Hello, I don't know whether this is relevant or not in the discussion, here are some explanations further to the ones provided by Ruppert. Airylab provides two telecentric lenses for the Celestron SC : - one for f/27 - one for f/35. Both share the same front doublet, but differ from the last lens (t...

Beautifull Valery !

Regarding the difference between image and posted image, it can be reduced by saving the image with a sRGB color profile. Unfortunately, not all browsers use color profiles which can lead to differences in contrast, color or luminosity. On top of that, monitors have their own biais. It could be a go...

Dear Alfred,
Thinking about it, it would be nice to have an image of the solar limb with the double stacked 1 A Alluxa filters. Just to see what does it look like.
Christian

Hello Alfred,
You seem to have found the right set up for Ca imaging with the C11.
Did you mean 1 nm or 1 A FWHM for the Alluxa filters ?

Great shots Marty !

There was some indication of first development of the light bridge on the Ca K image I took on August 7. It only took two days to split this small spot in two !

Thanks a lot !!

Mark, regarding the efl, I am not sure. In fact, I am looking for FD images taken on August 7th in Ca K to check the scale of the images taken with the N300 in this configuration.

Dear All, Seeing is having ups and down up there. Here are two images taken on August 7 with the Alluxa 0.44 nm FWHM filter and the 300 mm Newtonian : AR2770 : http://astrosurf.com/viladrich/astro/soleil/wl/2020/CaK-AR2770-7August2020-7h49mUT-N300-ASI290-Alluxa-150f.jpg Note the lightbridge inside t...

Thanks to all ! Sorry for my slow answer ... we have a slow Internet connection. There is not much activity, so I have seen no filament with this ca K filter. On top of that, the FWHM is probably too large. 1.5A FHWM would be more appropriated. The two filters (EO394-10 nm and Alluxa Ca K) are stack...

Dear All, Here is my first ever Ca K image taken with the 300 mm solar Newtonian telescope. The seeing was far from perfect, still there is a huge increase in resolution compared to the images taken with my 150 mm TOA refractor. A very different world opens to itself. A lot of detail is visible insi...

Dear All, Here is my first ever Ca K image taken with the 300 mm solar Newtonian telescope. The seeing was far from perfect, still there is a huge increase in resolution compared to the images taken with my 150 mm TOA refractor. A very different world opens to itself. A lot of detail is visible insi...

Thanks to all !

Nice shots Eric !

Let's hope there is a big one just behind...

Thanks to all ! Mark : yes indeed, the exposure time is pretty short thanks to the high transmission of the filter. I have tuned a little bit the set-up with the EO394 on a tilt mount to reject some internal reflection, and the Alluxa filter also on another tilt mount to tune it on Ca K. Alexandra :...

SDO/AIA is showing quite a firework on the east limb !

This is good news !

Hi Marty,
The 3-band animation is very interesting !

Hi Marty,
The 3-band animation is very interesting !

Hi,
AR2767 is on its journey accross the solar disk. The seeing was awfull due to very warm weather. Still I was lucky with a very short episode of good seeing :



Clear skies

Hi, At last, we have some activity on the Sun : http://astrosurf.com/viladrich/astro/soleil/wl/2020/CaK-AR2767-25july2020-TOA150-Alluxa-ASI290-90f.jpg And an image near the center of the solar disk : http://astrosurf.com/viladrich/astro/soleil/wl/2020/CaK-center-25July2020-8h45mUT-Alluxa-ASI290-120f...

Beatifull set of images an animation. Well done Stuart !

Hi Alfred,
This is great news you finally solved this issue !

Hello Eric,
Blank Sun but great shots !
Christian

Hi, I don't know whether this is the right place to post this ... We (Fred Jabet, Alexander Lhoest and myself) have measured a number of filters with a spectrometer from 300 to 1050 nm: http://astrosurf.com/viladrich/astro/instrument/filters/Filters.html This is not specific to solar astronomy, but ...