I plan on doing very simple white light imaging with a 150-600 zoom and a 1.4x extender.
Ca K imaging would be an option. Still, it would meant having more stuff to take by plane.

Great inputs Bob !

Hi Brian, About your 150 mm refractor, you can also use a subaperture 50 mm red filter for Ha, and a subaperture 50 mm blue filter for Ca K. All my Ca K images are done with a 50 mm subaperture blue filter. It is just OK. The only issue is to be able to install the subaperture filter far enough from...

but also frustrating because it is very noisy due to the very weak signal, and a [bad-word] reflection that I have never been able to eliminate it completely. I had completely the same with my 1a Alluxa, try reversing the filter, I found it went when I did this. Excellent idea ! Both faces look sim...

Thanks all for the comments. Christian,if I go ahead I'm limited to using a folded optical system to be manageable on the mount and fit in the dome. The mak I have an eye on (very preliminàry) is the 7" SkyWatcher OTA. It is just a potential option vs the SCTs https://skywatcher.com/product/bk...

Does the Astrosolar 3.8 film not work with the g-band filter? Could be a cheap workaround. In good conditions, you could use a 10 nm G-band filter with the Astrosolar 3.8. Here is an example with the Andover 430-10 nm) : http://astrosurf.com/viladrich/astro/soleil/wl/2023/2023-05-28-1139-ChrVldr-AR...

Amazing images Doug ! Resolution and processing are fantastic.

Maybe the first time these features are seen in a SHG image.

Hi Brian,

Maksutov-Gregory (SW, Celestron, ...) are quite bad in blue, but Maktutov-Rumak (Intes) are quite good :

http://astrosurf.com/viladrich/astro/in ... ak/Mak.htm

So it all depends whether it is a Gregory or a Rumak. Which model are your considering ?

Hello Sai, May I suggest you reduce a little bit deconvolution (or equivalent). Indeed, if we carefully look at the gray scale image, we can see that the solar disk is coverered by small black spots. All of these are artefacts. For example, you can have a look at what the solar surface really looks ...

The motions in the second one are fascinating !

Well done, with a nice processing, in particular the transition between the disk, chromospheric fringe and prominences !
The resolution is quite good too.
And nice trick to handle ghost images !

To put things in perspective, here are some examples of image obtained with this filter and a Hat8" :

https://www.flickr.com/photos/45136795@ ... 605283841/

https://www.flickr.com/photos/45136795@ ... 605283841/

That doesn’t seem like it is within spec. I’d want my money back!😡 Think of all the customers that don’t have the ability to measure their etalon. At what f-ratio did you test it or does this not apply with how you measure? Do you have any recent images with it? You said it all. Not all the custome...

Dennis wrote: ↑Tue Sep 19, 2023 2:42 pm How can this even happen in this price category.. can this be a damage from shipping?

I am afraid it is not the only one. I know at least two others like this.

hopskipson wrote: ↑Tue Sep 19, 2023 3:33 pm Does anyone have the transmission curve for the Baader 4x and 3x Telecentric? I

I have both TZ-2 and TZ-4, but I can't measure them for pratical reason. There are way too long

Nice filament, with fine structrure. Well done !

Nice filament, with fine structrure. Well done !

Hi, I've just measured a DayStar PE 0.6 A. The resulting FWHM is 0.95 A : http://astrosurf.com/viladrich/astro/instrument/spectro/Ha/DayStar06-S/DayStar06A-S.html Needless to say that the solar images obtained with this filter are consistent with the measured FWHM. Here is a summary table of measure...

marktownley wrote: ↑Mon Sep 18, 2023 9:38 pm Question to Christian et al; has the filter from a CaK PST or from a Lunt been scanned with the same resolution etc as the ALluxa 1a?

There is this very old post, unfortunately with low resolution :
viewtopic.php?t=12203

Wonderfull spot and image !

Thansk to all ! Dennis, I was lucky to have a very bright prominence. So it might be possible to do the same with a DS Lunt Ca K. Still with longer exposure time. Mark, indeed the high peak transmission of the Alluxa filters (> 80%) makes the difference for keeping exposure short and freeze turbulen...

May I suggest to post a non inverted version ?

Indeed, "natural" version are much easier to understand : areas in emission are white, while areas in absorption are dark, spots are dark.
With the inverted version, it is very confusing to understand what is going on in terms of solar physics.

Hi, Here are some images taken on September 7 with the double-stack 0.14 A setup : A nice prominence : http://astrosurf.com/viladrich/astro/soleil/wl/2023/2023-09-07-1051-ChrVldr-Prom-CaK-DS.jpg A filament (upper left of the image) : http://astrosurf.com/viladrich/astro/soleil/wl/2023/2023-09-07-101...

Splendid collection of proms Jim !

The second one is quite good Dennis. We can see rising fibrils !