf.com/viladrich/astro/soleil/wl/2019/21August2019-8h03minUT-...
by christian viladrich
Tue Aug 20, 2019 9:48 pm
Forum: This is SolarChat !!
Topic: Ha images with the C8 on August 18
Replies: 8
Views: 187

Ha images with the C8 on August 18

Hi, Now, here are the images taken in Ha with the C8 under excellent seeing condition at F/35 : http://www.astrosurf.com/viladrich/astro/soleil/wl/2019/Ha-18August2019-7h44minUT-C8-B1920-PE06A-N35.jpg http://www.astrosurf.com/viladrich/astro/soleil/wl/2019/Ha-18August2019-8h22minUT-C8-B1920-PE06A-N3...
by christian viladrich
Tue Aug 20, 2019 8:58 am
Forum: Solar Scope Modifications
Topic: Blocking Filter In a Collimated Beam?
Replies: 10
Views: 301

Re: Blocking Filter In a Collimated Beam?

No, I have not tested nor calculated it. If I take the example of a SolarSpectrum or DayStar etalons, there is already a 5 to 10 A BF in the body of the filter Adding a 4 A BF gives a little bit more contrast (see my test pages). The real benefit is with the addition of a 1.5A filter. I also tested ...
by christian viladrich
Tue Aug 20, 2019 8:46 am
Forum: This is SolarChat !!
Topic: HR granulation with the 300 mm Newtonian - 15 & 16 Aug
Replies: 11
Views: 177

Re: HR granulation with the 300 mm Newtonian - 15 & 16 Aug

Thanks !
Alexandra, I am contacting a friend who is a specialist of solar physics. I hope to have more information.
by christian viladrich
Tue Aug 20, 2019 8:37 am
Forum: Solar Scope Modifications
Topic: Blocking Filter In a Collimated Beam?
Replies: 10
Views: 301

Re: Blocking Filter In a Collimated Beam?

Hi Mark, The question of tilt / collimated or telescentric beam starts to become an issue with filters narrower than about 2 to 3 A. BF are usually about 5 to 10 A. So, it should not be a big issue. Regarding stacking an etalon and a BF, I've done many tests. For example here with a top quality 1.5 ...
by christian viladrich
Mon Aug 19, 2019 7:36 pm
Forum: This is SolarChat !!
Topic: HR granulation with the 300 mm Newtonian - 15 & 16 Aug
Replies: 11
Views: 177

Re: HR granulation with the 300 mm Newtonian - 15 & 16 Aug

Thanks guys !
Stu, I'll try and get the information.
Mark, this is my 300 mm solar Newton :
http://www.astrosurf.com/viladrich/astr ... /N300.html
by christian viladrich
Mon Aug 19, 2019 5:19 pm
Forum: This is SolarChat !!
Topic: HR granulation with the 300 mm Newtonian - 15 & 16 Aug
Replies: 11
Views: 177

HR granulation with the 300 mm Newtonian - 15 & 16 Aug

Dear All, Here are some more images taken at St Véran with the 300 mm Newtonian. August 15th, with the 396-5 nm filter. There is an incredible variety in the granulation cells. Some are very dark. In some parts, the intergranular region is very dark too : http://www.astrosurf.com/viladrich/astro/sol...
by christian viladrich
Mon Aug 19, 2019 5:01 pm
Forum: This is SolarChat !!
Topic: HR granulation with the 300 mm Newtonian - St Véran
Replies: 15
Views: 300

Re: HR granulation with the 300 mm Newtonian - St Véran

The Internet is back at St Véran ...
Thanks Bart, Stu and Mark !
by christian viladrich
Wed Aug 14, 2019 6:58 pm
Forum: This is SolarChat !!
Topic: HR granulation with the 300 mm Newtonian - St Véran
Replies: 15
Views: 300

Re: HR granulation with the 300 mm Newtonian - St Véran

Thanks to all !
Today was no good. We hope to-morow will be better.
Best wishes
by christian viladrich
Tue Aug 13, 2019 8:29 pm
Forum: This is SolarChat !!
Topic: HR granulation with the 300 mm Newtonian - St Véran
Replies: 15
Views: 300

HR granulation with the 300 mm Newtonian - St Véran

Dear All, Nice seeing condition this morning at St Véran (2930 mm) with the Newton 300 mm. This image was taken with an Andover 396 - 5 nm which appears to give excellent results. More to come in the next days. http://www.astrosurf.com/viladrich/astro/soleil/wl/2019/13August2019-8h16minUT-N300-396-5...